I disassembled and reassembled the y-carriage on my MendelMax during some maintenance, now the table jitters when printing. When moving slowly, it really only stutters in one particular spot. But when I speed things up, it jitters along the entire y-axis. I am using bolt-on bushing holders like on the Lulzbot AO101. At first I thought I had them too tight and things where binding. So I loosened them. Now I’m worried that maybe they are too loose, and they are leaning and getting out of alignment and causing binding. I’m not sure how to proceed.
In thinking the linear bearings are over constraining the stage. I’d say loosen, slide it around to make sure it runs free than, gradually tighten, while ensuring free motion. Others have mentioned this and I’ll reiterate, 4 linear bearings inherently over constrains, if the design can handle 3, use 3, but already ensure your rods are perfectly parallel, as no amount of adjustment in the bearings will fix this.
I’m thinking your bearings are too loose as more jittering when at higher speed is just chatter due to too much slop.
@Eric_Moy I agree with your thoughts on over-constraining when using 4 points of contact. I currently only have three bushings on my y carriage for that reason. I will keep trying the loosen/tighten method. I suspect one or the other (or maybe both depending on the bushing) is to blame. I was just making sure I had not overlooked something else.