After testing, I found that the longer bushing created too much friction on the rod so I changed the mountable bushing back to 11mm length. Also, these are a bit more work to install than just gluing them. There is a higher chance of putting the bushings on out of square if you do not take your time and get good measurements. Granted, it will be faster if I ever need replace the bushings.
I wanted to make bushings for the y axis that were more easily changed out than the given instructions on the Prusa build (gluing). The mounting holes are set to fit m3 screws.
The scad file is the original pla-bushing.scad file from the Prusa git with the added mounting arms. If you drop the .scad file in the folder with the configuration.scad your Prusa scad settings will work on this file. For example, I print my bushing with the rod size a little larger so I don't have to ream the bushing as much. So, in the configuration.scad file I change the bush_rod from 8 to 8.2.
The stl file I have given has the larger bush_rod size, so if it seems too big you may need to change the unit back to 8.
- Clean up and ream the bushings if needed (run the bushings across 8mm thread stock)
** Now the tricky part. There are probably multiple ways to do this but I installed them this way:
I found the easiest way to make your marks for where you need to drill the holes is to flip the printer on its back side. After snapping the bushings onto the rods (two per y-axis rod) place the bottom plate onto the bushings, holding it from behind. If you pull the bushings to the bottom of the rods the plate can rest on the bearing mud guard washers.
With your four arms set the bushings so they are a cm away from their respected edge of the bottom bed plate (see the image). Hold the plate so it is square with the rods and make marks on the plate inside the mounting holes. Drill the holes.
Bolt the 4 bushings onto the plate making sure they are well secured.
Pop the plate onto the y-axis rods. Make sure the plate moves back and forth smoothly and does not bind. If you have binding you either need to make sure your bushings are square or you may need to move the two y-axis rods closer together or further apart.
- Continue following the Prusa build directions.