I know this is an older post, but I can offer advice to anyone still reading this. Any laser, even a cheap Chinese one, should have a 3.0in or 4.0in lens, if you are going to cut acrylic. A 2.0in is okay for 1/8in or less, maybe 1/4in, at most. When you start getting into 8mm, 1/5in, etc. You have to have a longer lens. This is exactly what he concludes at the end. That the power is gone/out of focus, by the time it gets to the last 2mm of material. For what it's worth, focusing the 1.5in lens into the material some, actually makes the cut worse in many cases. That is the *main* reason for the larger gap at the top. In addition to using a longer lens, you should focus it right at the surface. For those discussion a collimator for the beam, you are in luck! The optically clear acrylic actually does this for you. When the beam is focused on the surface, the index of refraction straightens it out a bit. So, in any case, with any lens, focusing into the material gets you nowhere. (with *clear* material - a solid color is different) Very slow speed, is the main thing that gets rid of the "beam drag" Even using a powerful 150W laser that my company sells, I usually cut the power down to 80-100Watts, and go very slow (1.5in/s, or 38mm/s) I know that is still a lot faster than the 4mm/s in the video.
Hello Jason do you any manual or something that you can give, I really want to do better my work. Today I was trying to cut a piece of 10 mm, I think the laser in my job is 150w but the cut is really bad I was trying with 70% power and 3 mm/s do you have any advice for me. Thank you so much
Thx again Russ started with a 80w laser now have a 150 watt bigger bed size also and still your videos are so helpful, your stuff and the way you present are fantastic 2 years ago i got my first machine now Im running 2 Yes its Wayne with multiple sclerosis no won told my I couldn't so i did :-)
Hi Wayne Congratulations on your new acquisition. I presume that your experience with 80 watts convinced you that for all the cutting you do it would be more efficient with a more powerful tube?All best wishes for the future...maybe working towards #3? Russ
The beam drag is due to two factors and three for you , beam is step burning in the z axis , due to power /speed , and your Colling the work acrylic , so turn down the air flow to minimum , adj the internal focus lens , for a 3 mm . The damage at the base of your cuts is because the beam is past it's focal point , So get the head as close to the work piece as possible ( with a closer focal point internal adj ) and very low to know air flow should give good results . Nice video
Hi Rod I absolutely love acrylic as a material because it has some really great properties. You are right about speed. Slowing down does get rid of the beam drag eventually. and I also agree that air assist does have a cooling effect. From all my experimental work with acrylic there is one big factor that I did not understand at the time I made this video and and this is the light guide properties that acrylic possesses. This phenomenon is illustrated in ruclips.net/video/CdupovEe9hA/видео.html. This explains why in my early days I was able to cut 15mm acrylic (albeit at 1mm/sec) with just 30 watts of power. As you will see from this video, the focus point relative to the surface has little effect other than to make the cut very wide at the surface. Speed is the key factor to allow the beam sufficient time to "tunnel" through the material . It makes little difference to the cut efficiencty if you have lots or little air assist. What it does do is to change the surface finish of your edge. There is a slight gain in speed with full air assist because you are efficiently clearing the flammable acrylic fumes from the immediate cut area. Those fumes are absorbing some of your IR energy and decreasing the efficiency of your cut. It has taken me a long time to understand all the properties of acrylic and I'm not sure I have found all it's secrets even now.. Bear in mind that this series records my learning journey and I was sharing my discoveries at that point. Here I am two years into my journey and I still have much to learn. Thanks for your comment Best regards Russ
I just discovered your channel and let me say...you rock, dude! Your "journal" saves alot of us a ton of time and headaches. I'm wondering if you could compile a new video with your best thinking on the subject of cutting acrylic now that you have several years under your belt. Peace.
+JoePCP Hi Jo I just answered this comment and for some reason it got lost in the clouds. Thanks for you appreciation but remember it's ME that is learning and you just happen to be able to look over my shoulder at my successes, failures and mistakes because my other hobby is video. Best regards Russ
Thank you. This video was very informative. Getting to watch the process of trouble-shooting. Provided a lot of insight into the world of laser cutting.
On a 50W ULS laser cutter, beam drag is very obvious on 3/4" (19mm) solid poplar and pine. @11:30 you discovered focusing partway into the material for better cut, at the cost of slightly wider kerf. lens with longer focal length will also help.
I wonder what the refraction index of acrylic is at 10.6 um? Maybe this explains beam drag. i.e.: as the laser digs a hole, some of the power reflects and part of the energy that penetrates the acrylic has it's angle changed. A cool experiment would be to see at what angle relative to acrylic does the beam reflect so that the refraction index can be estimated at co2 wavelengths.
I went to the site and I don't see a download option...I'll have to check it out on my laptop when I get off....thanks Russ for your help...if I can't find it I'll let you know. Scott Thorne.
Thank you again for another great information video. Do you have any idea how to get rid of the vapour coming from the cut? Those often 'melt' or settle into my acrylic, ruining the surface image. An example is at 3.13 in this video to the right and left of the cut line. Thank you
Hi Acrylic might look like a soft easy plastic to cut and engrave but it has some unique material characteristics. It is solid at room temperature and then turns to liquid at 160C, It remains liquid for a short time until 200C where it turns into acrylic vapour (just like water turns to steam). There is NO chemical change, so as soon as it touches your work surface (or any other cold surface) it will condense back to liquid acrylic (just like steam turns back to water) which eats into your surface a little as it cools back to solid. That is why you get this misting effect that will NOT wipe off. Characteristic number 2. Just like a cup of boiling water will quickly fill a room with steam because the vapour occupies thousands of times more volume than the liquid, so is the case with acrylic. If you lightly pulse the surface of acrylic with low energy you will convert just a small volume of acrylic to vapour and it will explode UPWARDS like a volcanic ejection. However, if you increase the power you will be trying to convert much more solid into vapor and the uprush of gas is not quick enough to let all the expanding gas flow UPWARDS. There is so much volume that it gets forced sideways and IMMEDIATELY condenses on your work surface,. So there are TWO things you do not want during engraving. First you do not want any powerful air assist blowing fumes down onto your work , just a gentle airflow to protect your lens. Secondly you need the MINIMUM of power to mark the surface of your material . If you engrave deeply then you will suffer acrylic condensation no matter what. A good trick is to dither any bitmap image so that you are breaking up the power into discreet dots and short lines. Use low power. Cutting is different. Whenever you start a cut you will always have the explosive horizontal debris because there is nowhere else for it to go. Once your cut has started you need max air assist to blow the fumes out of the BOTTOM of your work, you do not want any fumes coming up. Hope this helps Best wishes Russ
@@SarbarMultimedia Dear Russ, thank you for such a prompt and detailed reply. After watching 8 hours of your videos yesterday I'm making progress with my machine!
Sir, thank you for another excellent video. It would be helpful if you could show exactly how you make the changes is the RDWorks software to change the "Laser through mode" and delay setting for the laser start. Again, thank you for your videos and the sharing of your knowledge and experiences.Randal
+Randal Sullivan Hi Randal Through Power is not something that we generally need on our low power machines. RDworks and the machine control system has been designed for many configurations and different power machines. When you get above 300 watts you can start cutting thin metals. With metal cutting you must PIERCE a hole though before you can start cutting. I'm sure that why this function is there. There are a few little used functions that are worthy of investigation (like, sew, lead-in and lead-out) in the near future so I will make a note and revisit Through Power again. This was my first time of playing with it so there were a few suprises. Thanks for your appreciation Russ
hi I was Wondering if you could help me please, I have a Chinese laser machine its 500 x 700 plate, and 60w laser, I can engrave ok but suddenly when i import a clip art , it engraves ok but with a double image on all clipart, also is it possible to cut 3mm wood with this machine, I would be grateful for any advice you can give me please. Many thanks Paul.
I am wondering what kind of base are you using. I mostly see people with Honeycomb bases that are metal. Yours looks like it is either glass or a big acrylic piece...
Hi Matt You must remember that you are following me on a journey of discovery and at this stage I have so much more to learn. I have not yet discovered the real value of air assist for cutting or the essential requirement for air flow management through the machine.. I have found that honeycomb tables are a bit of a disaster for most cutting because the beam reflecting off the metal edges of the cells cause burn marks on the back of your material. Lifting the material off the table prevents this reflection and also allows the fumes to escape freely below the material rather than being trapped in a long thin tube (the honeycomb cell). Air flow management and cut efficiency is a subject that would take me several pages to explain. If you serach for RDWorks Learning Lab Air Assist, you will come across several videos where I uncover the secrets. You will then begin to understand the reason why no machine should ever be fitted with honeycomb. It looks like a brilliant idea but turns out to be as brilliant as shaving with a blow torch. Best wishes Russ
What influence does total reflection on the just generated interface between a gaseous (its contents may vary quickly) and a solid phase have? The optical properties of the medium properties' change and transition(s) with the process of cutting / melting / burning / sublimation instantaneously. Various intermediate products will change the optical properties very dynamically. Moreover, the reflection on the bottom surface may contribute to the excavations visible in some of your experiments. I saw such variations that could be correlated to a supporting metal grid placed under the acrylic. Modelling the process called 'cutting' detailledly might lead to some interesting findings.
