Lars' v2 Ultimaker XY Blocks

youmagine

After switching to a GT2 belt configuration and needing a reliable belt clamping mechanism without integrated tensioning complications, I decided to design my own XY blocks. The factory bronze bushings are very susceptible to clamping deformation and bind, so I wanted something with separate bushing and belt clamping. I designed these around some replacement bushings I got from Robotdigg that have a 12mm outer diameter instead of the stock 11mm. I made provisions for inserting M3 nuts into the blocks for all connections, so no plastic threads are relied on. The one exception is that I left holes in the block back face to thread in an M3 bolt in various positions to trigger limit switches. You decide which need a bolt and where for limit switch triggering. Mock it up first because you won't be able to install those bolts once the block and perimeter shafts are installed. One of the biggest benefits of this design is the ability to square the print head by loosening a single bolt on each block to release the belt. This means no more fumbling with pulley set screws! The other benefit of this is that once the belt is released, there's almost no drag compared to loosening pulleys where you're still moving belts and spinning pulleys on the 8mm shafts. This gives you a much clearer picture of how freely your print head moves. I actually discovered that my printed print head was holding the 6mm shafts slightly out of square, so forcing them square to the 8mm shafts actually induced bind! You can simply loosen the belt clamps on two opposing XY blocks, move the print head back and forth by hand, and re-clamp.