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Phil
 Phil
(@phil-6)
Active Member
X-Axis Problems

Hi All,

I bought a second hand Prusa MK2S and I had to reassemble it and I've had problems with the x-axis after re-assembly. Now I've quite exhaustively followed help I've found between here and on the official guides buuut I still have problems.

https://drive.google.com/drive/folders/1vEksWuBK-xkvDlWaks9W4QPYNbSDssp2?usp=sharing

I've made 3 videos hopefully showing the problem.

So I'll list things I've tried and notes about it below-

  1. I checked the parallelism of the x rods, i.e. I moved the extruder head along the x-axis (after cleaning and lubricating it), it moves very smoothly.
  2. I checked the idler pulley for the x-axis and tested its movement, and its current tightness and I can move the extruder head just fine with the idler.
  3. I made sure the x carrier casing was not too tight (squeezing the bearings creating friction). And as noted, when the motor is disconnected, the extruder head moves very freely.
  4. The motor itself seems to run fine, when disconnected, I moved the x-axis via the LCD and it doesn't look to not work (seen in video)
  5. Now when I have set the belt tension at various settings from too loose to too tight, I get a range of problems as seen in the videos-
    1. If its too loose, you see the conveyor belt "shake" when its trying to move.
    2. If its too tight, there is so much friction that the motor is unable to move itself (shown in videos when I adjusted from too loose, I just tighten the motor position slightly and its now too tight -.- )
    3. If after I've connected the motor (checking belt tightness as seen in the video), there is a loooot of resistance, way more than the y axes which has the same belt tightness, I'm at a loss what to do.
    4. I felt at some points I had just the right amount of tension on the belt, but the motor was unable to deal properly.

Im wondering what else there is to try? Or what I need to do if I need to replace something.

 

Please help with my headache and thanks so much in advance guys!

Posted : 05/12/2020 4:20 pm
JoanTabb
(@joantabb)
Moderator
RE: X-Axis Problems

That looks like a mk2.5 to me....   
the Mk2 had a single sided extruder hobbed gear with a bearing idler, and a single tension screw on the right hand side plus a fixed heatbed with the PEI Sheet stuck to it, and no filament sensor. (look at the picture on this link    https://shop.prusa3d.com/en/upgrades/143-original-prusa-i3-mk2-to-mk2s-upgrade.html )

the Mk2.5 has a pair of Bondtech hobbed gears on the extruder motor, and two extruder tension screws inserted from the left, plus a removable build plate held to the heatbed by magnets  (Look at the second picture on this page  https://shop.prusa3d.com/en/upgrades/179-original-prusa-i3-mk2s-to-mk25s-upgrade-kit.html )
the Mk2.5 extruder assembly is almost identical to the mk3 extruder assembly, the difference being that the Mk2.5 has an endstop buffer

the Mk2.5S extruder assembly also has a pair of Bondtech hobbed gears on the extruder motor, and One extruder tension screw inserted from the left, plus a removable build plate held to the heatbed by magnets (it also differs from the Mk3S extruder because of the endstop buffer... )

Is it at all possible that you have the wrong firmware installed? 
I believe this is the correct firmware link   
https://github.com/prusa3d/Prusa-Firmware/releases/download/v3.9.1/prusa3d_fw_MK3_3_9_1_3518.hex

regards Joan

All of the recent firmwares are listed on this page  https://www.prusa3d.com/drivers/

This post was modified 8 months ago by JoanTabb
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 : 05/12/2020 6:53 pm
Phil
 Phil
(@phil-6)
Active Member
Topic starter answered:
RE: X-Axis Problems

@joantabb

Thanks for the reply, yes I missed the ".5" in the title, so it is a MK2.5S, but I couldn't find out how to edit my original post.

I'll double check the firmware! However do you have any ideas that when I have the motor setup, it seemed to be really difficult to move the extruder block along the x axis by hand (when I cam move the y-axis just fine)?

Thanks again for replying!

Posted : 05/12/2020 7:06 pm
JoanTabb
(@joantabb)
Moderator
RE: X-Axis Problems

@phil-6

Hi Phil, 
sorry no I have no idea at the moment, 

what did you have to reassemble? 
do you have any trapped wires? 

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 : 06/12/2020 1:21 am
Phil
 Phil
(@phil-6)
Active Member
Topic starter answered:
RE: X-Axis Problems

@joantabb

I pretty much did the whole reassembly (making sure everything was properly aligned to have an easier time calibrating), although the extruder head itself was left assembled so I didn't do that.

I'm not sure what you mean about trapped wires, on the head or on/from the motor?

Thanks!

P.S. To help the motor perhaps, is it okay to use WD40 or other lubricant down around the shaft that drives the conveyor belt?

This post was modified 8 months ago by Phil
Posted : 06/12/2020 10:40 am
JoanTabb
(@joantabb)
Moderator
RE: X-Axis Problems

Hi Phil, 

thinking about it a bit more. 

the issue seems to be with the X motor, the only place the wiring can be trapped, is between the Mini rambo case and the frame... 

have you considered swapping the motor connectors from X and Y motors on the mini rambo, and seeing if the stutter moved from the X axis to the Y axis...   if it moves the issue is on the electronics side, if the problem stays on the X axis the problem is on the motor or mechanicals of the X axis. 

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 : 06/12/2020 2:06 pm
Phil
 Phil
(@phil-6)
Active Member
Topic starter answered:
RE: X-Axis Problems

Ah nice idea, okay I will try that!

Posted : 06/12/2020 4:15 pm
JoanTabb
(@joantabb)
Moderator
RE: X-Axis Problems

WD 40 water displacement fluid is not a good option, 
WD40 is now a generic term for a range of products, some of the other products may be Ok. ~

the problem with any spray, is over spray contaminating the printer surfaces especially the build plate! 

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 : 07/12/2020 7:43 am
Phil
 Phil
(@phil-6)
Active Member
Topic starter answered:
RE: X-Axis Problems

@joantabb

Okay so I switched the x and y motor and tested, the y -axis moved completely fine on x - so that must narrow it down somewhat to the x-motor.

Im thinking to try use some lubricant (I have a chain oil I use for motorcycle and bike parts) that's quite high quality, can I try this? (I attached a picture of the area I plan to apply some lubricant. Otherwise should I order a replacement motor in the meanwhile?

Thanks so much for all your help thus far Joan!

This post was modified 8 months ago by Phil
Posted : 07/12/2020 9:00 pm
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