RDWorks Learning Lab 87 Maximising air assist efficiency
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- Опубликовано: 15 ноя 2016
- If you own a Chinese laser cutter this little series of videos about me learning how to use the free software provided, may solve the problem of trying to learn from a virtually unreadable manual.
I am nothing to do with RD Works, I am not an instructor and I am no expert. This series will document the essential bits of many hours of trial and error 
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This video is exceptionally informative. I was able to find an area in my air line that was way too restrictive. A little bit of drilling nearly doubled my air flow rate. Thank you for posting this!
I just drilled out my elbow fitting just about doubling the air flow and am now able to cut wood about 30% faster. Excellent! Thanks Russ! I seem to remember a video were you tested this and determined that air flow didn't really effect the cutting performance.
Awesome to watch your videos again as you pick stuff up that I missed the first time. Thanks Russ
Hello, I'm Jessica from China Dano Mechanical Equipment Co., LTD. Our company's main products include CO2 laser cutting machine, laser engraving machine, optical fiber marking machine and a series of ion cutting machines.If you have any needs, you can contact me at any time. My Whatsapp:+86 13285336692
I didn't know that the air would be that important, very informative - well done sir!
2019 almost 2020 lol and your videos are still useful, in two days I am about to get one of those K40 with the old heads, I already received the Cloudray upgrade head and mirror mounts set, I just bore out both nozzle tip and Air fitting, mainly because of your findings and the fact that mine didn't come with the air compressor, The Air compressor I do have is about like yours is. So, lol thank you for doing the math and experimentation for us.
Enjoyable to watch as always! I only got two smaller K40´s but there is always something to learn about lasers in your video whatever machine used :)
thank you for the video. I have my new laser in my shop and after putting it back together, (damaged in shipping) I look forward to all the testing before I begin.
Great description, exactly where I am on my 50watt Chas-ler .....................
G'day, it's great watching these, keep it up and cheers from down under.
Hi ingmar
Thanks for the kind words.It's good to know that this all works upside down as well!!
Best wishes
Russ
hello, thank you for your helpful videos I really enjoy and learn a lot watching your videos.
Nice job Russ. Have learned so many things that apply to any laser machine as an experience and principals. Deep knowledge is always a must thing even if i buy a high end laser machine. And now all this research proves why the price gap is so huge between a Chinese dragon and a branded laser. Basically they both do the same thing with a laser beam but the engineering and quality of materials under the hood makes the difference. Looking forward for some tests with the new Dragon :)
Thanks Polis
Yes there is still a lot to learn but knowledge gives you power over the process I feel pretty sure we now have all the outside pieces of the jigsaw in place but i's now all the annoying fiddly details inside the puzzle to be sorted!!!!
Best wishes
Russ
great videos ...like your thought process
Again awesome research. Thanks
Russ thanks for the analysis I also made a shroud extension for the 50mm lens. These pumps are not continuous flow more of a fast puff puff flow so I made an accumulator from an old pop bottle which acts as a capacitor does in an electronic analogue to smooth the flow. I didn't analyse it in your depth but convinced myself it improved the cut. I wonder if those little left over traces are due to this? Keep it up, good stuff as usual.
Very helpful video, thank you my friend
The difference between the 2 and 1.5 inch lens is the focal point. The focal point for 1.5" is very tight, and the 2" is a bit broader in length. The longer the focal length, the thicker you can cut. Very interesting on the air flow -- I have a compressor and have not played with that too much...but seeing this video makes me want to play with those settings.
Thank you for the explanation
Hi Russ...
"Pepsi" here.. ;-)
When cutting plywood I normaly just cover the hole in the nozzle with a small piece of masking-tape. Then i poke a hole in the tape by firering a pulse with the laser.
This will make the hole matching the beam and concentrate the airflow directly into the cut. I did some testing on this methode and found it very effective.
As you know from your work with industrial lasers, the beam has to be exactly in the middle of the nozzle to cut perfect in all directions. Of cause we are not using Oxygene or nitrogene as assist-gasses in our small world, but nozzle-centration is still a bit important for the cutting-quality. The small trick with the tape can "simulate" that we have a nice centrated nozzle, and we don't "spill" most of the airflow.
Best regards
Preben Hovedskou
Hi Preben
That's a really neat trick. I wonder if it would be even better with some thickness to the orifice ie a piece of 2 or 3mm thick acrylic rather than masking tape. Definitely worth experimenting with. If I make a video about it I will put your name in the video as credit for the idea. I can test the idea to see if it further improves my plastic nozzle extender . Many thanks for sharing that
Best wishes for the new Year
Russ
have you tried it ? waiting for your opinion on it & there is one more guy who tried this have a look ruclips.net/video/oQYQF3QKJPQ/видео.html
Hi Russ watched this video many times very helpful, I recently bought a new laser machine with 100w co2 tube got 70 l/m air pump with it which is just of no use for cutting mdf and Plywood too much charring.
Which air compressor would you suggest? Or do I even need to upgrade it?
Man I just found your channel and I love it, good job :)
Try some paper and silicone cut/engrave as well, that's is what I'm using my machine for and has been such difficult material to work with but is going well, would be amazing have somebody trying that out too.
Thanks for the videos.
I have done lots of paper and thin card cutting for example see ruclips.net/video/_3oUQ9gKjCk/видео.html
The trick here is to make use of the preionization zone that all tubes possess. It cuts with a very noisy hiss and will be found around 8 to 15% power setting.
I have never cut silicone but there is a mode that works extremely well for difficult materials . It's called DOT mode and basically allows you to automate pulse mode. You have to experiment with the parameters to get perforations that just join up to produce a cut.
Lots of learning to follow.
All best wishes
Russ
I feel like I’ve missed some settings somewhere. How do you slow down the cut speed of a file without needing to go back to the PC and resave the file?
Also is it possible to move where the start point is? Say I’m cutting a test square then I want to cut another. Right now I move the sheet I’m cutting but I’d like to move the laser head. I can’t do that without going to the pc and resaving :(
When you run a file from the PC take a look at the machine display panel and you will see at the top TEMP FILE. That means your program is temporarily stored in machine memory. If you now press Enter Enter you will be presented with a screen display for editing the basic speed and power parameters. Press the ZU button to jump between windows and press Enter Enter when you have set your new parameters. I would DOWNLOAD that test square so that it remains in your machine. You will then always be able to easily access it via the FILE button.
