Prepping for a 24hr Lemons Race in September and I need decals and numbers.
Bought a cheap Roland style drag knife and some vinyl.
Designed/3d printed a mount for the drag knife to mount to my Dewalt Collet with adjustable spring tension.
Having a radius problem on corners and curious if anyone could help with the current tool definitions or if there needs to be a new tool for drag knives. The blade of the knife is slightly offset from center, so the machine needs to go past the corner a bit before turning. (about 0.8mm past)
You can see in the photos that the corners are a bit rounded.
Any ideas to get crisper corners?
The other issue I’m having is if I have it cut the whole 0.8mm vinyl in one go, it’ll leave a little tab at start/stop points that doesn’t get cut. Possible to have it cut over the beginning point slightly?
I currently have it set as a single flute, 1mm diameter, 0mm corner radius.
Should not post this in the Beta area. You will have limited viewing.
Little tab: I think MillMage has a lead-in and lead-out option somewhere in there. Sharp corners: Not possible. Think of a car pulling a trailer or you dragging a piece of rope. Turn the corner and the trailer tracks the inside of the car tracks. Draw it on paper and you will see what I mean. I do not think drag knives were ever intended for precision cutting.
Hmm, any way to switch this post out of the beta area?
The sharp corners can definitely be improved. The blade just has to go past the corner the distance of the blade offset. The offset is how much the tip is offset from the center of rotation. As it drags past the corner, it aligns the cutting part with the next line. It then curves to the next line and continues having the cut align square and perfectly with the next line.
Lots of other software can do it. VCarve, Fusion 360 with an add-in, KiriMoto, cricuts are pretty dang precise, ESTL cam, etc…
I played around with a bunch of things last night. Most promising(Free) seems to be Kiri:Moto. See attached for what Kiri:Moto made and the imported sketch into millMage.
Seems like millmage could do this pretty easily with a tool offset or new tool type.
A little more advanced feature; when going around a tight corner, the material will tend to bunch up. So most of these other softwares have a feature where the knife lifts out a little bit so just the point is touching at the corner as it rotates. When continuing on, it plunges back down.
Yes, but then the line after the turn will be in the wrong location. You would have to backtrack the offset before proceeding in the new direction. I imagine the drawing would need a spike at each corner.
MillMage is a CNC Mill control software, although we would love to have it control any CNC based machine. Some operations can be easily adapted to MillMage, but a drag knife requires special operations. The Cricut is the only item you listed I know for sure has this capability. MillMage is brand new, so it needs time to mature and grow. The market will decide what direction.
Also, you find those Kiri:Moto corners acceptable?
I’m going to add that I’m not the only one in the team who’s excited about drag-knifes.
Nice job with the design of the collet holder!
With the Lead-In and Lead-Out options, you are definitely on the right track for self-rotating knifes like yours, but I didn’t have a chance yet to try them myself.
They are currently only available in LightBurn, and on the wishlist for MillMage.
