This may have bearings on my bearings...

A couple bearing questions if anyone happens to have a moemnt to answer them. Specifically relating to the Z axis.
So, at the moment I have Lulzbot Ao-101 style pillow block Igus bushings on the Z axis. It works pretty well, and faily fast, but If there is something out there I can do to improve accuracy, I’d like to explore it. I see the TAZ uses LM10UU bearings / bushings. I also see a variety of mods using LM8UU bushings already in existance. I kind of like the size of this printer, so I don’t really want to go with a bigger one like a TAZ, but i wouldn’t mind making it a bit bigger / altering it / etc to get enough accuracy to try that bed leveling trick if I need to, because that thing is just neat!

So I’m wondering, assuming I want to stick with some sort of solid rod, but don’t necessarily mind changing out for something different / larger / multiple rods assuming i can make a part to make it fit, what is the ideal bearing type for the Z axis? is an LMxUU bearing significantly better than a pillow block one? Is there a better choice? Are the 10’s going to be worth the effort to make a bearing holder over the LM8UU’s if those are the best choice? I kind of don’t want to go to the extreme of mounting a full up linear rail on the Z axis, since that looks like it would be painful to engineer without basically ending up with a different printer.

So what would you put in if you were going to rebuild a portion of that axis, or would you?


We went from the pillow block style to the LM10UU style when we went from 8mm rods to 10mm rods. The 10mm versions of the pillow blocks are really huge, so there weren’t good mounting options. The LM10UU ones we use are the same material. Either will work fine.

My thought at the moment is to keep the 8mm solid rod, just because I already have it, but try and make a “Taz style, but horizontal X axis” bearing and acme nut modification The gemoetry woks with a little modification, but the sticking point in my brain at the moment is the rod clamps for the X axis. Specificallt those inboard clamp screws for the upper and lower halves. Widening the clamping surface wouldn’t be an issue for clearance, but putting the clamp bolts outside the rod would reduce the downward force slightly. I don’t know if that would be an issue though. I really like the fact that the TAZ bearing mount is a contiguous unit though, so I don’t want to split the bearing mount if i can help it. The part I’m really interested in is trying to fit the acme nut mount, The anti backlash and anti wobble portion of that look like a major improvement over the AO-10x series mounting style. The problem is making it fit. It could go above or below the rod clamp, but that offset from the X motion axis might cause problems. My current thought is to take the TAZ acme nut holder, lenghten it by about 15-20mm on the plastic flex portions, and cut a channel in both sides of the flex section to fit above and under the rod clamps, with the spring tube running down the middle of the two x rods where the old Acme nut mount was before. I’m still plaing with the layout in inventor to see if I can make something work.
I’m thinking at a minimum i’m going to have to install the lowered Z motor mounts and a shorter rod coupler to make everything fit.