Spur centers are easy to sharpen. Somebody suggested a file, I do mine on
the bench grinder. You could also use a sanding disk, a belt sander, or a
Dremel. No sense spending money for a new center when a minute or two is
all it takes to make yours sharp. If you use power tools instead of a
file, dip it in water every few seconds to keep the metal from overheating
and drawing out whatever temper it may have.

-mike paulson, fort collins, co