- I've got a stock Taig CNC mill with their controller and I'm trying out Mach2 after using
TurboCNC for quite a while. I'm running into an intermitant motor slippage problem on
the Y axis. It appears to only hapen during rapids and when it does, the motor just stops
untill part way through the rampdown. This doesn't happen at all in jog. X and Z seem to
be holding up ok so far. I've adjusted the max speed and acceleration down several times
without much improvement. The slippage happens at various points and the table moves
smoothly by hand so I don't think it's a mechanical problem. I did not experience this
problem with TurboCNC but I don't think it was running quite as fast.
I tried the search function here but it doesn't seem to work well in this group. Maybe due
to the high message traffic ? In any case I was wondering if anybody has compiled a list of
"typical" tuning values for various machines or configurations ?
The problem is that your machine is too slow. Your running in constant velocity mode. Mach3 tries to maintain it's velocity while turning a corner, so one axis has to start moving before the other one is finished. The best way to fix this is to increase acceleration. But there are other options.
In General Config, enable "Stop CV on Angles>" and set it to 89. That should help.
You can also try running in exact stop mode. At higher speeds, it can cause a lot of shaking, but it might not be too bad at the slow speeds you're moving at.
Your combination of 425oz motors and .1" pitch screws is a very poor choice. Those motors have very high inductance, and can't spin very fast. Those screws require high rpm's to get decent speed.
Switching to 380oz motors and 1/2-10 5 start screws would give you at least 10-15x better performance.
----- Original Message -----
Sent: Saturday, August 02, 2014 5:44 PM
Subject: [mach1mach2cnc] Motor Tuning
I am finishing a home built cnc router with plans and parts from buildyourcnc.com 425 oz/in motors, single start .1" lead screws, ab nuts. Want to make wood signs, mostly cedar. Presently have x and y set at 20k steps, 18" velocity and 2.5" acceleration. It seems to be switching from y-direction to x-direction too soon resulting in rounded corners. I wanted to attach a pic but not sure how. Will start a photo file called Capnbobbo.
Any advice or comments welcome and appreciated.
This email is free from viruses and malware because avast! Antivirus protection is active.