[VIDEO] Prusa X-Axis Wobble

Hi all,

I was hoping you could please help. I'm building a Prusa i3 kit that I bought from China, and I've been having some issues with various parts of the frame being wobbly.

Having taken a video, the vendor tells me this is normal, but it my eyes it's absolutely not okay. The whole printer head assembly can be wobbled on the guide rods.

That said I would really appreciate some points of view on the video. Likely causes, and ways to rectify would be great too. :cool:

Here's the video:

https://drive.google.com/file/d/0B78...FZbnFfeHM/view

Well I have only had one printer (extremely rigid steel Createc i3), but the extruder does the same thing. I think it's the nature of these linear bearings. Has not affected print quality yet, although I'm keeping speeds down.

is the play between the bearings and the shaft? or between the bearings and the carriage?

A lot of printers have similar amounts of wobble. And it probably will print OK. I would be very tempted to add another linear bearing in line with the one on each rod just so it can't wiggle as much.

It's the cheap Linear bearing that they make. The more money you pay, the better bearing you get. I deal with these type bearings all the time and these are pretty much what came with my Geeetech Prusa but they are ok for the time being. Look on ebay for some rexroth or other name brand. The other trouble is, too, that these carriers are so small, the bearings are also very small which might make the difference too.

I was happy to see this thread.

I just got a used Geeetech Prusa i3 that the original owner assembled but apparently never got working correctly. This is my second Prusa-type printer, so I'm familiar w/the design and firmware. I've been able to get it working and calibrated.

Trouble is, I see the same problem as described above. The bearings for the X and Z rods (which actually effect the X and Y play of the extruder head) are loose on the rods. If I wiggle the bearings side to side against the rods I can see a small gap. I believe this translates to an unusual amount of wobble in the print head, since it's "multiplied" by 4 loose bearings. I don't have any looseness on my other printer.

I don't have a problem buying new bearings or rods, but how do I know which one is it?

Thanks.

Hi, Sorry to bring up an old thread but couldn't find any other posts or information about this problem.

Have you reduced the wobble by any chance as I am having the same problem and it is effecting print quality. its only on one side of the print, where it wobbles the most.

Quote:

---

Originally Posted by drinu16

Hi, Sorry to bring up an old thread but couldn't find any other posts or information about this problem.

Have you reduced the wobble by any chance as I am having the same problem and it is effecting print quality. its only on one side of the print, where it wobbles the most.

---

I replaced bearings and rods and it did improve things to the point where I wasn't getting any more wobble/looseness.

What I found was that the old bearings were actually OK (or perhaps more standard), it was the rods that were undersized. I mic'd both the old and new rods, and the old rods were slightly smaller diameter. I probably could have gotten away with just replacing rods, but there was no way to tell in advance. But just because my rods were the issue doesn't mean that will follow for your problem (that is, assuming you can actually see a sloppy fit between your bearings and rods). As always, your mileage may vary.