Your other issue is just as simple (when you know how). Press the arrow buttons to move the head to a new position and then press the ORIGIN button to make that your new start and finish point. Before you run the test square you can check its position by pressing the FRAME button.
Best wishes
Russ
The pumps we`re using are high flow/low pressure. Really low. So my guess is that reducing the pressure loss across the whole system will have a significally higher impact than switching to a bigger pump.
So I started analyzing the airpath on my machine:
pump => hose fitting => silicone tube => case connector (4mm) => black hose (3.7mm) => fitting to head (2.5mm) => nozzle (4mm) (I havent measured the pump/fitting/silicone tube on the outside of the machine since they all seem to be more than 6mm in diameter).
Especially the inner diameter of the tube seemed to be a major limitation.
Some tinkering later:
I changed the hose to one I had laying around: It's nominally 9x6mm but just fits 8mm push-in fittings. The fitting on the head was changed to a 8mm straight one which I drilled to 6.5mm ID (for some reason it had a smaller hex on the inside). Finally I threw together some connector to the outside of the case that's also >6.5mm in ID.
The improvements are massive! Where before I could barely feel the airflow there is now a cold breeze even 10cm away from the nozzle! Sadly I can't provide any comparison since I have neither the same tube nor the same wood available.
Conclusion: A mod that's definitely worth doing!
Now I need to think of a way to reduce airflow for cutting acrylic :)
Can you help me please :)? I have air pump nozzle 2,5 mm -> silicone hose 6mm -> black hose 3,7mm - > laser head connector 2,5mm -> laser nozzle 4mm. Must I change tube for bigger (you wrote 8mm) or the same as air pump nozzle (2,5mm)?
Great video! Thank you for the concise/thorough explanations!
Spectacular!
Hi Ginny
I have travelled far on my learning journey since this video 4 year sago The lessons I learnt at this stage have been with me on that journey. In a video I published recently using an RF tube system that I added to a machine like this even more starkly demonstrates the improved cutting efficiency you can achieve cutting organic materials like wood if you understand a bit about physics and fluid dynamics. . That sounds very expert and pretentious but in reality it means keep the work to material gap small (3mm max) ,the air pressure low (3or4 psi is perfectly adequate) and the nozzle orifice as small as possible (2mm to 2,5mm max).
see this video from about 30 minutes ruclips.net/video/bh4qvwZFzg0/видео.html
Best wishes
Russ
Hi Russ, a related question as I assemble bits in anticipation of my laser arriving on Tuesday. I've attached a length of 6mm ID clear hose to a small cheap 12V inflatable toy pump and attached it to one of my variable lab supplies. Running it at about 6V (to extend it's life and reduce noise) I get a good stream of air from the nozzle end, similar to blowing on something with a medium human puff if you know what I mean! Would that be about the amount of air you get from your little compressor? Cheers, Ingmar
Hi Ingmar
The whole secret of air assist is how efficiently you can get it INTO the cut. Most machines are supplied with a nozzle that has a 4mm hole. That is quite bad news because it means the airstream is moving at a large diametern and slow velocity and is less efficient at getting into a a 0.3/0.5mm wide cut width. Reducing the bore to about 2mm has a significant efficiency benefit so your little pump will suffice but concentrate on getting as much of you available air as possible into the cut. Fot acrylic the flowrate needs to be low but for wood and all organic materials it needs to be as much as possible to clear the IR absorbing smoke from the immediate cut area (in the cut not just the surface)
Best regards
Russ
does it really make sense to drill out that elbow? A temporary constriction in the path of a compressible flow (gas) doesn't have an effect on the velocity and pressure of the output (bernoulli effect). Though adding a constriction at the end of the line (like you did with the 3mm cap) will increase the velocity and decrease pressure.
Good video, a few points from my side. Firstly we always recommend you install the air assist through a regulator and proper air compressor, the difference is amazing, the fish tank style pumps puff a lot and the air flow is not always clean. Also if you are using ruida based controller there is an output that control a solenoid valve whcih can trun the air assist on automtacilly so its no running the whole time the compressor is on.
Hi
I have moved on from this stage in my learning journey and done modifications to my machine in ruclips.net/video/ZKC8Byc8y28/видео.html
Sadly , my opinion of using a shop compressor is opposite to yours. Firstly the shop compressor compresses air to 1000 to 120psi (about 8bar). In doing so it dramatically heats the air and charges a reservoir/receiver. Draining a receiver of water that has condensed in the bottom is a task that few carry out regularly, hence there will always be water in your receiver. Hot air absorbs lots of water. So now you are sending high pressure warm, high humidity air into a regulator (and oil and water trap?)where there is some sort of pressure reduction, Is this done before you send your still warm air into the 4mm bore pipe that takes the air to the head? My guess is yes. thus you will still have reasonably high pressure air you are feeding into that restricted airway What size hole is in your nozzle? Some nozzles are 2.5mm bore and others are at least 4mm. The fitting into the head will sometimes be 2mm bore (if it is an M5 thread) or more often 3mm bore for an 1/8"bsp fitting, There is a very high possibility that this is the final restriction and it will be smaller than the nozzle bore. So as the high pressure air rapidly expands inside the nozzle, it will cool down ( that's basic physics...Boyles Law) and in doing so will not be able to retain the dissolved water. It will appear as vapour inside the nozzle where the laser beam will heat it up and any oil and water vapour will explosively turn to gas and impinge on the lens. The debris on ONE FACE of the lens will gradually heat up and do several things. It will burn onto the anti-reflective coating and eventually bond with it , thereby reducing lens efficiency and eventually the uneven heating between upper and lower lens faces will cause the lens to crack. This is not theory , I have two lenses to prove it, before I worked out what my shop compressor was doing. I now use the silly little Airtac pump supplied (I use an ACO-0019E) because it is OIL-FREE, , tries to supply high volumes of air (120l/min) which it cannot do because the pipework limits the flow. The air pressure never rises above 5psi so there is little compressive heating, the air does not sit in or pass through a reservoir (so no water pick up) and when it eventually expands there is insufficient pressure drop to create vapour in the nozzle. This is where the real trick to cutting lies. You have to get your nozzle with a small 2.5mm bore to within 3 to 6mm of your work face so that you can EFFICIENTLY get a good flow of air THROUGH your cut. High pressure air always means rapid expansion as it exits to free air. How much of that air is getting into the kerf. The higher the pressure the more rapid the expansion.
