Thread: Which wheel do I keep?

Redbeard, is the 36/60 a grey wheel? If so keep one for mower blades of the like. Keep your woodworking tools away from those temper wreckers.

I left the 60g wheel on the grinder and kept the course one in case I ever needed it. Over 10 years later I cant remember where it is. Even the 60g grey wheel hardly ever gets used. Things may be different if you do metalwork projects.
Regards
John

RB, are the wheels white or grey? Grey are for HSS (M2) and white for high carbon steel (O1).

If you are grinding HSS lathe chisels, then it does not matter, since the HSS will not over heat. I'd use the 80 grit.

However, if you want to grind O1 steel, then you are in a bit of trouble if the wheels are grey. Assuming that they are all white wheels, the best wheel to use is the coarsest grit, which is the 36. The worst to use is the 80 grit. Why? Because the coarser the grit the cooler it will grind. Higher grits create more heat. High carbon steel blades will be at risk for over heating and losing temper.

What colour are the wheels and is there anything written on them (they will tell us whether the wheels are hard or soft and friable).

Regards from Perth

Derek

Carborundum wheels are usually grey/charcoal coloured and are not suited for high speed steel tools and preferred for low carbon and high carbon steels. Aluminium oxide wheels can be white or pink and are recommended for high speed steel tools. Both types need to be kept clean and sharp. Low and high carbon steel tools can be ground on carborundum wheels if the wheel is allowed to cut and light pressure pressure applied, without quenching in water.
When I started my apprenticeship as a carpenter we were taught to let the wheel do the job it is designed to do, we never used water to prevent overheating of the steel.
The 36# wheel is good for initial shaping to get appropriate bevels etc. but the 60# is better for restoring the hollow that is lost after honing several times.

Jim

Jim and I are appearing to say opposites, but actually we are sort of in agreement.

For years, before the white wheels were common, the wheels that came with bench grinders were the grey type. They were used for all steels. Since most tools steels were high carbon (O1 type), they were used for high carbon. The grey wheels are generally very hard and not particularly friable. This means that they do not break down easily, and the surface gets clogged and smooth. This ends up creating heat. It is very easy to burn (over heat) O1 steel on such wheels. The higher the grit the more these wheels create friction ... = higher heat. It is even more important that these wheels are regularly surfaced to keep the grit fresh and sharp if you wish to avoid heat. The only steel that is really safe with an inexperienced grinder is HSS (M2) as that is impervious to heat. That is what I meant when I wrote they were for HSS.

White wheels can be more friable, but this is not guaranteed. Like grey wheels, they come in different grades of hardness and friability. The most friable wheels are the blue wheels, such as Norton 3X. Whatever you get, this type of grinding is best done with a coarse wheel, generally 36 grit. And you still need to dress the wheel frequently to ensure the grit is fresh and sharp.

Now there is a better alternative - CBN wheels. They are more expensive, around $200 each. That is the bad news. After this is all gets better and better.

CBN is almost as hard as diamond and, better, unlike diamond, it does not wear at speed. The wheels are metal, some aluminium and some steel. They come balanced and run smoothly. Because they never wear, they never need dressing, and because they never need dressing they do not get smaller. Which means that all settings remain constant. Further, because the wheels are metal, they act like a large heat sink, and they grind cool. It is possible to overheat a blade, but you have to work at it to do so. And best of all, instead of using a coarse stone to keep the heat down, you can use a fine grit - I use 180 grit - and this leaves a smooth edge/hollow which cuts down on the honing that follows.

Regards from Perth

Derek

Hi Redbeard,

In answer to you original question, I would recommend you keep both, 36# for re profiling and the 60# grit for restoring the hollow on the tools after frequent honing. I don't recommend you use a grinding wheel for sharpening, that is better done with a fine stone or perhaps one of the new diamond honing plates.

Hope this helps with your original question.

Jim

As I originally stated, the sharpening wheel is an 80 grit, white aluminium oxide wheel, specified by Norton for high speed steel. The original wheels on the grinder are standard grey carborundum. I've left the 60 grit wheel on for general grinding and shaping.

Thanks guys.
Redbeard

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Originally Posted by Redbeard

As I originally stated, the sharpening wheel is an 80 grit, white aluminium oxide wheel, specified by Norton for high speed steel. The original wheels on the grinder are standard grey carborundum. I've left the 60 grit wheel on for general grinding and shaping.

Thanks guys.
Redbeard

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Redbeard, you are on the right track! I have kept both carborundum wheels originally fitted to my 200 mm Abbott & Ashby grinder and must confess that I have rarely used either. They are useful for the odd task such as "putting an edge" on a pick, crowbar or mattock occasionally. As I'm predominately a wood turner I only use the Abbott & Ashby grinder with aluminium oxide wheels (pink & white btw) for the "roughing" gouges and to reshape / re-profile scrapers, gouges etc. I use the Tormek for most tasks and also use diamond honing plates very often to maintain an edge on skew chisels etc.

Hope this link explains bench grinder wheel selection Which Grinding Wheel Should I Choose? | Norton particularly note

"As a general guide, the harder the material, the softer the grade of wheel required."

Wheels Bench - 38A | Norton Abrasives | United Kingdom