Core loose

Hey folks; I am finally assembling the Primo 25.4mm and have run into a problem. The zip file I have with all of the files is from 6/24. The core clamps are loose, really loose. The rails do not touch all three bearings. There is no way to get them to. These are the V shaped parts that attach to the X and Y gantry rails.

I saw a note about this and if I read this correctly, the core holes are in the wrong spot? God I hope not. Anyone run into this and what was the solution. I am reprinting one to the clamps to see if that does it.

Please help.

According to Brian the problem should not really be obious with the 25.4mm version. For the F version there are modified clamps, not for yours though.
The first suggestion is always to completely take the core clamps off and tighten the single “tightening bolt” first, then screw them to the core again.

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After reprinting two of the clamps, there is a significant difference between them. It had to be some sort of slicer issue. I have not compared the sizes of the files from June to the ones from Oct. I cannot believe that they are different. I am printing the other two now. They seem to be smaller and fitting much better.

More to come on this. I at a loss on what happened.

OK, here is an update. After reprinting all of the clamps and drilling both the core and clamp the holes to make them uniform; it is much better. However I am still having issues with some of the bearing clearances. I ordered new bearings and should have them today (gotta love Amazon). I am hoping that these are better. Some of the ones that I have a really really still and do not spin freely. They feel like they are packed. I am going to pull it apart again and try a different set. I am hoping that this helps. More to come.

OK, I think I found the problem with the June 2020 STL’s. I outline this on a recent BLOG post about my build. Take a look and let me know what you all think.

@vicious1, I remember something about changing the depth of the motor mounts. I don’t remember anything else.

All the files get marked with a revision number if anything changes, eg “V1”. If it does not have that it is an original part. The 25mm version of the machine was released as a beta since I can not source the tubes to test it. When you downloaded the first parts you had there should have been “beta” on the file links, and the main page posts, FB, and the forums all had info links as we discovered and tested the fixes. When everything was resolved the beta tag was removed.

We found that the Rollers need 1mm extra on the stepper M3 mount screws, and the core and core clamps had a 0.2mm error. Neither of these errors effected all users but I changed them any way to be correct. I am not sure why your other parts seem to be a differnt size.

As for not responding to you on FB or here right away. I do not spend more than a few minutes on FB a week the forums is where I spend all my time and it is still not enough. Here…well I get 30-90+ emails a day and I try to do my best to get to all of them, in order. I currently have 129 outstanding posts to read. Please understand I can not keep up with build blogs, fb, reddit, twitter, instagram, or discourse as well as the forums. I choose to spend my time here where things are public and searchable…and I love 95% of the people that hang out here help a lot…the other 5% well…they make me laugh so they are pretty cool as well.


Thank you for the response. I totally get that you are a busy guy, no worries. In the past I would have gotten something, but this go around it was nothing. I am and have been a large supporter of this project including making a donation to the cause a few years ago. I did post this issue here hoping to get your attention. I was going to send you a note directly, however you have asked to post things here.

For whatever reason, the files that I had were not marked Beta. I would have waited until the production files were posted. I completed reprinting, almost everything, and the fit is significantly better. Changing the bearings to a better quality helped with how smooth the axis’s move.

If I fall into the 5%, I am sorry that you feel that way.

Thank you for your time and whatnot.

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No you are certainly most welcome here. I just saw you comments on your blog and seems to be presented as I am unreachable or ignoring you. Just wanted to clear up any uncertainties you had about that.

You are most certainly welcome here and the 95-5% is a joke (and I meant all 100% are awesome for various reasons). We really do not have any issues here ever. In 5+ Years I can remember 2 people kinda getting rowdy and one is still around under a new name and the other, well he still posts elsewhere on a regular basis his hate for me. 1/~999,999 ain’t bad.

Are there any issues left? Do we get to see a crown?

Thanks for the follow up. The Z axis assembled and it is smooth. I have not started tramming it yet. I have to complete the belts than the physical items are complete. I am working on the electronics enclosure and the ESP32 board. I should have something “working” in the next few days. I have to put the spoil board together as well. I will post an update when I have it working. Should be soon.

Thanks for the follow up and I will update the BLOG post with the update.


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The adjustment process happens in stages and is complete before belts are installed. I have some diagrams in the build instructions.

Thank you for the information. I am done with the squaring step and have installed the belts. I need to tram the spindle (DW660). Some shims should take care of it on the mounts for the router, but I need to have it running to test it. I will be posting something in the build area soon with pictures, etc. More to come.

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A good way to test it is with the perpendicularity tester that Ryan posted in prusaprinters or thingiverse. If you don’t have a printer, you just need to chuck a long (6") piece of wire and bend it out so it just touches the spoil board a few inches away. Then turn the collet by hand and look for low and high spots. It makes any errors in perpendicularity really obvious, so don’t shoot for perfect.

That is the plan. The machine is within 1/32 square before the limit switches. We will have to see what happens when I get the electronics running. Cutting area is 24"x24"x4". Table is 44"x44" with a 5" torsion box for flatness. The Blog article has most of this already. Here is what it looks like. Everything is tight and square, axises are smooth. I will post over in the build section after more items are running and the spoil board is in place. Next week or so if all goes well. Let me know what you think. As a side note, a cover is slated for sometime in the future.

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Looks great! same work area as the one i’m building now. i hope it turns out as nice as yours!

Good luck and i cant wait to see the crown!

sounds like Ryan needs an assistant :slight_smile:


As promised, I have updated the post with our interaction. Thank you for the continual support. Please continue to keep up with my project. Any input that you have is always appreciated.