Wobble Print Head Printrbot

I've been searching and reading through all the topics on linear bearings and I'm more confused than ever as to what combination of bearing and shaft would produce the best results.

Here's a video of my head wobble and I cannot see the bearing moving at all within the head assembly only on the shaft.

Video of Print Head Wobble

I see discussions on different shaft materials and it sounds like chromium is a good choice but I'm not totally sure.

I see linear bearings ranging in prices from $2.00 to $50.00. I'd really like to get some good bearings that won't allow the wobble but not at fifty bucks each. By the way these are the 8mm X-axis bearings on my Printrbot.

I look forward to replies.

I'd suggest more points of contact, like two bearings along the shaft.
It looks like there is enough room for two, and not reduce your print area.
You could use your printer in this sloppy condition and print your new design having two bearings and will replace some of the wood bits.

there is likely slop in the wood and in the bearing.

There appears to be some movement between the wood and the bearing, which is not good.

Even the cheap linear bearings work well of the shaft is the right diameter but it has to be precision ground to h6 tolerance or better.

You need two bearings on the same rod to prevent angular motion like that. I.e. the carriage should have at least 3 bearings whereas yours only seems to have two.

It might be possible to get away with two if they are extra long ones. Standard LM8UU allow some angular play, which helps with alignment.

Edited 1 time(s). Last edit at 05/04/2013 05:52PM by nophead.

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A quick help for this is to use a second bearing on the top of the x carrage. (Note. my kit came with a spare bearing for this)
then use thingvers model "Printrbot LC X-Axis Stabalizer" thing 42480 to hold the two bearings together on the carrage.

The use of two bearings will reduce the available x travel to about 5.5 inches, but that is also the distance between the bed mounting screws, which also limits the usable size.

you can also do the obvious workarounds that have been around a while tape around the bearings where it is held in place by the wood. use kapton tape to fill the space voids. it wont be perfect, but the motion should be reduced.