I have a taz 4 I’m rebuilding and upgraded the z axis to a taz 6 z axis. Part of that upgrade required me to replace the 10mm smooth rods for the x axis with 12mm rods. So i ordered the bushings (rjmp-01-12) and reprinted the x-carriage but the bushings don’t fit tight inside the bearing holders like the 10mm ones did. They are very loose and can become dislodged and completely fall out with just a firm tap. Is there a simple solution out there for this or do I just need to modify the designs and reprint until i get a good fit?
I assume you didn’t order the bushings from Lulzbot?
My guess is the reprint of the carriage didn’t exactly print the dimensions within tolerance. What material did you print it in? I think most Lulzbot parts were designed to be printed with PetG.
I would just try stuffing something in there between the outer bearing and the bearing holder. I know it’s a tight fit and you can’t literally stuff something in there. I would try one wrap around of electrical tape on the bearing and then press it in there,
I didn’t buy them from lulzbot. I don’t think it was a problem with my printing tolerance. The printer that I used is pretty dialed in and it’s the same printer I used for the 10mm bearing holders and they fit fine. Probably the cheap chinese bushings are out of spec compared to igus brand. I printed everything with ABS.
I thought about stuffing something in there to shim it but I figured it might cause the bushing to sit crooked and cause issues with it sliding across the linear rods. I think I’m going to try printing a sleeve for them. Basically a single perimeter vase the exact size of the inside of bearing holder. I can slide the bushing into it then the whole thing into the bearing holder. Hopefully it works.
Well yeah I agree with that, that it’s probably out of tolerance. I don’t think there’s too much stress put on the bearings where they’ll be problematic if you get them in there tight by whatever means. Even a glue might help. I don’t know what works with ABS but for PLA to PLA acetone works wonderfully! Chemically bonds the pieces together with a little chemical heat reaction.
I think you have this figured out. Good luck! 
Just a small drop of Super glue on the edge junction will work fine. Much pressure on the printed part will cause it to crack between layers if you did not print it properly. Too much glue will make replacemnt much harder Note: Do not get it on the rod!