Contact wheel size - resulting grind question

Hi Everyone, I would need some help! :)

I have shaved with quite a few razors, and have made about two dozens of them, but I am a bit confused about what custom razors makers are calling 1/4 or 1/2 hollow razors. I used a 6" for my grinds, and if I grind a 7/8 wide blade almost up to the spine, from 1/4 thick stock, than thats about the hollowest I can reach without picking up a smaller wheel to remove some more steel from the upper segments. About how accurate are these numbers here?

For 7/8 razors:

10" - wedge
8" -1/4
6" -1/2
3"-2" - hollow

I think Butch posted these numbers some years ago. Are these about accurate? Can I call a 7/8 razor hollowed on a 6" wheel a half hollow grind?

As a side note, what wheels do others use to grind their 1/2 hollow razors?

I would appreciate any kind of answers, it would help me a lot! :)

I would use my 4" wheel to make a half hollow on a 7/8s or 8/8s. When I grind, the hollow in the blade does not usually match the diameter of the wheel. I tend to grind troughs or hollows then blend them together. I kind of think of it as, the edge area, the spine area and the belly area. I usually get the edge area and spine area where I want them then blend the belly area to match the two areas. I think I am in the minority grinding this way.

Charlie

As Charlie says, there is no 1 to 1 ratio usually. The reason is that if you have a hollow with the radius of a 10" wheel so that the hollow fits the wheel snugly, then abrasion becomes agonizingly slow. Heat buildup will increase rapidly.

The reason is that the pressure gets divided along a very big surface. This means a sharp drop in abrasion (because the teeth don't gouge deeply). And because abrasion drops but not friction, heat will get much more time to penetrate.

When grinding, you will usually want to have only a small surface contact with the wheel. That means you have to manipulate the blade so that you make a hollow that is slightly bigger than the wheel. One of the razors I am currently finishing was ground before I had my big grinder. I used a 1" wheel to grind the entire hollow. It's not really that difficult.

I use the 10" wheel only in the initial grind in order to check the surface for pits and to make sure I have a symmetrical blank to start with.

I have a 4" wheel coming just because of this. I am going to grind my razors starting with a 8" wheel, and when I have a hollow going than follow it up with the 4" contact wheel in the beginning. I have a 2" wheel already, so I will try a few full hollows too when I will have the time to.