Nema 17 motors from Mcmaster-Carr. Are they worth it?

HI all. I just wanted to see if any of you fellow reprappers have any experience buying stepper motors from Mcmaster-carr, and if the quality of the motor justifies the price? In my current core xy build I planned on reusing the stepper motors from my wanhao i3 which are:

42HS34(L)-0954-JA05 (0.95 amps),
and
42HS34(L)-1204-JA05 (1.2 amps).


I planned on using the 0.95 amp motors as the xy and extruder motors, and one of the 1.2 amp motors for my z axis, with the duetwifi powered by 24 volts.

But after receiving items from Mcmaster that actually matched their spec sheet exactly I am tempted on spending the extra money to make sure I get what I paid for, instead of relying on questionable spec sheets and buyer testimonies.


According to the duet wifi wiki/instructions these motors are not optimal, but I was going to test them out and set my motors' currents at 80% or whatever the manual tells me to do and follow the established convention for driving motors and see what happens. Or am I better off just finding quality nema 17s (if there is a notable difference in quality between the ones on amazon vs McMaster-Carr )for the xy and extruder and calculating the needed torque to move my print bed in the z direction and going from there ?

I

In a word: No. I tend to use OMC motors (https://www.omc-stepperonline.com/) which are quite reasonably priced, actually have data sheets, and are easily ordered on-line. I've also used SureStep motors from Automation Direct (https://www.automationdirect.com/) which are pretty nice but a little more expensive. That said, I've also used a lot of random eBay steppers (Wantai, etc) that are pretty good, but like you say, it's a little harder to know exactly what you are getting.

In any case, using the motor specs for calculating loads is a little tricky even if you are given a speed-torque curve because they usually only give a single curve, typically with a supply voltage of 24v (you're in luck!). The curve will be lower for 12v supplies more commonly used. I use 19v laptop supplies, and I've got zero chance of finding a 19v torque curve. Also keep in mind that you typically want something like a safety factor of 2 on the torque when dealing with stepper motors.

Edited 1 time(s). Last edit at 11/15/2017 01:44PM by LoboCNC.

No. McMaster will provide high quality components, but they tend to mark that kind of low-volume stuff up tremendously. They don't list the brand you will be receiving on their webpage so you cannot perform a cost comparison - but if you were to order a stepper motor from them I am confident that you would find they charge 60-100% above more direct suppliers.

If you want a quality stepper motor I would probably look at Misumi or AutomationDirect; but I've found the low cost Chinese Steppers (OMC in particular) to be very good as well.

Running an $80 stepper with a $4 A4988 doesn't seem particularly smart. I'd personally only worry about stepper motor quality if you need very good linearity when micro-stepping, and are also paying $100-300 on the drive.

Thanks for the advice. I will shop around.