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MK3S+ - cannot calibrate X axis belt tension  

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preclowski
(@preclowski)
Active Member
MK3S+ - cannot calibrate X axis belt tension

Hello guys.

My printer, MK3S+, is pretty new. Its year old and printed about 500m of filament. It worked fine at first, but it degraded over time.

When Im trying to perform belt calibration it ALWAYS return value 235-242. There are just two states of calibration possible - calibration fail (belt too loose) and 235-242 range (which is too tight). When Im calibrating belt tension I can hear nice bass sound, same like my Y axis which is 278-279, I can feel tension is good with my finger. Tension metering tool from printables shows perfect score. Belt reacts to calibration. But when I run belt test from menu... 235-242. Nothing can change that!

What I already tried:
- there are no scratches on metal rods
- X axis move little less smooth than Y axis
- Extruder slows down a little in middle of axis (but only moved by motor, by hand I dont feel any obstacles)
- I already replaced bearings and rods on Y axis (old rods also arent scratched)
- Belt looks good, I dont see wear on teeth
- My Z axis is super loud, especially when going UP
- I tried to loose and tight screws that holds extruder
- I marked points to properly position bearings (bearing balls cannot be on top of rod)
- It was tested on firmware 4.11, 4.12RC, 4.12

I have no idea what to do next :/ I think it started when my fuse broke and I replaced it, but cant confirm. Fuse probably broke because short in heater. Lets say printer works and print currently, but this affects quality comparing to my old prints.

Did you faced something like this? Any ideas?

This topic was modified 12 months ago 2 times by preclowski
Posted : 28/02/2023 2:38 pm
Zoltan
(@zoltan)
Member Moderator
RE: MK3S+ - cannot calibrate X axis belt tension

Did you try to change the belt itself? It can lose (my guess) an elasticity over time.

even an old man can learn new things 🙂
Standard I3 mk3s, MMU2S, Prusa Enclosure, Fusion 360, PrusaSlicer, Windows 10
PRUSA MINI+ Prusalink + Prusa Connect

Posted : 01/03/2023 5:55 am
preclowski
(@preclowski)
Active Member
Topic starter answered:
RE:

No because I dont find anything wrong with belt. It might be good idea. Im also planning to reprint whole axis with petg+cf including extruder and reassembly them, but its big step and it will push chaos to debugging process. I must verify as much as possible before doing this.

What are chances that good looking and good feeling belt is broken somehow? I mentioned at begining - printer is just one year old. And I was able to calibrate it at beginning (i think so).

I want to be positive before Ill contact prusa support for replacement or just add it to cart because I need to order some filament.

This post was modified 12 months ago by preclowski
Posted : 01/03/2023 11:04 am
Diem
 Diem
(@diem)
Illustrious Member
RE:

The belt tension figure is a measure of the resistance felt by the stepper when moving the axis. On a correctly set up machine this does equate, roughly, to belt tension.

But other things can affect mechanical resistance.

Clean and lubricate the smooth rods. Check the idler pulley is not clogged, out of line, or damaged (loosen the belt and try turning it with your fingertip, is it smooth?)

With the belt loose try turning the stepper motor by hand; is it smooth?  You should feel the steps but no grating and no variation.

Retighten the belt until it just begins to make a low musical note when plucked...

Make your next print this:

https://www.prusaprinters.org/prints/46639-tension-meter-for-the-gt2-belts-of-i3-mk3s-or-prus

It MUST be printed in Prusament PETG or the spring tension will be wrong.

 

My Z axis is super loud, especially when going UP

This may be a seperate issue; lubricate those smooth rods too - but NOT the leadscrews.  Check the top end supports are fitted as in the manual and have not come loose.

Let us know how you get on.

Cheerio,

Posted : 01/03/2023 11:15 am
Zoltan and preclowski liked
Zoltan
(@zoltan)
Member Moderator
RE: MK3S+ - cannot calibrate X axis belt tension

Do not rush without reason,

does the extruder move smoothly without the belt?

The printer is really measuring the move resistance (via TMC drivers loop back current) it can be caused by bearings resistance, by inproper parallelism of the x rods.

 

even an old man can learn new things 🙂
Standard I3 mk3s, MMU2S, Prusa Enclosure, Fusion 360, PrusaSlicer, Windows 10
PRUSA MINI+ Prusalink + Prusa Connect

Posted : 01/03/2023 2:56 pm
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