DIYbanter - View Single Post - 3-4" grinding wheels

Dave Baker

wrote:
Can you still get these in the UK? Wolfcraft and others make them,
but I can't find an importer or a source. I really don't want to
have to find space for a bench grinder, especially as it won't be
appropriate for my primary task (sharpening gardening tools, such
as sickles and shears).

And the diddy little shaped grindstones are even less use :-(

You want a Dremel or similar. A small stone running at high speed will
remove metal without wearing itself out. The key is surface speed which is
ideally the same for all grinding wheels. Basically an inverse relationship
between diameter and rpm. The technical term is SFM (surface speed per
minute). I have professional cylinder head porting gear but then that's what
I do (did) for a living and a 1 inch diameter stone running at 15000 rpm
will sharpen anything to a razor edge with no discernable wear on itself. I
use mine on the shears, secateurs and lawnmower blades.

A bench grinder is not ideal as you say because it has too many bits in the
way for a long blade like a scythe. Even something as big as a 4" stone in a
normal drill is no use because the surface speed is too low. Dremels run at,
I think, up to about 30000 rpm so even a half inch stone will do a very good
job. An angle grinder is a bit rough for precision work although with care
you can sharpen stuff with one. A small stone in a high speed tool gives you
much more control though.
--
Dave Baker