Finally got my MPCNC build. Started printing the parts over 2 years ago, but never had the time to really build it.
I think I still have a little problem some where. When I checked for squareness it didn’t look good at all.
The biggest problem and easiest to fix was a loose pulley. Check them all and they are tight now.
Next where the steppers skipping steps. I use a Ramps 1.4 board with old A4988 stepper drivers. (bought the set in 2017, but never used it before) The stepper motors I use where listed as 2.5 Amp and “compatible with 42BYGHW811” Maybe these are a big much for the A4988, but should do fine with the MPCNC only running slowly without load. I have the A4988 close to max with a vref of 1.8 volts.
Now I can run the MPCNC repeatedly through it’s full motion and always end and the marks I made. Looks like that fixed that problem too.
The only thing left is the accuracy. When I mark the corners of a 400x400 mm square with a 1 mm drill (more accurate and less work than mounting my wobbly penmount) I measure close to 401 on both X and Y. With Y a fraction less than X. Even 401 mm is close to expected 400 mm, but I thought with the belts, pulley’s and number of steps that 400 mm would be easy to hit.
Any idea where to look for a fix?
Thanks,
Rob.
MPCNC Primo
x=675 y=600 z=81
V1CNC_Ramps_Dual-2.1.1 firmware
Mega 2560 R3
Ramps 1.4
A4988 stepper drivers r100 = 0.1 ohm
2004 controler LCD