I'm new to the group and I could use some help with a problem that I'm having. I just built a new cnc machine and I keep running into a problem that I can't figure out. I've been doing some test cuts, problem is they always come up short on one end. I thought it was a backlash problem so I put the dial indicator on the machine and ran it to an inch. It came up like .040" short. So I tried adding a backlash command to the ini file and that didn't fix it, so it wasn't a backlash problem. Then I tried messing with the steps and finally got it to come out right. Run it to an inch, dead on 0, run it back to 0 and end up dead on 0 again. So then I run the program again and the whole thing is now to long. It always seems to come up short on one end. Checking the math the steps are right, I have a 20 tooth pulley on the motor and a 40 tooth pulley on the leadscrew, running in full step mode, so that comes out to 1600 steps per inch, which is what I have in the program. It's almost like it's a compounded problem, like it's off a small amount but then when you cut through the whole part it adds up. But the weird thing is that it's off on one end. The part I'm cutting resembels a comb, where you have slots cut into the part every so often, there's a wider section at each end, on the far end it's right, on the 0,0 end of the part that wider section is to short.
I'm using an older hobbycnc driver that I've had for a number of years, it's not one of the newer pro boards. I've done a number of checks and backlash doesn't seem to be the problem. Any help anyone can provide would be greatly appreciated. Chris http://www.blowyourbrassoff.com http://www.builderofstuff.com http://www.myspace.com/builderofstuff http://www.myspace.com/builderofbluesharps Just a man, his shop, and a long list of unfinished projects... ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
