To start off, here is a link to the machine I recently built http://www.cnczone.com/forums/diy-cn...build-log.html I should mention also that the only other wood I have cut was mdf which cut just fine, nothing like this. Today I have been trying to cut out parts on veneer plywood, which I know can be tricky to cut, but I have been having terrible problems. Ill first discuss my setup then show problems. I am using a BRAND NEW white side 1/8 inch upcut bit and mach3, while generating toolpaths with cambam. To get this out of the way, I doubt cambam or mach3 is the problem.
So I starting cutting a mdf plywood type of wood that looked like mdf between two sheets of very thin wood, at 16,500 rpm at 30 ipm with that feed rate or anything calculated. The surface splintered so much that it looked like utter crap, but for the most part I could sand it all down and other than the missing spliters the edge quality was fine, not nearly as good as I have seen from others. I thought it might just be this weird plywood.
Tried 3/16 inch straight flute, better results (random design)
Thinking it was because of this weird plywood, I cut again on high quality 3/8 inch birch plywood, and it was the biggest mess I have ever seen. I tried with both 3/16 inch straight flute and the 1/8 upcut and same results that is in the picture.. It was barley even cutting, rather just getting all stringy and looking like ****.
At this point you are prabably cringing at that quality. Yet I am hesitant to say that this is not the worst.
I tried to problem solve by messing around with feed rate and spindle speed, and I found that I can get no splinters but still quite a bit of fuzz and stringy chips when I go 80ipm at 21,000 rpm. Good, but still not anywhere great. However these were simple squares. picture not uploaded
I went ahead and went back to the mdf plywood material and cut at the rates I found to work the best, and this is where my hopes were crushed. There was no splinting and surface quality was much better but still fuzzing up when cutting against grain (compare fuzziness to first 3 pics) but the actual accuracy and precision of the cuts was unbelievable.
The small slots...yeah those are suppose to be rectangles (with rounded edges of course) but I dont even know what the hell that shape is. All I know is that going from 50ipm to 80 ipm made the cuts go from crap, to well, worse. Its hard to imagine this is backlash, because I am using 2 start percision acme rods with anti-backlash nuts on all axis, so the entire machine has be structurally weak and move alot, although it seems pretty rigid. Whatever is causing it is preventing it from even completing the cut, not finishing the corners off. Also on the gear shown below, as well as every other peice, it leaves a nasty line where the separate layers are, regardless of the speed. I was hoping I could machine at least 100ipm but I cant even do 80ipm without rectangles looking retarded.
Any advice? I know a compression bit would probably solve the splinting and fuzzing, but it wont fix the problem with the inaccuracy going at 80 ipm and I dont want to spend $70 on a small bit that will probably break soon. I want to try to use the upcut bit I have, but I can get a white side 1/8 straight flute bit if it will improve it alot more. But more importantly I want to address the problem with the cutouts not being rectangular, and why a medium speed of 80ipm is affecting my machine so terribly.