I picked up a few scrap motors from radial arm saws that had a manufacturing defect. They were perfect for grinders and only a left hand nut was needed to secure the stone wheel.
The saw motor case provided lots of clearance for access to the wheel.
That home built grinder continues to provide useful service after years of rough handling. For drill, milling cutter and lathe tool sharpening I use a smaller grinder with green wheel option on one side.
I have found that grinders dedicated to different purposes are ideal. You can't have too many grinders.