Some questions about contact wheels for hollow grinding. Serrated vs. Plain

Motor City Mike

Well-Known Member
I've come to the realization that I need a larger wheel for hollow grinding. I have an 8" now and want to move into a 12" or 14"

I have a couple questions.

What's the practical difference between smooth and serrated wheels?

Want hardness is best or which do you like best? I see 70A Duro seems to be quite common.

Lastly, what size wheel would you recommend for hollow grinding?

TIA
 
What's the practical difference between smooth and serrated wheels?

A smooth contact wheel removes material at a lesser rate, but leaves a smoother finish. A serrated wheel removes material at a higher rate, but leaves rougher finish.

Want hardness is best or which do you like best? I see 70A Duro seems to be quite common.

70 durometer has been the standard for a long time, based on the fact that it hard enough to "hold up" reasonably well under grinding applications, yet it's soft enough to "flex".... meaning that you don't have to be "prefect" in your grinding technique to get a "good" grind. Harder wheels tend to leave a lot of "lines" and if you make a bobble with a harder wheel, the mistake causes much more damage then with a softer wheel. Personally, I've gotten away from rubber contact wheels and have only urethane wheels in the shop..... they are less expensive, don't dry rot, and in the same hardness, hold up better/longer then rubber contact wheels.
I've slowly replace/gathered my urethane wheels over the years..... with the majority of them coming from Sunray Corp, out of North Carolina.

what size wheel would you recommend for hollow grinding?

The answer to that is very much each maker's opinion. Personally, I do very little hollow grinding, simply because I consider it inferior for "using", and find it's more about "looks". When I do hollow grind, it's generally on a 10" wheel, but I know of folks who go much larger. As you get past 10", the wheels become increasingly expensive, and I believe there comes a point when the overall cost surpasses the returns you can get.
 
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