Advice on grinder selection

Having failed to find a supplier of fine wheels for my elderly double-ended 3000rpm five inch bench grinder I have decided to keep it for coarser work and buy a new one for which I can buy, or which already has, a 100 or 120 wheel for fine grinding of HSS lathe tools and perhaps a green grit or whatever is recommended for trimming tungsten carbide drills.

I think that it will have to take at least six inch (150mm) wheels to obtain the above grades.

I am very much out of date: please can anyone give me advice on a make

and a helpful supplier?

Thanks.

I have an old 5" grinder , just used for drill sharpening now. I bought a 6" machine, just about any of the cheaper machines will do, they are all about the same. Just make proper rests, and be prepared to change at least one wheel, both if you need green wheel, but for carbide use a cheap diamond disc.

Can I ask a stupid question here.

To cut and shape HSS tools do you need a high speed grinder?

It's the surface speed that does the cutting, not the revs/min. So any standard bench grinder with the correct wheels will cut HSS. Running too slow will wear the stones very quickly.

Thanks Gordon.

I guess by that a larger wheel is better, say 6" rather than 5" ?

Sorry to hog your thread Merlin.

If one is sharpening High Speed Steel cutters, then white grit wheels are to be preferred. As these are used extensively for tool and cutter grinding they are relatively easy to locate, most suppliers to industry will have them. However, they will have large central holes and need adaptors. One advantage of this is that they can be changed from one shape to another without the need to redress them.

For use in the home workshop the actual grade is not critical, any grade being sold for tool and cutter grinding in industry should be OK. 4", 5" or 6" wheels will be OK at 3000rpm but of course the smaller will be cheaper.

You could of course take a standard off hand grinder, 5" or 6" and adapt it for taking these wheels with a the shop off hand grinder just used for basic grinding. see my webpage

**LINK**

I was informed a few years back by a supplier that diamond wheels were not suitable for high speed steel, but believe that I have read recently that grades for high speed steel are now available, is that so and are they expensive can any one say.

Harold

Nice reply Harold, you have forced me to buy more of your books

Hi All

Harold says of white wheels :-

| "However, they will have large central holes and need adaptors."

Largely true, however it is possible to get at least one HERE with a smaller hole - though at a premium price. I have one on my bench grinder. I am flogging away with the construction of a Stent grinder but wonder if I would be better opting for Harold's excellent design!

Regards

Norman

The article on using a waterstone grinder for tools actually grinds HSS excellently if slowly. Tormek certainly recognise this and suggest their jigs are used with an off hand grinder for initial shaping and with the waterstone for sharpening. They sell a kit to adapt things for this but in fact an aluminium block suitably drilled with a locking screw works well at scrapbox prices. The adaptor fitting for the waterstone can then be used on either the high speed off hand grinder or the low speed wetstone. I was about to build Harold's grinding rest but I'm now not going to bother particularly as the tormek 4 facet drill holder/sharpener can easily be modified to sharpen milling cutters.

BW

Andries

I too have a 5" grinder which uses 5" x ½" thick wheels. I haven't tried this, but I wonder if it may be possible to use 6" x 3/4" wheels by possibly making new wheel washers and guards.

Probably be cheaper to buy new though.

Just an idea, that's all.

Peter G. Shaw

Much safer and better to go diamond, no risk of flying stones and you can put a much better edge on HSS or cobalt or carbide than white or green ever will. But the use is limited, you take off small amounts to maintain ( or greatly improve) the edge so rests and jigs are very desirable. The diamond wheel lasts and lasts and lasts......

Diamond wheels are the same kind of price as stone age jobs but they do take a bit of getting used to, you carefully centre the ali wheel- no dressing to centre. Arc Euro have a good note on diamond wheels on their web site- well worth looking at.

I have a couple of Tormeks for sharpening HSS wood chisels works great, but remain quite shocked at the price of their drill sharpening device! I will stick to the Vertex T&C with diamond as that works on cobalt and carbide too.

Billy.

Peter, check the spindle speed of your 5" grinder befor fitting 6" wheels, it may well be to fast and exceed the safe speed!

The drill sharpener is in fact the only thing I bought for the Tormek kit. Inherited the rest from my Dad and rarely used it till that MEW article came along. Now it sits on the bench and gets used regularly.

Andries

This Site also sells wheel reducing bushes for a nominal £2.60 'per pair I assume' although in the past I have made my own from Nylon/plastic/hard wood/Alu.Just don't make them too tight a fit otherwise you will create stresses in the centre,a decent push fit is all that is needed.

George.

Better safe than sorry but it is very unlikely to be a problem as these bench grinders use direct drive from a single phase induction motor. Depending on the number of poles the motors are rated at 1400 rpm or (usually) 2800 rpm. Six inch wheels should be rated at about 4000 rpm.

Yes a new grinder would be cheaper but the wheels are usually poor quality and wear quickly.

Russell.

Gordon,

Speed rating is 2850rpm. Thanks for the reminder.

Peter G. Shaw