i believe i found the issue with my bed twist problem

While pulling and cleaning the glass bed, I felt a lot of play in the aluminum bed. It turns out one of the bearings is so shot that it rotates easily putting stress on the other three. It will lift and rotate by several mm that you can see at the bearing itself. Huge gap around the rail. I have only owned my Taz 4 for about four months and really don’t print more five attempts a week. Really disappointed.

If I am going to have to pull it and replace, I guess its time to replace them with ball linear bearings. Time to dig for that information.

Has anyone gone to a larger diameter rails? 12mm? 14mm? 16mm?

Another option is mini rail or equivalent (http://www.pbclinear.com/Mini-Rail-Miniature-Linear-Guide?utm_source=RelatedItem&utm_medium=Internal&utm_campaign=Related%2BItem)

I’ve built several CNC routers and printers and the couple of times I’ve used linear guides and rods, I’ve been disappointed. My plan for the KITTAZ is to replace at least X and Y with rails. For X I’m thinking about MakerSlide. Not sure how it would fare for the Y though, need to do some more research. If it can support the load, it would be a great way to go for the Y too.

I was thinking about going to the MakerSlide as well but chose the just upgrade the shafts and put linear bearings on mine. ~$80 on eBay for the shafts and bearings and no need to refabricate the printer. I’ll save that for my second one. Here’s a thread with all the upgrade info.
https://forum.lulzbot.com/t/linear-bearing-backlash-big-x-axis-issues/966/1

So far, my KITTAZ has not displayed any issues with bed twist or other misalignments. But to be fair, I used a granite (2’x3’) surface plate and checked alignment with a height gauge and other tools.

When I stretch the X axis on RazzMaTAZZ I will go with some form of rail. Haven’t decided which yet.