Bearing Grooving Jig

This thing is a simple jig to allow you to grind a groove on a plain roller bearing using an abrasive wheel and a Dremel or other die grinder type equipment. One the reasons you might want to do this is for your extruder idler bearing, this will help keep the filament on axis. One of the problem I have experienced with my (poorly made?) hobbed bolt extruders is the filament wandering up and down the hobbed portion of the bolt. So I was inspired by ebay seller you2bay http://myworld.ebay.co.uk/you2bay/ who sells grooved bearings to have a try at this and it works great. My first attempt was just to grind the bearing by hand but I think this is a much more repeatable method. Please take care and use safety glasses as a bare minimum safety equipment when ever you are grinding anything.