There's a lot to love about the Prusa printers, but the Y axis belt line is not one of them. A 16T pulley on the motor, a 20T pulley on the idler, and an offset going through the belt holder introduce Z axis forces on your bed as it traverses along Y. These parts allow you to use a 16T idler and get a perfectly parallel belt line, keeping the bed more level as it travels.
User RHDreambox designed replacement parts to fix this on the stock MK3, but relies on quality assembly to achieve belt tension. These parts provide adjustment via screws.
Built for Bear
User pekcitron designed an excellent frame replacement for modern members of the Prusa i3 family of printers. He's also built an excellent replacement X axis and extruder that makes the belt line parallel, adds a built-in belt tensioner, and improves the extruder itself.
There are a few parts in this "thing". You will need the right set of belt holder, idler slide, and idler mount for your printer. There are a few preassembled kits (zipped STLs) as well.
- Y axis belt holder for the mk42 bed
- Y axis belt holder for the mk52 bed
- Y axis idler slide for Bear users.
- Y axis idler slide for stock MK3 users. (Not yet tested; beware!)
- Y axis idler mount for Bear users (OpenBuilds V-slot)
- Y axis idler mount for almost-Bear users (Misumi T-slot)
Stock-MK3 tensioner (not the stock idler!)
Feedback told me that the slot-mount holders were harder to center than they needed to be because the screws were behind the slide. Good criticism, so I made mounting ears instead. It was also called to my attention that the naming of the Y belt holder files wasn't quite right. Fixed! I'm also working on an easier-to-use version of the belt holder.
It's a day off work so it's a day for maker-ing. I've back-ported the belt holders from my "Serious business" mod since the tooth profile is better. I've also modified the Bear version to have a slightly different V-slot profile on feedback that it was slightly too-big. Finally, I added the sight-line to the stock MK3 flavor mount. New Solidworks source is up. It's now the 2019 version. Happy holidays!
3-4 perimeters; 20% gyroid infill.
Be especially careful printing the toothed parts. You may want to use smaller layers, and you'll certainly want to tune your linewidth to get a nice shell.