Here you will see me cutting 10mm plywood with a 1.5" lens and my silly Chinese air compressor.. The cut has a char-free edge and smoke free top and bottom Two dead lenses and two bad weeks with a shop compressor when I first got my machine 3 years ago, convinced me to work with LOW pressure but to use the air efficiently.
ruclips.net/video/LArKiymBry0/видео.html
Thanks for the comment because it has allowed my to explain the physics behind my apparent illogical decision to stay with a low pressure oil-free compressor. The other obvious advantages are quietness, very little power usage and instantaneous flow at the nozzle because there is no reservoir to charge.
Best wishes
Russ
Did you 3D print the shroud? If so, could you share the file?
I'm guessing that the poorer cut you got when switching back to the 1.5" lens would be due to the shallower focal length?
Hi Steve
There was no 2 hours of 3D design and programming involved and no overnight print session. It was 10 minutes work on my toy lathe. I thought I was going to either add an O ring to get the fit or add a screw (with the risk of setting the nozzle off axis) but I was lucky with the fit.
Best regards
Russ
i was wondering with a comment that one of my associates mentioned on the air assist. i was thinking that the standard pump is a constant pumping in which the air pushed through is a cycle. would it make any difference if a compressor wws connected and the air assist is connected to it and controled flow using a air valve. that will give a constant air flow instead of pump cycle.
Would a more consistent air flow be more better in the cutting?
Hi Cary
Yes the airflow is pulsing but because of the length of pipe from the pump and the compressability of air there will never be a point in the cycle where there will be zero airflow at the nozzle. You could easily remove most of the pulsing by adding a 5 litre plastic bottle into the line to act as a non-storage reservoir (the technical term is accumulator). It may have a small benefit to cutting wood but I suspect it will not be worth the effort. I have considered it and possibly I should have tried/demonstrated it in my video. It may be worth a revisit to answer the question for all
Many thanks for the comment
Best regards
Russ
wonderful set of videos, some of which I have watched multiple times. what brand of laser tube are you running in your machines?
www.aliexpress.com/store/product/1200MM-60W-Laser-Tube-60W-co2-Laser-Power-Supply/321243_1109607209.html?spm=2114.12010608.0.0.wDQqRI
Hi Eddie
This is what I fitted to my original machine 10 months ago.(actually the 70 watt tube). I have been VERY pleased with it's performance. My new machine is a 60 watt EFR tube that was somewhat more expensive at the time I bought, That tube will be replaced by Thinklaser at the end of 1 year because that's all part of the warranty service pack.
Have a great Christmas
Regards
Russ
Thanks for your feedback
Hi,
try it with 3mm nozle distace !
cut will be more eficiency and goes faster.
burning will be better like a turbo in the car engine.
Hi Russ, great exploration of this topic. Do you think that there is some benefit to be gained by trying to get the air to flow in a more laminar way? They use this trick for water fountains so not sure if this would be the same outcome for air.
Hi Felisha
That's a fantastic idea....if only it were that simple. Sadly air is not as controllable as water. Water is not compressible so it responds very differently to air. Pop a balloon full of water and it will stay as a lump and hit the ground. Pop a ballon of air and will just expand to zero pressure escaping along a path of least resistance. Yes you can get laminar airflows but at such low velocities and flow rates to be unsuitable for our situation Airflow over an aircraft wing is a great example of high speed laminar flow where a very thin film right next to the wing surface is laminar. Laminar flow filter cabinets are the opposite extreme using a whole block of slow moving air. The only sensible way to get air into the kerf is to impart it with sufficient velocity to it so that it can bludgeon its way into the gap. You do that with differential pressure and a nozzle with as small an orifice as practical, usually with a straight tube form before the exit point and as close to the work as practical. My plastic nozzle could have been more efficient if the gap was 2 or 3 mm rather than the 6m m I finished up with, but the point was proven.
Thanks for your comment. Who knows what silly idea might turn out to be useful. It made me stop and think if this was in any way possible. Was I missing a trick by understanding the conventional flow dynamics? Was there a novel way to exploit it?
Best regards
Russ
That's pretty good for such low pressure. I run mine at 30-40 psi 20 mm/S
Where can I learn more about lens sizes? I'm a little lost when it comes to 1" vs 2" lenses.
Great videos by the way. Very informative.
Hi Brian The essence of lenses is very simple in that there are materials, diameters, form and focal length/ The materials available are Zinc Selenide and Gallium Arsenide. The GaAs is best if you have a high power tube over 100 watts say, but there seems little difference is overall performance, just more expensive. The diameter is all to do with the requirements of your machine so remove your exising lens and measure it's diameter befor ordering a new lens. The form is of two shapes. plano convex and meniscus. The first has a flat side (which you mount so that it faces down to the work) where as the bottom face of a meniscus lens is dished a bit like a saucer. The meniscus lens type has a more precise focus point and is more expensive but for general cutting performance I prefer the plano convex lens. . There are generally three commonh focal distances. This is the point away from the flat side of the lense where all the light rays are concentratedat a single point. A 2" (50.8mm) lense is a good general cutting lens but for fine engraving the 1.5" (38.1mm) meniscus lens is a bit better..
In reality there is a lot more to know about lenses and I have just started work on a massive task to examine all lens types and how well they cut and engrave. Don't hold your breath becaue it is several weeks of work.
There is a recent 3 part video about lenses if you have the patience
ruclips.net/video/5fgw5hnU8EY/видео.html
Best wishes
Russ
Hi Russ,
Love the series of videos 'Learn with Russ', as a newbie, they are really helping me.
One issue I am having problems with is foam and in particular neoprene. 10mm Neoprene really seems to be difficult to get to cut, I end up having to do 3 passes, but then end up with lots of charcoaled edges that makes a right old mess! At 60% power and 5mm/s the laser only cuts approx 3mm deep! On these setting I can cut 10mm wood without problems - even better after watching your latest video and drilling the elbow. I can cut 12mm foam ok, but neoprene is the problem which doesn't make sense as neoprene is more dense than form, but less dense than wood!
Your wisdom on these material densities would be most welcome.
Thank you.
