Hi Martin
Steve mentions the Tormek. A friend has one and it is a woodworkers tool, not a metal workers. It is low speed and which is fine for carbon steel tools. It has a 50mm wide wheel and rests which allow you to sharpen chisels, gouges, plane and planer blades up to about 200mm but it is too slow for the sort of metal removal you need for HSS cutting tools. It is also set up expressly for grinding on the periphery and does not take other wheel shapes.
I would as I said earlier go for a six or eight inch grinder.
For HSS get either white Aluminium Oxide wheels or diamond wheels. The white AO are specifically made for grinding HSS and have high removal rates with minimal tool heating. You have to keep the tool in one place for quite a while with the pressure on to burn it. I was quite suprised when I first used one, having previosly used Silicon Carbide wheels which are really rubbish for HSS.
Diamond wheels are better for TC than HSS though there are many who will dissagree with me. In the past, HSS has tended to load diamond wheels and destroy the diamonds more quickly. I haven’t used one for some time so that may have changed and there are others here who may be able to correct me on that point.
White AO wheels tend to be cheaper than diamond wheels so that may be a factor for you too.
I would have a plain wheel and a cup wheel in 60 grit and possibly one each in 80 grit. Use the fine grit for smaller tools like drill bits 3mm and under.
100mm cup wheels here in AU cost about $26.00 each and 200mm plain about $32.00.
Whichever way you go, you will have to make up arbours for the wheels to get them spinning accurately. And in a trap for young players, different manufacturers have marginally different spindle hole sizes which means they are not interchangable.
I have several white cup wheels from Norton which all fit the same arbour. I recently purchased a pair of Kinik green wheels which are nominally the same but will have to make new arbours for them.
Most manufacturers nowadays ship their wheels with stepped nylon bushes to account for different spindle sizes. They are okay for general purpose grinding but for tool grinding you are better to make your own.
All of the above can be acheived very well on a 150mm grinder, However……..
For polishing you need a minimum 750 watt 200mm grinder. Get a taper arbour (about 8 pounds) and several mops. Before taking the taper arbour away, ask to see it running on a grinder so that you know it runs concentrically. I have been caught out several times in the past. Decide which side of the grinder you are going to use for polishing because the arbours are available in left and right hand thread.
My experience of polishing stainless is that once you have worked through your abrasive grades on the linisher down to a blunt 400 grit, a sewn mop with some green stick will give you a mirror finish. I have found that a leather wheel just heats the metal up too much and that an unsewn mop does nothing at all except spit out of fluff into your face.
When you set up for polishing, make sure the machine is well bolted down and that you have plenty of room all around. If you mount the grinder on a bench, make sure that the polishing end of things hangs over the edge as far as possible so that if the peice you are pilishing gets caught, you can let it go and it should just fall to the floor rather than bounce off the bench and stab you in the guts. You also need plenty of room to move your workpiece around the mop.
Don’t wear gloves.
Wear eye protection.
Wear a leather apron.
Don’t smoke.
Eat your greens.
Don’t touch strong drink.
Keep it in your shorts.
Lawrie.