Hi Ulrich Many people have suggested that the marks on the edge when you cut acrylic are caused by the stepper motor. I am equally certain that they are NOT related to the stepper motor. For many years I owned a metal laser profiling business and although this is a COMPLETELY different sort of machine and has insufficient power to cut metal, I do believe that the well researched mechanism that causes striations on the edge of cut steel is occurring when you cut acrylic When you cut mild steel you use pure oxygen as the assist gas at about 1 to 1.5 bar. The mechanism described in the following text pages 24 to 26 causes exaggerated edge marking. books.google.co.uk/books?id=PrguBAAAQBAJ&pg=PA24&dq=arata+and+miyamoto+laser+cutting+mechanism&hl=en&sa=X&ved=0ahUKEwj3xL_vqNHPAhVCD8AKHWF7AgYQ6AEIOzAB#v=onepage&q=arata%20and%20miyamoto%20laser%20cutting%20mechanism&f=false When you cut stainless steel the process is completely different. You have to use an oxygen-excluding cover gas in the form of pure nitrogen but at pressures of 12 to 15 bar. Even though there is no exothermic reaction to melt ahead of the laser beam, similar but less obivous edge marking still occurs I am suspecting the the heat zone when acrylic sublimates, extends out in front of the beam and causes this same stop start mechanism of cutting. Too much air assist in the cut zone reduces the cut efficiency and also reduces the "flame polishing" effect. I use a very low airflow to cut acrylic, just enough to keep the gas flowing out the bottom of the cut. I shall shortly be taking delivery of another laser machine but this machine is SERVO driven. This will prove the point (or otherwise) about stepper marks during cutting. However greyscale engraving is a different matter that has got to be looked at in more detail when I have two machines to compare. Best regards Russ
Hi Russ, thanks for the information on steel cutting - I am still far from that... Re the striae: Is the laser driven in a pulsed mode, or CW? The former might be causing the stripe pattern - but then, the stripes should be clearly travel speed dependant. Another vague thought: Mechanical resonance within the acrylic board caused by shock waves (like cavitation in water) when the sublimation starts in an enclosed volume that then bursts outwards? So many mysteries... ;) Cheers, Ulli
Hi Ulrich These cheap lasers are not RF driven and so the beam is basically continuous (as for as the eye can discern) Take a look at ruclips.net/video/mXIDwQxhX3k/видео.html starting at about 12minutes. I was investigating a strange performance region in my tube as the nitrogen partially ionizes. To prove that the beam was pulsing I ran the speed at max of 500mm/sec and was able to measure the pulses. Once I increased the power such that the ionization was complete and the power supply had switched to its stable 17kv working range the the beam was showing no hint of pulsing. Maybe this answers your question Best regards Russ
Thank you Sir for your videos! I saw them all because i am up to buy that GH350 Laser engraver too;) so my question is if you already made a "best pracitse" table with all your experience for different materials and its best Laser speed and power?
+thomy0168 Hi If you go to the Thunder Laser website site and download their version 8 of RDWorks, www.thunderlaser.com/down When you click on one of the coloured cutting power/speed layers , it will open a window. At the top of the window you will find a Parameter Library that Thunder Laser have thoughtfully populated with commonly used material data. Each machine could be very different depending on tube power,and focal length of lens, so this data is a jumping off point. Sadly you will have to note the best settings for your machine as and when you find them. Sorry I can't be more helpful. Regards Russ
Could a collimated beam (passing through a converging lens to tighten it up then through a diverging lens to bring it back "straight") solve this problem altogether? I'm trying to remember the college-grade optical physics course which I took over 20 years ago...
Hi Claude Hi Claude There is one massive problem with trying to apply conventional lens theory to our IR beam . Lens theory assumes a uniform collimated beam and usually monochromatic.. We have the single wavelength (10.6 microns) but the beam is not uniform, It's energy density is close to Gaussian (a normal distribution) About 70% of the beams energy is contained within 1/3 of its diameter.. Unfortunately beam drag has nothing to do with the convergence or divergence of the beam. it i all to do with energy per unit of time. When you try to cut too fast the bottom of the beam starts to drag as it runs out of energy. If you slow the cut then there s sufficient energy per unit of time to damage the material vertically. To demonstrate this time and energy principle, pass your hand over a candle flame. The faster you move your hand the less heat you will feel. Slow right down and the heat will have sufficient time to reach the damage threshold for your skin.. Ouch. Best wishes Russ
@@SarbarMultimedia In fact I should have specified the "hourglass shape" of the cut when I was referring to "the problem". Thank you for your response. My optics course is really far back in my memory :-)
@@claudehebert3131 Hi Claude You may be a bit surprised about your hour glass supposition. I am close to completing my VERY in depth study of cutting with various materials and lenses. The results so far are rather interesting. I'll say no more at present. Best wishes Russ
When cutting such a thick material, the first thing I would have tried is of course lowering the focus point into a mid depth of material, instead of surface. That makes all sense of course.
Hi Vlad. Your theory is a bit of a myth. I have done many experiments and my advice is ALWAYS set the focal point on the surface, especially with acrylic The basic idea for this myth is a misinterpretation of advice that Trotec give in there guidance for cutting acrylic ABOVE 10mm thick. The big problem is that we do not have the RF driven tube that you will find in a Trotec machine so the effect of the beam is totally different. You will need lots of power and a 5" focal length lens. You can read this for yourself at the top of page 5 in the following document howtolaser.com/blog/how-to-laser-cut-acrylic/. It confirms that up to 10mm thick you keep the focus on the surfsce Until you have experimented for yourself, I would stay safe and ignore the myth. Best wishes Russ
SarbarMultimedia i actually did and it worked better when i lowered. But none of my experiments are even nearly as sophisticated as yours, so I’ll just take your word for it and will follow your advice then! Thanks again for providing so much research on youtube for us. Best channel for DIY lasers, period. I bought K40 first for $350, but didnt realize it would be that bad. So decided to return that one and I have 50W machine on order now which I bought for $1350. Slightly more powerful tube there, but also all components are 5x better than K40. Will be worth the investment.
The next size machine will definitely be better than the K40. I suspect you are buying from ebay? It's good value for money but will probably not be a reliable machine until you fit a new tube and power supply. The ones supplied will almost certainly be sub standard because the Chinese have worked out that people buying from ebay are fairly naive of the technology and it will take a long time to work out that what they have bought is not the real deal. Sorry to be pesimistic but my evidence base is huge. Best wishes Russ
SarbarMultimedia no problem. I have been working with China on relatively large scale for over 7 years. I know exactly what they do and how this machine is built. I just accept it for $1350 with free 2day delivery. I thought of building my own, but I have too many projects now already in progress. So, decided to just buy. If anything is sub-spec on this machine, they will have to adjust the price for me. I am not one of those naive consumers :))) My last buy from ebay was a 6040 CNC router for $1400, and I ended up only paying $400 for it due to a lot of mess that they made in that machine. So, with that said, I will be thoroughly examining this laser machine, including tube check for conformity sticker etc. if they use reject tubes for $350 K40 machine, it is totally ok. Reject tube for $1350 machine - i will not be ok with. And if they do use reject tubes, and I find that out, it will just cost them money on this order.
Hi Mark Others have suggested the same and even gone off to make their own versions and trials.....never to report back. The proper beam collimators I have seen basically only allow the high energy density part of the beam into the lens. In my logical world that implies that I could be preventing 20 to 30% of the available power ever reaching the lens. Beyond that unacceptable objection, cost, space and addition head mass would then become issues. I have done a couple of experiments using a 4" FL lens to focus the beam down before passing it through a 1.5" FL lens. No staggering results but I have not completely dropped the idea. Thanks for the comment Best wishes Russ
I see... more complex than I had thought. I was just thinking of an additional lens after the focus lens to stop the divergence. As my wife likes to ask "How hard can it be?"
+freebird1963 If you fire the beam at a piece of acrylic which you can see through ( or any other material that you cant), The beam will pierce a hole vertically into the material. If the material is reasonably thick (6mmor more) and you now start moving the beam slowly, you will begin to cut a linear grove through the material . When the beam is moving VERY slowly. the cut will be vertical. But as you start to increase the cut speed the bottom of the beam (which has less energy density because its past the smallest focus point) will be cutting less efficiently. and will start dragging behind the beam entry point. Provided you do not exceed the cutting speed for the BOTTOM of the beam the cut will be right through. It's this loss of cutting ability with depth that causes beam drag. This can be clearly seen in this video and at the end I drop the focus point and the bottom of the beam now has more power and the cut becomes more upright. and has better cutting penetration. Hope this is a clearer explanation. Best regards Russ
Hi Dainis If you watch ruclips.net/video/OCVsMXw6yh4/видео.html You will see that I am testing the original 70 l/min pump against a new 140l/min pump. I regulate the air to the nozzle with a little ball valve that allows FULL bore flow. If you have a screw restricting elbow I would suggest throw it away and replace it with a normal elbow, but you will have to modify it as I show in the video. The ball valve I used was like this www.ebay.co.uk/itm/6mm-to-6mm-pipe-Pneumatic-Ball-Valve-On-Off-Flow-Push-fittings-OEM-/112303492406?epid=11002970582&hash=item1a25cf4d36:g:SrgAAOSw2gxYo5i- Best rgards Russ
SarbarMultimedia Thank you very much. Miss this video. I've watched a lot of your videos and they're very helpful. Next week I'm going to order identical 50w laser. At this moment i have only 7w laser diode engraver.
