[Poppey]

Hi,
I'm getting finished with my slant bed cnc lathe with atc turret.
Just hooked up the stepper motor on the 8 tool atc turret.
The tool change is done by activating an air cylinder, than turning the turret 45 deg by a 2 pole nema 23 stepper motor. Holding torque is 220 N.cm. 4.2 amp.
The problem is that the motor can not hardly turn the turret.
I have tested the turret breake out torque to be. 14 N.cm(10 kg at 7 cm). I pulled it with a fishing scale.
The turret is timing belt driven with a ratio of 2:1.
I have set the driver to 4,2 amp and 10x microstep. Power supply is 48 vdc.
Are there any changes I can do with the drive set up? Use Mach3 turn. 125 steps per unit that should turn the turret 45 deg. Speed may be set to fast 600 units/min?
Bigger motor or a gearbox?
Thanks for any advices.



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[Jim Dawson]

You might try 1/2 step, you should have more torque that way. Also, it this is a new and tight installation, you might try just running it in jog mode for about an hour in each direction just to seat things in a bit better and loosen it up..

[Poppey]

You might try 1/2 step, you should have more torque that way. Also, it this is a new and tight installation, you might try just running it in jog mode for about an hour in each direction just to seat things in a bit better and loosen it up..

Thanks Jim,
I trid it but see that the torque is 700 N.cm which is far beond the nema 23 motor. I need to find a way to soften up the turret. There may be some misalignment or something after I stated to operate it with the cylinder. There are two roller thrust bearings and one small ball bearing in the plunger side. Otherwice there are two bronze brgs that may be out of alignment. The turret is screwed together of plates, the same is the lathe.


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[RCaffin]

Try reducing the speed to 1/10th and see what happens? And cut the accelleration down as well!
Cheers
Roger