Z axis on wrong side
I’m assembling an XL. The very first step of the kit assembly instructions say to know the difference between the left and right Z axis. Yet the picture showing the difference wasn't clear enough for me. I think they both need to be clearly labeled - with a sticker on each motor or some other unambiguous visual clue.
Be that as it may, I put them on the wrong side. The rotating one is on the left and the fixed on the right. Now I’m trying to connect the build plate, which of course doesn’t fit. What to do?
How do I take the rails off to swap sides?
Will that even fix the problem, or will I need to take the entire printer apart and start over?
Update: Z axis on wrong side
I discussed this with Michael in a support chat, asking whether I should swap the slider to the correct side by taking both off their rails or whether I'd have to disassemble the printer to the point where the left and right side z-axis assembly could be installed on the proper side. Michael strongly encouraged me to disassemble and start the build over. Thanks for the input, but I ignored that advice.
What I did instead was to take out the green stops at the top of each z-axis rail. Then I carefully turned the 80% assembled unit on its side so that the left rail was horizontal. Then I slid the slider off the end of the rail, being careful that my cupped hand caught all the roller bearings that fell free once the slider was free of the rail. BTW, there are 15 1mm balls each side, for a total of 30 per slider (X2 sliders). Then I slipped the unit over on its opposite side and slid the right-hand slider off its rail, again being careful to catch all the balls.
When I put all the balls of the rotating slider back in place and carefully slid it onto the still horizontal rail of the z-axis rail installed on the right side. As I put the slider on, about 15 of the 30 roller balls fell down into my cupped hand. I put them in a container, rotated the unit into an upright orientation, and spent the next 40 minutes or so carefully "spoon-feeding" the balls into their proper place. This was done by picking up each ball using a slightly magnetic jeweler screwdriver. Then I would slowly, and carefully slide the slider up about 4 mm past the top of the rail. This would, in theory, give me just enough room to push the ball into the roller-bearing channel. If I'm making it sound like this was easily accomplished, it was not. Sometimes the magnetism would cause one of the balls already in the channel to come out, drawn as it was to the screwdriver tip. But after a time, I was able to get the bearing channels refilled with all 15 balls on each side of the two sliders - 60 balls in total.
As difficult as it was to fix my mistake this way, it did work out. I'm convinced that the time I spent doing this was about half the time it would have taken to disassemble the printer, swap the z-axis assembles to their proper sides, then reassemble to that point. I only felt comfortable solving the problem this way because I sat down to the task with the mindset of a surgeon. I was exceedingly careful, patient, and methodical. You’ll have to be all that as well if you try this. Believe me, I understand why I was discouraged from taking this course.
Yes, I’m an idiot for not picking up on which z-axis assembly went on which side. But again, I strongly encourage the Prusa team to use stickers or some other visible means to visually distinguish the left and right z-axis assemblies.
RE: Z axis on wrong side
Hi ,
My XL was dropping some balls too last week.
I had some bed leveling issues, and followed a mod in another tread about removing the upper Z-spindle bearing caps.
After a few weeks of printing I got bed leveling issues and started all over with the calibration proces from the printer menu.
In this proces the bed went all the way up without touching the nozzle and not stopped by de caps.
With a closer look I found ball bearings on top of the linear z rails on both sides, which came out of the bearings, luckily they were held to the top by the grease.
Disassembling the whole machine was not an option, so I found out that it is possible to remove the linear rails by removing the 7 torx bolts.
They loosen up quite easy and the spindle gives enough room to let pass the torx screwdriver on an angle (don't force it tho).
The bolts from the rail are mounted within a strip in the extrusion with threaded holes, which needs alittle help with assembling because it is a little shorter than the extrusion.
It can be easily hold up with an awl or small screwdriver and then install one of the bolts
All the bearings where removed over a large container and I came to the conclusion the bearings have 2X33 balls each.
In this way it is would also be easy to swap the rails from left to right.
I still haven't found why the callibration test drove the bed to its end, but all is running smooth again.
Cheers, Roland
RE: Z axis on wrong side
Thank you so much for posting this! I stupidly removed both arms and lost all the bearings.
One pro tip that we found out was using a silicone grease sort of as a glue to hold all the balls in place while loading it onto the rails. With out the grease several attempts failed and balls went everywhere.