TAZ 6 Z-Upper tolerance?

I just finished upgrading my home-built TAZ 5 to the TAZ 6 design. Works great! (Though it was a bit of a pain to have to rebuild the whole frame just to add an extra 10mm width, but I’ll get over it…)

My question today is, should the smooth rods and the skate bearings fit snuggly in the holes of the z-upper part? Or is it designed so that they have a little bit of play and aren’t completely rigid in the holes? I’m asking because with the parts I printed (with zero horizontal expansion) have quite a bit of play around the smooth rods and the bearings. For example, you can’t install the bearing into the z-upper part because it’ll just fall out. You have to put the bearing on the lead screw first and then push the whole assembly into the z-upper part.

I ask whether that’s intentional because, normally, when I print parts with zero horizontal expansion, I have to use a rasp to open the holes up just slightly so the smooth rods will fit at all. I also know that having a little bit of play at the top would free up the lead screws and make them less likely to bind. But if that were the intent, I’d expect only to have the skate bearing be loose, not also the smooth rods.

One last point that might be relevant: I printed it in Colorfabb nGen.

Those bearings are intended to have a little bit of play, it might help to see a video of exactly how things are sitting up to get a better idea of if the amount of play you are seeing is normal. If you are curious we have an assembly guide that shows how the Taz 6 frame is assembled which might help you in getting that put together: https://ohai.lulzbot.com/project/taz-6-frame-assembly-version-2/taz-6/

I don’t foresee these being printed in NGen being an issue, but we use ABS at a 70% infill on the standard detail profile to print our parts in production. NGen is relatively close in physical properties to ABS and since this part shouldn’t be seeing a lot of heat the slight temperature difference between the filaments shouldn’t be an issue. NGen is pretty good in terms of thermal warp so I don’t think it will have an affect on the dimensional accuracy of your holes.

Alright, thanks! Good to know about the bearing intentionally having a little play. My concern is now about the smooth rods, which it seems should be locked in tight. I’ll see if I can make a video tonight or tomorrow. Hopefully you’ll be able to see it in the video.