Acme Screw and Bearing

Does anyone know how I can purchase a new acme screw and bearing for my X carve. The bearing lost one side of the metal plate protecting it (no idea how that happened) and thing my acme screw is slight bent as it has been having issues homing the z axis and staling out after multiple checks and fixes.

Ask customer service about the bearing:

part number 30169-01

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Awesome thanks. Where did you even find that. I looked at the inventables store and couldnt find that anywhere?

If you recall the assembly instructions, they had each part with a part number. I upgraded a Shapeoko2, so I checked a lot of the stuff for sale. :-). If you look at “shop”/" shop all categories" at the top of this page, it has the majority of the stuff they sell. The Bearings page comes up as a blank for me.

Highly unlikely the screw is bent, and nearly impossible for it to become bent after assembly.
The improper design of the screw has a shoulder that seats against the bearing when pulled tight by the top nut. The machined diameter that goes thru the bearing creates a partial shoulder because it’s machined on an acme thread. When pulled tight by the top nut, the screw pitches towards the unsupported side of the shoulder, creating a runout condition. It can create a bind condition towards the top of the travel. There’s enough available slop in the assembly that it doesn’t bind towards the bottom of the travel.

One fix, (not ideal, but it works) is to tighten the nut just enough to pull the assembly together. Further tightening will place forces on the screw that cause it to pitch to the unsupported side of the shoulder.

thanks for this. So that makes sense, i just put the screw in my drill press and turned it on to see if I could see the bend and could not. So when tightening that top nut we have to only tighten for is needed not tighten it down as much as we can.


You’re very wecome Christopher, I’m glad this info helped! I’ve seen this issue play out on the forum over and over again, but no one (prior to you) has seemed to comprehend this issue in spite of how many times I’ve tried to expose it and explain it. I even told Inventables about it directly, but they apparently don’t recognize it for the problem that it is. It shouldn’t be that difficult to grasp the concept.

Partial shoulder + sloppy fit in the bearing + tight fitting delrin nut spells trouble.