On 23 Sep, 23:02, Stephen wrote:

Cold chisels and sds chisel bits were what I had in mind.

How many of these are you realistically planning on sharpening?

I have several "old style" grinders and rarely use them (lathe tools
only). On the rare cases when I do need to sharpen a cold chisel, I'm
usually on-site, up to my ears in plaster dust and have an angle
grinder with me but not a bench grinder. You can imagine the rest...

to sharpen wood chisels I would need a water cooled one?

Yes. This depends somewhat on the steel used and the quality of both
chisel and the work you're planning for it, but broadly yes.

You'll see woodworking tools, particularly Stanley plane irons,
advertised as using chrome molybdenum vanadium steels. This is a _bad_
thing in a plane iron - the steels are softer, "gummy" to sharpen and
you can't get a good edge on them (my notion of "good" is pretty high
here). These HSS-like alloys are used because they increase the
softening temperature of the steel, thus allowing them to be ground in
factories on fast, dry air-blast wheels, thus reducing costs. Note
that you can't have a grinder like this yourself - you won't get the
cooling air jet (serious HSE issues involving dust extraction), so
you're going to be running even hotter.

The best chisels around are 50+ year old Sheffield-made chisels with
very simple alloys of high carbon steel, particularly if you can find
laminated ones. These are fairly easy to sharpen, but do need to be
kept cool if they're not to draw the temper. Any powered grinding
needs to be wet. For another thing, the angles are more acute, so an
edge has much less "body" behind it to distribute heat by conduction.
Then their final grinding (bevel & honing) really needs to be done by
hand (only takes moments) because a mechanical wheel would have to
have very expensive bearings to give the necessary stability.

I'd strongly recommend a starter sharpening kit for woodworking of a
cheap powered wet wheel for resurrecting car-boot sale chisels, a
cheap combination waterstone (1000 / 4000 grit on each side) and a
read of Leonard Lee's "Sharpening" book. You might find Scary Sharp
worth a look too (silicon carbide wet & dry paper stuck to glass).
Oilstones are a pain, diamond and ceramic are expensive for good
quality.