Wanhao DI3 X Idler Upgrade by ftk1

Last crawled date: 3 years ago

This is an X axis idler upgrade for the Wanhao Duplicator i3 and clones. Since the stock idler pulley is supported only on one side, it tends to get skewed with the tension causing mis-alignment and increased wear.
This part utilizes a longer bolt to create support from the other side of the carriage to keep the idler pulley perpendicular to the belt. The only extra part needed is an M5x45 bolt. This design was inspired by The_Monstro's x idler, but does not require drilling holes or disassembling the carriage from the printer.
This upgrade can install in place, but it is a little tricky:
Disassembly
1) Raise the carriage at least half way up the Z axis
2) Release the belt from the print head
3) Using a hex key, unscrew the idler bolt from the bottom of the carriage. This will be tedious since there is only room to turn about 1/4 turn each time, but fortunately, the bolt only needs to be unthreaded a few millimeters
4) Once the bolt is released, you'll find that the pulley and bolt is jammed between the back wall of the carriage and motion rods. Unloosen the nut behind the pulley a few turns using a needle nose plier through the hole the belt goes through and the hex key from the bottom, until you're able to remove the pulley and bolt from the bottom
5) Remove the nut and bolt from the pulley, save nut for the new idler mount.
Assembly
1) There is a threaded insert that the stock pulley mounted to. The printed idler spacer mounts over this protrusion. Thread the new bolt from the back side of carriage until it sticks out a few mm inside. Then use the end of the bolt to guide the spacer into place. It will fit snugly over the insert. My insert had a blob of welded metal, which is why the spacer has a cutout to accommodate it.
2) Bring the pulley with belt into position by the spacer, then thread in the bolt until it is through the pulley and flush with the end.
3) Use the nut that was removed from original bolt and press it into the hole of the new idler mount
4) Guide the idler mount from the bottom of the carriage up to the pulley with the inserted nut facing forward and the thicker leg facing toward the center of the printer.. The left leg of the mount will align vertically with the hole that the belt goes through and the part will fit snugly in the carriage
5) Start screwing in the bolt from the back feeling for if the bolt is aligned to the hole. When aligned, the idler mount won't push out from the carriage when the bolt is tightened. Try to keep the mount pressed down fully in the carriage, then tighten bolt as far as it will go until it is flush with the back of the carriage.
6) Re-mount and tension the belt