Platform CNC | Making a Drag Knife
HTML-код
- Опубликовано: 17 сен 2024
- I have always wanted to develop my own drag knife to cut cardboard, wood veneer, paper etc... In this video I 3D print and test a prototype and then mill the final working knife out of aluminum.
---
I figured I had better add a mechanism for sending out the cadwork for the Drag Knife since there has been so many people asking for it. I though this might be an interesting approach!
www.grunblau.co...
Please allow 24 hours for me to send you the files!
The bearings you will need are 1/2" ID X 1.125" OD bearings found here...
www.vxb.com/pag...
I made mine tonight from a 3/8" aluminum plate that was anodized black. With the exception of snapping an 1/8" end mill (and chip welding the HELL out of the another), I still managed to get good results. Also, this was my first time cutting aluminum on my CNC. Thanks for the plans Brian. The experience was well worth the price of a beer.
I started making the parts today from Brian's drawings. Looks good, I bought the beer and had the files within 12hrs. Thanks! Made the bearing holder pieces tonight and hope to cut the main blade holder tomorrow if all goes well. Once I get it all built I will try to post a video of it in use! Sure beats spending $200 to buy a ready made one! Gerald
I started testing my drag knife based on Brians's design and right out of the gate I had issues with the knife not tracking properly. Well it turns out that while grease in the bearings is good for hi speed usage it creates far too much drag in this application. I pulled the dust shields and cleaned the bearings fully of grease and just used a very light oil. Tracking response of the blade is now very very good. Gonna look for some ultra low friction bearings to use in my final build. Gerald
Thank you for showing your mistakes! It's amazing how much you can learn from mistakes over our triumphs.
Finally I have a need for a drag knife, was happy to buy a beer for the plan set! Thanks for the work you put into documenting your projects, always visually appealing to read over.
Your videos are great. I would recommend something different than wd40 as a cutting lube though. Give Hornady oneshot cleaner/dry lube a try. It works amazingly on aluminum and acrylic. Actually produces a better surface finish than flood coolant on aluminum when used on my manual machines or my Tormach.
Hi Brian,
Thanks for sharing your design and creating the video. I just looked at your router design and it is beautiful and priced very well. My son and I are building a router this summer from scratch and I wish I had seen your machine as I would have jumped right in and ordered. I just bought you a beer and the drag knife will be one of our first projects!
Thanks
Brooks
Is there any one willing to share the file with me please can you send it to my email adres 4fietsen@gmail.com thank you very mutch for sharing.
This is a great idea, obviously I bought you a beer. Purchased one on your other plans as well. It is cool when people that know share. I am still new at this so it helps a lot. Cheers
Fantastic! Blow the suds off this one! Looking forward to receiving the files.
Very cool drag knife, I especially like the process of development so glad you put it in the video.
Bought the beers!
Ready to see the goods as it looks like a fun project to build!
Amazing work and professional result
I have one comment not regarding the knife but regarding the process of cutting
When the tool broken and you stoped the machine before the machine go back to zero it suppose to make the Z-Axis to go to its maximum height before other axis or maybe you will damage your work piece in other projects
You can modify this option from your sittings
Wish you all the best
This one is on me !
Can't wait to receive the file. It will be a nice tool for my upcoming holiday projects.
Fantastic. Beer bought, looking forward to the cad files.
just found this and love the build! Beer bought and looking forward to making something based on your design. Thank you!!!
Hey, thanks!
Hey We're you able to get this cut and built ? Currently looking for a drag knife for my new CNC.
Gladly bought you a beer for the files for this amazing knife Cheers!!
+Steve Pitre Where are these files available for purchase? Did you just email him?
Up at the top there is a link to buy him a beer then he sends you the files
i had the same idea i just didnt developed more i just got it in my nid draw it and the i just left it and now i see you making something that i had in my mind wow good job very nice work
Also just bought you a beer, hope it takes good. Looking forward to the files.
Roger
Have a beer on me, my friend! I enjoyed this video and have decided to invest in this tool for my company. Thanks!
