@clayD reached out about cutting 4mm coroplast on the cnc with a drag knife. I have no idea what coroplast is but clay says it’s cuttable with the knife.
@bwatt do you want to do some more experiments with the drag knife?
Is everyone available Friday evening?
I’m posting this publicly because anyone is welcome to join.
I’m available on Friday evening. How about our typical 7 PM at ASMBLY. I’ll bring my SST Drag Knife
Coroplast is the corrugated plastic that the bandit signs that litter our street corners are made of. I have an unfortunately endless supply of that stuff.
Thanks for following up guys. I booked the machine for 7. I’m not sure if I’ll be able to attend yet.
The guys are on for tonight, and it should be a great experience. Stop by and join them if you have a chance. Besides seeing the drag knife in action, you’ll get to hang out with an amazing crowd!
I’ve done some work with a drag knife. The thickness of what you are cutting is a key issue. I’ll try to be around tonight.
The SST drag knife actually makes that much easier (it’s got an on tool depth adjustment) than most. I was very pleasantly surprised with mine
I have an inexpensive one from dogriver and it has 2 fixed point adjustments. The sst one sounds nice
Although James can’t make it sadly, I’ll be there with my SST Drag Knife, but if you’re thinking I can tell you everything you need to know to use it, I can’t, I’m clueless and leave it to others to drive-the-drag.
I will be there too. I bet between the all of us we can figure it out
Don’t be me: edit the gcode to remove spindle start up, lol.
I don’t think I will make it, so I came here specifically to say this! A drag knife at 18,000 rpms is dangerous and frightening!
(VCarve writes the g-code with a “speed 0” and “spindle start” command. But our controller doesn’t recognize the "speed 0” command, so you get spindle start at the default speed!)
Regarding what I was saying about thickness: I was trying to cut thick single sheet cardboard, ~3/16” thick, using Joe’s drag knife (which I should really return to him some year). The design had some fairly tight turns (I was trying to cut a puzzle), but the trailing edge of the razor was lagging in the turns and tearing everything up behind. I really needed a thin, nearly vertical cutting surface.
The coroplast is much thicker than what I was cutting, so your cuts are going to have to be correspondingly gentler.
Fun was had by all who attended, @clayD @Kasper and @bwatt. When I arrived Clay had already put down his 4x8’ sheet of coroplast on the large CNC. First Clay brought a custom pen attachment which we used to test out the CNC path. Clay had already created a toolpath using the VCarve drag knife gadget so he tried that first successfully. Next he cut out two ghosts also using the gadget generated toolpath too. Finally on “JOY” he shifted to a standard VCarve profile with ramped lead ins, and drag-knife corners. Both approaches worked just fine, yet some small places had to be hand cut afterwards. We were cleaned up and done by 9:00 PM. P.S. We might have left the spindle speed set to 0.0 instead of its normal 300.0 - if you in early on Saturday and could check and adjust it that would be helpful.
And
