bent stepper motor shaft

Hi guys, im assembling my prusa mendel i2 and i noticed today that my steppers have the shaft a bit bent.

The only one that is straight is the one for the extruder.

For z i wont bolt down the stepper so they can move freely to compensate the wobble.

For x and y i thing that the belt tension can compensate it.

Im not going to buy new steppers now, i have to recover some money first

Do you think that i will have troubles?, should i try to get them straight?, any hints on how to do it without taking the motors apart?

thanks!

stepper shaft bent, I'd be asking why. possibly the motor is damaged and has been dropped. personal experience, throw it away before you spend a lot of time with issues

it was my fault.

i wasn't careful when i removed the original pulleys.

as i said, cannot afford new motors now, so, i will use them and see if they are broken, if so, i will get new ones in a month or 2.

Living in Argentina is not easy for a tech geek.

sorry that is a real bummer, but still you should just wait. if you are insistent, a trait i am sometimes, then do this, take the motor apart to remove the rotor shaft from the stator electromagnets.





wrap the rotor shaft in tape, as any and i mean any dusk or metal contamination will completely destroy motor

grip shaft from close to rotor as possible, then grip other side, bend back strait, or take entire bent end and place it in vice to angle the bend to be going into the vice, then tighten vise and straiten out. this may work, be careful, you are weakening the metal, and if it is not precisely aligned then motor will get damaged in use.

I did the same on my Prusa motors. I spent a long time getting the shafts true again using a pair of locking pliers.

I have my least straight motors on the Y axis with only zip tie supports and the straightest on the extruder. In the 7 months I've had it running I haven't had a bit of trouble because of the motors.

perfect!,

thanks guys!

I thought I was told never to take apart a stepper motor because it will lose performance (torque). Not sure why (magnetics would be my guess) and it also makes me wonder how they are built in the first place(??). Sounds like you guys have pulled it off and still had functioning stepper motors. From another forum on the web and don't if it is true:

"This topic came up in another group. The stator acts as a magnetic "keeper" for the rotor.

Nothing like running an experiment to know if something is true or not.

I had a motor I didn't care for (MO62-FD04), so I ran dyno tests on it that showed 112 in-oz low-speed torque. I removed the rotor for 5 seconds, then replaced it and re-ran the dyno test.

The low-speed torque now was 70 in-oz, or only 62% of what it was before disassemby.

You may not notice the loss in torque but it is real and it is there."

that is interesting. from personal experience there should never be a reason to take it apart, if there is then just through it away, as there are too many problems that happen. But sometime with buget constraints we have to do things different.

... older steppers aren't so 'sensible' for dismanteling as modern high-torque hybrid types - here you need a special methode with centering iron tubes, that 'shortcut' the magnetic fields and prevent high field gradients on the edges, that will permanently weaken the magnet poles in the rotor ...

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

If you are talking about those recycled copier steppers with metal alloy pulleys already fitted - there are plenty for sale on fleabay - then the best way I found to remove them is to shatter the pulley with a cold chisel. Place the pulley on a solid object like an anvil or the back of a good vice and give it a few quick raps with a big hammer and cold chisel. There is no risk of bending the shaft or damaging the motor if you only hit the pulley and it will split the pully easily.

---

_________________________________________________________________________________________

Richmond, New Zealand
Thingiverse ~ YouTube

I use a nut splitter to the same effect.

---

Help improve the RepRap wiki! Just click "Edit" in the top-right corner of the page and start typing. Anyone can edit the wiki!

Thats exactly how i bended my shafts

Next time im going to use a nut splitter



Wired1 Wrote:
-------------------------------------------------------
> If you are talking about those recycled copier
> steppers with metal alloy pulleys already fitted -
> there are plenty for sale on fleabay - then the
> best way I found to remove them is to shatter the
> pulley with a cold chisel. Place the pulley on a
> solid object like an anvil or the back of a good
> vice and give it a few quick raps with a big
> hammer and cold chisel. There is no risk of
> bending the shaft or damaging the motor if you
> only hit the pulley and it will split the pully
> easily.

i use bolt cutters, slightly off center.

Haven't bent one (yet) but the nut splitter idea is a much better idea. You could probably use a cutting disc on an angle grinder too if you are careful,

---

_________________________________________________________________________________________

Richmond, New Zealand
Thingiverse ~ YouTube

you could use about any method likeable i guess. bolt cutters cutting inwards towards the shaft, off to the side enough to miss the shaft, but enough to crack the external gear attached takes about 10seconds with bolt cutters. perhaps it is overkill.