Stepper Motors Power On Kick Sound

[Cartierusm]

OK, so when I start up my system I turn the computer on first, then launch Mach 3, then turn on a power strip which turns on the Keling Drives, Keling Motors and Motor and BOB Power supplies. When I do this the motors make a sound like they are twitching or clenching, hard to describe, not a bad sound but a sound like it's gettting power. Now I'm not sure how steppers motors are built, but I know this is not a problem and completely normal. Now I've switch the unit on while watching my Laser Center Finder on the gantry and it actually doesn't move at least not move as far as the eye can see. So what is really going on? If I bring my gantry to 0,0,0 before I turn it off for the night will this kicking move the gantry out of it's position. I'm asking so I can get it set up perfect and just bring it back to 0,0,0 every night. Thanks

[YZF]

The sound is the magnets and the coils inside the stepper aligning with each other once current is applied to the coils. That's pretty normal. Your gantry may come back up at the right place or it may not, once you power off there is nothing holding it in place so a truck passing by could cause it to move slightly or gravity could cause your Z axis to move down slightly. It really depends on your setup and how much movement you care about.

[Cartierusm]

I care about a lot of movement, but my machine is pretty isloated. But what I'm concerned with if the magnets and coils aligning actually move the motor spindle. Thanks.

[ger21]

I think that when you turn on the drives, the motors will move to the nearest half or full step. Not 100% sure, but I think so. So most likely, your motors will turn a little when you turn it off.

[Cartierusm]

That's what I figured, but at least I'll know it's close.

[YZF]

Originally Posted by Cartierusm That's what I figured, but at least I'll know it's close.

Being a bit nit-picky I hope it's ok...

It may actually move as much as two steps worst case ... If it doesn't move on its own and you power it off at exact the same phase the drive comes up with it shouldn't move at all. You can check the phase with a voltmeter on the step motor wires (measure between A and A/ and B and B/).

Another way of looking at it is if you call your power on position (0,0,0), move back to (0,0,0) and power off. As long as you don't drift more than 2 steps away you'll be exactly at the same position...