SC8UU compatible linear bushing with M4 thread

thingiverse

A M3 screw bushing that is SC4 compatible with 6-32 threads. No locknuts needed, a small nozzle (I used a 0.3mm nozzle and a 0.2mm layer height) and low layer thickness allow the printing of the 6-32 thread (6-32: 0.6mm pitch, 0.5mm groove depth) and inner fins. If the thread wears down a locknut can be used. The bushing design is based on the SC4UU shape by [username], which has some spring functionality. Version 1 features a smooth running thread that may wear out quickly. Version 2 has a very tight thread that will not wear down, but needs to be screwed in with force. Version 3 allows for tilting in one direction to compensate bent rods (see the colorful picture). A shorter SC4U version is available and an extended SC4UU model is also provided. A stiffer version for use on the x-axis was added. Send a message if you encounter any problems or have suggestions. Using plastic bushings instead of bearings reduces noise, provides a tighter grip on the rods resulting in less jitter, and helps to eliminate rod wear. Note: Ensure low friction levels post-printing (see below) as this can lead to backlash issues. Print Settings: Rafts: No need to worry about rafts. Supports: Not needed. Resolution: Print at 0.3mm nozzle, 0.2mm layers. Notes: Use PLA instead of ABS and print without supports. You might need to cool the printing process with active cooling to avoid overheating issues due to heavy vibrations that can occur while printing. Also be aware that due to this intense shaking, you may need to add a brim at the base of your print to prevent damage or loss of parts. Post-Printing: Important Obligatory task Place an 8mm clean and lubricant-free smooth rod (grasp Grinch74's suggestion for soap-cleaning rods before installation) into the bushing. Be prepared to exert some force in doing so. Next, perform 'burn-in' - an essential step in this process. If possible use a portable electric screwdriver to rotate the rod as you keep hold of the bushing to prevent accidental rotation or rod bending (see photos for illustrations). You can apply heat with rapid rotations to quickly warm up and soften the inner layers of the bushings that will adapt themselves to conform closely to the round shape of the rod. Continue to rotate for a minute, moving it back and forth until there is minimal resistance. Now you are able to remove your electric screwdriver (electric tool removal might be done without assistance). Continue further refining this fit by holding the hand-operated handle, allowing more smooth movement to adjust the shape better to the new rod surface that it was burned onto. It must become as smooth and friction-free possible because high friction levels can cause motor skips or introduce unwanted backlash. For burn in optimisation tip - one should try to slightly roughen rods at both ends (through rasping them). An alternative option of drilling an 8mm hole with the help of a power drill, suggested by KR2 at http://www.thingiverse.com/thing:18219