Belts losing tension
I have a perfectly squared gantry.
My belts keep reurning to 80hz after tuning them to 85hz. I have done this once meaning my belts are stretching and not staying at 85hz.
Before I contact support I wanted to see if this happened to other people?
RE: Belts losing tension
You say that the belts "keep returning" to 80 Hz, but also write that you have re-tensioned them once. Which is it? I have seen several reports that new belts had to be re-tensioned after a while, but not several times in a row.
Also, on what timescale did that relaxation to 80 Hz happen? (After how many hours or printing and days on the calendar, roughly?)
Maybe take a closer look at the belt tensioners too. There were reports of the nuts eating into their plastic mounting blocks, until they could eventually move freely. That could be another cause for losing belt tension.
RE:
Finally someone else with this issue. Just today i was getting annoyed because the printer needed a few seconds longer for homing than usual. And i checked belt tension. It went down to 80hz again and i have it 85hz for sure.
And like Fandango writes, i have a perfectly squared gantry too.
If i would give it a timeframe id ballpark it at about 10 heat cycles / 20hours printing for mine.
I can easily retension in a minute because i know excatly how much i need to turn. But it is very annoying.
It must be that my tension screw is not having any securing in the plastics it passed through. The square nut cannot secure against unwinding of the bolt. Tehre are vibrations and heat cycles. The screw needs to be secured somehow.
RE: Belts losing tension
both belt tensioners are new, but this was happening before these were replaced.
They were replaced after one of the tensioners broke (during a tech support session where I was being assisted to square the gantry up).
I will monitor the tensioners and see what is up.
Just FYI, this is news to me but might not be for either of you, PRUSA has updated the belt tenesioning processed for the core one on the webapp only. Prusa app still reflects the old procedure.
I am unsure as to why the communication broke down so bad, I have been relying on the app while it was unbeknown to me that there was another set of instructions.
THE NEW BELT TENSIONING HZ
Are 98 for upper belt, and 92 for lower. Also, the way the reading is taken is different that before.
RE: Belts losing tension
The new tuning instructions at https://belt.connect.prusa3d.com/ are a mess, in my opinion. "Pluck the upper belt (in the middle)" -- which belt is that even referring to? A single picture would clear things up, but we don't get one. And the instructions at https://help.prusa3d.com/article/adjusting-belt-tension-core-one_845048 still reflect the old procedure.
I suppose the "in the middle" part just means that some free belt section should be plucked in its center, i.e. equidistant from both idlers at its ends. But that leaves a choice of the left, right, front, or back pair of belts. (There are "upper" and "lower" belts everywhere, of course.) So which one is it? Are we to assume the front belts which run along the X gantry, since they are the most accessible ones?
RE: Belts losing tension
I called support.
It's all done at thr front. To the left of the extruder.
No longer going in the enclosure for this.