This tool is used to remove press fit crank bearings typically found on mountain bikes and race bikes. Although there are commercial tools like this made out of metal, I could not find any at my local bicycle store and I did not want to wait for the internet to deliver one for me, so I made one myself.
I should point out that this tool, although functional, is not going to last very long. It is effectively a disposable use once tool. At least that was the case for me, but my bearings were in very bad shape and I had to bang pretty hard to get them off.
The procedure is simple: Insert the narrow end into the crankshaft and then press the tool until the cone pops into place. Then use a rubber or wooden mallet on the tool to press out the bearing.
I parameterized the
.scad file so you can configure the size of the tool. The included
.stl file fits bearings with 30 mm inner diameter.