Stepper motor pulleys won't go on

Anyone else have a problem with the pulleys not going on? Miched the shafts at .25 but the pulleys were .247. Customer service sending new pulleys. Frustrating as I finally took a day off work and can’t complete my build.

Looks like that one missed the final ream to .2505" Was this one pulley or all that you received.


One of my pulleys was super tight but I managed to get in on with just hand pressure.

A little heat might help… worth a try while you wait.

I’m thinking that a .003" shrink fit would be a little to much. You would have to get it in exactly the right spot the first time cause there would be no moving it.


Ok, I could be wrong.

I’m usually surprised by how much aluminum shrinks and expands. Once heated, there should be enough time to get it on and aligned… but maybe not.

I had some problems as well, getting the pulleys on the Nema 23 axels. I used some hand force too but then the axel of the stepper motor slid inwards a few mm. My build hasn’t finished yet and I’m hoping for the best.

Maybe someone can give me advice how to restore or maybe leave it as it is. (The pulley is properly aligned though)

Just wanted to say that I ordered my machine several months ago, maybe 7. Just now getting to putting it together the rest of the way, and I ran into this problem 7 months ago, and simply skipped putting them on at the time… The problem is still here, maybe there was a batch of some that didn’t get that final cut.

Call Inventables, they should take care of it for you.

One of mine was really tight, but I was able to use it.

i emailed them, might give a call in a day or too if no response. I also am having a guy from maintenance at work take a few thousandths off my acme rod where it is supposed to go through bearing and pulley as it is over-sized for them as well. But that should be fixed easily, not going to bore or sand down the pulleys and stepper motor shafts…

Thanks for the reply!

Build has finished some time ago. Nema 23 motor still works fine, no problems with it at all. Stepper motor can handle some force probably.