Hi First I must let you know that in the following video I fitted what I thought was a new 60 watt tube. It turns out that I had been sent a 70 watt tube 1250mm long. Ever cautious about over driving the tube I had established that the max allowable current was claimed to be 25mA. I know that Chinese manufacturers often quote the current for achieveing their max test power which in this case I guessed was 80 watts. So my first task with this new tube was to check the power output related to the %power and the actual mA current flow. . You may have missed the following video (start at about 15minutes) and you will see me testing the tube up to 90% power and plotting a graph of the tube's characterisics. Based on that graph I decided that 22mA was a safe maximum and that produced 70 watts of output at the tube. To drive at that current level meant I could never exceed 65% power setting. There is NO fixed relationship between % power and tube power. People mistakenly think that if I run a 60 watt tube at 100% power you get 60 watts of output. Wrong, What you will get in very short order is a dead tube caused by over driving it. Now just for estimation purposes lets assume I get 4% power loss at each mirror and also across the lens. Forget the compound effect and just accept that I get 16% loss between tube and the work surface ie my 70 watt output will become about 60 watts of usable power. I hope this answers both your questions ruclips.net/video/zCTrRT1C_eY/видео.html Best regards Russ
ok ye that explains, it, because noway could a 50w cut 8mm using 4 speed and 65%, anyways great vids i had browsed a bunch not the whole series but quite a few, i guess i will look forward to retirement as well and spend time doing allot of useful vids as well. good job russ.
Hi Lenny Acrylic is a unique plastic with properties that are analogous to H2O. It is solid at room temperature (ice) but at 160 C it immediately becomes liquid (water). At 200 C it evaporates (steam) into acrylic vapour and can be recondensed back to solid acrylic upon contact with a cool surface. Its a weird quirk of physics that both cast and extruded materials are exactly the same molecular structure but they have different properties. The extruded acrylic seems to have a much lower thermal conductivity, although it cuts just as easily as the cast acrylic. The lower thermal conductivity retains heat in the walls of the cut for significantly longer and whilst above 160 C , will allow the thin film of liquid acrylic on the walls a few mm behind the cut to "level" out. It is this mechanism that creates the polished finish to the cut. Below 5 mm thickness it is almost impossible to get that same finish with cast acrylic unless you dramatically reduce the cutting speed (50% or less). Cast acrylic cuts are burr free but run your fingernail over the top or bottom edges of an extruded acrylic cut and you will detect a noticeable burr. Best wishes Russ
@@SarbarMultimedia thanks for the info. will give it some more tries with different settings. the one I made started to crack all over after a few days.
Hi, wondering if you could help. I have a piranha 5060 that ive just bought. got it set up and laser aligned, thanks to your videos and others on RUclips :) sent a test file to the laser and when i click start it says not enough extend space? have you any idea what this means and how I could fix it? Thanks Maggi
Hi Maggi My guess is you are trying to engrave a bmp file. If so then you are using scan mode. My guess is that you are trying to run your program from right in the top left corner (or maybe top right ,depending on where you machine runs to for its 0,0 datum). If so, move your cutting head out into the work area to about 20,20. This will probably cure your issue. When you scan, the head has to run to the end of your picture and turn off the beam. The head then has to travel further to decelerate and turn round, whereupon it has to accelerate back to your chosen speed before turning the beam on again. This over-travel zone is the EXTENDED SPACE and will vary depending on the speed you scan at. More speed requires more extended space If you set the origin point so that part of your program is outside the work area then you will get an X or Y "slop" error. Neither error is clearly explained anywhere. Hope this helps if not shout out again. Best wishes Russ
Thank you Russ, one for your help and two for your prompt response. I tried moving the laser head manually but it just reverted back to the top right corner when i hit start. how exactly do i move it without it doing this? sorry to be a pest, total newbie here and itching to get started :)
Hi Maggi I am now 2 years ahead of you but it was a bit difficult to start with because there was no one to turn to apart from condescending experts who were very possessive of their experience. Hence I had to learn the hard way and that what my videos are about. I am not teaching but you can learn along with me. I try to remember those early naive days and despite trying to be inclusive with my explanations to suit all levels I sometimes forget a few obvious points. In your case you either have not yet found the origin button on your machine or your RDWorks software is not at the normal default setting. There are several unknowns in your situation that will help me if I understand. How are you running your machine because there are 3 options. 1) is your PC remote from the machine and you are transferring programs via USB memory stick? 2) is your machine connected to your PC via a USB cable/Ethernet cable?/wireless bridge connection? 3) Are you downloading programs from your PC to the machine via the connection in 2) or are you running your program via the RDWorks START button? Your answer will allow me to better advise you. Best wishes Russ
Thank you Russ. I think had i have bought one 2 years ago with so little information on them i would have given up! I'm only now getting a little understanding thanks to the help of generous souls like yourself who put the info out there willingly. I've been slowly going through video tutorials (how I found you :)) but it gets a little mind boggling lol I work primarily in Photoshop for all my designing and now have to change file types for vector which is a little daunting. I've downloaded inkscape as illustrator is ridiculously priced and i already pay annual subscriptions for Photoshop and Lightroom. I still have to somehow teach myself Rdworks :0 not the easiest program to understand even with tutorials. So, onto your questions. Yep I found the origin button but it doesn't seem to move anything when i push it? pc connected via usb I'm just downloading the design to the laser right now and then working from the control panel. Maggi :)
Hi Maggi I think this conversation will be more useful off-line because we can exchange data and pictures. Use the You Tube messaging system (that is private) to send me you email so that I can answer more fully. Best wishes Russ
I recently installed RD Works controller RDC6442G ,I went into settings on my laser machine and on my computer and changed the bed size settings but it is still saying not enough extend space. I have been on to cloud ray laser but I cannot make sense of thier instructions.Is there any advice you can give me please?
Hi Paul Part of your program is outside the area of your table. When you look at your program in RDWorks there will be a little green square in one corner of your drawing. That is where your head will be to start the program.I guess your are running your machine directly from the pc and just pressing the START button to run the program? Your problem is occuring because your ORIGIN is in the wrong place. If that little green square is at top left for example then manually drive the machine so that the head is nearly at the back left corner. Now press the origin button and that should fix your problem. Best wishes Russ
Hi Russ thanks for your help. My machine is working as it should now i have just got one question. When ingraving lettering my machine now only ingraves 1 letter at a time have you any suggestions why it would do this. Thanks Paul
hi i have just bought a BORDOR 40W LASER which is a very neat machine and it comes with RDWORKS have e you ever seen these lasers and if so what do you think of them, dermot love your videos
Hi Dermot I have not seen one before but I looked at their videos and it looks like a well designed machine. The impression given is that it's fitted with a RECI tube. I was not aware that RECI made anything less than 100 watts (unless it's a custom order) It certainly is a meaty looking tube....but only 40 watts??? What size is the table/work area? How much does it cost landed? Keep in touch and let me know how you get on with it. It looks as though this one will work well straight out of the box......and more importantly KEEP running reliably Thanks for the kind words and the interesting information. I often get asked to recommend machines. That's obviously quite difficult as I only have one machine's worth of experience. However, from all the issues people bring to me I now know a lot about many machines. So it will be good to hear of something different that I can pass on to others, especially if it's reasonably priced, and by that I don't mean Ebay cheap.
