Hi all,
I’m looking to replace the below stepper motor. I saw on this post there were gear mods required. I’m hoping to find a direct plug and play and have found three very close matches. (CW-Motor do not sell the original any longer).
I’m struggling to come to a conclusion on which would be most suitable having come to my limit of smarts with this kind of thing…
Any pointers would be greatly appreciated.
The dimensions and amperage etc are as close as I can find.
This is mine:
Here’s an ugly secret: the motor in your machine was whatever the factory had on the shelf when the tech screwed it into place. They had that particular motor because they ordered a couple of pallets from whoever had the best price on NEMA 23 motors a week earlier.
Bottom line: if the shaft diameter, length, and flat length match, the motor will work just fine.
CAUTION: They all have a 6.35 mm shaft, which seems very very unusual for a machine built anywhere other than the USA. Are you absolutely certain the shaft on your OEM motor is 6.35 mm = 1/4 inch, rather than 6.000 mm?
Despite the picture of its flatted shaft, the HS motor says nothing about a shaft flat. I’d avoid it just on that basis; you can always file a flat on a shaft, but it’s tedious.
I have no idea why the all-black HP motor is more expensive than the silver-and-black HS and HE motors.
Thank you, a great insight!
@PhilG what small drive gears did you order in the end - do you have a link?
As you mentioned, these are NEMA standard motors and these sizes are standardized, at least that’s the theory. NEMA is an American standard.
I would expect the dimensions to be English based. But as typical… it’s not very clear where these came from.
Data-Sheet-Stepper-Motor-Support.pdf.txt (839.0 KB)
I’d replace it with someones else’s NEMA at a lower cost…
Good luck
That’s certainly true for the bolt locations, but anything about the shaft will be a free variable: that data sheet puts a 1/4 inch shaft on the NEMA 23 and a tidy 5.00 mm shaft on the NEMA 17.
Trust, but verify! 
The attached drawing was just emailed over by CW-Motor, quite a few differences between the proposed replacements I linked to and this original.
57BHH51-280A-25C-1样本.pdf.txt (106.8 KB)
What’s worse, it appears the 90deg screw rotation location in the drawing doesn’t appear to be so in the photo… 
The motor shaft is
The diameter is so far different from the 6.35 mm = 1/4 inch that you (presumably ) measured as to suggest they just sent you a random stepper motor diagram with no relation to what’s actually in the machine.
All the electrical specs are similar, simply because all steppers of that general size have similar electrical specs and will work in similar applications.
Yikes! I’m not sure how I would ever have successfully troubleshooted that problem. Good on you!
Hi Simon thanks for your reply, did you change the stepper and then find it was the relay. how did you test for the relay, my machine is moving slower since i replaced the stepper and only half way across the bed, how do i check the relay, Sam
Hi Sam, I didn’t end up replacing the stepper as I found this burnt out number 7 connection (rotary switch) and decided it may be somehow related. Swapped the black relay over with one from ebay and hey presto, fully working again!
what was the problem with your laser, was only 1 x or y axis working, i turned my machine off sent to homing position and it crashed, shut it down and moved arm to right, then tried to move down and it would not move, thats where the problem started, was it the same for you, interested… sam
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