Z Axis Motor Selection

Running a stepper via pulley to the quill pinion.
My first attempt using a Nema 23 381oz/in 3.5A motor 1:2 ratio. The motor only groaned.

With the pinion removed, lifting the quill with a scale underneath read 17lbs.
Turning the pinion end, with a torque wrench, lifting the quill, read about 3lbf, or 48 ozf.

I dont understand why the motor wont turn ?
Have 381 motors 1:2 ratio, running X and Y, no prob.

I tried using the Stepper Motor Calcs xls spreadsheet, but was stumped at the Load Inertia and Load Torque part.
Its setup for leadscrew, not rack/pinion (pulley/mass).

I dont feel like guessing at this point. A larger motor, Nema 34 will also require purchasing a separate driver.

Do you have a photo?

I have an SX3, cncfusion kit, and a 906 oz motor at 48v on the Z from cncrouterparts, driven by a G540.

If I've understood other threads, its de-rated to just over 500oz. No gas strut or counter weight yet, but it does move the head nicely. Not up and running full time yet, but close. I don't have any of the resistors in on the Z axis. Using the pre-made DB9 connectors w/resistors, also from cncrouterparts, on the 380oz motors for the X and Y axis.

Doh,
Just figured out what you're moving and its not the Z axis. Apologies.

Curious why doing the quill instead of the entire head? My mill before installing the motor was a pain to raise the Z.
But please, post pictures! This idea using smaller steppers only sounds intriguing. A nice way to save a few dollars between the motor and the Z ball screw.

Sorry not to follow up.
Purchased a separate BOB and driver for a NEMA34 1230ozin stepper. rated 11.3W
Though rated at 5A, Im pushing 5.5A thru it.
It does move the quill, its torque to drill or mill isnt enough. I could do better w/ a hand drill.
It will drill aluminum using 1/4" through 1/4", but feedrate has to be F1.5. I had feedrate at F3, it would stall.
Crap !
The driver is 6A, PS is 48V 7.5A.
Now to purchase another motor, which should have done the first time.
NEMA42 3256ozin, rated 32.6W. 6A
If you really believe any of those ChiDingaLing motor specs.

Why not use a higher gear ratio, 10:1 or more? You can achieve that with a chain drive.

Quote:

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Originally Posted by kNucklBustr

Sorry not to follow up.
Purchased a separate BOB and driver for a NEMA34 1230ozin stepper. rated 11.3W
Though rated at 5A, Im pushing 5.5A thru it.
It does move the quill, its torque to drill or mill isnt enough. I could do better w/ a hand drill.
It will drill aluminum using 1/4" through 1/4", but feedrate has to be F1.5. I had feedrate at F3, it would stall.
Crap !
The driver is 6A, PS is 48V 7.5A.
Now to purchase another motor, which should have done the first time.
NEMA42 3256ozin, rated 32.6W. 6A
If you really believe any of those ChiDingaLing motor specs.

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11.3W? Are you sure? That's very low. As is the 32.6W.. The driver would output 288W (at 48V) (U x I -> 48V x 6A)

Quote:

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Originally Posted by hub

11.3W? Are you sure? That's very low. As is the 32.6W.. The driver would output 288W (at 48V) (U x I -> 48V x 6A)

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New motor- NEMA42 3256ozin,
6A
14mH
5.44 V
32.6W

Max driver- 6A

Quote:

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Originally Posted by kNucklBustr

New motor- NEMA42 3256ozin,
6A
14mH
5.44 V
32.6W

Max driver- 6A

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That's a LOT of torque for just 33W... It doesn't make sense to me.. I have never seen anything that low power vs that high torque. 3.3k ozin = 23Nm torque.
Something must be wrong...

Quote:

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Originally Posted by hub

That's a LOT of torque for just 33W... It doesn't make sense to me.. I have never seen anything that low power vs that high torque. 3.3k ozin = 23Nm torque.
Something must be wrong...

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Heres the motor purchased w/specs- Nema42 Stepper Motor3250oz

For example, a JVL 21Nm (2974ozin) stepper is rated 9A 80V, which is 720W.
If 6A & 5.44V gives you 23Nm then that's great! Lots of power save.

Quote:

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Originally Posted by hub

For example, a JVL 21Nm (2974ozin) stepper is rated 9A 80V, which is 720W.
If 6A & 5.44V gives you 23Nm then that's great! Lots of power save.

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You're saying that 48v, instead of the 5.5v, should be used to calculate W ?
Then it would be 288W.
But still a null point, considering 1) max amperage of driver, 2) no room for a 1:3 pulley.
3) last bit of money Im throwing into this setup.

Quote:

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Originally Posted by kNucklBustr

You're saying that 48v, instead of the 5.5v, should be used to calculate W ?
Then it would be 288W.
But still a null point, considering 1) max amperage of driver, 2) no room for a 1:3 pulley.
3) last bit of money I'm throwing into this setup.

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I had a closer look at the specs in the link you gave, it says 6A / phase and 2ph, so it would be 12A. And it says 4.8V rated.. That would be 57.6W.
I'm just guessing here, but I seriously doubt that 4.8V is right.

If it works well, you're fine, but if not I would try more voltage by slowly increasing until performance is good enough.

Hub

Why don't you calculate how much torque you need before spending money on the big motors? It's a simple gear ratio calculation. Assume you need at least 100 lbs of downward force for drilling.