Hi
Foam is a very sticky melty material Constant power is a killer on such materials. Instead of cutting select DOT mode. There are lots of parameters to play with but the principle is to produce a series of overlapping perforations. You may hit a good mix quickly but if not then persevere because your answer is definitely in there. Start off by setting the manual power button to max power. (for your machine 60%?) Put a piece of masking tape under omder your piece point and do a pulsetimed pulse to find out what time it takes to piece through. You will see from the masking tape if/when you have made it through. that will be onr major parameter nailed then it will just be frequency and speed.
Good luck and thanks for the kind words
Russ
Thanks Russ, sounds good, I will give it a try.
To lower my air flow , I put a valve inline to a tee connection. If I want less air, I exhaust the air through the tee. This way the pump is not overworking due to restricting the airflow directly.
If you jump tp ~116 ruclips.net/video/ZKC8Byc8y28/видео.html you will see that I have included auto switch that so that the pump is only running during a program. If this is insufficent pump "unloading " for you there is a simple alternative dump circuit similar to your suggestion that always bleeds off excess air
ruclips.net/video/3nvAuz2i6H8/видео.html
I have never bothered to implement this variation because my pump really does not get over hand hot (40 to 50C) but I a a detailed circuit diagram if anyone should need it.
I will shortly be doing a fit of an "off the shelf" kit of parts to my Lightblade machine that will make it simple for most people to implement the changes I made in #116.
Best wishes
Russ
Russ, you are the best presenter I have seen on Lasers. Thank you so much for your time and patience.
Hi, good works thanks for share.
Laser tube is 60w but what %power you used and what lens, thanks.
You use top material as focus point?
Hi Eduardo
These test have been a prelude to further experiments later in my learning journey. What I have found is that you do not need high air pressure to get an efficient cut, you need to make sure that what air you have is sent efficiently into the cut itself to blow the fumes out of the BOTTOM of the cut.. This efficiency can only be achieved if you keep the nozzle within 6mm of the work surface and also that your nozzle orifice is in the 2 to 2.5mm size range. I have measured flows in the 8 to 10 l/min doing a very satisfactory job.
Although there are a few delicate material exceptions, in general cutting will be done at the max current limit for your tube. Depending on your tube that could be anything between 60% and 85%, I then adjust the speed to get a clean through cut.
I have found that in general the best place to focus is on the surface. However in my next round of experiments with lenses I shall be investigating the slight benefits of setting the focus a short distance into the material. This does allow you to cut a little faster but the cut is wider and often a bit messier. Why? I don't yet understand, so that's one of the many things I plan to experiment with.
Best wishes
Russ
Great video , i am going too do the same , what switch are u Using for manual switch on ?
Hi Fredrik
Here is what I bought.6mm pie size. There are lots on ebay and Amazon
www.ebay.co.uk/itm/Pneumatic-Push-In-Fittings-Air-Valve-Hose-Pipe-Connector-Joiner/202544633106?hash=item2f2899d512:g:WpwAAOSwLNxcHFCv
Best wishes
Russ
as a follow up from my previous comment on the compressor option, i have replaced the typical air pump with a 24L compressor. i have an external valve control which also strip out the moisture before going into the laser with a dial valve control.
With my initial reference of using the air pump to cut 3mm plywood i can cut at 60% at 24mm/ sec. Once i swap with the compressor, with adjusting faster air flow, i can cut on the same power but cutting at 50mm/sec which is 100% faster. definitely with a stronger airflow, it definitely helps makes the cut speed faster. may be diffirent with thicker material bit for 3mm the speed is definitely 100%.
Hi Cary
Thanks for that feedback. That just confirms exactly my findings To cut plywood you need maximum power and run as fast as the speed will let you go. If you do not get enough air into the cut the smoke builds up and does two things. Firstly it reignites within the cut and causes chearing of the edge and it also absorbs the IR energy , thus decreasing the cut efficiency. Air ,Air and More Air produces a cleaner faster cut. Care though. not for acrylic.
Seasons greetings
Russ
SarbarMultimedia will try out for aceylic next week after i work out some designs for somw gifts for my client.
another thing i did on my cutter was also with regards to my exhaust system, i have enabled 2 suctions. one at the bottom and another at the back of the cutter. so with the 2 suction cleared the smoke out faster which allows better cut speed on the same pump. as what you mentioned, more smoke causes drop in cut power. so this dual exhaust and the compressor give a quite high speed in cutting.
will try out the acrylic next week on the new system and see how is the result.
Seasons greetings to you too🎉
Where might one find a pneumatic flow controller like you have on your air hose?
Hi Steve they will be all over ebay. Here is a typical for you tostart with
www.ebay.co.uk/itm/Nylon-Pneumatic-control-BALL-VALVE-hose-tube-inline-push-fit-connector-air-line-/321631499160?var=&hash=item4ae2bb3398:m:m_o3pxfpTvAUZmXPw-nquxg
You will be able to find one from China for about $1
The great thing about it it is a FLOW control that will allow full bore flow for wood etc ate strangled flow for acrylic and paper.
Bet regards
Russ
Great work. Again!!
Have you done any testing with air blowing from the top down AND from the side?
Hi Chad
This work was done during my progression towards an understanding of the physics of cutting. When I understood that aspect of cutting it all fell into place about the importance of air efficiency and not necessarily volume or pressure. I had tried bothe top and side air assist and neither were of any value.. In essence you need air in the kerf for cutting and no air for engraving (except that required to protect the lens) A very recent demonstration of how cutting efficiency is important to cutting can be seen from 30 minutes
ruclips.net/video/bh4qvwZFzg0/видео.html
The point here is that a small orifice, low pressure (therefore low flow) air assist can be very EFFICIENT if you can force most of it into the kerf. Air is a compressible fluid , thus it will always expand as it exits the nozzle orifice. The higher the pressure the more rapidly it expands so less of it gets into the kerf. The trick is to keep the work to nozzle gap as small as reasonably possible. 2mm to 3mm is ideal as is demonstrated in this video.
Best wishes
Russ
@@SarbarMultimedia Interesting. I guess I missed the video, if there was one, about side airflow.
I appreciate the video you shared in your above response. The end nozzle that you have on the lens tube came from where? Did you design it? If so, could you send me the design, or point me to where it is on your website? Otherwise, I can design one. If I do that, what is the diameter of the nozzle opening? Is it 3mm like you mentioned in a previous video from years ago? Would making a closed end, that I then burn a hole through with my laser be practical, or would the hole be too small?
