Trouble upgrading Mk3 to Mk3s: belt tension?  

RE: Trouble upgrading Mk3 to Mk3s: belt tension?

Posted by: @markcc

Hi.

I've got a Mk3, and I got the Mk3s upgrade kit. I finished installing it, but it's failing the self tests. I suspect it's related to belt tension - but all of the instructions say to check the belt tension by looking at the belt status on the LCD menu under settings.

There is no belt status option under settings on my printer. 

 

The info screen reports that it's a Mk3s. I've verified that it's running the firmware from the prusa3d_fw_3_9_3_MK3S that I downloaded.

What am I doing wrong?

 

Thanks,

 

       -Mark

Belt Test is in the Calibration Menu, not Settings.

RE: Trouble upgrading Mk3 to Mk3s: belt tension?

@clarmrrsn

Thanks. I'm not talking about the belt test, but the belt status mentioned here: https://help.prusa3d.com/en/article/adjusting-belt-tension-mk3-s_112380. It says to run the belt test or self test (which I've done), and then go to "LCD-menu -> Support -> Belt-status", to get the current tension. That's what I can't find - I can run the test, which fails and reports an X length error - but I should be able to check what the current tension is according to the docs, but I can't seem to do that.

RE: Trouble upgrading Mk3 to Mk3s: belt tension?

I suspect If it does not pass the belt test then probably no figures to report to you.  I have just checked my support menu and listed as an option for me.

How tight is the belt? You should just about be able to press the top and bottom together gently with 2 fingers as the tbe page attached, you are pretty much just taking any slack out of the belt, not too tight or too loose.

If you switch off are you able to move the carriage very slowly all the way right and then left without feeling any tight spots?

Check ths grub screws are tightened correctly onto the X motor, one needs to be on the flat. Did you grease the bearings/rods on the x axis?  Also check the motor pulley has clearance between it and thr motor.

Could just be some resistance on the x axis, does it stop during the belt test before the carriage travels fully right then back fully left?

Sensorless homing will activate if it feels resistance, it fails due to detecting what it thinks is a crash.

RE: Trouble upgrading Mk3 to Mk3s: belt tension?

@clarmrrsn

Thank you! I think I understand now: that entry will only show on the menus after it's successfully run enough of the test to get a tension reading.

Right now, it starts moving the head, moves about 8cm to the right,  and then comes back to 0 at the left and reports the error. It feels smooth to me when I move it by hand when the printer is off - I don't feel any rough spots where it grabs.

After work this evening, I'll try disassembling the extruder enough to get to the belt, and try to tweak it, and see if that helps. Based on this, I'm guessing that it's too loose. It doesn't look like the belt is sagging at all, but it takes almost no pressure from my fingers to push the two sides of the belt together.

Thank you again for the help!