About this 3D model

This is a modified herringbone drive gear, designed to eliminate the tendency for the original to be off centre when clamped, which leads to varying resistance when the rack is moved. You need to use a 45mm m5 part-threaded bolt with this, with the threads cut off. File a flat onto the bolt shaft where the grub screw will contact, to prevent the drive rotating under load. Tip 1: Mark where the flat is on the top of the shaft, so you screw the grub screw in the right place. Tip 2: If the rack is very tight when the brake is fully loose, print a replacement brake and sink it below the printer bed by 0.7mm or so. Extras needed for the mod: 45mm part-threaded m5 hex head bolt; m3 grub screw 6mm long; m3 nut I printed this in PLA with 100% infill and no brim. 0.2 layers, 0.4 nozzle.