@@greenacresfarms
Hi Chad
If you visit the Cloudray website and look for the C series lens tube , I have found that to be the perfect lens holder. It can handle 4", 2.5" and 2" focal length lenses that are 20mm diameter. In addition, because it has an M22x1 thread, it will take what I call a CUTTING nozzle NO3 which has a 2.5mm orifice. There is also a short nozzle that will allow you to use a 1.5" lens 20mm diameter.. PLUS you can get the compound lens kit that screws into that 22mm thread and is superb for photo engraving. The nozzle that holds these two lenses can be used for any type of engraving because it has a 6mm diameter orifice.
see
www.cloudraylaser.com/collections/nozzles-lens-tube
As I mentioned earlier, air is a compressible fluid. You need to get an adequate flow of air through the kerf. Blowing from the side or above is 99% inefficient at achieving this because the air pressure (and flow) are diluting for every mm you travel. (because the air is expanding). Your idea to make the hole smaller has merit but is a balancing act. If you make the hole small then you are increasing the pressure difference across the orifice and also limiting the flow. Ideally you want to achieve laminar flow but that is almost impossible with a small column of air. A sharp orifice will certainly destroy any attempt to create laminar flow, instead you need a section of parallel tube, typically this length will be 2 or 3 times the diameter. Generally this is not practical so 1:1 is what we have to work with. Thus low pressure, low flow and being as close to the work as practical is the ideal solution.
Best wishes
Russ
Is there a 3d printer file to make that extension? I made one by gluing acrylic together but it's not that nice
Hi Tim
As you move further into my journey you will see I have completely redesigned my head so that it now takes short and lung nozzles and anython for the short focus (21mm) compound lens to the 4" lens to suit either engraving or cutting, This temporary extension was really to prove that you must not let your air assist spread out in the big gap between nozzle and work if you are cutting, the efficiency with which you can deliver airflow into the kerf is vital for cutting most materials.
Best wishes
Russ
i have tested the gap at 5.5mm but on the same settings it seems does not have a nice polished finishing relative to if setting it at 8mm. i may need to tweak the settings to match that setting.
one additional thing i noticed that if i set the power and speed for an opaque acrylic, somehow it will not cut as effectively when that same settings is used for a clear or tinted acrylic. not really sure why but i can only conclude that the clear one the laser light can scatter more inside the clear acrylic while the opaque ones concentrate it better.
Hi Cary
That's an interesting observation and just the sort of problem that fascinates me. I'm not planning to race you to an answer but I'll put it on my long list of interesting subject to video and play with. If you find out the answer first and are happy to tell me I'll show the world and you get the credit
Have a great Xmas
Russ
Very intersting video! :)
I‘m currently struggeling with one challange I have with my laser. I‘m using masking tape and want to paint the engraving afterwards.
It apoears to me, that the paint won‘t stick propperly to the engraved surface due to burn marks within the engraving. Any clue how to improve this? Thank you :)
Hi Nils
Part of your problem is the air assist and part is your lens and power settings.
When you fire the laser beam at an organic material it stimulates the SURFACE molecules to heat up. When the temperature rises above some critical level. the material experiences a chemical change. In the case of wood it first scorches then starts to evaporate the cellulose creating flammable fumes and sticky tars. It leaves behind a residual carbon layer which absorbs the energy quickly and heats to more than 3000C (with more chemical changes before that final temperature)where the carbon then evaporates leaving behind clean wood. This whole process keeps happening layer by layer to cause and engraved surface.
When you engrave, you are converting solid material to gas/vapour/fumes which are hundreds of times more voluminous that the original solid material. Watch your engraving very carefully and you will see that the fumes squirt upwards just like a volcano. Those are the TAR laden fumes that you are blowing down onto your work when you use your air assist
The deeper your cut the more rapidly you are converting solid to fumes and in such circumstances the gas does not get a chance to explode UPWARDS. Instead , the only way for the fumes to escape the cut zone is SIDEWAYS......all over the surface you have just exposed.
You need to do several things.
1) Choose a longer focus lens 2.5 or 4"
2)Choose a nozzle with a large orifice (typically 4 to 6 mm)
3) Set your air assist to just a whisper to stop the lens from fogging up and NOT blow the fumes back down onto your work
4)Make the gap between nozzle and work surface at least 12mm ( the bigger the better)
5)Do not run at high speed or high power. Set the power to 30 to 50% and find a speed that leaves a nice clean surface
6)Make sure you calibrate and set your scanning reverse offset to match the speed you are using
7)Set your line spacing (INTERVAL) to as large as possible (it maybe 0.2mm). You do not want to double burn lines
8)Modify your machine to get a good CROSSFLOW of air ACROSS your work. see ruclips.net/video/AHnJ2WxNo5Q/видео.html from 42:20
Best wishes
Russ
Hi Russ,
Such a great video (even though its a few years old)
The extention or shroud, where did you get that? :)
Hi I was just something I made very quickly from Delrin (acetal copolymer) to explore the principle. It is not a suitable material for any real use because it will either melt or catch fire. I have done a lot more work on air assist since then.
There is only a limited amount of air you can force down a 0.2mm wide kerf and many believe that throwing 2 bar pressure at the problem gets good results. At the same time they are using a nozzle with a 4mm orifice that sits 19mm above the work. Air is compressible and the more you compress it the faster it expands when released into the big wide world. I really cannot comprehend how some people can be so illogical in their thinking. Small orifice (about 2mm), small distance to work (3mm max ) and low pressure (0.2bar is entirely adequate)
That way you can EFFICIENTLY evacuate the fumes from the cut face out of the BOTTOM of the cut.
See this video from 33:30 to see the effectiveness of distance from work
ruclips.net/video/bh4qvwZFzg0/видео.html
There are nozzles available at Cloudray .com that fit an M22x1 lens tube thread . This size is fairly common but there is no standardization
Best wishes
Russ
@@SarbarMultimedia
When having that small of a distance to the work piece, wouldnt that make the beam out of focus? Due to the focal length? :)
@@sorenac Absolutely YES...... but only if you left the lense where the manufacturer decided it should sit. How many laser machines do you think has he ever worked with? Ok so we agree. .. There are so many different lens tube designs that I cannot suggest a solution for your situation but basically you have to find a way to move the
nozzle forward to reduce the gap to the work. You must leave the lens at its correct focal distance. Depending on how much distance you need there are lens tune extenders (about) 12mm
see www.cloudraylaser.com/collections/nozzles-lens-tube/products/extension-ring-for-c-e-series-cutting-head
Check your lens tube thead becaise this only fits M22x1 thread.
