On 22 Sep, 15:20, Stephen wrote:
Hello,

I'm looking to get a bench grinder to sharpen some chisels. I see some
have discs six inches wide, others are eight inches; is one any better
than the other?

Bigger is vaguely better, as the resultant grind has less of a hollow
to it. However this is a very minor point.

I see most grinders have two discs: a coarse and a fine one but a few
are wet and dry. Is there any advantage to a wet and dry one,

I'd strongly recommend the sort with a 10" slow water cooled wheel.

Double-ended coarse/fine fast grinders with small wheels are OK for
most metalworking applications, such as cold chisels and HSS lathe
tools. However we now have angle grinders for many other tasks and
there just aren't that many things for which is the best sort of
grinder.

For woodworking tools, these grinders are much too fast, too hot and
rather too coarse too. They're better than nothing if you want poor
results on HSS woodworking tools in a hurry, but that's about it. I
wouldn't even use them for woodturning tools (which are generally more
robust to abuse in grinding). In particular, they'll ruin good edges
in good steels by overheating them.

If you do see a woodworking grinder, then it's usually slow-speed,
large wheel diameter and water cooled. I've a Record one (rebadged
Scan) that's quite cheap, the popular Tormek is 200 quid+ and there
are some Creusen grinders that are very similar to the typical
metalworking grinder, except for running at half the speed (1425, not
3450).

A useful compromise for the DIY workshop is a cheap (I've seen 30
quid) double-ended grinder with a worm drive to a 10" wet wheel.
They're noisy, the wheels are a bit too coarse and the dry wheel is on
the small side, but they're 30 quid... These are useful for
woodworking tools, the wet end at least. I use mine for the
woodturning tools and for initial shaping of newly forged tools or
refurbishing and reshaping of old damaged S/H chisels. Then it's the
Record for rough grinding, then hand stones for actual sharpening.