The next round is on me - just sent you a beer. Thanks for sharing your design.
Brian, thanks for making plans available to us and at a fair price. Beer money sent your way.
Suds up... :-)
Chris
I watched this in 2013 and said to myself that I would buy the plans for this when I got a cnc machine... and I just bought you a beer. :)
Thanks so much for making the plans available. I laid out plans based on your drawings/post on one of the CNC forums. Cut the first test in some scrap Baltic Birch today. Came out nice. Plastic then Aluminum will be next. Being as how I'm copying your work. I will go to your link & buy you a beer.
(BTW, your CNC is fantastic -- both metal and MDF. Wish I was rich.)
Beer up Brian, you got another coming, thanks for sending plans. :]
You've got a tall frosty Schlitz headed your way! Thanks
That was hugely informative and entertaining! Never thought of using WD-40 as a cutting fluid! I just sent you a beer. Enjoy!
Beer sent! Looking forward to building this.
Beer sent. Nice design. Looking forward to it.
Nice! Beer money sent. Looking forward to the drawings
Thanks for this! Cant wait to get the file! Just ordered bearings, and on my way to get some aluminum sheet.
I am sure you may have heard by now to always ramp and use 3d tabs on harder materials.
Good luck and have fun!
Do you have more pics of the unit to help with assembly?
Beautiful job. Would you be willing to share or sell the plans for the drag knife?
Sent you a beer, looking forward to the file of the drag cutter.
This is great. Did you ever try the acrylic version to see if it worked?
It would be great if you'd shared your drawings for this.
I'm gonna rip a page out of your book :D
Thanks to you showing us your mistakes I have a much anticipated project to start!
How is the angle of the knife rotated? does it just rotate on it's own because of the direction of the XY Travel?? if so what is the offset of the knife tip with respect to the center of the ZY zero point. You probably can't cut circles smaller than this offset???
I am asking for an explanation?
The tip of the knife point is offset from of the axis of rotation. This way the knife drags and can freely rotate on the assembly, which aligns itself along the travel vector as it cuts through the material. Once the knife is plunged into the material along a path until the cut is complete, and will continue raising and plunging the blade to complete cuts on other lines within the design.
The gcode generated for drag knife use compensates for the knife offset by overshooting on sharp corners so the knife tip is in the corner as it moves the head assembly and rotates the knife to the new travel vector.
So you'll see travel paths that overshoot and swing around sharp corners to prevent the knife from cutting material it shouldn't.
EX: www.cambam.co.uk/forum/index.php?action=dlattach;topic=1244.0;attach=3231;image
And yes, you can't really cut shapes tighter than the offset radius of your axis of rotation. The other issue is the type of material your cutting and the likely hood of tear out due to how little travel the cutting blade makes.
@@brandtleymcminn when watching the video, it looks like the knife is actually turning with the motor, is it truly just turning on its own due to friction?
I'm pretty sure the "Cricut" machines you find at sewing and craft stores use the same drag knife concept
When doing drag knife operations, the software generating the tool paths arcs the carriage in a circle around the point of the knife so that it "turns" the knife when it's dragging though the material.
Donek tools calls them "corner actions", and they have a video that explains how most drag knife systems operate ruclips.net/video/tNMvzJu9VO8/видео.html
Enjoy the beer. :-) Do you have any suggestions about CAM? I use Sheetcam and I understand it can accommodate drag knife tooling, but would appreciate any suggestions.
Just bought a beer as well! Waiting on files!
Nice Work
Would love to see more videos of the machine itself in action. (Various things being cut out) Been trying to push myself to buy a CNC for years now but am in that awkward ring for the woman stage so I'll get shot if I don't do that first. Currently debating on the platform or on of the procnc kits from routerparts.
+Hugh M (SPECTER) buy a decent cnc and make her a ring with it ;-)
I sent you a beer Brian - looking forward to making this knife
+steve pudney Files sent!
its probably been mentioned, those two hold downs are backwards. some may say it doesn't really matter, and in this type of setting it probably isn't an issue. though, just thought I'd mention it.
+Phillip Craggs Thanks for your comment! I sort of use those hold downs in the best way that fit what I need them to do. This orientation gave me a better location on the stock than the long way since the threaded inserts in my spoil board are predetermined. It might also have something to do with how much thread I had available on the bolts. Whatever gets the job done!
What if you inverted the printed parts? Have the spindle grab a metal rod inside the bearings, and the printed support on the outside. This way plastic would be considerably stronger.
Nice work Brian...
Did you design the tip of the knife exactly on center, or slightly of center?
Thanks! The tip of the blade trails the center by 1/8" The other thing I learned is that the vertical edge of the front of the blade is also needed to aide in the rudder effect.
Brian Oltrogge The vertical edge of the front of the blade? I'm not quite sure what you mean. Do you mean the dull side of the blade that pears into the paper should not be vertical?
The dull edge (trailing edge) should be vertical to act as a sort of hinge and to maintain a constant interaction with the material no matter the depth. Hope this makes sense.
It does make sense Brian, I understand.. :) Thanks for sharing the knowledge buddy !
Brian Oltrogge Brian, does your cutting path software have automatic compensation for that 1/8" trail, or do you work it all out by hand?
i think the plastic version wouldn't have broken if the lateral forces could be reduced. so, just before sharp turns, if the knife could be lifted just to pivot on the surface it can orient itself freely in the direction of the cut. then plunge down and continue. however for such a thing there would have to be some smart gcode generation where it knows when to lift. just thinking aloud..
What I don't understand is that spindles have high quality bearings with minimal run out. Chucking a drag knife into one means that any forces/play are also affected by the spindle. So why put a bearing assembly into the drag knife? why not just chuck a knife holder and let the spindle chuck rotate? not seeing what I am missing....
Try rotating the spindle with your hand. The mass you need to push is a lot more.
This is really cool! Thanks for making the file available!
You bet! Good Luck with your build!
Hola, excelente, el motor que sostiene a la cuchilla esta energizaqqdo como para girar hacia la direccion de corte? Si es asi, podrias explicar como es su conexion con la placa por favor? Muchas gracias.
Thanks very cool, I really like your buy me a beer idea. I would have bought you a 12 pack for the plans, $5 is very fair. Looking forward to building this.
Great video mr Grunblau/Oltrogge. Did you superglue the alum. to the painters tape, too? or just tabs? Your CNC router is well built
Nice cutting. Do you lift the cutter a little bit in every change of direction?
I don’t believe so. The tool path was written with the drag knife add on for V-Carve... The engagement with the material is partially required for the rotation of the knife.
Great Video thanks for share...Gretings from Merida Mexico
Really inspiring! It is really great to see how you executed a concept on your cnc machine.
I am confused about the shanks. It appears your milled end has a square shank. How did you make it round to fit in the bearings? Also, I don't understand the opposite .5" shank that goes into the router. Is that just a piece of drill rod? How is it fixed to your tool?
Yes, you are correct, the knife part is a square shank. This is then slightly chamfered and pressed into the round holes of the bearings. I will likely epoxy and fill the moon shaped openings between the bearing ID and the shank. If I had the benefit of a lathe, I would use smaller 3/8" ID bearings, and turn the shank to fit. The shank that goes into the tool is aluminum tube that is press fit with epoxy into the top piece of aluminum. Thanks for the comments!
That was really cool, thanks for sharing!. Machines building machines...
Beer sent. Thanks for sharing!
Have you considered using a roland type vinyl cutter knife. It would allow for more intricate cuts.
my thoughts exactly. What is the purpose of building a when you can mount a vinyl cutter knife to your cnc?
Brian,
Shutmymouth genius.
I don't know what you're drinking that costs 5 bucks a throw: mine is 5 bucks for 3 gallons... I sent one your way anyway, but feel you are going to get way more beer than you need to be consuming.
