Simple i3 x-axis strain relief bracket

thingiverse

Simple i3 x-axis strain relief bracket (for x-axis idlers with offset leadscrews) (v1.1 update, added ability to adjust arm lengths in scad file) (v1.2 update improved customizer support) A critical design flaw in many Prusa i3 X-axis setups occurs when tightening the x-axis timing belt, causing the tension to pull on the z-axis straight rods and leadscrews, which can bend the z-rods or even pull the leadscrews off vertical. One viable solution is to print a complete new x-axis setup with tensioners that load the x-axis rods instead of the z-rods. For example, Smooth X-axis for Prusa i3 with Leadscrews by MazaaFIN (http://www.thingiverse.com/thing:1103976) or Prusa i3 improved XZ axis by jkoljo (http://www.thingiverse.com/thing:372056). However, these print projects seem challenging for beginners like myself to work up to. But with patience and practice, I'm confident that one day I'll be able to tackle them successfully. I have a MaxMicron Prusa i3 clone with an x-axis setup where the leadscrews are offset from the straight z-rods, similar to the HIC design by Zeigbo (HIC Prusa I3 X-axis Motor Carriage OFFSET Z-AXIS RODS by Zeigbo: http://www.thingiverse.com/thing:712896). This offset allows all four of the leadscrew mounting screws to be used, unlike many inline versions where only three of the four are used. It also provides enough clearance for a simple bracket that can solve the strain problem well enough to keep going and work up to bigger prints. So, I've designed a simple clip-over bracket to put the x-idler stress back onto the x-rods. While it's not as fancy as an actual tensioner, it's much simpler and gets the job done. Here is a parametric scad file that fits my MaxMicron, and probably any printer with an idler like the "HIC Prusa I3 X-axis Motor Carriage OFFSET Z-AXIS RODS." It can be adjusted for other dimensions if needed. I used 5mm thickness, but it might be worth trying different if you prefer. The STL is the most likely fit, saved from the scad file, set to use M3 captive nuts and 20mm M3 screws. The scad has options for M4 screws and M5, but the M5 option may require some work to get the larger nuts to fit outside the x-axis rod holes without weakening the bracket too much. Print Settings: Printer Brand: RepRap Printer: MaxMicron Prusa i3 Rafts: No Supports: No Resolution: 0.25mm Infill: 40% for strength Notes: To get a very close fit, I partially printed a few layers, measured carefully, and scaled if needed. The closer the fit, the better. Post-Printing: Assembly: Press in the M3 nuts, start the screws, clip the bracket over the idler, and adjust the screws until the leadscrews stand vertical and stay that way as the carriage moves up and down. Once set, the stresses on the bracket are not too excessive, friction in the normal x-rod holes still contribute, but the bracket stops the rods from creeping.