Ultimater 3 - Y axis motion is choppy. Need help fixing.

[ctmgoblue 0]

I've used my Ultimaker 3 for a little while now and had good success with printing.  

 

I recently had a very bad crash on an overnight print.  The print head seemed to stop moving and continued to dispense PLA.  The PLA shot up into the printer head assembly and completely ruined.  

 

I'm in the process of replacing the printer head (I have purchased the spare parts for this), however, in doing so, I've noticed that the motion of the y axis is not smooth.  

 

The x and z axis both move smoothly when I move them by hand.  When I move the y axis, it's choppy, somewhat "clicky," and resists motion a bit.  I've lubricated the rods and that doesn't affect the resistance/sound.  I've also disassembled the y axis parts, but when I do so and move them independently, I can't isolate or recreate the problem.  

 

With the y axis disassembled, the black sliders (accept the rods that go to the printer head assembly) move freely on the rods without issue.  The rods spin freely on their own and don't show any bending or damage.  Indexing, by hand, the spool by the motor seems to be OK although it is the trickiest to move (wires/location) and is the least smooth.  

 

Any thoughts on what could be causing this?  I feel I need to correct it before I finish reassembling the printer head assembly and try to print again.  

 

My main thoughts:

• X axis control motor has gone bad and needs to be replaced.
• Perhaps rubber bands have stretched a bit and are no longer the exact same length causing fighting between the two pull mechanisms.  (No visible signs of wear, but maybe it's slight?)
• Bad bushings in the housings in which the rods seat.

 

Another thing that seem less likely:

• Rods are slightly bent causing extra resistance when sliders move on both simultaneously.

 

Can anyone be my hero and help me get my printer back to a happy place?

 

Thanks in advance!

 

 

 

[Enigma_M4 85]

Hi,

 

you seem to be on the right way.

When I read you changed the print head revovering a head flood, I remembered an issue I had when reseating the print head cable some time ago (ic20-error). After retighening the four long print head screws, the movement on Y-direction was also choppy. SLIGHTLY loosen the four long screws (just releasing torque a bit) solved it for me, so I suppose some interference with the linear bearing inside the print head.

Maybe it helps for you.

 

Regards