Best wishes
Russ
Thank you for your video. How can I get in touch with you? I have a few questions and I need your help.
Hi
Recently You Tube shut down it's private messaging system. All you can now do is add you email address to another comment and I will immediately delete it from public view and contact you
Best wishes
Russ
It's the pressure that matters here. 70l pump generates 0.03MPa, 140l - 0.033 MPa. Since thin tubing is used, the difference in actual volume of air passed thru is relatively small. Larger diameter tubes would help, however nozzle will be the bottleneck anyway.
Hi
In the last 4 years since this video I have done a lot more study into this and I am very happy that I now understand the efficacy of air assist and how to extract maximum efficiency. The only flow that is important is the flow through the kerf and NOT through the nozzle. Many people are using large shop compressors and high pressure to achieve your goal of more flow through the nozzle. The problem is that air is a compressible medium and as these experiment indicate , the smaller the nozzle orifice and the closer you can get to the work , the more EFFICIENTLY you can get flow through the kerf. The kerf is only typically 0.2mm wide I would therefore. The goal is to get flow through this VERY restrictive channel. This is the REAL restriction in the system we and NOT the pipe work or the pressure. We all know what happens when you release high pressure air into the atmosphere......it expands rapidly. How much of that air ever gets into the kerf? As you rightly observed, doubling the pump flow rate was nothing but a waste of energy because the very small increase in pressure resulted in an equally small increase in flow. At the time my imagination overpowered the fluid physics and tempted me to try the higher flow pump. but it did teach me some valuable lessons.. My other two machine are still using the little 70l/min pumps and proper cutting nozzles. For absolute proof of this take a look at this video from 33:30
ruclips.net/video/bh4qvwZFzg0/видео.html.
Thanks for the great comment because it has allowed me to expand on your observation for others to understand.
Best wishes
Russ
@@SarbarMultimedia Your comment is surely full of useful info! I had it in my head, that if I used really high pressure (like 8bar, yes - 8bar), I would get perfect cuts with absolutely no charring. I looked through tons of compressors to suit my needs, just to find out, that anything above 30psi (2bar) doesnt really make any difference. So, I ended up with a heavy-duty airbrush compressor, which can hold constant 30psi no problem. I will fully put to use your tips on how to make it even more efficient - so thank you!
Hi Russ. Another big thanks for your hard work from the South Pacific! I'm cherry picking your fantastic selection of experiments to help with ordering and modifying a 1390 cutter from china. you've probably covered this somewhere already but have you any data on laser tube lifespan relative to it's output percentage? Should I over-specify the wattage and run at sub 100% in the interest of longer laser tube lifespan? I'm looking for as high as possible production speeds, almost solely cutting 6mm hardwood plywood, currently weighing up W4 tube @ 100-130W and W6 tube @ 130-150W. Cheers
Hi
I'm in an airport lounge killing time. I don't have access to my video files that would explain more about your tube.
If you are only cutting then power is what you need. I have used W2 W4 and W6. Personally I am yet to be impressed by a Reci tube. Very expensive an over specified. Go to the Reci website and look at the operating conditions in section 2. The 150watt headline is a max test output which you will not be allowed to do because this will over drive your tube and invalidate the warranty. The recommended NORMAL running current will give you 130 watts BUT read on an it says if you want decent life from your tube then drop another 2mA. The net result is you are paying a lot of money for what is effectively a 120 watt tube. Look at the 150 watt EFR OR SPT tubes. ...... no such strings.
For this high wattage do not buy cheap ZnSe lenses. For your application I would suggest a 50.8mm (2") focal length gallium arsenide lens. This material is suited to high watts and despite being opaque to visible light (beam combined will not work) it is still about 97% efficient.
Best wishes
Russ
Woking on phone is so limiting!!! Forgot to answer the lifespan question.
The manufaturer specifies a max drive current which you should not exceed. Overdrive the tube and you will shorten its life. Lots of myths about tube life but my contacts in China who are close to the tube manufacturers tell me that tube life is not a statistical science but more of a pragmatic guesstimate. Many Chinese companies run their tubes 24/7 flat out and this practical data forms the basis of tube life claims. The tube is supplied with a warranty and that warranty begins the day the tube is tested. Thus if you buy a tube that is new but12 months old, it will work perfectly but may have no warranty. In general you can expect 3 to 4 years of life from a tube, even if you use it at it's max normal current. The CO2 in the tube will eventually be degraded and your tube will die over a week or two.
For efficient cutting you need to run at max allowable power and set your speed to the max that will allow your pieces to drop out.
Best wishes
Russ
@@SarbarMultimedia Thanks very much for getting back to me so quickly with that helpful info. Is my bias toward higher power and cutting eliminating any possibility of wood etching/engraving? Is there a power sweetspot I should be considering where I still have decent etching/engraving capability while maintaining a fairly good rate of cut or am I starting to look at a dual tube machine? - Thanks
@@floobs73
Hi Nick
Sweet power is 60 to 80 watts. have seen some 100 watt tubes doing a pretty good job but there is no definite guarantee because no two tubes are exactly the same. If you want to do more cutting then I think an 80 watt EFR or SPT tube will work well. I would consider staying with a single tube machine because there will only be half the potential set up issues
God luck and best wishes
Russ
Thanks mate. Love your work!
You've got a jig to place material at an angle to check the "working envelope" (beam concentration) of both lenses.
Maybe you should compare the working envelope differences between a 1.5" focal length and a 2.0" focal length lens, and see if that didn't have some effect on why you couldn't get much better performance out of your 1.5" focal length lens, as maybe your thickness of material prohibited better performance because of the larger included angle of the shorter focal length lens.
I wouldn't be even a bit surprised if your cut quality drops off MUCH faster as your focal length decreases, as your angle test video displays a decided "curve" going from a "fuzzy" cut to a sharp cut,and then dropping back to a fuzzy cut as you come into and then go out of precise focus. The longer focal length lens "should" stay close to precise focus longer because it has a smaller included angle due to its longer focal length.
And given this, I wonder what would happen if one were to acquire a lens with a 6" focal length.
