I’ve seen references to people using a drag knife to cut through leather, but I wasn’t sure if that was possible for leather up to about 3mm. My laser cutter goes through it just fine, but I was looking for a cleaner edge by using a drag knife. Are there any other options for my CNC?
Interesting use. There are different blades that can be used. I would think the drag knife I sell could be used up to about 1.5mm, I think. But there are some that use exacto blades or larger. There is even one in the forums that has a tangential stepper to steer the blade depending on how fancy you want to get.
I have one of your drag knifes, but I wouldn’t consider it for the leather application. A quick Google search turns up a few homemade and purchasable knives, although none of them look like they’d “cut it”. The other posts I’ve seen might have just been cutting through much thinner leather; this is for large knife sheaths. Thanks!
Disclaimer: I’m a drywaller.
Have you tried a drywall or wood cutting bit and adding a lead in? You would probably have to pull the leather pretty tight and use tabs so things don’t get “interesting”.
Not cheap but pretty much what you are looking for, I think…
I had wandered across links to the Donek, but didn’t really see them in action like that. Thanks for the video! I think it would probably do better for the larger cuts in the leather and it’s a very good option to consider.
Ultrasonic knife would be ideal
@Doug, those are pretty cool! Now if Ryan would just add that to the store…
We had a rep bring one in to my last job, we got to play with it for a while. You know when a rep is sent out with it it is a little complicated and a lot expensive.
Did the drag knife with MP CNC manage to slice thick leather?
I actually have seen the professional CNC leather cutters, they use either a very stout drag knife or a “Pizza” wheel. Infact one system used the same wheels that you could buy at JoAnn Fabrics.
Wouldn’t it work fine with a regular wood bit?
Just use some double sided tape or some kind of easy to clean glue, stick your leather to a wood plank and mill it with a wood bit.
Not sure if this option works fine since I never tried, but I don’t see any reason why it shouldn’t.
That is pretty much the exact type of system that the Professional CNC Leather cutters use.
What kind of edge did the laser cutter make on thick leather - got any close-ups? And what kind of laser do you use?
I think a stepper to control the angle is unnecessary if you give it a bit of “castor”. Do this by putting the blade point a smidgen behind the vertical axis of rotation (same way a castor wheel works).
If you look at videos of deep cuts with sharp turns, they change direction by lifting almost out of the leather, so that only the very tip of the blade is still in, the blade can then spin as it is dragged in a new direction for a millimetre, then the blade is plunged back into the material for another long and deep cut. Does anyone know the easiest way to generate the G-code for this manoeuvre?
Another question is can it be done with the MPCNC? Understandably, there are a lot of heavy lateral forces in cutting leather and the taller the drag knife and longer your z axis and legs, the more diabolical this is going to be. Obviously blade quality will also be crucial.
I have not finished building my MPCNC yet, but I have already designed a new drag knife if anyone wants to take a look and maybe even try it. It uses 3D printed parts, 2 skateboard bearings, a magnet and 3 M4x30mm bolts and nuts.
Here is pic and a link to the STLs on Thingiverse
The laser left a burned edge, but it’s pretty clean. I’m using a K40 laser, which is a 40-watt Chinese unit. Sorry, but I don’t have any pictures of the few tests that I ran. I was able to make some fairly small and clean holes, so it could do a good job.
I’m sorry… I just saw this. The corner actions from that Donek video is explained quite well on this page and video. They have a free download of an Xcel spreadsheet which will add those corner actions to your gcode.