Z-Axis & X Gantry Mounts for Acme Nut Blocks

thingiverse

I had a multitude of problems with z-banding on my AM8, and having spent more than I could afford on high-quality 8*8 lead screws and hardened steel guide rods, I couldn't simply give up and switch to linear guides + belts. I figured the best way to achieve good Z was to get the vertical elements as tight to the gantry and to the frame uprights as possible. I also wanted to squeeze more Z out of the frame - I was losing 40-odd mm with my old setup. This rig, combined with the titan X carriage, gave me that extra Z and solved the regular screw-induced z-banding. If you decide to try this setup for yourself, there are a few things to note: 1) Ignore the lower screw-hole in the motor & lower smooth-rod holders - they were an early idea that didn't work as well as I hoped. You only need to use the ones in the top surfaces of the fillets and metal components keep the parts in correct alignment. 2) Use decent rods. 8mm smooth rods tend to be straight, or not, but 8*8's can weeble-wobble all over the place as the solid centre is c.6mm, and soft metal makes that worse. It's worth the extra cost. 3) Check the coupler centres. I went through a lot of frustration trying to find out why the bottom of the screws wobbled, & changed out both couplers twice. Turns out all 4 of the first 2 pairs had the 8mm hole slightly off centre! I was very frustrated... The last pair were both good. 4) Get everything absolutely vertical. The way to start is with the smooth rods - I made the top mount the base point so set those firmly in place first, then lock down the bottom, then the motor mount, then the acme nut. The secret is check and double-check until you're sure. The parts are all 100% infill, so they can be cinched down tight with 8mm flanged-button m5's into hammer-nuts; material isn't important as long as it's stiff enough not to flex as you tighten down the screws and during printing. Note: The bottom Z rod bracket needs to be printed x1 as-is, and x1 mirrored (most slicers can do that). It's not critical though - 2 of the same will work fine just not look so tidy.