Send me a plan for this when you wake up. ;^)
--
Davod
@Hooked On-CNC
To quote from "The Princess Bride": "I doan theen 5 dollarth meanth what you theen it meanth..." :^) Even if you got nothing other than the warm feeling of rewarding a fellow cnc pioneer for designing, implementing, filming, and posting his inspiration, it would be worth the value of a 5 paper USD.
(However, you do get the plans too... mine arrived within 8 hours. I got one each of: 3dm, dxf, and stp files. My MeshCAM software can only read the dxf, and it not properly, but I can see the design well enough to know something will be able to read them.) [Note to Brian: STL too? Thankth.]
Cheers!
Is there any way you could see if you could make a glass cutter out of the parts from the drag knife? I would love and buy the plans for that!
Hello, great video! Quick question - how come you used two bearings opposed to just one? (to get more shaft engagement b/w the bearings and the rectangular "shaft"?)
Thanks! Two bearings limit the play that a single set would have. If you cut a section through the shaft you would see four bearings in the section rather than two. The further these bearings are apart, the more resistance to rotation there will be. -|:|- vs -|:|-|:|-
@@Grunblau Thanks for the reply! I see - did you try just one bearing originally?
Brain Oltrogge, Where did you get that collet for the Porter Cable? I have a similar set up, just bigger, but I appear to be running the same router you have.
Sean G Hi Sean, I actually did a video showing when I converted the collet. It can be found here ruclips.net/video/qLWxyy5XKJwM/видео.htmline is from PreciseBits.com...
For your sharp corners, do you add extra cuts? Since the blade contact with the material is behind the axis of the router spindle, to make sharp corners, do you travel the spindle past the cut, then lift up, move, then start the next cut early to align the blade? It's kind of hard to explain but I think I saw something like this when I was researching the Donek drag knives
Yes, the CAM software compensates automatically for the trailing blade.
+Brian Oltrogge That's good. Props to you for building this yourself!
Brian,
nice job! I bought you a beer and looking over the plans. Just have one question. How is the knife holder retained inside the bearing? The knife holder is a square shank. Square peg in a round hole.
Thanks! Can't wait to build one.
What are your thought on this Brian?
The square shank must be rounded off on the corners as required to allow it to be press fit into the bearing. I made the shank a little longer on mine so I would have more room to hold it in a 4jaw chuck on my lathe for turning to a snug press fit. Easy enough assuming you have a lathe. I used a very small TAIG lathe for this. Gerald
Any information on how the shaft is being made *and* attached to the upper bearing holder? I don't see any Screws securely attaching it to the bearing holder.
Also... From the looks @08:33 it applies as if there's nothing but friction or heavy use of Locktite that could prevent the blade holding piece from falling out of the bearings?
Not much use showing interest in making one of these when the plans ask for tools I'll most likely not have in my possession =)
looks like there is a small ridge that the down slope of the blade buts into, and then screws pinch it tight. with the right amount of screw torque the hardened knife blade will dig into the soft aluminum too.
Love it, I may make one!
Brian Oltrogge! I appreciate your wit and pointed me in buying the design project! The Carries buy when you and my new CNC in my new little shop! I would like to know what format are the digital files! Greetings! I subscribe, I hope any advance contribution to our CNC router to contribute to the wider use of them! More than this, my deep gratitude for their generous project! Worth more! But even thank !!!
I am designing something like this for a alternate head for my Laser etcher (2w laser cutter). I see that the design changed allot from the 3d printed to the milled version. Do you think the new design would hold up better than the original printed design if also printed? Was the printed one ABS or PLA?
a question, the knife is being moved by the motor, or is following the movement of the axes of the engines?
Great design! Got your plan. I am using cambam to generate the tool path. What is the aluminum stock thickness you are using?
Great video! Can you please provide a little more info on the machine itself? I'm looking to either build or buy a machine that can cut coroplast, wood, and aluminum (max thickness of 1/2"). Did you buy or build this unit? How much does it cost? Can it cut coroplast, wood, and metal? Any information and/or guidance would be greatly appreciated. Thank you in advance.
