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rear motor threaded rod question  

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chmax
(@chmax)
Estimable Member
rear motor threaded rod question

Hi, I am going through my upgrade kit and so far all went great. Now I did install the xy assembly (step 73) and the rear threaded rod is not centered on the assembly part and touches it slighly (see picture). Is this going to be a problem? nothing mentioned in the build guide on this. How do I fix it?

Many thanks for any input.

PS: I did try the search function but I didn't manage to get anything useful.

Best Answer by hyiger:

 

Posted by: @bowtie6

I have a question, that has to do with the rear threaded rod...  

What is the consensus about using the remixed part that allows use of a bearing to center the rod?  Is that a worthy mod or something that would have adverse results? The model I am talking about is:  https://www.printables.com/model/1278603-core-one-rear-z-axis

Thanks!

Reading the comments, some have experienced an adverse affect. So, in my opinion, I wouldn't bother with that. In my case it was sufficient to loosen the trapezoidal nut screws, center the rod with my finger, and while holding it in-place, incrementally tighten the screws. Once that's done, the rod retains a center position. 

 

Posted : 12/08/2025 9:14 am
k1mu
 k1mu
(@k1mu)
Trusted Member
RE: rear motor threaded rod question

 

Posted by: @chmax

Hi, I am going through my upgrade kit and so far all went great. Now I did install the xy assembly (step 73) and the rear threaded rod is not centered on the assembly part and touches it slighly (see picture). Is this going to be a problem? nothing mentioned in the build guide on this. How do I fix it?

Many thanks for any input.

PS: I did try the search function but I didn't manage to get anything useful.

First, make sure the screw is properly aligned. To do that, raise the bed and loosen the nuts on the trapezoid nut in the back center. Don't remove, just loosen them slightly.  Then move the bed to the bottom and tighten them back up.  Does that center the shaft?

If not, raise the bed so you can access the screws for the Z motor.  Since this is hitting on the right side, loosen the screw holding the motor on the right side slightly and tighten the one on the left. Don't crank it down, as you're screwing into plastic, but it won't take much to torque the shaft back into vertical. 1/8 of a turn, check the shaft, etc.    I had to do this for my C1 to make it align properly.

Posted : 12/08/2025 12:45 pm
1 people liked
bowtie6
(@bowtie6)
Eminent Member
RE: rear motor threaded rod question

I have a question, that has to do with the rear threaded rod...  

What is the consensus about using the remixed part that allows use of a bearing to center the rod?  Is that a worthy mod or something that would have adverse results? The model I am talking about is:  https://www.printables.com/model/1278603-core-one-rear-z-axis

Thanks!

Posted : 12/08/2025 3:00 pm
hyiger
(@hyiger)
Estimable Member
RE:

 

Posted by: @bowtie6

I have a question, that has to do with the rear threaded rod...  

What is the consensus about using the remixed part that allows use of a bearing to center the rod?  Is that a worthy mod or something that would have adverse results? The model I am talking about is:  https://www.printables.com/model/1278603-core-one-rear-z-axis

Thanks!

Reading the comments, some have experienced an adverse affect. So, in my opinion, I wouldn't bother with that. In my case it was sufficient to loosen the trapezoidal nut screws, center the rod with my finger, and while holding it in-place, incrementally tighten the screws. Once that's done, the rod retains a center position. 

 

Posted : 12/08/2025 4:28 pm
1 people liked
SgtCaffran
(@sgtcaffran)
Estimable Member
RE: rear motor threaded rod question

 

Posted by: @bowtie6

I have a question, that has to do with the rear threaded rod...  

What is the consensus about using the remixed part that allows use of a bearing to center the rod?  Is that a worthy mod or something that would have adverse results? The model I am talking about is:  https://www.printables.com/model/1278603-core-one-rear-z-axis

Thanks!

It's a bad idea! The purpose of the threaded rods is to position the bed in the Z direction. The purpose of the smooth rods is to position the bed in the XY plane. When you fix the rear threaded rod at the top, you are actually forcing it to also act on the bed in the XY plane, fighting with the smooth rods. You are essentially changing its fundamental purpose in a negative way.

Posted : 12/08/2025 7:49 pm
3 people liked
chmax
(@chmax)
Estimable Member
Topic starter answered:
RE: rear motor threaded rod question

This made it for me: loosen the trapezoidal nut screws, center the rod with my finger, and while holding it in-place, incrementally tighten the screws. One of the rods was slightly off and i did the same with the motor mount: loosen, manually center, retighten.

Thanks to all that contributed!

Posted : 13/08/2025 10:01 am
1 people liked
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