Upgraded leadscrew now stepper stalls on Z axis. What are my options?

[Swarfing]

Al

i used the same steppers with 12x3 square thread on less voltage than you on my last machine and got good results. Yours should be fine so some tweaking in EMC2 looks like a turn before splashing out. You would be better off spending the cash on ballscrews and nuts with better rails and bearings. Throw us you config for a look and let us know if your motors are wired bipolar or uni?

[Jonathan]

Throw us you config for a look and let us know if your motors are wired bipolar or uni?

Config will be useful. He said they're wired bipolar parallel, so that's good.

Yes I agree ballscrews will be a better upgrade, however to answer your question those 3Nm motors are good. Especially with the PM752 drivers and 70 volts, but for your size machine 50V and PM542 will be fine - you'll find them a lot cheaper on eBay.

I have some of those motors too. Their inductance, 10mH, is very very high for that size motor so they will never go particularly fast on only 30V. You can get round that by using pulleys to lower the motor speed for a given feedrate, i.e. put a big timing pulley on the motor and a smaller one on the screw. Ideally HTD pulleys. But wait and see what the configuration is first...

Your screws are 8 TPI, so the pitch is 3.175mm, but they're 4 start so the lead is that multiplied by 4, which is 12.7mm. Have you entered 3.175mm in EMC instead of 12.7mm? If so then the Z-axis is actually going 4 times faster than it says which probably explains why it can only go 'slow'?

Probably stating the obvious, but check that you can spin the screw freely by hand and that there's no tight spots?