William James Hi William, I designed and built the machine. It is a Platform CNC and I do make kits for them. I don't really advertise the kits as I can only do about 12 of them at a time and I don't want to start a long waiting list. I do about one run every 2 months and take deposits on the slots. It is first come, first served. Search for Platform CNC, for more info. Yes, it can cut everything you mentioned...
Brian, its a really nice job... im designing a similar one to be fitted by standard cutter blades (heavy duty olfa blades) my aproach was pretty different but yours looks much suitable to me, cause i dont have a lathe but i do have a cnc router. Im really interested in a piece of the workflow that you didnt show, how did you fit the blade holder shaft right into the bearings
The aluminum rectangle that is formed at the end is just larger than the ID of the bearings. I put a tiny chamfer on the edges and pushed it into the bearing. I will likely JB Weld it in there as a forever solution once I am okay with giving up those bearings to the project.
Got the files really fast, unzipped and all fine !!...thks Brian !
One thing I wouldn't assume....what did you used for the round shaft ??
and if i may, is it press fit in the upper bearing !!?.or.....how is it all assembled ?!
Thks, Robert
rmesvp The round shaft is a bit of 1/2" OD aluminum that is press fit flush into the top of the bearing holder with a bit of epoxy. Hope this helps!
Brian Oltrogge Yep....very much,,,Many thks for this and all....Later
can you email me the file?
Jonathan Lowe See the comments above. Brian is asking for a "beer" $5.00 and he'll e-mail it to you. And is quite quick to respond. www.grunblau.com/BeerBMO.htm
The files you send will I be able to create tool paths using V Carve pro? Also I was thinking making it out of that PVC board Star board material do think it will be strong enough ? When using the drag knife and creating tool paths you have to use profile only correct..I want to cut leather with it thin stuff .040-06 thick..Do the drawings come with a material list for the bearings and what ever you use to attach to router?
That is so cool!
hello brian can you just tell me one thing?
the piece that you made in aluminium that suports the knife is rotation works by the router our by the movements that the cnc made in the X and Y axis?
Did you test the acrylic knife? If so, was there a difference in cut quality between aluminum and acrylic?
No, I didn’t. I think it would probably suffer the same fate as the 3D printed one, unfortunately….
Brian,
Got the plans, thanks. I know I watched somewhere and saw where you showed what the material was, Aluminum 6061 but I cant remember what the thickness was, looks like 1/2" or 5/8". When I brought in the STL file into my Aspire software, it looked like the thickness of the blade holder on the outside was very thick. I'm sure it's pilot error, any help appreciated.
Like I said, pilot error, was so into watching the CNC work that my eyes did not see the writing on the video. My bad, I'm good to go. Will post when I make one for sure.
Hey Brian is this Your Machine And If it Is What Would It cost About and great videos by the way
I get that you enjoy your beer but... Why don't you sell this as a completed product also? Would it be to cost prohibitive?
Did you make the entire CnC apparatus yourself? I've considered making a router wood/aluminum cnc myself. Yours seems very elaborate and nice.
+Jason McKinney Thank you! Yup I made it myself. Building your own CNC (or assembling a kit) is a very rewarding and enjoyable thing to do.
Looks like a good design! I'm tempted to try something similar.
How close to the center axis is the tip of the blade? I guess it must be slightly behind center in order to drag properly - while at the same time not too much, in order to maintain precision. How did you balance that trade-off?
The software compensates for the drag of the knife. It will go beyond the corner by the length of the offset and then swivel in an arc to the next direction. If I remember correctly, my offset is 1/8"
+Brian Oltrogge Makes sense, thank you. I also assume there is some friction in the axel holding the knife keeping it from turning while traveling without cutting. (I own an X-Carve, and are trying out different ways to use it. )
Good work!
Hi Brian- I milled out the drag knife from your plans! They were awesome! What are the settings you use in Vectric Dragknife toolpath gadget? Thanks!
This was just a guess on my part, but they worked pretty well for 1/16" thick cardboard.
The settings were...
Cut Depth + .06"
Swivel Depth .02"
Blade Offset was .125"
Number of passes = 2
beer bought. I would also love to get the plans. Thank you very much.
