NEMA 17 stepper focus motor?

[Jeffc]

I have a clement focuser with a robofocus (RF) motor. The RF motor is too slow for the clement.

Here's a post of someone replacing the RF with a Nema 17 stepper. I'm thinking of doing the same.

https://www.cloudynights.com/topic/4068 ... 11-review/

Does anyone know if the pegasus UPBv2 can drive regular off-the-shelf bipolar steppers?
The documentation seems to indicate this, but I'm under the impression the RF uses 12v on the coils while the stepper spec I looked at used 3.6v.

Thx for any pointers or info.
(I'm not very knowledgable with the details around steppers... I understand the principles, but not the myriad of specifications.)

-jeff

[Evans]

CloudyNights reply is correct. Most motor can work with higher voltage and provide higher torque.
Although, it is advised to better use a NEMA stepper motor that works with 12V in its specs.
If you check http://stepperonline.com you can find a suitable one
This is because the motor can draw more current than 3.6V requires and the stepper controller might not be able to provide this current level.

[Jeffc]

Thx for the pointer to stepperonline.

I'm reading the UPBv2 manual and see this on page 8 (https://pegasusastro.com/wp-content/upl ... l_v1.5.pdf)

> Controller can only drive unipolar & bipolar stepper motors. It can support max 2.4 Amps (1.2 Amp per phase).

I see the 1.2 amps / phase.

However, I'm unclear on what voltage is used (which would determine the current draw of the stepper).
Is it 12v?

Assuming 12v, then yes the steppers rated at 3.6v / 1.5amp will draw much more current at 12v.

Ok.. so checking stepperonline, there's not a lot of 12v steppers in the popular with low current ratings Nema 17 form factor.

I did find a nema 14 rated at 12v , 0.4A , 30 ohm coils. This seems to be well under the rated 1.2amps for the UPBv2.
The holding torque is 20 oz. in., but the focuser I have has nearly zero lift required -- the clement has spring hinges and a lead screw for adjusting the focus requiring near zero effort to move.
(I was looking for something with a bit more holding torque, but I think think is ok for this purpose.)

Btw, The nema 17 motor I happen to have is rated at 3.6v and 1.5amp/phase.
If I understand correctly, this will draw too much current from the UPBv2.

thx.

[Evans]

The stepper controller of UPBv2 provides 12V to motors.
I recommend this 12V rated motor: SKU: 17HS15-0404S.
The 3.6V will work (current draw should be fine for the UPBv2 controller) but as I haven't tested it I cannot recommend it

[Jeffc]

Thx Evans.

That's what I'm thinking also.

-Jeff