After about 2 months I wanted to start on a new laser project with my K40 and I found a mouse nest under the laser-bed. Although it was a nice nest, one of the building materials were wires in different colors. A better inspection showed that the wires from the stepper motors plus the safety-switch wires have been removed and used as a building material.
I have taken the gauntry out to replace the wires but I saw that they were soldered directly to the stepper motors so I was thinking of just replacing the stepper motors with new ones. These are the old ones:
Now I have found some new stepper-motors online, the standard Nema 17 ones but I read that the are Bipolar. I don´t know what that means, can those be used or would you recommend other stepper-motors?
That’s perfectly fine. Bipolar means they use two coils and four wires to control them. That’s the most common type and 99% sure also used in your laser.
The NEMA motor number gives the physical size of the motor, but doesn’t cover any other specifications.
The “17” means the motor case is (about) 1.7 inches across and has mounting holes on a 1.7 inch circle.
You must also match these to your existing motors:
Case length → so it fits in the same place
Shaft diameter → so the pulleys fit
Shaft flats → so the setscrews seat correctly
Maximum winding current → for the same torque
Winding resistance → for the same power dissipation
Motors with longer cases generally have longer / more motor windings, so it can produce higher torque for a given current. Matching the case length means the motor will have approximately the same torque, even in the absence of any other specifications.
The motor winding resistance should be on the order of a few ohms. Back in the day, before cheap microstepping drivers, you could get motors with high resistance windings intended for crude full-step drivers that didn’t work with microsteppers. Those days are likely over.
Protip: don’t deploy “poison” traps, because the mice will crawl off into your walls to die, whereupon the tiny carcasses stink for months until they desiccate.
Thanks for the info, there is not much information about the standard stepper motors besides the size I measured. I didn´t measure the thickness of the shaft, thanks for the reminder. I found motors with the same size so they would be ok I think and they are not that expensive.
And yes, I will place some mouse-traps. We live in an old farmhouse and mice are quite common here. My wife didn´t want me to kill them so I got some friendly mouse traps and they work great with peanutbutter. I have to drop them off around 2-3 km from the shed so they won´t find their way back in…
The switch from “Wow, I’m impressed by your building skills, Mr. Mouse” to “I recognise that earth wire you thieving b*****d” has me howling with laughter. Thank you!
We live in an old farmhouse and mice are quite common here. My wife didn´t want me to kill them so I got some friendly mouse traps and they work great with peanutbutter. I have to drop them off around 2-3 km from the shed so they won´t find their way back in…