hi the machine cost me €2400 from China and i should have it in about 4 weeks so i am learning rdworks at the moment, in other words i see more of you then i do my wife lol,,can you tell me in rdworks how do i get the blue arrows to the left like on your machine. Dermot
Hi Dermot I have answered you arrow question elsewhere. As I said, I know nothing about this machine so keep in touch, From what I can see it does not have an ammeter fitted and if it is a 40 watt machine the maximum drive current should be limited to 16mA....it will be interesting to find out what the tube manufactures recommendation is. Unless it's a customer made special, Reci don't make tubes for those low wattages. I would seriously advise ordering yourself a cheap chinese analogue ammeter www.ebay.co.uk/itm/91C4-DC-0-30mA-Class-2-5-Accuracy-Analog-Ammeter-Amperemeter-Gauge-/351749565079?hash=item51e5e86a97:g:HjsAAOSwmtJXUVFu so that you know exactly what you are doing to your tube. Overdrive your tube and it's warranty will be void. That's why they don't fit an ammeter and don't advise the max running current. It seems that Bodor are reputable enough to tell you what that NORMAL max drive current should be. If you don't know already then email the question to them. Fitting an ammeter is very easy ruclips.net/video/xDZmuxq5BEM/видео.html If your machine arrives before you ammeter then do not use %power above 60%. I made this mistake by thinking I was allowed to use 100%. I trashed my first tube in record time through ignorance and is great for the sales of replacement tubes!!!! Best regards Russ
Hi Russ I never got the answer to the arrow question, would you mind sending it to my email address, thank you for all your help and keep the great videos coming. dkprinting@gmail.com god belss
+coralsign Hi This was a demonstration to show that you DO need to put your focus point into the material to get a good cut on thicker materials. I put it on the surface to start with so that you could see the beam drag phenomenom. I did also mention that because I have a 38mm focal distance lens that sits 6mm above the surface , when it comes to cutting 8,10,12 and 15mm acrylic I cannot get anywhere near the centre of the material (just 2 or 3mm lower) but I can still get good cuts.. Thanks for your comment Regards Russ
+coralsign My background in industrial metal cutting lasers indicated that I would need lots of air assist . When I first had my machine I fitted a gauge and used my little shop compressor but I soon found out it was not necessary. The little pump supplied was adequate. BUT, you will see that I do have a 38mm focal length lens and the nozzle is only 6mm above the cutting area. If you have a 51mm lens then your nozzle will be about 20mm above the surface. This is fine for engraving and for cutting acrylic but for cutting wood of any sort there is a burning action that takes place and the dense smoke right in the cut will absorb some of the infra-red energy and decrease your cutting ability. This is when you need a good airflow so you might want to try experimenting with another separate air supply pointing directly into your cut It does not have to be high pressure , just well directed. ALL smoke should appear below your material there should be none leaking off the surface. Good luck best regards Russ
Hi Russ, again thanks for all your work here, but in this video, I actually think you are saying something that is not correct and now when I was reading your comment here I find it a little divergent. You are saying that people with a 2.0 lens and higher will not be able to cut so thick material, that is not correct! (at least for what I have been reading a couple of times) You actually use longer focal length when you need to cut thicker material! The longer Focal length, the less Power loss, because you have a longer depth of field. All this talk about Focus points and Focal length is actually Interesting, because as you know I'm working as a Graphic Designer now, but I have been a Professional Photographer for around 20 years. And I can recognize a lot of the things we are talking about from Photography, and it is, in many ways the same principles with Focal points and Focal lengths. So here is something you maybe can use in practic: In Photography, when you are using long lenses with a very shallow depth of field, and you as an example, are out in the nature, and you want to get maximum depth of field with that lens, then you should NOT do what a lot of people are doing. Many people think, that if they focus on the background, everything will be sharp. That is wrong! The correct and best way is to select and put your focus point approx 1 third into the scene. That is because the depth of field, also called DOF is shorter before the focus point, than behind the Focus point. The only thing we don't really have here on the lasers, is that we can't change the aperture, at least not as simple as on a Photographic lens. Another thing about Focus I have heard you mention in a video (Can't remember which one) where you was correctly talking about the acceptable focus depth. That actually have a name, it is called "Hyper Focal distance". A lot of things are the same as in Photography or at least very similar in the principle. You can, kind of also compare the shutter speed with the speed on the laser :)
Hi Klaus I can only speak with the experience of my own 40 watt tube days. But somebody else had the same issue and I explained it in the second of the videos below Here are a couple of later videos on lense that you should help answer your question ruclips.net/video/1yMAr75h5O8/видео.html ruclips.net/video/61bGzWicRRk/видео.html Your observation about asymmetry in the beam before and after the focus point will also apply to the laser lens but is basically ignored because the distances over which you use the lens away from the focus point is so short that it's effect is negligible. Berst regards Russ
You are both right and wrong. If you turn the airflow to almost zero then you decrease the cutting efficiency and allow heat to build up in the cut. That heat build up allows a thin film of liquid acrylic to form in the kerf just behind the cut and this liquid has a levelling (polishing )effect on the edge striations. That is the theory behind reducing the air assist BUT it rather depends on the type of acrylic you are cutting. If it happens to be extruded acrylic sheet then you will get the polished edged with or without air assist. If it is cast acrylic then you will really struggle to get a good flame burnished finish, not only will you need to turn off the air but you will need to run at least 50% slower to allow the heat to build up.The thinner the cast acrylic the more difficult it will be to achieve that heat build up in the cut . Cutting thinner cast acrylic with a longer focal length lens helps with heat build up. So it's not just as simple as turning the air assist right down. NEVER turn it off or you will coat your lens with acrylic vapour. Bet wishes Russ
@@alifyaanidyanina965 Hi Alifya I have done more experimental work on this subject but it is best summed up in this video ruclips.net/video/ygN_GJwPLQM/видео.html&index=48&list=PLPWEtx5V9DqEogIeYRdcG_KYcB7UL2Qmn Best wishes Russ
+BEGHIBEGH Derradji Hi Click on the Sarbar logo and then the ABOUT tab. You will then find you can message me privately. Send me your email and then I will respond and you can describe your problem and send me a file maybe. Regards Russ
Hi Don Here I am at least a year on and still wrestling with the problem you observed ie a non 90 degree cut. I know the beam is vertical to the surface of my material because I check the beam position 5mm away from the nozzle and drop the table about 150mm and check that I still have beam coincidence I do this both with and without the lens so I absolutely know my beam is truly perpendicular. This problem only shows itself with acrylic and only when the material exceeds 5mm thickness. I have two machines both set by the same method and both exhibit similar off vertical cuts in the Y axis. Both Y+ and Y- cuts are leaning the same way, Without knowledge of how I set the machine, the cut characteristic leads one to the conclusion that you have reached. I can in fact make the cut vertical by setting the head out of square. This fixes the problem (for acrylic) but does not explain it. It is on my long list of strange phenomena that I need to investigate. I do not experience the same out of trueness with 10mm plywood. If you jump forward to #120 where I demonstrate the strange tunneling properties of IR light in acrylic, I'm convinced that the off-square issues have something to do with this property. I have just recently acquired plenty of 10mm acrylic to experiment and investigate this problem in a near future video Thanks for the comment All best wishes
I hear what your saying if you but a spinner and it doesn't wobble you will know... our cutter gets used by many people all he time and had to be aligned from time to time and i get so irritated when i want to cut a perfect part and its off 90. i'm not referring to he normal v cut from top to bottom . it may be the camera but one side of your blocks looks to have more angle then the other . here is a great link for alignment not done ny me ruclips.net/video/e1c3keOKL6Y/видео.html
Hello again Russ, would it be possible for you to email me a copy of your electrical prints, I'm changing the power supply and it would be helpful....thanks Scott Thorne.
+Scott Thorne HI Scott Go to the ThunderLaser site www.thunderlaser.com/down and download the RDC 6442 manual. That's where the circuit diagram is. Best regards Russ
Hi The bad news is that you are not using acrylic. How can I be sure? Because acrylic is akin to H2O. Acrylic is solid and clear at room tmperature. At 1 degree C, ice becomes liquid. At 160 C acrylic becomes liquid. At 100C water boils, evaporates and becmes steam. At 20-0C acrlic boils and becomes acrlic vapopur (steam) Hold a cold surface to eitherannd they recondenswe. It is impossible to burn or char water and so it is with acrylic. The only difference with acrylic vapour is that you can heat it further and it becomes an inflammable gas, Ii is impossible for the cut to biurn and char. I would suggest that you have probably tried to cut polycarbonate that creates masses of brown fumes or maybe PET which cuts with a reasomabl;y clean edge but produces masses of yellow fumes. Other clear materials include styrene or ABS. You should not be cutting either of these because they produce toxic fumes.
@@SarbarMultimedia thx for the response here in Norway the shops dont Even know what they sell themself. Am suspecting it is PET from your response as it left a yellow Power on the nozzle. Is this also damaging to the machine?
@@Actio83 I have cut quite a lot od PET.. It cuts at quite a high speed and leaves fairly cleam edge but I pesonally never want to breath those fumes. I am fairly confident there is nothing in the fumes to damage the machine but you havee to leave the protective film on or the yellow fumes stick to the surface and are not easily removed.. PET is a cheaper alternative to p[olycarbonmate and is what they use for fizzy pop bottles . It has a fairly wide rand of temperature where it remaiss soft and can easily be blow moulded.
@@SarbarMultimedia I was also unfortunate and had the vent hose loose so it filled the shop with smoke… opened the gate and aired out the room but did inhale a bit. Hopefully not dangerous in on off insistents. That a lot for the help, hard to find knowledge on this
@@Actio83 Hi The good news is that It cant be that toxic because you made it to the door to ventailate the shop!! Serously though. Lots of inhalation willbe bad for you but such small and short term exposure will not harm you
I know this is an older post, but I can offer advice to anyone still reading this. Any laser, even a cheap Chinese one, should have a 3.0in or 4.0in lens, if you are going to cut acrylic. A 2.0in is okay for 1/8in or less, maybe 1/4in, at most. When you start getting into 8mm, 1/5in, etc. You have to have a longer lens. This is exactly what he concludes at the end. That the power is gone/out of focus, by the time it gets to the last 2mm of material.
For what it's worth, focusing the 1.5in lens into the material some, actually makes the cut worse in many cases. That is the *main* reason for the larger gap at the top. In addition to using a longer lens, you should focus it right at the surface.
For those discussion a collimator for the beam, you are in luck! The optically clear acrylic actually does this for you. When the beam is focused on the surface, the index of refraction straightens it out a bit. So, in any case, with any lens, focusing into the material gets you nowhere. (with *clear* material - a solid color is different)
Very slow speed, is the main thing that gets rid of the "beam drag" Even using a powerful 150W laser that my company sells, I usually cut the power down to 80-100Watts, and go very slow (1.5in/s, or 38mm/s) I know that is still a lot faster than the 4mm/s in the video.
