Thread: Establishing a Bevel

Originally Posted by PapaBull

If a manufacturer thought 12 degrees or 13 degrees was just as good as 11 degrees, I imagine that's what they'd have built into their razors.

I don't think so. What determines the bevel angle in a razor is the ratio between half the spine width and the size (width) of the blade. The reason is that the spine and edge both contact the stone. You can't escape it; it's physics. So, a manufacturer who makes a 5/8 with a fat spine will have a larger (shallower) bevel angle than one who makes a razor with a thin spine. It's the fatness of the spine that limits how sharp a bevel angle you can have.

That doesn't happen with a knife, since the spine is off the stone when you're sharpening. You can choose your angle and trade off sharpness and durability of the edge.

Joe, let me rephrase that, since you, apparently didn't understand what I was saying.

Do you really believe that the ratio between spine width and length of blade, which determines the actual degree of angle of the blade was arrived at arbitrarily or just "happened"? While it's absolutely true that the width of the spine and length of blade (i.e. 5/8, 6/8, etc) determines the degree of the bevel, have you considered the possibility that the manufacturers made the spine the width needed for the proper bevel instead of just getting whatever angle they ended up with with whatever spine width happened to come off the grinder?

p.s... I wonder how many of the 5/8 razors with the "fat spine" are actually 5/8 razors instead of razors that were "fixed" by taping the spine and honing the crap out of it so the owner could try to pass the razor off as "mint".

Originally Posted by randydance062449

I used to use coarse grits to remove the nicks and restore the bevels. But... I noticed that when I would reach the 8000 the razor would occasionally develop microchips.

When I stopped using grits coarser than 4000 that problem almost disappeared. My speculation is that the coarser grits created "fractures" in the steel.

That's an interesting observation. If your theory is right, I wonder why you don't see the fractures with the 4K, but you do with the 8K.

Maybe the coarser grits just weaken the structure of the metal and you don't notice the effect until you try to put a real thin edge on the blade. The weakened metal just can't maintain the edge and portions collapse, forming micro-chips. You and I have noticed something similar with an oxidized edge.

Originally Posted by PapaBull

Do you really believe that the ratio between spine width and length of blade, which determines the actual degree of angle of the blade was arrived at arbitrarily or just "happened"? While it's absolutely true that the width of the spine and length of blade (i.e. 5/8, 6/8, etc) determines the degree of the bevel, have you considered the possibility that the manufacturers made the spine the width needed for the proper bevel instead of just getting whatever angle they ended up with with whatever spine width happened to come off the grinder?

I sure did consider it! That's why I checked a whole bunch of new or lightly honed razors for spine width. You can find quite a variation. Check it out. And after I measure the spine thickness and blade width I can calculate the bevel angle, which also has corresponding variation.

There may be a minimum spine thickness that will insure blade integrity over the life of the blade, but after that it's just a function of the ornamental design (spine thickness needed to get a desired effect).

Originally Posted by Joe Lerch

There may be a minimum spine thickness that will insure blade integrity over the life of the blade, but after that it's just a function of the ornamental design (spine thickness needed to get a desired effect).

I guess we just disagree. I don't think the spine thickness is an arbitrary width based on the designer's/grinder's ornamental preferences. Spine thicknesses were designed to provide the proper bevel, in my opinion. And I prefer to keep that bevel intact by honing blade and spine together whenever possible. They're designed to wear at the same rate. A razor honed from a 6/8 to a 5/8 over it's life will also have had the spine honed from a width appropriate for a 6/8 to a width appropriate for a 5/8. Pretty ingenious, if you ask me, so I don't try to outsmart it just so that I can keep my razors looking like they've never been honed. I figure that's a bit like rolling back the speedometer on a car, anyway. It looks good, but it won't make the car won't perform like a new car - and a razor that's had it's "spine protected" won't perform as it was designed to perform, either, with the angle getting more and more obtuse with each honing.... but that's just my opinion. Who knows, huh?

The spine to blade width ratio is 3.5. It is stated in the german book from the 30' called Das Rasiermesser. That's why the spine gets thicker when you progress in razor's size...

Nenad

I think you guys ought to examine some of your razors (I did). You might be surprized art the variation in spine width in a given size of razor. Of course I'm talking about razors that haven't been honed significantly.

Originally Posted by superfly

The spine to blade width ratio is 3.5. It is stated in the german book from the 30' called Das Rasiermesser. That's why the spine gets thicker when you progress in razor's size...

I think we've been trhough this once before. The reference you sited related to a specific type of razor, not in general. The 3.5 ratio will give you an angle of over 16 degrees, which is more than what I've found in any razor.

If you want to know the angle of any of your razors, take the ratio between half the spine thickness and the razor width. That's the tangent of half the bevel angle. Look up the angle in a table or use the "arctan" (also tan to the -1 power) on a calculater. A 1/7 ratio gives you 8.1 degrees and you bevel angle is 16.2 degrees. Do you have that on any of your new or lightly honed razors? A 5/8 razor with a 1/8 spine (kind of typical) has 11.4 degrees.

The spine gets thicker when you progress in razor size because you need the heavier spine to support the razor.

If you want some examples, I'll post spine widths for different razors in my collection. Try it with yours.

Originally Posted by Joe Lerch

I think we've been trhough this once before. The reference you sited related to a specific type of razor, not in general. The 3.5 ratio will give you an angle of over 16 degrees, which is more than what I've found in any razor.

Found it on RazorCentral, here's the link...

http://www.en.nassrasur.com/razorcentral/archraz2.html

I think it is ment for all razors in general. Anyways, I don't care, as long as my razor is sharp enough...

For all newbies, check Artur Bohn's razor central, it has some great info on razors and shaving...

http://www.en.nassrasur.com/razorcentral/index.html

Nenad