Could it make setting the focus noncritical, given that using your angle video and the curves displayed, that within a given range of maybe 15 mllimeters the focus would be "precise enough" to do a good job?
Would the increase in focal length flatten the curves displayed in that video due to much lower included angles?
After all, the beam at the focal point should produce an exaggerated "X" getting wider both above and below the precise focal point.
Anyways, all your videos are thought provoking, very thought provoking, and that's a good thing. I enjoy them..... a LOT.
Hi
Thanks for your interest because the whole subject of lenses is steeped in theory . The theory is well proven and tested under certain controlled laboratory circumstances, The problem I encountered was what is happening to the light intensity within the beam as it focuses and because for our application of lenses, more light intensity=more material damage. There is no research work I could track down that helps with this. Hence, I have undertaken a whole body of experimental work to try and decode exactly how the focused beam works for OUR application of lenses. There are lots of sessions between #160 and #172 that follow my progress but two in particular that will help clarify your "possibly" and "maybe" thoughts. After all my work I have no doubt about anything to do with lenses I now know absoloutely how and why they work the way they do for our application.
ruclips.net/video/zJjAr-TANQk/видео.html
ruclips.net/video/iOsVvz2zEBY/видео.html
Best wishes
Russ
What would happen if instead of 4mm all of that were say 8mm or 10mm using a 3mm orifice where the laser comes out?
To understand the answer to your question you will have to work backwards through the system. If the nozzle is going to be 3mm diameter then the flow through that orifice will be directly related to the pressure drop across the nozzle. Now I'm guessing at numbers to put some perspective on the problem. The 70litre/min pump is capable of achieving 5psi BUT that is only if there is ZERO flow. If you were to put a 3mm orifice right at the pump the pressure in the pump would probably be less than 0.5psi because that's all the BACK PRESSURE that would build up in trying to achieve this 70 l/min flow rate..If you turned that orifice into a piece of 3mm tube ,say 5m long, then I guess it would require as much as 2.5psi to achive the same flow rate, but well within the capability of the pump.Add a few sharp corners and disruptive connections producing turbulent flow and and you lose another 2.5psi. These last two losses are all due to flow VELOCITY. if you change the bore of the pipe from 3mm to 4mm you have almost doubled the area and hence halved the velocity of the airflow (not the flow rate) and these friction and turbulent losses decrese dramatically. So stick a 3mm orifice on the end of a 4mm tube 5m long and the tube losses are close to zero again and the only place that limits the airflow is the orifice. HOWEVER, try and double the airflow with the 140 l/min pump and you are now back to too much flow for the tube size and the losses go back to more that the pump can deliver (5 psi) plus the fact that trying to push 140l l/m through a 3mm orifice may now require 5psi before you start. Combine these two effects in a VERY complex mixture and you have effectively strangled the flow. This is what I was seeing with the high flow pump. The next size pipe up from 6mm will be 8x1 ie 6mm bore, this will be about 250% more area and would get back to a situation where all the pressure build up will be at the 3mm nozzle and not in the tube. 8mm tube may just about be practical, but is it really worth it when you can easily fix the existing system to extract full efficiency from the small pump?
Great question and I hope that my grossly oversimplified attempt at describing the flow dynamics has helped rather than confused
Best regards
Russ
For cleaning wood-cutting residue off the bed, we abandoned acetone or isopropyl alcohol or any other caustic liquid for common white kitchen vinegar a while ago. Seems to be at least as effective as any other cleaner but so non-toxic that it's literally food.
Great tip Steve. Many thanks for sharing. I'm not so sure about its effectiveness on the sticky acrylic condensate. Any thoughts? I'm off to raid the wife's chemical support cupboard because I'm sure I've seen some white vinegar spay in there.
Best wishes
Russ
We cut both wood and acrylic, along with other things (I believe one member tends to cut a lot of teflon-coated fabric) and the vinegar is all we use anymore.
Thanks will test and pass on...may be good for cleaning mirrors and lenses also?
Regards
Russ
i would stick to isopropyl/distilled water mix 90/10 for lens solution- i use this on glasses and camera optics and camera sensors. only because vinegar might leave more residue- also be sure to wipe away excess and always have your cloth lubricated as even cloth can cause micro-scratches but fluid does not seem to. perhaps use your air-assist to dry and blow away debris
also great job drilling the pneumatic joint- super brave.
Have you consider using a mix of air and CO2 or argon to reduce charring?
I come from a metal laser cutting background where where we used huge amounts of pure nitrogen as a cover gas for cutting stainless steel and oxygen as an accellerant for cutting mild steel. CO2 and Argon are expensive gasses and I'm not sure that their use for hobby work could be justified. The point of my exploration was to prove that the more efficient you can make fume removal from the kerf, the cleaner and faster you can cut. Max out the power and run as fast as conditions and lens will allow and you get a pretty good job without the extra expense and complications.
Thanks for the suggestion it seem to have validity. BUT if you stop and think about it for a few seconds and ask "how does the wood cutting action take place?" You will realise that wood does not MELT under the action of heat, it chemically oxidizes (burns). The clue is in the word oxidizes. I'd be pretty sure that excluding the oxygen will KILL the cutting action. I DONT KNOW for certain, I'm just using logic and experience. If you have a workshop that has the bottled gas, perhaps you could experiment and let me know the results. Sincere thanks
Russ
SarbarMultimedia thank you for your replay. I have been asking myself this for a long time. I don't have bottle gas in my humble setup. But your points are completely valid and you have the experience. Perhaps I will try in the future. I have learnt so much from your learning process. I have enjoyed every single bit of your videos. Thank you again
Russ, do your purchased thumb-drive videos include comment history? If not it should. If does please render my comments. ron
Secondly , If increasing the air volume extraction preseed increased air compressor volume would this induce change in wood edge burn and or effect acrylic edge thickness cooling and power density of cut.
Hi Ron
There are no comments on the USB..... that would be an awesome task that I would not want to undertake. The volume of extract air will have a very small effect on the cut quality. The controlling factor is the amount of air that you can force into the cut itself. Acrylic cutting is a sublimation process and needs anything from very little, when you are trying to achieve a polished edge , to half flow for an efficient cut but with more edge striations.. Any organic material cutting is by a burning (chemical decomposition ) process and needs copious amounts of air in the cut to dilute and evacuate smoke. Smoke is a great absorber of IR energy and so decreases your cutting efficiency if you do not keep the cut area free.
