[strangetanks]

So this is my 4th cnc router build. Putting the machine through it's paces making some saw horses and it's acting very strangely. Designed in solideworks, toolpath generated in mastercam and running mach 3 on my cnc machine. Pretty much the same setup I've used before with no problem, but now its doing this. At first I thought I was losing steps or something, but I can run the same gcode again and it hits the exacts same spots on the next run. I can't figure out whats going on. The picture was of a nested bunch of parts on a sheet of plywood. So I ran the part by itself and it did the same thing.

The toolpath on mastercam and mach3 looks perfect and doesn't reflect this weird tool offset.

Attachment 336716Attachment 336716

[awerby]

Do you have backlash compensation turned on? If so, Mach3 will add steps to the toolpath, which can cause anomalies like that.

[strangetanks]

Well...in case anyone stumbles on this thread for future reference. I have 2 motors on my Y axis. One of the pulleys inside the 1 to 3 gearbox had a bunch of swarf at the bottom of the setscrew thread from its fabrication and was slipping. So it was racking the whole x axis every time it changed direction. What had me so confused was that it repeated the same thing over and over and looked like it was a problem with the toolpath and not a hardware problem.