4th axis brake enquiry

[BobTSkutter]

Would a closed loop stepper motor be any use? I would have thought the "closed loop" would prevent un-requested movement and behave a bit like a brake.
regards
bob

[marbles]

Would a closed loop stepper motor be any use? I would have thought the "closed loop" would prevent un-requested movement and behave a bit like a brake.
regards
bob

I suspect the answer is probably yes but the gear thats on it isnt too bad, its not closed loop though.

Current 4th set up
3DM860, 24~80VAC 30~100VDC 7.5A 20KHz PWM
Nema 34 , 8.5Nm, 5Amp
80V + 600W switching power supply.

[m_c]

Would a closed loop stepper motor be any use? I would have thought the "closed loop" would prevent un-requested movement and behave a bit like a brake.
regards
bob

Yes and no, would be the answer to that.
The big benefit of using a closed loop stepper in this application, would be they do tend to self correct to a certain amount so would move the stock back into position, and they would let you run things far closer the motors limit, however any movement could still scrap the part.
It's a case of balancing up your needs, and what compromises you can make.

I have just thought of one option if you don't need much speed, how about mounting a stepper onto a cheap rotary table?
They should be adjustable for backlash, and they'll give you lots of gearing in a compact format

[marbles]

Yes and no, would be the answer to that.
The big benefit of using a closed loop stepper in this application, would be they do tend to self correct to a certain amount so would move the stock back into position, and they would let you run things far closer the motors limit, however any movement could still scrap the part.
It's a case of balancing up your needs, and what compromises you can make.

I have just thought of one option if you don't need much speed, how about mounting a stepper onto a cheap rotary table?
They should be adjustable for backlash, and they'll give you lots of gearing in a compact format

I was in the workshop today trying to learn how to program simultaneously 4th axis and had a bit of wood on the 4th. When I put some pressure on the edge of the wood I can see a small amount of movement at the motor. I’ve got a digital driver on that 4th and wonder if it might also ‘have a go at’ self correcting, not as good as a closed loop thought i’m sure.

From the movement I could see it looks like the wee pulley on the motor needs some mechanical advantage help so I think your idea of the rotary table might be better. I see people using 30:1, 100:1 gearing, what kind of gearing is on a rotary table. At this point I wish I knew more about mechanical engineering. ..

All things considered was pretty surprised my attempts without using specific kinematic actually worked to program some simultaneously 4th axis action just using a basic mach3 post processor?!