Sent!
Great !!!
Me too am ready to buy the plans for the drag knife
I find a similar donektools drag knife, but it is too expensive :-(
Please ;-)
Hi, what software do you use, how do you tell spindle to turn when change direction of cutting?
nice video - I'm using the same tooling - 1/8" 2 flute and 1/4" o flute. Just curious what were your spindle speeds?
Could I have a set of the prints are the model file of this drag Knife. I work at a local university as a temp. and would like to help the students out. They are staring a sewing class and we have a cnc router that could make this. I think this would help cut materials for the sewing class to make clothes out of?Thanks for the video and the idea, and mostly for sharing with us here in tube.
so how does a drag knife work? Does the router turn the blade or does it do it on its own when the cnc goes in a certain direction?
This is Awesome Brian, Just bought you a beer, can I ask what cad program did you design this in, I'd love to come up with some gadget like this to make and sell but I just cant come up with any ideas. Can't wait to build mine. Thanks . Graham
Graham Prinn Thanks Graham! I design most everything in Rhino 3D and use RhinoCAM for the tool paths. For some things I use Solidworks, but Rhino is much more free form. Good luck with your drag knife!
Even if you already have enough beer, I send a bootle for a state of emergency.
Can you advise on the way the top goes together? I am trying to convert the .dxf you send to Vectric VCARVE, which is a learning experience, but the part that I don't yet understand is how the shaft attaches to the drag knife. Is this just a metal rod presses into the bearing from the top? and then the post on the drag knife is pressed into the bottom, and the two bearings are "sandwiched" in the two pockets of the bearing holders?
+Bruce Lunde The metal rod is pressed into the top cover with a bit of superglue. It only goes the depth of the top. Only the square shank of the blade holder should interact with the inner raceways of the bearings.
Thanks Brian, and I read the .txt file (that was included in the plans) I had missed before, where you explained it already!
At what rpm did your router run?
Cool project, and thanks by the way.
brian, what did you do to control the wood router to turn at precise degrees? how about the software u used?
AllForTheGame The knife swivels on its own using bearings. The CAM program adds a small swivel movement at the corners. I intend to make a tangential knife as well at some point. That one will actually be controlled by Mach3.
Brian Oltrogge Nice work!! for a tagential knife you will need a different more advance machine or head, or is just the software??
Buying that man a BEER!!!
Haha! Thanks!!!
+Brian Oltrogge hi for the file to work with my router do I do? I can reply on my email russo7000@gmail.com thanks.
Cool
what brand of endmill are you useing for the 6061, seems to cut like butter
devilmastah The 1/8" endmill is an off the shelf Freud solid carbid 2 flute cutter. I know that there are more specialized cutters with coatings specific to aluminum, but for $19 a pop it isn't the end of the world when they break. The 1/4" endmill is a Onsrud O flute for aluminum. Problem I have with it is that for small pockets like for magnets, it will leave a bump on the floor of the pocket as it doesn't have a true flat end.
Great knife setup. Just getting into CNC world and getting a lot of ideas. What is the device you have the drag knife mounted in? I know it is not a router and am keen to know so I can look to include in my CNC build.
Thanks in advance!
its a normal router...
Okay, thanks for that. just looked slightly different.
yeah its a trimmer router from bosch, routers like that are also available from akita and de walt
Thanks for the awesome work!
Have a nice beer :p
HOLA SALUDOS DESDE CHILE, CUAL ES EL PRECIO PARA FABRICAR UNA.. PARA COMPRARLO..!!!
Thanks for the video...off topic question: name of the melody, the first melody?
How many RPM did you use por aluminium?
And what CAD CAM software did you use?
Im trying to make my own drag knife to!
Manuel Vicente Pardo Alvarez Good question, I think it was around setting 3.5 ish. I tend to not change that a lot. Higher RPMs and I can't stand the sound, lower and the router will drag down on heavy cuts. I'd guess around 13,500 RPMs
very nice, thanks for sharing