Hello Jason do you any manual or something that you can give, I really want to do better my work. Today I was trying to cut a piece of 10 mm, I think the laser in my job is 150w but the cut is really bad I was trying with 70% power and 3 mm/s do you have any advice for me. Thank you so much
Your attention to detail and practical demonstration of issue/solution makes it very easy to understand and learn from you
been searching for this most underated channel !!!! finally :D
Wow! What a great video. Great way of looking at thins. Thank you very much. Greeting from Mexico :D
Thx again Russ started with a 80w laser now have a 150 watt bigger bed size also and still your videos are so helpful, your stuff and the way you present are fantastic 2 years ago i got my first machine now Im running 2 Yes its Wayne with multiple sclerosis no won told my I couldn't so i did :-)
Hi Wayne
Congratulations on your new acquisition. I presume that your experience with 80 watts convinced you that for all the cutting you do it would be more efficient with a more powerful tube?All best wishes for the future...maybe working towards #3?
Russ
@@SarbarMultimedia yes I've got a big contract cutting 10mm acrylics needed the power
The beam drag is due to two factors and three for you , beam is step burning in the z axis , due to power /speed , and your Colling the work acrylic , so turn down the air flow to minimum , adj the internal focus lens , for a 3 mm . The damage at the base of your cuts is because the beam is past it's focal point ,
So get the head as close to the work piece as possible ( with a closer focal point internal adj ) and very low to know air flow should give good results .
Nice video
Hi Rod
I absolutely love acrylic as a material because it has some really great properties. You are right about speed. Slowing down does get rid of the beam drag eventually. and I also agree that air assist does have a cooling effect. From all my experimental work with acrylic there is one big factor that I did not understand at the time I made this video and and this is the light guide properties that acrylic possesses. This phenomenon is illustrated in ruclips.net/video/CdupovEe9hA/видео.html.
This explains why in my early days I was able to cut 15mm acrylic (albeit at 1mm/sec) with just 30 watts of power. As you will see from this video, the focus point relative to the surface has little effect other than to make the cut very wide at the surface. Speed is the key factor to allow the beam sufficient time to "tunnel" through the material . It makes little difference to the cut efficiencty if you have lots or little air assist. What it does do is to change the surface finish of your edge. There is a slight gain in speed with full air assist because you are efficiently clearing the flammable acrylic fumes from the immediate cut area. Those fumes are absorbing some of your IR energy and decreasing the efficiency of your cut. It has taken me a long time to understand all the properties of acrylic and I'm not sure I have found all it's secrets even now..
Bear in mind that this series records my learning journey and I was sharing my discoveries at that point. Here I am two years into my journey and I still have much to learn.
Thanks for your comment
Best regards
Russ
I just discovered your channel and let me say...you rock, dude! Your "journal" saves alot of us a ton of time and headaches. I'm wondering if you could compile a new video with your best thinking on the subject of cutting acrylic now that you have several years under your belt. Peace.
Another superb analytical video Russ I look forward to the next one.Regards Joe
+JoePCP
Hi Jo
I just answered this comment and for some reason it got lost in the clouds.
Thanks for you appreciation but remember it's ME that is learning and you just happen to be able to look over my shoulder at my successes, failures and mistakes because my other hobby is video.
Best regards
Russ
Thank you. This video was very informative. Getting to watch the process of trouble-shooting. Provided a lot of insight into the world of laser cutting.
Russ
I found it and have it printed out....thanks a million my friend, that will make this much easier.
On a 50W ULS laser cutter, beam drag is very obvious on 3/4" (19mm) solid poplar and pine.
@11:30 you discovered focusing partway into the material for better cut, at the cost of slightly wider kerf. lens with longer focal length will also help.
A very helpful insight thanks, hopefully going to try cutting acrylic tomorrow.
I wonder if going slow is better than going faster with 2 3 passes. I will test when I get mine.
I wonder what the refraction index of acrylic is at 10.6 um? Maybe this explains beam drag. i.e.: as the laser digs a hole, some of the power reflects and part of the energy that penetrates the acrylic has it's angle changed. A cool experiment would be to see at what angle relative to acrylic does the beam reflect so that the refraction index can be estimated at co2 wavelengths.
I went to the site and I don't see a download option...I'll have to check it out on my laptop when I get off....thanks Russ for your help...if I can't find it I'll let you know.
Scott Thorne.
very informative and explained in a simple way thanks you
Thank you again for another great information video. Do you have any idea how to get rid of the vapour coming from the cut? Those often 'melt' or settle into my acrylic, ruining the surface image. An example is at 3.13 in this video to the right and left of the cut line. Thank you
Hi
Acrylic might look like a soft easy plastic to cut and engrave but it has some unique material characteristics. It is solid at room temperature and then turns to liquid at 160C, It remains liquid for a short time until 200C where it turns into acrylic vapour (just like water turns to steam). There is NO chemical change, so as soon as it touches your work surface (or any other cold surface) it will condense back to liquid acrylic (just like steam turns back to water) which eats into your surface a little as it cools back to solid. That is why you get this misting effect that will NOT wipe off.
Characteristic number 2. Just like a cup of boiling water will quickly fill a room with steam because the vapour occupies thousands of times more volume than the liquid, so is the case with acrylic. If you lightly pulse the surface of acrylic with low energy you will convert just a small volume of acrylic to vapour and it will explode UPWARDS like a volcanic ejection. However, if you increase the power you will be trying to convert much more solid into vapor and the uprush of gas is not quick enough to let all the expanding gas flow UPWARDS. There is so much volume that it gets forced sideways and IMMEDIATELY condenses on your work surface,.
So there are TWO things you do not want during engraving. First you do not want any powerful air assist blowing fumes down onto your work , just a gentle airflow to protect your lens. Secondly you need the MINIMUM of power to mark the surface of your material . If you engrave deeply then you will suffer acrylic condensation no matter what. A good trick is to dither any bitmap image so that you are breaking up the power into discreet dots and short lines. Use low power.
Cutting is different. Whenever you start a cut you will always have the explosive horizontal debris because there is nowhere else for it to go. Once your cut has started you need max air assist to blow the fumes out of the BOTTOM of your work, you do not want any fumes coming up.
Hope this helps
Best wishes
Russ
@@SarbarMultimedia Dear Russ, thank you for such a prompt and detailed reply. After watching 8 hours of your videos yesterday I'm making progress with my machine!
Sir, thank you for another excellent video. It would be helpful if you could show exactly how you make the changes is the RDWorks software to change the "Laser through mode" and delay setting for the laser start. Again, thank you for your videos and the sharing of your knowledge and experiences.Randal
+Randal Sullivan
Hi Randal
Through Power is not something that we generally need on our low power machines. RDworks and the machine control system has been designed for many configurations and different power machines. When you get above 300 watts you can start cutting thin metals. With metal cutting you must PIERCE a hole though before you can start cutting. I'm sure that why this function is there.
There are a few little used functions that are worthy of investigation (like, sew, lead-in and lead-out) in the near future so I will make a note and revisit Through Power again. This was my first time of playing with it so there were a few suprises.
Thanks for your appreciation
Russ
+SarbarMultimedia Hi Russ,Thank you for the response and I look forward to your next video!Randal
hi I was Wondering if you could help me please, I have a Chinese laser machine its 500 x 700 plate, and 60w laser, I can engrave ok but suddenly when i import a clip art , it engraves ok but with a double image on all clipart, also is it possible to cut 3mm wood with this machine, I would be grateful for any advice you can give me please. Many thanks Paul.
I am wondering what kind of base are you using. I mostly see people with Honeycomb bases that are metal. Yours looks like it is either glass or a big acrylic piece...
Hi Matt
You must remember that you are following me on a journey of discovery and at this stage I have so much more to learn. I have not yet discovered the real value of air assist for cutting or the essential requirement for air flow management through the machine.. I have found that honeycomb tables are a bit of a disaster for most cutting because the beam reflecting off the metal edges of the cells cause burn marks on the back of your material. Lifting the material off the table prevents this reflection and also allows the fumes to escape freely below the material rather than being trapped in a long thin tube (the honeycomb cell). Air flow management and cut efficiency is a subject that would take me several pages to explain. If you serach for RDWorks Learning Lab Air Assist, you will come across several videos where I uncover the secrets. You will then begin to understand the reason why no machine should ever be fitted with honeycomb. It looks like a brilliant idea but turns out to be as brilliant as shaving with a blow torch.
Best wishes
Russ
What influence does total reflection on the just generated interface between a gaseous (its contents may vary quickly) and a solid phase have? The optical properties of the medium properties' change and transition(s) with the process of cutting / melting / burning / sublimation instantaneously. Various intermediate products will change the optical properties very dynamically. Moreover, the reflection on the bottom surface may contribute to the excavations visible in some of your experiments. I saw such variations that could be correlated to a supporting metal grid placed under the acrylic. Modelling the process called 'cutting' detailledly might lead to some interesting findings.
Hi Ulrich
Many people have suggested that the marks on the edge when you cut acrylic are caused by the stepper motor.