Best regards
Russ
Russ did receive my request to rake equity of the videos content. A comment you recently made to me "Frankly Scarlet I don't give a dam" led me believe it was a subject you might consider. If not , let know that. When is LL88. Looking forward. ron
Does such air compressor have any overheating issues?
Hi
No I have been running one for about 5 years now and on one of my machines it is on continuously whenever the machine is switched on. It is still working perfectly and gets to maybe 50 or 60 C. On my other two machines I have designed and fitted an auto air assist system see ruclips.net/video/ZKC8Byc8y28/видео.html
This system is available through Cloudray see www.cloudraylaser.com/products/ultimate-air-assist-set
Best wishes
Russ
Hello Russ, I just started following your channel as I research buying a Laser. I was wondering if you could comment on the low cost C02 lasers with the two heads that claim to have metal cutting capabilities? Google has not been much help on this. Thank you
Hi Daniel
I have a lot of experience at using and running real metal cutting lasers of the industrial type Cutting metal is a completely different technology to these non-metal cutting "engraving" machines. Firstly you will need a special cutting head for metal that will allow you to feed pure oxygen into the cut for cutting mild steel. Stainless is a completely different process because you need more power and huge amounts of VERY high pressure nitrogen. If you watch any of the you tube videos cutting stainless you will always hear the high pressure gas but never see it. Unless you intend running it as a business it's not a cheap hobby. I advise calling a local laser profiling business and request a visit to see the technology. Then you can go asking questions of Chinese machine suppliers
Best regards
Russ
Thank you, for your response it supports my belief that if it sounds to good to be true it probably is.
There are some machines equipped with dual source that could use both Co2 laser and Fiber laser. But more expensive than others.
after running some 5mm acrylic cutting, adjusting the air assist support, the difference is with a stronger air assist, the top edge of the cut will be slightly frosted compared to the bottom edge.
However, when lowered the air flow to even lesser than my original pump, it gives better flame polish finish. however, i will get flame shoot out at the bottom of the acrylic. the paper cover does protect the acrylic, so there is no surface damage. will need to explore is there any possibility on minimizing the flash flame below the acrylic while having a slow air on the air assist
Hi Cary
You were warned it's not the same as wood. The cutting action is not a chemical decomposition by burning but a direct conversion to gas (sublimation) with no liquid phase.
There are two possible answers. If you are flaming the fumes it means there is excess energy after you have cut through. You can balance this with adding a bit more air assist or run a bit faster so there is less excess energy when the cut is through. Have you set your focus point 2.5mm into the material? The second and very interesting option is to explore the DOT mode. It has some great uses and beccuse it can use high energy intermittent pulses it can do great things with difficult to cut materials like foam which would normally melt away or catch fire.
Best regards
Russ
SarbarMultimedia my focal distance is 8mm from the tip of the head. I have the adjustable laser head. I did try to increase the speed but I am getting banding problem on the slightly higher speed. I did see my lens has a small slit hole through the coating. It may be causing the unusual banding problem. So one of the main problem is even if I go slightly faster, I will not get the nicer polish edge finish. Will try out some other settings once I finish with my current projects and my new lens arrive. Also got a new set of k9 mirrors. The price of the set of 3 is between MO mirrors and the silicon mirrors. Will see how that one turns out.
Hi Cary
8mm seems an odd distance What focal length lens do you have?
Be VERY gentle with those K9 mirrors. The are basically a crown glass base with a gold flash on the surface. There are not very durable and if you break through the gold, the glass underneath is fully absorbent of the IR radiation, will heat up and crack.
Best regards
Russ
SarbarMultimedia my lens is a 20mm FL50.8mm and the manufacturer came with a 8mm spacer for that original lens. my original mirrors are MO mirrors which i notice is beginning to have a darker shade in the middle. Probably will measure the depth of the lens again. but last time i did a focus test and 8mm seems to be the smallest beam cut.
Anyway now i no longer user a spacer but using a filler gauge and caliper to measure exactly 8mm and then use that filler gauge bundle to correctly set the gap😁😁
To cut 5mm acrylic you will need to reduce your gap to 5.5mm. That will also allow you to go faster.
Best regards
Russ
Compressed air is better right?
Hi Michael
Take a look at this more up to date video which should answer all your questions
ruclips.net/video/79VZjMdfBmI/видео.html
Best wishes
Russ
so maybe consider checking all the air pipe fittings to see if they could also benefit from boring out to 4 mm?
It is a valid point but I know these fittings pretty well and simple elbows and straight couplings will not suffer the same issues . The main reason the swivel elbow was designed the way it was is because it contains an O ring seal in that small bore section. I suspect my 4 mm hole is pretty close to the bottom of the moulded O ring groove. Luckily it didn't break into it or I would be looking for another tube fixing solution!!! Not all machines will be piped the same as mine so it is worth checking your machine, especially any swivel fittings.
Great comment. Many thanks
Russ
no worries.. every mL counts in efficiency :)
Hello Rush ... is it possible to do quality photo engraving with dsp aw708c lite.merci ... DOM
I bet their are glass blowing companies in the UK that are struggling with sales. If they made laser tubes, we could buy them cheaper (no import TAX) and they could make a nice profit!
Hi Andy
millenniumlasers.co.uk/assets/laser-tube-specifications-ml20-150-1.pdf
No prices available
Best wishes
Russ
Hi all does anyone now the model of compressor that is in the video
Yes Mark Its a Hailea AC0 009E
Best wishes
Russ
Scientific Method 101 : Change ONE parameter at a time!
I agree but there is a 101A that I use for short cuts when I know roughly what to expect. If that expectation is not realized then it's back to 101.
Thanks
Russ
Russ without attending classes where would a lip moving reader learn Coreldraw.
You Tube will have hundreds of videos on this subject
I had no clue you could cut ply, and not burn the edges...
Hi Phillip
A lot has happened between then and now and just recently I revisited the subject of air assist. You may like to check this out
ruclips.net/video/79VZjMdfBmI/видео.html
Best wishes
Russ
@@SarbarMultimedia Hello ! I actually watched part of it, before watching this one. My father in law "always" drains the air out of his tank at the end of the day. We're in the Mid-South USA, and it gets very humid here. I'm anxious to get back and try cutting with my 55w Monport laser. Been busy engraving powder coated tumblers for a week. Thanks for all the videos too.
To much work has to be done to these machines.