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Elle Skye
(@elle-skye)
Active Member
Belt tension?

does anyone know what the belt tension is supposed to be on the core one L? Mine seems a bit loose from the factory (especially compared with my core one) but it seems to print ok. I wanted to double check it. 

when I stein it’s like 60hz but prusa recommends over 90s for the original core one. And I can’t seem to find any details on the help articles 

Posted : 11/11/2025 10:15 pm
darksharpie
(@darksharpie)
Estimable Member
RE: Belt tension?

Use the belt tuner in the firmware, that should let you know if it needs tightening (and it also shows the proper values,  looks like between 85 and 95 Hz).

 

 

Posted : 13/11/2025 12:59 am
Ruebarb
(@ruebarb)
Active Member
RE: Belt tension?

One of the 1st reviewers to get the printer, said they were told they would need to adjust the belt tension when they receive the printer. As it appears you likely got your printer in the 1st batch, this may also apply to you.

Posted : 14/11/2025 2:33 pm
1 people liked
Ed
 Ed
(@ed)
Eminent Member
RE: Belt tension?

My fresh Core ONE L upper belt was at 82 Hz, lower belt is at 81 Hz. I had to tighten both screws by a little over 2/3 of a turn (the Torx is 6-sided) to reach 94 Hz / 92 Hz. Measured using the Belt Tuner webpage.

Posted : 16/11/2025 7:44 pm
1 people liked
Elle Skye
(@elle-skye)
Active Member
Topic starter answered:
RE:

mine seemed to be around 60 hz loose from prusa, i ended up doing a full turn on each side then ran the printer option for calibrating, it required about another 1.5 turns each side to get it to the right frequencies.

Posted : 17/11/2025 4:12 am
JoShoeAh
(@joshoeah)
Member
RE: Belt tension?

Stumped with this on my new Core One L too. Noticed the belts seemed loose, found they were around 82 for the top and low 70s for the bottom. Attempted to tune up to the recommended values, but can't get the bottom belt above 88hz with the top one below 98hz. Online / printer tells me this means there's an alignment issue, but nothing looks out of alignment at all.

Any ideas from any other Core One L users before I reach out to support in frustration? Suspect FedEx were anything but gentle during shipment, but still wasn't expecting to have to faff too much with the documentation saying it was all pre-calibrated 😄

Posted : 19/11/2025 9:47 pm
JoShoeAh
(@joshoeah)
Member
RE: Belt tension?

Started from scratch with loosened belts and managed to get things sorted (just about). Both belts are just about within the acceptable range from each other now, so I'll take it - fingers crossed whatever the supposed alignment problem was doesn't rear its head again.

Posted : 19/11/2025 11:48 pm
Raaz
 Raaz
(@raaz-2)
Reputable Member
RE: Belt tension?

Just out of curiosity:
Is there a belt tuning menu in the Core One L that really has the same frequencies, as the non-L?
The belts are longer, so the frequency at the same tension will be lower.
If you set both printers to identical frequencies, the L belts will be tensioned quite a bit more.

Posted : 20/11/2025 2:37 pm
hyiger
(@hyiger)
Noble Member
RE: Belt tension?

 

Posted by: @raaz-2

Just out of curiosity:
Is there a belt tuning menu in the Core One L that really has the same frequencies, as the non-L?
The belts are longer, so the frequency at the same tension will be lower.
If you set both printers to identical frequencies, the L belts will be tensioned quite a bit more.

I totally agree with this, I would assume that Prusa made this adjustment for the new belt tuning wizard?

Posted : 20/11/2025 5:18 pm
JoShoeAh
(@joshoeah)
Member
RE: Belt tension?

The new wizard does appear to have the same values, from my experience. I'm hoping that's by design 🙂

Posted : 20/11/2025 5:57 pm
darksharpie
(@darksharpie)
Estimable Member
RE: Belt tension?

Just checked again with the latest firmware on both.

CORE One:  between 90 and 98

Core One L: between 85 and 95

Posted : 21/11/2025 1:21 pm
4 people liked
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