I am equally certain that they are NOT related to the stepper motor. For many years I owned a metal laser profiling business and although this is a COMPLETELY different sort of machine and has insufficient power to cut metal, I do believe that the well researched mechanism that causes striations on the edge of cut steel is occurring when you cut acrylic When you cut mild steel you use pure oxygen as the assist gas at about 1 to 1.5 bar. The mechanism described in the following text pages 24 to 26 causes exaggerated edge marking.
books.google.co.uk/books?id=PrguBAAAQBAJ&pg=PA24&dq=arata+and+miyamoto+laser+cutting+mechanism&hl=en&sa=X&ved=0ahUKEwj3xL_vqNHPAhVCD8AKHWF7AgYQ6AEIOzAB#v=onepage&q=arata%20and%20miyamoto%20laser%20cutting%20mechanism&f=false
When you cut stainless steel the process is completely different. You have to use an oxygen-excluding cover gas in the form of pure nitrogen but at pressures of 12 to 15 bar. Even though there is no exothermic reaction to melt ahead of the laser beam, similar but less obivous edge marking still occurs
I am suspecting the the heat zone when acrylic sublimates, extends out in front of the beam and causes this same stop start mechanism of cutting. Too much air assist in the cut zone reduces the cut efficiency and also reduces the "flame polishing" effect. I use a very low airflow to cut acrylic, just enough to keep the gas flowing out the bottom of the cut.
I shall shortly be taking delivery of another laser machine but this machine is SERVO driven. This will prove the point (or otherwise) about stepper marks during cutting. However greyscale engraving is a different matter that has got to be looked at in more detail when I have two machines to compare.
Best regards
Russ
Hi Russ, thanks for the information on steel cutting - I am still far from that...
Re the striae: Is the laser driven in a pulsed mode, or CW? The former might be causing the stripe pattern - but then, the stripes should be clearly travel speed dependant. Another vague thought: Mechanical resonance within the acrylic board caused by shock waves (like cavitation in water) when the sublimation starts in an enclosed volume that then bursts outwards? So many mysteries... ;)
Cheers,
Ulli
Hi Ulrich
These cheap lasers are not RF driven and so the beam is basically continuous (as for as the eye can discern) Take a look at ruclips.net/video/mXIDwQxhX3k/видео.html starting at about 12minutes. I was investigating a strange performance region in my tube as the nitrogen partially ionizes. To prove that the beam was pulsing I ran the speed at max of 500mm/sec and was able to measure the pulses. Once I increased the power such that the ionization was complete and the power supply had switched to its stable 17kv working range the the beam was showing no hint of pulsing. Maybe this answers your question
Best regards
Russ
Thank you Sir for your videos! I saw them all because i am up to buy that GH350 Laser engraver too;) so my question is if you already made a "best pracitse" table with all your experience for different materials and its best Laser speed and power?
+thomy0168
Hi
If you go to the Thunder Laser website site and download their version 8 of RDWorks, www.thunderlaser.com/down When you click on one of the coloured cutting power/speed layers , it will open a window. At the top of the window you will find a Parameter Library that Thunder Laser have thoughtfully populated with commonly used material data. Each machine could be very different depending on tube power,and focal length of lens, so this data is a jumping off point. Sadly you will have to note the best settings for your machine as and when you find them. Sorry I can't be more helpful.
Regards
Russ
+SarbarMultimedia thank you!
Could a collimated beam (passing through a converging lens to tighten it up then through a diverging lens to bring it back "straight") solve this problem altogether? I'm trying to remember the college-grade optical physics course which I took over 20 years ago...
Hi Claude
Hi Claude
There is one massive problem with trying to apply conventional lens theory to our IR beam . Lens theory assumes a uniform collimated beam and usually monochromatic.. We have the single wavelength (10.6 microns) but the beam is not uniform, It's energy density is close to Gaussian (a normal distribution) About 70% of the beams energy is contained within 1/3 of its diameter.. Unfortunately beam drag has nothing to do with the convergence or divergence of the beam. it i all to do with energy per unit of time. When you try to cut too fast the bottom of the beam starts to drag as it runs out of energy. If you slow the cut then there s sufficient energy per unit of time to damage the material vertically. To demonstrate this time and energy principle, pass your hand over a candle flame. The faster you move your hand the less heat you will feel. Slow right down and the heat will have sufficient time to reach the damage threshold for your skin.. Ouch.
Best wishes
Russ
@@SarbarMultimedia In fact I should have specified the "hourglass shape" of the cut when I was referring to "the problem". Thank you for your response. My optics course is really far back in my memory :-)
@@claudehebert3131
Hi Claude
You may be a bit surprised about your hour glass supposition. I am close to completing my VERY in depth study of cutting with various materials and lenses. The results so far are rather interesting. I'll say no more at present.
Best wishes
Russ
When cutting such a thick material, the first thing I would have tried is of course lowering the focus point into a mid depth of material, instead of surface. That makes all sense of course.
Hi Vlad.
Your theory is a bit of a myth. I have done many experiments and my advice is ALWAYS set the focal point on the surface, especially with acrylic The basic idea for this myth is a misinterpretation of advice that Trotec give in there guidance for cutting acrylic ABOVE 10mm thick. The big problem is that we do not have the RF driven tube that you will find in a Trotec machine so the effect of the beam is totally different. You will need lots of power and a 5" focal length lens. You can read this for yourself at the top of page 5 in the following document
howtolaser.com/blog/how-to-laser-cut-acrylic/. It confirms that up to 10mm thick you keep the focus on the surfsce
Until you have experimented for yourself, I would stay safe and ignore the myth.
Best wishes
Russ
SarbarMultimedia i actually did and it worked better when i lowered. But none of my experiments are even nearly as sophisticated as yours, so I’ll just take your word for it and will follow your advice then! Thanks again for providing so much research on youtube for us. Best channel for DIY lasers, period. I bought K40 first for $350, but didnt realize it would be that bad. So decided to return that one and I have 50W machine on order now which I bought for $1350. Slightly more powerful tube there, but also all components are 5x better than K40. Will be worth the investment.
The next size machine will definitely be better than the K40. I suspect you are buying from ebay? It's good value for money but will probably not be a reliable machine until you fit a new tube and power supply. The ones supplied will almost certainly be sub standard because the Chinese have worked out that people buying from ebay are fairly naive of the technology and it will take a long time to work out that what they have bought is not the real deal.
Sorry to be pesimistic but my evidence base is huge.
Best wishes
Russ
SarbarMultimedia no problem. I have been working with China on relatively large scale for over 7 years. I know exactly what they do and how this machine is built. I just accept it for $1350 with free 2day delivery. I thought of building my own, but I have too many projects now already in progress. So, decided to just buy. If anything is sub-spec on this machine, they will have to adjust the price for me. I am not one of those naive consumers :))) My last buy from ebay was a 6040 CNC router for $1400, and I ended up only paying $400 for it due to a lot of mess that they made in that machine. So, with that said, I will be thoroughly examining this laser machine, including tube check for conformity sticker etc. if they use reject tubes for $350 K40 machine, it is totally ok. Reject tube for $1350 machine - i will not be ok with. And if they do use reject tubes, and I find that out, it will just cost them money on this order.
Hi Vlad
Good luck with your purchase. Let me know the final outcome.
Best wishes
Russ
Would having a collimator help reduce the beam width and straighten it out, or is that cost prohibitive?
Hi Mark
Others have suggested the same and even gone off to make their own versions and trials.....never to report back. The proper beam collimators I have seen basically only allow the high energy density part of the beam into the lens. In my logical world that implies that I could be preventing 20 to 30% of the available power ever reaching the lens. Beyond that unacceptable objection, cost, space and addition head mass would then become issues.
I have done a couple of experiments using a 4" FL lens to focus the beam down before passing it through a 1.5" FL lens. No staggering results but I have not completely dropped the idea.
Thanks for the comment
Best wishes
Russ
I see... more complex than I had thought. I was just thinking of an additional lens after the focus lens to stop the divergence. As my wife likes to ask "How hard can it be?"
Hello very informative video for a newbie. I have a newbie question. What is the beam drag and how can you tell that is dragging ? THanks
+freebird1963
If you fire the beam at a piece of acrylic which you can see through ( or any other material that you cant), The beam will pierce a hole vertically into the material. If the material is reasonably thick (6mmor more) and you now start moving the beam slowly, you will begin to cut a linear grove through the material . When the beam is moving VERY slowly. the cut will be vertical. But as you start to increase the cut speed the bottom of the beam (which has less energy density because its past the smallest focus point) will be cutting less efficiently. and will start dragging behind the beam entry point. Provided you do not exceed the cutting speed for the BOTTOM of the beam the cut will be right through. It's this loss of cutting ability with depth that causes beam drag. This can be clearly seen in this video and at the end I drop the focus point and the bottom of the beam now has more power and the cut becomes more upright. and has better cutting penetration.
Hope this is a clearer explanation.
Best regards
Russ
Russ, Thanks very much for that explanation. Understand much better now. Thanks !
.
Hello! How do you regulate air pressure? Do you use original membrane pump or compressor with air tank?
Hi Dainis
If you watch ruclips.net/video/OCVsMXw6yh4/видео.html
You will see that I am testing the original 70 l/min pump against a new 140l/min pump. I regulate the air to the nozzle with a little ball valve that allows FULL bore flow. If you have a screw restricting elbow I would suggest throw it away and replace it with a normal elbow, but you will have to modify it as I show in the video.
