For those of you that prefer a right angle grinder, try the Makita flex wheel. It'll grind circles around the older original wheels.  This blade pictured was sharpened while I was setting in the comfort of my chair with the blade extended across my knee.  The other picture is a piece of re-bar that needed threads on a stretcher for an outdoor chair repair.  Solution for precision sizing.  Grind it down while rotating it with a variable speed drill.  Once again, the Makita flex wheel.
If you're gonna do it you may as well be comfortable and have fun doing it. :laughing: