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Lightn
(@lightn)
New Member
X-Axis Issue

The x-axis on my printer is starting to concern me.  I've printed about 3 dozen hours and it has been going pretty well.  But there is this high pitched rattle on certain larger x moves.  There have also been flecks of black rubber on the bed.  I thought that was from the belt as the x-carriage crashed a couple times early on, I think from this issue: https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/27 .  But recently I got a very large x-axis layer shift on my print.  I didn't see it happen, but I happened to check on the print shortly after it did.  It looks like the head failed to move to the left by about a centimeter a few layers into the print.  I restarted the print and it then completed successfully in 5 hours.

The x-axis linear bearings seem to be rubbing against the linear rods and slowly flaking off.  See this picture.  Moving the head by hand, it seems to take more force to move it left than right.  Any idea what is causing this or how to fix it?

Linear bearing flaking

Posted : 12/01/2020 5:51 am
Alpengeist
(@alpengeist)
Eminent Member
RE: X-Axis Issue

did you tighten all the screws on the MINI? ... out of fear it could be a little loose?

Posted : 12/01/2020 12:34 pm
unknwnrider
(@unknwnrider)
Eminent Member
RE: X-Axis Issue

Check your extruder cable bundle. It is likely too short which is causing your issues. When the head moves far left, it is being pulled “up” because of the short cable bundle. This can make the head harder to move, cause premature wear, Z height issues, etc. 

you can test this by powering off the machine, moving the head far left. If it holds on its own, your cable is ok. If it moves slightly back towards the right, your cable bundle is too short. Cut the 3 zip ties holding it in place and readjust. 

Posted : 12/01/2020 2:35 pm
Lightn
(@lightn)
New Member
Topic starter answered:
RE: X-Axis Issue

I have not adjusted the screws on the MINI.

The cable bundle seems a little short, but is not really applying much tension. It does not pull it back even when all the way to the left. And my print was only using the right 3/4 of the bed when it had the issue.

I had a new issue today. It couldn't even complete the mesh bed leveling because it couldn't complete some moves to the left. With the motors off it was very difficult to move to the left by hand, even at the far right position, but then easy to move back to the right.

I talked to Prusa support and they asked for a video. Suddenly it worked and was easy to move by hand. They suggested that I lubricate the x-axis. The mini seems not to include the Prusa lubricant like the MK2/3, so they suggested lithium grease in a tube.

Does anyone have a suggestion of brand? Local stores seem to have Lucas Oil White Lithium Grease. Does that sound like a good option? Or would Permatex 80345 from Amazon be better? I can't find the brands listed on the Prusa maintenance tips page (GLEIT-µ HF 400 or Mogul LV 2-EP) in the US.

Posted : 14/01/2020 1:29 am
Crawlerin
(@crawlerin)
Prominent Member
RE: X-Axis Issue

Here is good article on this topic: https://prusacommunity.com/set-your-bearing-straight/

People swear by Super Lube grease with PTFE, I believe it is 21030 synthetic grease with Syncolon, correct me on ecact number. Other option is lithium soap grease. You won't go wrong with either.

Posted : 14/01/2020 2:18 pm
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