The ball valve I used was like this
www.ebay.co.uk/itm/6mm-to-6mm-pipe-Pneumatic-Ball-Valve-On-Off-Flow-Push-fittings-OEM-/112303492406?epid=11002970582&hash=item1a25cf4d36:g:SrgAAOSw2gxYo5i-
Best rgards
Russ
SarbarMultimedia Thank you very much. Miss this video. I've watched a lot of your videos and they're very helpful. Next week I'm going to order identical 50w laser. At this moment i have only 7w laser diode engraver.
couple questions. u said you measured 60w coming out but this is a 50w laser machine? and during this test you had it set at 65% the whole time?
Hi
First I must let you know that in the following video I fitted what I thought was a new 60 watt tube. It turns out that I had been sent a 70 watt tube 1250mm long. Ever cautious about over driving the tube I had established that the max allowable current was claimed to be 25mA. I know that Chinese manufacturers often quote the current for achieveing their max test power which in this case I guessed was 80 watts. So my first task with this new tube was to check the power output related to the %power and the actual mA current flow. . You may have missed the following video (start at about 15minutes) and you will see me testing the tube up to 90% power and plotting a graph of the tube's characterisics. Based on that graph I decided that 22mA was a safe maximum and that produced 70 watts of output at the tube. To drive at that current level meant I could never exceed 65% power setting. There is NO fixed relationship between % power and tube power. People mistakenly think that if I run a 60 watt tube at 100% power you get 60 watts of output. Wrong, What you will get in very short order is a dead tube caused by over driving it. Now just for estimation purposes lets assume I get 4% power loss at each mirror and also across the lens. Forget the compound effect and just accept that I get 16% loss between tube and the work surface ie my 70 watt output will become about 60 watts of usable power.
I hope this answers both your questions
ruclips.net/video/zCTrRT1C_eY/видео.html
Best regards
Russ
ok ye that explains, it, because noway could a 50w cut 8mm using 4 speed and 65%, anyways great vids i had browsed a bunch not the whole series but quite a few, i guess i will look forward to retirement as well and spend time doing allot of useful vids as well. good job russ.
maybe someone already asked.. does it matter if it casted or extruded acrylic??
Hi Lenny
Acrylic is a unique plastic with properties that are analogous to H2O. It is solid at room temperature (ice) but at 160 C it immediately becomes liquid (water). At 200 C it evaporates (steam) into acrylic vapour and can be recondensed back to solid acrylic upon contact with a cool surface.
Its a weird quirk of physics that both cast and extruded materials are exactly the same molecular structure but they have different properties. The extruded acrylic seems to have a much lower thermal conductivity, although it cuts just as easily as the cast acrylic. The lower thermal conductivity retains heat in the walls of the cut for significantly longer and whilst above 160 C , will allow the thin film of liquid acrylic on the walls a few mm behind the cut to "level" out. It is this mechanism that creates the polished finish to the cut. Below 5 mm thickness it is almost impossible to get that same finish with cast acrylic unless you dramatically reduce the cutting speed (50% or less). Cast acrylic cuts are burr free but run your fingernail over the top or bottom edges of an extruded acrylic cut and you will detect a noticeable burr.
Best wishes
Russ
@@SarbarMultimedia thanks for the info.
will give it some more tries with different settings. the one I made started to crack all over after a few days.
Hi, wondering if you could help. I have a piranha 5060 that ive just bought. got it set up and laser aligned, thanks to your videos and others on RUclips :) sent a test file to the laser and when i click start it says not enough extend space? have you any idea what this means and how I could fix it? Thanks
Maggi
Hi Maggi
My guess is you are trying to engrave a bmp file. If so then you are using scan mode. My guess is that you are trying to run your program from right in the top left corner (or maybe top right ,depending on where you machine runs to for its 0,0 datum). If so, move your cutting head out into the work area to about 20,20. This will probably cure your issue. When you scan, the head has to run to the end of your picture and turn off the beam. The head then has to travel further to decelerate and turn round, whereupon it has to accelerate back to your chosen speed before turning the beam on again. This over-travel zone is the EXTENDED SPACE and will vary depending on the speed you scan at. More speed requires more extended space If you set the origin point so that part of your program is outside the work area then you will get an X or Y "slop" error. Neither error is clearly explained anywhere.
Hope this helps if not shout out again.
Best wishes
Russ
Thank you Russ, one for your help and two for your prompt response. I tried moving the laser head manually but it just reverted back to the top right corner when i hit start. how exactly do i move it without it doing this? sorry to be a pest, total newbie here and itching to get started :)
Hi Maggi
I am now 2 years ahead of you but it was a bit difficult to start with because there was no one to turn to apart from condescending experts who were very possessive of their experience. Hence I had to learn the hard way and that what my videos are about. I am not teaching but you can learn along with me. I try to remember those early naive days and despite trying to be inclusive with my explanations to suit all levels I sometimes forget a few obvious points. In your case you either have not yet found the origin button on your machine or your RDWorks software is not at the normal default setting.
There are several unknowns in your situation that will help me if I understand. How are you running your machine because there are 3 options.
1) is your PC remote from the machine and you are transferring programs via USB memory stick?
2) is your machine connected to your PC via a USB cable/Ethernet cable?/wireless bridge connection?
3) Are you downloading programs from your PC to the machine via the connection in 2) or are you running your program via the RDWorks START button?
Your answer will allow me to better advise you.
Best wishes
Russ
Thank you Russ.
I think had i have bought one 2 years ago with so little information on them i would have given up! I'm only now getting a little understanding thanks to the help of generous souls like yourself who put the info out there willingly.
I've been slowly going through video tutorials (how I found you :)) but it gets a little mind boggling lol I work primarily in Photoshop for all my designing and now have to change file types for vector which is a little daunting. I've downloaded inkscape as illustrator is ridiculously priced and i already pay annual subscriptions for Photoshop and Lightroom. I still have to somehow teach myself Rdworks :0 not the easiest program to understand even with tutorials.
So, onto your questions. Yep I found the origin button but it doesn't seem to move anything when i push it?
pc connected via usb
I'm just downloading the design to the laser right now and then working from the control panel.
Maggi :)
Hi Maggi
I think this conversation will be more useful off-line because we can exchange data and pictures. Use the You Tube messaging system (that is private) to send me you email so that I can answer more fully.
Best wishes
Russ
I recently installed RD Works controller RDC6442G ,I went into settings on my laser machine and on my computer and changed the bed size settings but it is still saying not enough extend space. I have been on to cloud ray laser but I cannot make sense of thier instructions.Is there any advice you can give me please?
Hi Paul
Part of your program is outside the area of your table. When you look at your program in RDWorks there will be a little green square in one corner of your drawing. That is where your head will be to start the program.I guess your are running your machine directly from the pc and just pressing the START button to run the program? Your problem is occuring because your ORIGIN is in the wrong place. If that little green square is at top left for example then manually drive the machine so that the head is nearly at the back left corner. Now press the origin button and that should fix your problem.
Best wishes
Russ
Hi Russ thanks for your help. My machine is working as it should now i have just got one question. When ingraving lettering my machine now only ingraves 1 letter at a time have you any suggestions why it would do this. Thanks Paul
hi i have just bought a BORDOR 40W LASER which is a very neat machine and it comes with RDWORKS have e you ever seen these lasers and if so what do you think of them, dermot love your videos
Hi Dermot
I have not seen one before but I looked at their videos and it looks like a well designed machine. The impression given is that it's fitted with a RECI tube. I was not aware that RECI made anything less than 100 watts (unless it's a custom order) It certainly is a meaty looking tube....but only 40 watts???
What size is the table/work area?
How much does it cost landed?
Keep in touch and let me know how you get on with it. It looks as though this one will work well straight out of the box......and more importantly KEEP running reliably
Thanks for the kind words and the interesting information. I often get asked to recommend machines. That's obviously quite difficult as I only have one machine's worth of experience. However, from all the issues people bring to me I now know a lot about many machines. So it will be good to hear of something different that I can pass on to others, especially if it's reasonably priced, and by that I don't mean Ebay cheap.
hi the machine cost me €2400 from China and i should have it in about 4 weeks so i am learning rdworks at the moment, in other words i see more of you then i do my wife lol,,can you tell me in rdworks how do i get the blue arrows to the left like on your machine. Dermot
Hi Dermot
I have answered you arrow question elsewhere. As I said, I know nothing about this machine so keep in touch, From what I can see it does not have an ammeter fitted and if it is a 40 watt machine the maximum drive current should be limited to 16mA....it will be interesting to find out what the tube manufactures recommendation is. Unless it's a customer made special, Reci don't make tubes for those low wattages.
I would seriously advise ordering yourself a cheap chinese analogue ammeter www.ebay.co.uk/itm/91C4-DC-0-30mA-Class-2-5-Accuracy-Analog-Ammeter-Amperemeter-Gauge-/351749565079?hash=item51e5e86a97:g:HjsAAOSwmtJXUVFu
so that you know exactly what you are doing to your tube. Overdrive your tube and it's warranty will be void. That's why they don't fit an ammeter and don't advise the max running current. It seems that Bodor are reputable enough to tell you what that NORMAL max drive current should be. If you don't know already then email the question to them.
Fitting an ammeter is very easy
ruclips.net/video/xDZmuxq5BEM/видео.html
If your machine arrives before you ammeter then do not use %power above 60%. I made this mistake by thinking I was allowed to use 100%. I trashed my first tube in record time through ignorance and is great for the sales of replacement tubes!!!!
