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Simple fix for X-axis length self-test error  

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roc856
(@roc856)
Active Member
Simple fix for X-axis length self-test error

Printing fine for a couple of months, but I went to demonstrate the self-test to someone yesterday and it failed the X-axis length test!

This morning I started to investigate and found some gunk on the rails (see photo). Wiped it off with a cloth, and then it passed the test.

Maybe this can help someone else. Apparently, it doesn't take much to make the printer think it's reached the end of its travel.

gunky rails

Posted : 26/11/2021 5:08 pm
BogdanH
(@bogdanh)
Honorable Member
RE: Simple fix for X-axis length self-test error

That thing on rails are remains of bearings grease (which doesn't cause error, of course). Or am I looking on wrong thing?

[Mini+] [MK3S+BEAR]...
Posted : 26/11/2021 9:00 pm
roc856
(@roc856)
Active Member
Topic starter answered:
RE: Simple fix for X-axis length self-test error

BogdanH: Could be remains of bearing grease. But, as I assembled the printer only weeks ago, I haven't added any grease to what it came with. nor have I ever greased the rails. But, since the error went away when I removed the grease, I think that's what was causing the error.

Posted : 26/11/2021 10:55 pm
Dan Rogers
(@dan-rogers)
Noble Member
I think you have found a problem... you didn't grease your bearings

Removing that smidge of oil didn't solve your problem.  Your problem is intermittent.  Your bearings are starting to sieze up because you did not pack them with grease when you assembled your printer.  As this will get worse and you'll be back and realize that your assertion here is goofy... you will need to disassemble your X and Y and Z axis and pack your bearings following the bearing maintenance instructions.

 

Posted : 27/11/2021 10:20 am
roc856
(@roc856)
Active Member
Topic starter answered:
RE: Simple fix for X-axis length self-test error

Was I supposed to pack the bearings with grease? Here's what the Assembly Instructions book says: "The printer's package contains a lubricant, which is intended for maintenance. No need to use it now the bearings are lubricated."

I find it odd that excess grease being deposited on the rails is a result of a lack of grease.

Posted : 27/11/2021 4:18 pm
BogdanH
(@bogdanh)
Honorable Member
RE: Simple fix for X-axis length self-test error

If you bough pre-assembled printer, then bearings were most probably lubricated by Prusa -yes, these remains of grease on rails indicate that.
But if you bough the kit version (where each bearing is packed/sealed separately), then bearings are not lubricated -you need to lubricate them.

[Mini+] [MK3S+BEAR]...
Posted : 27/11/2021 6:04 pm
roc856
(@roc856)
Active Member
Topic starter answered:
RE: Simple fix for X-axis length self-test error

Well, if what you say is true, this is a real screwup by Prusa, which I find difficult to believe in such a meticulously designed kit, with such a fine assembly manual. They have advised me to assemble a defective printer.

What's your interpretation of the sentences I quoted from the assembly instructions? They are from Step 19 on page 25 of the assembly instructions.

Perhaps your experience with assembly is with an older kit?

Posted : 27/11/2021 6:45 pm
BogdanH
(@bogdanh)
Honorable Member
RE: Simple fix for X-axis length self-test error

...so I assume you bough kit version.
What I wrote above, is from information I gathered on web (and also in this forum). Prusa doesn't make linear bearings, they get it from manufacturer (i.e. Misumi or elsewhere). As far I know, no manufacturer lubes the bearings, unless, it's a special order for special usage (price increases in that case of course). Linear bearings from factory only have "rost" protection -which is not lubricant.
But to be 100% sure about your purchase, you should ask Prusa support.

[Mini+] [MK3S+BEAR]...
Posted : 27/11/2021 8:43 pm
roc856
(@roc856)
Active Member
Topic starter answered:
RE: Simple fix for X-axis length self-test error

OK, BogdanH... thanks for the clarification. I have in fact queried Prusa support, and I'll post what they say here to finish off this thread for those who may come across it in the future.

Posted : 27/11/2021 9:00 pm
roc856
(@roc856)
Active Member
Topic starter answered:
RE: Simple fix for X-axis length self-test error

Here's what I got from Prusa: "... you don't need to lubricate the bearings when installing them. They are prepared by the manufacture to be installed and used directly with the printer."

Posted : 29/11/2021 4:15 pm
Dan Rogers
(@dan-rogers)
Noble Member
Yeah, that's an error in the manual.

Happy printing.  Looks like you are all set then.

Posted : 29/11/2021 4:43 pm
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