Core One - Belts tension adjustment - Your opinion, please - General discussion, announcements and releases

RE: Core One - Belts tension adjustment - Your opinion, please

jan.d.slay — Fri, 23 Jan 2026 12:52:20 +0000

I hadn't thought about it that way before. Very interesting. The pictures speak for themselves.

It's just more noticeable with shiny filament ;-)

More pictures? Sure! If you click on “Write reply” again, there's a small “Add Media” button above the reply field ;-)

Before I repeat the above adjustment routine, I'll print a “cube” or test object before and after.

RE: Core One - Belts tension adjustment - Your opinion, please

Conrad — Fri, 23 Jan 2026 12:46:11 +0000

Here's the cube with more grazing lighting. BTW, don't be confused by moiré patterns from the monitor pitch if you don't zoom in.

2ae86c80-dsc_3676_proc.jpg

RE: Core One - Belts tension adjustment - Your opinion, please

Conrad — Fri, 23 Jan 2026 12:44:35 +0000

Here's a 20 mm calibration cube lit nicely. (Isn't there some way to attach more than one image?)

3d05cd1a-dsc_3682_proc.jpg

RE: Core One - Belts tension adjustment - Your opinion, please

Conrad — Fri, 23 Jan 2026 12:42:02 +0000

And here it is lit a bit differently. So, take all pictures with a grain of salt.

2a1275b4-dsc_3666_proc.jpg

RE: Core One - Belts tension adjustment - Your opinion, please

Conrad — Fri, 23 Jan 2026 12:40:50 +0000

On the original topic of VFAs, I'll throw in yet another complication. One of my main hobbies is photography, so I'm sensitive to lighting of textures. The surface finish of a part has a huge amount to do with the visibility of VFAs. Glossy bad, matte good. I printed a 3X AAA battery holder for charging using Prusament PETG in grey. It's matte, for reasons I'm not entirely sure of. If it gave it to you under any normal room light, you'd say wow, this is nearly perfect. Can't see any VFAs at all. Yet, with the right grazing light from the right size LED panel, it looks as bad as anything. Here's a photo.

b72a13db-dsc_3667_proc.jpg

RE: Core One - Belts tension adjustment - Your opinion, please

jan.d.slay — Fri, 23 Jan 2026 06:09:21 +0000

Ohhh I just found your page earlier today (after seeing it in a comment on the assembly guide). Nice write-up! Prusa should adapt the official belt tension guide with yours, since it is much clearer on how it should be done! 🙂

I think that owners of C1 or C1+ devices are unlikely to voluntarily test anything if the machine is running flawlessly.That's why it's probably difficult to find an objective comparison result from another user.

RE: Core One - Belts tension adjustment - Your opinion, please

abmantis — Fri, 23 Jan 2026 01:55:42 +0000

Posted by: @conrad-2
You might, but they aren't and the interaction between the adjustments would drive you crazy. The belt tuning utility works the way it does for a reason, and it works well. I went through some similar thoughts when first starting out, enough that I dug fairly deeply into the system. I'll eventually set up a Core One page on my site and edit and move this but see if you can get anything useful from it. I'm new enough at this that I still make mistakes! https://conradhoffman.com/CoreOne_assy.htm

Ohhh I just found your page earlier today (after seeing it in a comment on the assembly guide). Nice write-up! Prusa should adapt the official belt tension guide with yours, since it is much clearer on how it should be done! :)

RE: Core One - Belts tension adjustment - Your opinion, please

jan.d.slay — Thu, 22 Jan 2026 16:17:06 +0000

I'll try it out over the weekend just to see how it goes (practice makes perfect).

If it leads to worse results, then I'll see and understand that for myself.

RE: Core One - Belts tension adjustment - Your opinion, please

Conrad — Thu, 22 Jan 2026 15:03:49 +0000

You might, but they aren't and the interaction between the adjustments would drive you crazy. The belt tuning utility works the way it does for a reason, and it works well. I went through some similar thoughts when first starting out, enough that I dug fairly deeply into the system. I'll eventually set up a Core One page on my site and edit and move this but see if you can get anything useful from it. I'm new enough at this that I still make mistakes! https://conradhoffman.com/CoreOne_assy.htm

RE: Core One - Belts tension adjustment - Your opinion, please

jan.d.slay — Thu, 22 Jan 2026 06:57:45 +0000

To be honest, at first I also thought, “Damn, how much is 2/8?” 🤣

It's usually not a good idea to tighten the belt screws asymmetrically.

Yes, okay, that's what I did at first. Adjust evenly on the left and right to get the right frequency.

That's why I wrote that the belt needs a certain amount of tension, which may be visible from the outside via an indicator.

IMO, if things are very close this might work, but because of the interaction between the adjustments and the overriding need to keep the X-axis square, it can't be recommended.

I will work through it step by step several times over the weekend and test it.

I would argue that if these metal brackets were more solid, you could also adjust them individually without running the risk of deforming the frame.