# Is this normal? (loose grub screws on rail bearing)

**URL:** <https://forum.onefinitycnc.com/t/is-this-normal-loose-grub-screws-on-rail-bearing/5584>\
**Category:** Original/PRO Series (Buildbotics) (Gen 1)\
**Created:** [May 16, 2021, 11:16pm UTC](https://forum.onefinitycnc.com/t/is-this-normal-loose-grub-screws-on-rail-bearing/5584 "2021-05-16T23:16:34Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![WorksTheWood](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.onefinitycnc.com/worksthewood/32/1553_2.png) [@WorksTheWood](https://forum.onefinitycnc.com/u/WorksTheWood)\
**Post date:** [May 16, 2021, 11:16pm UTC](https://forum.onefinitycnc.com/t/is-this-normal-loose-grub-screws-on-rail-bearing/5584/1 "2021-05-16T23:16:34Z")

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I feel like there’s something off with the top bearing on the left side of my x rail. It’s reveal is about 1.25” more than the other 5 on this part.

I have only done a few test pieces, and I cannot remember if this is where it was upon assembly. I feel like I would have noticed something like this, but maybe I’ve just been too happy with the tests so far and I’ve avoided nitpicking!

I can’t say that it has affected performance, again because I am not really asking much of it yet, but I’d rather everything be in order as I step up demands.

It will rotate about the third rail, but it will not slide along the rail, just in case that helps anyone in diagnosis.

Should I/how do I remedy this?  
Thanks for any help/guidance.

 ![image](https://us1.discourse-cdn.com/flex022/uploads/onefinitycnc/original/3X/7/4/74fcda313fdae165582bac711232c6a57c0410bb.jpeg)

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**Author:** ![Hermsen.BJ](https://avatars.discourse-cdn.com/v4/letter/h/779978/32.png) [@Hermsen.BJ](https://forum.onefinitycnc.com/u/Hermsen.BJ)\
**Post date:** [May 17, 2021, 1:23am UTC](https://forum.onefinitycnc.com/t/is-this-normal-loose-grub-screws-on-rail-bearing/5584/2 "2021-05-17T01:23:07Z")

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Yeah that isn’t right… @OnefinityCNC are there instructions for reseating the bearings? I don’t recall seeing this one before.

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**Author:** ![OnefinityCNC](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.onefinitycnc.com/onefinitycnc/32/7_2.png) [@OnefinityCNC](https://forum.onefinitycnc.com/u/OnefinityCNC)\
**Post date:** [May 17, 2021, 1:57am UTC](https://forum.onefinitycnc.com/t/is-this-normal-loose-grub-screws-on-rail-bearing/5584/3 "2021-05-17T01:57:23Z")

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Looks like the grub screws came loose. Slide the bearing back in place and tighten them down:

 ![thumbnail_bearing hold down pins](https://us1.discourse-cdn.com/flex022/uploads/onefinitycnc/original/2X/c/c28da2c565264cb00f6222e3aea246140a3f115f.png)

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<div class="post-metadata">

**Author:** ![WorksTheWood](https://sea2.discourse-cdn.com/flex022/user_avatar/forum.onefinitycnc.com/worksthewood/32/1553_2.png) [@WorksTheWood](https://forum.onefinitycnc.com/u/WorksTheWood)\
**Post date:** [May 17, 2021, 10:17am UTC](https://forum.onefinitycnc.com/t/is-this-normal-loose-grub-screws-on-rail-bearing/5584/4 "2021-05-17T10:17:45Z")

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Thanks for the response and picture with the details. I was able to get the bearing placed properly and everything tightened back down. Everything seems to be in working order so no damage done.

While I have your attention here, are there any places where you’d recommend using thread locking compound on any screws/bolts?