Thread: Is my near-wedge a near-wedge?

Neil any idea how fast those huge wheels turned?

It looks like a 1/2 hollow to me. Some of the more computer people here at SRP could post a link to the illustration's of straight razor grinds and shapes. that would answer you question completely. A true wedge or near wedge would feel like a wonderful peace of steel that when hone good will just about shave by it's self. just gently guide it and it'll do the rest.

Originally Posted by rhensley

It looks like a 1/2 hollow to me. Some of the more computer people here at SRP could post a link to the illustration's of straight razor grinds and shapes. that would answer you question completely. A true wedge or near wedge would feel like a wonderful peace of steel that when hone good will just about shave by it's self. just gently guide it and it'll do the rest.

In the library The straight razor - Straight Razor Place Library .

Bob

Originally Posted by Tarkus

Neil any idea how fast those huge wheels turned?

I haven't really got a good answer to that, Darl.

One would think that the speeds would be constrained by the water mill providing the motive force, turning slower or faster according to the whim of the river. However, this could not be allowed, so there was a gearing mechanism on the main drive shaft, which allowed it to go slower or fastr than the waterwheel itself.

One thing to take into consideration is 'bursting force', that is the amount of speed the wheel can cope with before bursting asunder, which was a common occurrence with the natural sandstone that was used. Once you know how much the wheel can stand before this happens, you can decide on an optimal speed for a particular size wheel, and add a safety factor by keeping well under this speed.

The other thing to recognise is that at the the outer edge, the surface feet per minute (sfpm) of the wheel passing a given point will vary according to the size of the wheel. The actual revolutions per minute do not count, except as a factor in calculating the sfpm. Sfpm is a combination of the velocity (rpm) and the diameter of the wheel. The rpm is taken as the spindle speed. A rough (not very accurate in decimal places, but accurate enough) formula is

sfpm = 1/4 diameter of the wheel x rpm.

So, not only do we have to specify the actual diameter of the wheel in use, but we have to determine the speed (rpm) of the main drive shaft, the gearing ratio being used, and the size of the waterwheel itself along with the average flow rate of the river.

I would imagine that the speeds were much lower than we use today. Belt grinders work best for our purposes at 1800 rpm or less, eg 1440 rpm, but I would think the big old sandstone wheels would be somewhere around 600 rpm or less. Mind you, that is only a guess.

Regards,Neil

Originally Posted by Neil Miller

I haven't really got a good answer to that, Darl.

Looks like a pretty good answer to me, Neil. Very informative. Thanks for sharing!

Rob, as far as I'm aware, Wacker has offered at least four different grinds on his 6/8 razors (there may be more):

- '1/1 hohl' = hollow

- '1/4 hohl' = quarter hollow (but more like half hollow)

- 'Stosser' = wedge (but more like quarter hollow)

- 'Special razor' = a blade which Wacker claims combines the advantages of a wedge (stiffness) with the advantages of a hollow (flex). I haven't seen him say much more on this but looking at my blade it looks like the upper part of the blade closest to the spine is thick like a wedge, while the lower half close to the edge is very thin like a hollow.

All have nice straight grinds, very hard steel and shave beautifully.

I'm heading out but can try and post pics tomorrow. cheers.

Originally Posted by MichaelS

Rob, as far as I'm aware, Wacker has offered at least four different grinds on his 6/8 razors (there may be more):

- '1/1 hohl' = hollow

- '1/4 hohl' = quarter hollow (but more like half hollow)

- 'Stosser' = wedge (but more like quarter hollow)

- 'Special razor' = a blade which Wacker claims combines the advantages of a wedge (stiffness) with the advantages of a hollow (flex). I haven't seen him say much more on this but looking at my blade it looks like the upper part of the blade closest to the spine is thick like a wedge, while the lower half close to the edge is very thin like a hollow.

All have nice straight grinds, very hard steel and shave beautifully.

I'm heading out but can try and post pics tomorrow. cheers.

I'm not sure about the 6/8 blades, but my 7/8 says "Stosser," but it's definitely not a wedge. And there's a near-wedge in the 7/8 family -- the Keilshchliff. Whatever grind mine is, it shaves very nicely -- probably a lot like the "Special" you mentioned. It feels much more substantial than the other hollow-ground razors in my rotation.

My "Stosser" also says "Keilschliff" on it, aren't they the same thing?

Originally Posted by MichaelS

My "Stosser" also says "Keilschliff" on it, aren't they the same thing?

I don't think so. I know "Keilschliff" translates to "wedge cut" in English. "Stosser" is, I think the transliteration of "Stoßer," which means something like "piercing" or "pushing." I should probably ask my German brother-in-law to give me an official translation. But that would mean actually talking to him. :|

Originally Posted by Neil Miller

Belt grinders work best for our purposes at 1800 rpm or less, eg 1440 rpm, but I would think the big old sandstone wheels would be somewhere around 600 rpm or less. Mind you, that is only a guess.

Regards,Neil

Neil, I'd reckon less is more likely.
My 8" wet grinder runs @140rpm. I'd have thought 600 rpm would kick up quite a rooster tail of water on large diameter stones ?