Prusa I3 - Z Axis Anti-Backlash Nut with Home Depot Springs

thingiverse

This DIY anti-backlash nut design is ideal for printers using 5mm rods. I highly recommend this design only for printers with Auto Bed Leveling (see explanation below as to why) The .STL file includes a pair with mirrored versions (one side is thicker to compensate for the thinner wall on side facing the printer part) You will also need: 1) A separate pair of 5mm nuts 2) 1 Spring set from Home Depot (refer to picture) 3) 4 washers 5) Only if you have an X-Axis belt tensioner: If the belt tensioner is secured with a Hex Cap M4 screw, replace it with an M4 screw featuring a Button or round Cap. If you do not make this replacement, the part will bump against the screw. Instructions: 1) Print the 2 parts (mirrored versions) 2) Prepare the part carefully (further instructions below). 3) Remove your rods, remove the existing 5mm nuts 4) Mount the printed part with the nuts (2 existing from the rod + 2 new), washers, springs 5) Install the part in each rod. This may also be a good opportunity to clean your rods and lubricate as needed. 6) Install the rod with the new part in the printer. The top of the printed part will fit in the printer's 5mm nut catcher - refer to picture) 4) Rotate both rods by hand to check if they rotate freely after you mount them in the printer Some background: Without bed Auto-Leveling, repraps using screw rods only move the Z axis upwards layer by layer. In this case gravity keeps the nut sitting against the bottom of the thread. With Auto-Leveling, the printer will move the Z Axis up and down during print (similar case to CNC machines and Delta printers). If the nut is not running on the thread tightly there is a possibility of introducing a small Z variance due to the tolerances between the nut and the thread. This simple device ensures the nuts are always sitting on the thread by pushing two nuts against each other using a spring, with a washer interfacing between the spring and the nut. Print Settings Printer Brand: RepRap Printer: Prusa I3/Graber/Rework/Wilson parts Mashup Rafts: No Supports: Yes Resolution: around 0.15 (multiple of your nozzle width) Infill: 100% Post-Printing Part preparation Removing the support from the holes is tricky due to the fact this is a small piece and if you are not careful, you may crack it. You will also want clean removal so that the washer and the nut will sit perfectly. (the .STL has been adjusted so that the nut and the washer will fit comfortably after printing to make preparation easier) With very thin pliers start by pinching and pulling the supports from holes, then use an allen screwdriver or any small cylinder to "punch" the support out. The support should come out clean after some back and forth. You could use a drilling machine rotating really slowly but in my experience this makes it more difficult to remove the supports cleanly. You will also need ensure the hex sides of the part that go into the 5mm nut catcher are well finished and flat (you may need some filing or sharp knife finishing). Finally, clean the part from any PLA or ABS debris you could stick to the rod before installing on the rod. You can wash, blow air, etc..