Printer fails x axis length self test. The end of a long list of failures
 
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Printer fails x axis length self test. The end of a long list of failures  

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Lynn
 Lynn
(@lynn)
Eminent Member
Printer fails x axis length self test. The end of a long list of failures

I've used this MK3S printer for 5 months and have run 16 kg of filament through the unit.  In the past month, I have had the hot bed thermister fail due to a broken wire, failure of the x carriage bearings (indicated by loud grinding noise and a cascading set of crash detection failures.) Over the same period, I have had to re-calibrate the unit at least 20 times, each attempt taking more effort to get it accomplished.      When I replaced the termistor and bearings I redid the wiring  from the extruder to he control board to ensure there were no interference's to extruder movement.  I had to disable crash detection to keep the printer running, even though there was no obvious indications of a crash. Belt tension was in the middle of the specified band. 

Over the past week I had to increasing deal with mesh leveling errors,  leading me  replace the P.I.N.T.A. sensor. 

Today's status,  It will not pass the self checks past the x-axis length check.  I have moved the axis from left to right using the settings menu, and was able to move it from frame to frame with no interference, a total of 255 mm.  When the x-axis check runs it only goes about 220 mm to the right and returns to the 0 position, and then throws the error.  I have tried resetting to factory settings multiple times and followed all the suggestions I found on this forum to get this test to pass,  no avail.  Let me reiterate, there is no contact between any wiring and any part of the frame,  the carriage is making contact with the z-axis bearing assemble during this test, and none of the tie wraps or wiring are making contact with the frame.  When traveling to the right, the carriage does not travel full lengthen before it returns to the left and I seem to remember that it used to. 

As I mentioned, I used  this printer a lot and need help resolving this issue.

Thanks for any help.

 

Posted : 10/03/2020 2:08 am
JoanTabb
(@joantabb)
Moderator
RE: Printer fails x axis length self test. The end of a long list of failures

Does the X axis move smoothly by hand? 
did you lubricate the linear bearings?
does the X axis idler rotate freely? 

I have had the X axis bearing collapse and cause rough movement
Is your X motor pulley on the correct way round?
does your X motor pulley rub on the plastics?  

regards Joan

 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 10/03/2020 3:02 am
Lynn
 Lynn
(@lynn)
Eminent Member
Topic starter answered:
RE: Printer fails x axis length self test. The end of a long list of failures

The X axis does move smoothly, with no catching and no changes in pressure along most of the entire length travel. It does require slightly more pressure to move to the extreme right, the last inch or so.  I checked the smooth rods to ensure they were parallel.  They are also very smooth with no sighs of rougness.

I changed the carriage bearings with new freshly lubricated ones last week.

I loosened the belt and could rotate the idler pulley with the end of the Allen wrench pretty easily. I also check to see if the pulley was getting closer to he plastic (walking along the screw) during carriage movement. It looks like it is firmly fixed in place. 

I initiated the self check again after these checks and if failed again.

I had a thought to try loosening the top screws on the extrude back and then did the checks.  This time it completed the checks.

This is very frustrating.

Posted : 10/03/2020 4:13 am
rmm200
(@rmm200)
Noble Member
RE: Printer fails x axis length self test. The end of a long list of failures

Slightly loosening the extruder bearing screws is one of my standard recommendations on X axis problems.

Too tight can crush / misalign the bearings.

You should see what over-tightening the U-Bolts of Death can do to the Y axis.

Posted : 10/03/2020 3:44 pm
Lynn
 Lynn
(@lynn)
Eminent Member
Topic starter answered:
RE: Printer fails x axis length self test. The end of a long list of failures

I do understand the concept of over tightening and it's consequences, but in this case the screws are basically finger tight.  This should be added to all the maintenance documents as the last time I reference them they call for tightening these screws securely.

 

Posted : 11/03/2020 12:38 am
drpeej
(@drpeej)
Trusted Member
RE: Printer fails x axis length self test. The end of a long list of failures

This sounds to be exactly the same problem I have just experienced in my Mk3S which is the same age as yours.  I have just posted a question about it.   

Unlike you,  my printer has been very reliable till now and I haven't had to do any maintenance repairs.

Posted : 30/03/2020 2:39 pm
drpeej
(@drpeej)
Trusted Member
RE: Printer fails x axis length self test. The end of a long list of failures

Although my X movement appeared to be smooth I greased the X rails using the supplied grease and it appears to have fixed the problem.   

The set up configuration wizard seems to be working now

Posted : 30/03/2020 5:20 pm
rmm200
(@rmm200)
Noble Member
RE: Printer fails x axis length self test. The end of a long list of failures

Glad it is working.

Small note: The supplied grease is to go inside the bearing, not on the rail.

The grease seals on the bearing (intended to keep grease in) will push grease on the rail away in short order.

Posted : 30/03/2020 7:06 pm
drpeej
(@drpeej)
Trusted Member
RE: Printer fails x axis length self test. The end of a long list of failures

@robert-rmm200

Well it worked 🙂

Posted : 30/03/2020 7:33 pm
drpeej
(@drpeej)
Trusted Member
RE: Printer fails x axis length self test. The end of a long list of failures

Further to this,  I have just done an 8 hour print which worked fine.   Applying the grease in the non-approved way has fixed the problem.

btw - if the grease is meant to go inside the bearing assembly,  how do you get it in there without a complete disassembly?

Posted : 31/03/2020 8:44 am
Steve
(@steve-5)
Trusted Member
RE: Printer fails x axis length self test. The end of a long list of failures
Posted by: @drpeej

btw - if the grease is meant to go inside the bearing assembly,  how do you get it in there without a complete disassembly?

Unfortunately you don't.  Disassembly is required to properly grease the bearings.  As Robert noted the seals at the ends of the bearings keep any meaningful amount of lubrication from getting to the bearings.  You will want to schedule some down time to do this as the problem will just keep coming back until you do.  The other problem with oiling or greasing the smooth rods is that the lubricant attracts dust and can end up on your build plate affecting print adhesion.

Regards,

Steve

Posted : 31/03/2020 9:10 pm
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