Best regards
Russ
Hi Russ I never got the answer to the arrow question, would you mind sending it to my email address, thank you for all your help and keep the great videos coming. dkprinting@gmail.com god belss
For cutting i put the focal point in the middle of the acrilic, not in the surface. Surface only in engraving..... Carlos
+coralsign
Hi
This was a demonstration to show that you DO need to put your focus point into the material to get a good cut on thicker materials. I put it on the surface to start with so that you could see the beam drag phenomenom. I did also mention that because I have a 38mm focal distance lens that sits 6mm above the surface , when it comes to cutting 8,10,12 and 15mm acrylic I cannot get anywhere near the centre of the material (just 2 or 3mm lower) but I can still get good cuts..
Thanks for your comment
Regards
Russ
+SarbarMultimedia Thanks A lot Russ !! Regards from Brasil !!!
looking for information about air assist. i will see all your Channel !!
+coralsign
My background in industrial metal cutting lasers indicated that I would need lots of air assist . When I first had my machine I fitted a gauge and used my little shop compressor but I soon found out it was not necessary. The little pump supplied was adequate. BUT, you will see that I do have a 38mm focal length lens and the nozzle is only 6mm above the cutting area. If you have a 51mm lens then your nozzle will be about 20mm above the surface. This is fine for engraving and for cutting acrylic but for cutting wood of any sort there is a burning action that takes place and the dense smoke right in the cut will absorb some of the infra-red energy and decrease your cutting ability. This is when you need a good airflow so you might want to try experimenting with another separate air supply pointing directly into your cut It does not have to be high pressure , just well directed. ALL smoke should appear below your material there should be none leaking off the surface.
Good luck
best regards
Russ
Hi Russ, again thanks for all your work here, but in this video, I actually think you are saying something that is not correct and now when I was reading your comment here I find it a little divergent. You are saying that people with a 2.0 lens and higher will not be able to cut so thick material, that is not correct! (at least for what I have been reading a couple of times) You actually use longer focal length when you need to cut thicker material! The longer Focal length, the less Power loss, because you have a longer depth of field.
All this talk about Focus points and Focal length is actually Interesting, because as you know I'm working as a Graphic Designer now, but I have been a Professional Photographer for around 20 years. And I can recognize a lot of the things we are talking about from Photography, and it is, in many ways the same principles with Focal points and Focal lengths.
So here is something you maybe can use in practic:
In Photography, when you are using long lenses with a very shallow depth of field, and you as an example, are out in the nature, and you want to get maximum depth of field with that lens, then you should NOT do what a lot of people are doing. Many people think, that if they focus on the background, everything will be sharp. That is wrong! The correct and best way is to select and put your focus point approx 1 third into the scene. That is because the depth of field, also called DOF is shorter before the focus point, than behind the Focus point.
The only thing we don't really have here on the lasers, is that we can't change the aperture, at least not as simple as on a Photographic lens. Another thing about Focus I have heard you mention in a video (Can't remember which one) where you was correctly talking about the acceptable focus depth. That actually have a name, it is called "Hyper Focal distance". A lot of things are the same as in Photography or at least very similar in the principle. You can, kind of also compare the shutter speed with the speed on the laser :)
Hi Klaus
I can only speak with the experience of my own 40 watt tube days. But somebody else had the same issue and I explained it in the second of the videos below
Here are a couple of later videos on lense that you should help answer your question
ruclips.net/video/1yMAr75h5O8/видео.html
ruclips.net/video/61bGzWicRRk/видео.html
Your observation about asymmetry in the beam before and after the focus point will also apply to the laser lens but is basically ignored because the distances over which you use the lens away from the focus point is so short that it's effect is negligible.
Berst regards
Russ
Thank you, Sir,
What power is your laser tube??
70 watts
Very informative, thank you.
well explained mate.
If you want like a crystal edge finish, remove the air
You are both right and wrong. If you turn the airflow to almost zero then you decrease the cutting efficiency and allow heat to build up in the cut. That heat build up allows a thin film of liquid acrylic to form in the kerf just behind the cut and this liquid has a levelling (polishing )effect on the edge striations. That is the theory behind reducing the air assist BUT it rather depends on the type of acrylic you are cutting. If it happens to be extruded acrylic sheet then you will get the polished edged with or without air assist. If it is cast acrylic then you will really struggle to get a good flame burnished finish, not only will you need to turn off the air but you will need to run at least 50% slower to allow the heat to build up.The thinner the cast acrylic the more difficult it will be to achieve that heat build up in the cut . Cutting thinner cast acrylic with a longer focal length lens helps with heat build up. So it's not just as simple as turning the air assist right down. NEVER turn it off or you will coat your lens with acrylic vapour.
Bet wishes
Russ
@@russsadler3471 Thanks for the explaination, very usefull
@@alifyaanidyanina965
Hi Alifya
I have done more experimental work on this subject but it is best summed up in this video
ruclips.net/video/ygN_GJwPLQM/видео.html&index=48&list=PLPWEtx5V9DqEogIeYRdcG_KYcB7UL2Qmn
Best wishes
Russ
Compliment from Palermo ( Francesco 66 old)
hello . thank you for all your vidéos . i have a problem with engraving text in arabic . please help me .
+BEGHIBEGH Derradji
Hi
Click on the Sarbar logo and then the ABOUT tab. You will then find you can message me privately. Send me your email and then I will respond and you can describe your problem and send me a file maybe.
Regards
Russ
+SarbarMultimedia . hi thank you again here it is my email : d_beghibegh@esi.dz .
send me your's please .
you look like you need the align your beam angle to make it %90 to the surface at this date
Hi Don
Here I am at least a year on and still wrestling with the problem you observed ie a non 90 degree cut. I know the beam is vertical to the surface of my material because I check the beam position 5mm away from the nozzle and drop the table about 150mm and check that I still have beam coincidence I do this both with and without the lens so I absolutely know my beam is truly perpendicular. This problem only shows itself with acrylic and only when the material exceeds 5mm thickness. I have two machines both set by the same method and both exhibit similar off vertical cuts in the Y axis. Both Y+ and Y- cuts are leaning the same way, Without knowledge of how I set the machine, the cut characteristic leads one to the conclusion that you have reached. I can in fact make the cut vertical by setting the head out of square. This fixes the problem (for acrylic) but does not explain it. It is on my long list of strange phenomena that I need to investigate. I do not experience the same out of trueness with 10mm plywood.
If you jump forward to #120 where I demonstrate the strange tunneling properties of IR light in acrylic, I'm convinced that the off-square issues have something to do with this property. I have just recently acquired plenty of 10mm acrylic to experiment and investigate this problem in a near future video
Thanks for the comment
All best wishes
I hear what your saying if you but a spinner and it doesn't wobble you will know... our cutter gets used by many people all he time and had to be aligned from time to time and i get so irritated when i want to cut a perfect part and its off 90. i'm not referring to he normal v cut from top to bottom . it may be the camera but one side of your blocks looks to have more angle then the other . here is a great link for alignment not done ny me ruclips.net/video/e1c3keOKL6Y/видео.html
Hello again Russ,
would it be possible for you to email me a copy of your electrical prints, I'm changing the power supply and it would be helpful....thanks Scott Thorne.
+Scott Thorne
HI Scott
Go to the ThunderLaser site www.thunderlaser.com/down and download the RDC 6442 manual. That's where the circuit diagram is.
Best regards
Russ
White Ruth Anderson Kevin Young Michael
My acryllic just chars and burns
Hi
The bad news is that you are not using acrylic. How can I be sure? Because acrylic is akin to H2O. Acrylic is solid and clear at room tmperature. At 1 degree C, ice becomes liquid. At 160 C acrylic becomes liquid. At 100C water boils, evaporates and becmes steam. At 20-0C acrlic boils and becomes acrlic vapopur (steam) Hold a cold surface to eitherannd they recondenswe. It is impossible to burn or char water and so it is with acrylic. The only difference with acrylic vapour is that you can heat it further and it becomes an inflammable gas, Ii is impossible for the cut to biurn and char. I would suggest that you have probably tried to cut polycarbonate that creates masses of brown fumes or maybe PET which cuts with a reasomabl;y clean edge but produces masses of yellow fumes. Other clear materials include styrene or ABS. You should not be cutting either of these because they produce toxic fumes.
@@SarbarMultimedia thx for the response here in Norway the shops dont Even know what they sell themself. Am suspecting it is PET from your response as it left a yellow Power on the nozzle. Is this also damaging to the machine?
@@Actio83
I have cut quite a lot od PET.. It cuts at quite a high speed and leaves fairly cleam edge but I pesonally never want to breath those fumes. I am fairly confident there is nothing in the fumes to damage the machine but you havee to leave the protective film on or the yellow fumes stick to the surface and are not easily removed.. PET is a cheaper alternative to p[olycarbonmate and is what they use for fizzy pop bottles . It has a fairly wide rand of temperature where it remaiss soft and can easily be blow moulded.
@@SarbarMultimedia I was also unfortunate and had the vent hose loose so it filled the shop with smoke… opened the gate and aired out the room but did inhale a bit. Hopefully not dangerous in on off insistents. That a lot for the help, hard to find knowledge on this
@@Actio83 Hi
The good news is that It cant be that toxic because you made it to the door to ventailate the shop!! Serously though. Lots of inhalation willbe bad for you but such small and short term exposure will not harm you