Razor size vs sharpness

[bluefoxicy]

I had a thought about straight razor honing.

When you hone a razor, the spine of the razor rests on the stone. Significantly, the distance from the spine to the tip and the thickness of the spine affect the angle that the blade takes to the stone.

So, for all other things equal, a 5/8 razor would be sharper than a 3/8 razor, and a 7/8 even sharper, correct? The angle taken to form the blade would be much more shallow, leaving much less material near the tip, and a much finer blade....

EDIT: My Dovo 5/8 is honed, while the Sheffield is not honed; the sheffield's also a bit smaller, so I had a look. It's meaningless until I finish restoring and honing the JB&S Sheffield, but holy crap, the Dovo has an unbelievably narrow blade

 

[WittyAg]

I suppose mathematically you could get a keener edge with a taller blade. Someone would have to take a couple of actual measurements and do a little trig to find the angle of the point (smaller angle = sharper). Physically, I don't know if you could tell a difference. I thought taller blades were typically a little bit thicker at the spine though?

http://www.1728.com/trig4.htm

 

[Bertilak]

I had a thought about straight razor honing.

When you hone a razor, the spine of the razor rests on the stone. Significantly, the distance from the spine to the tip and the thickness of the spine affect the angle that the blade takes to the stone.

So, for all other things equal, a 5/8 razor would be sharper than a 3/8 razor, and a 7/8 even sharper, correct? The angle taken to form the blade would be much more shallow, leaving much less material near the tip, and a much finer blade....

I doubt all other things would be equal. Wouldn't the manufacturers be "keenly" aware of blade geometry and be sure they got it right? Those manufacturers probably had some experience with this stuff.

 

[gugi]

So, for all other things equal, a 5/8 razor would be sharper than a 3/8 razor, and a 7/8 even sharper, correct? The angle taken to form the blade would be much more shallow, leaving much less material near the tip, and a much finer blade....

Well, all other things being equal yes shallower angle means sharper i.e. less resistance for severing a hair.
Now the problem is that making everything else equal is rather hard task, and I must add rather pointless.

Someone would have to take a couple of actual measurements and do a little trig to find the angle of the point (smaller angle = sharper). Physically, I don't know if you could tell a difference.

I most certainly can tell the difference. As far as measurements go Glen started a thread some time ago to collect data on the subject. It must have at least 50 razors already, likely more.

 

[TstebinsB]

How would things ever be equal? I don't see it.

 

[Bacchus]

Yes if all other thing were equal, a wider blade would be sharper... if you could even hone it to the same degree. I shallower angle also means that the edge is weaker and more prone problems. If I remember correctly the butter zone is between 15-17 degrees?

 

[leighton]

I had a thought about straight razor honing.

When you hone a razor, the spine of the razor rests on the stone. Significantly, the distance from the spine to the tip and the thickness of the spine affect the angle that the blade takes to the stone.

So, for all other things equal, a 5/8 razor would be sharper than a 3/8 razor, and a 7/8 even sharper, correct? The angle taken to form the blade would be much more shallow, leaving much less material near the tip, and a much finer blade....

EDIT: My Dovo 5/8 is honed, while the Sheffield is not honed; the sheffield's also a bit smaller, so I had a look. It's meaningless until I finish restoring and honing the JB&S Sheffield, but holy crap, the Dovo has an unbelievably narrow blade

How do I put this....

Yes, but they increase the spine thickness along with the size of the razor. So, no.

 

[Sticky]

Best bevel angle: http://www.bladeforums.com/forums/showthread.php?t=543800. Sometimes knives and razors are very similar.

 

[mdunn]

Best bevel angle: http://www.bladeforums.com/forums/showthread.php?t=543800. Sometimes knives and razors are very similar.

Like when? Straights have a thin edge and trade resiliance for being supersharp to chop through hairs with ease. Kitchen knives etc have a much thicker edge so that they dont become blunt as soon as they touch the chopping board

 

[Sticky]

Notice in the link that HoB uses 15 degrees included angle on his "choppers".

Bevels can also be set in an identical manner (i.e: make 2 bevel planes meet, then polish). The only difference being final pressure and the grit progression. Some knives will take an 8k edge just fine.

 

[richmondesi]

Like Leighton mentioned, you have to consider the thickness of the spine as well. So, if spine thickness is the same, then yes it the wider the blade the sharper the edge. However, you get to a point of diminishing returns below approximately 14 degrees. Anything below that point, and it seems* that the edge won't hold up to shaving routine and maintenance too well. I'm really interested in checking the results from Glen's thread.

*from all that I've read.

 

[English]

I agree that the spine gets thicker as the width increases. keeping the bevel angle the same accross a range of widths.

I wonder what the angle is on a DE razor blade though because they have a very narrow spine. Just joking.

Another variable in the equation is the angle you use to shave. I find the riskier looking big wide blades are actually ***** cats because I hold them at a much narrower angle to my skin during the shave than say a standard 5/8" blade. The narrower the angle ofcourse, the less the chance of niks or cuts.

 

[GsSixgun]

You have to be very careful with Razors, there are so many variables out there... We continue to collect data on that thread...

I wouldn't ever make a statement like below 14 degrees you have diminishing results nor the other way around, of over 20 degrees is too steep...
Without a doubt a razor will come along and prove you wrong...

What we are finding is that most vintage razors fall between 11 and 22 degrees with many falling at 16.. Do not make the assumtion that 16 degress is perfect either, it does not mean that, it just means that seems to be the center...

IIRC much of the data that I have seen of DE's and Feathers elude to higher angles and then some have a double bevel on top of that ... Some of the Feathers were measured at 25 degrees you have to dig for that info yourself I dont have the link handy...

My research so far has me thinking that I would not call any angle the sweet spot as of yet, or the standard....

 

[richmondesi]

You have to be very careful with Razors, there are so many variables out there... We continue to collect data on that thread...

I wouldn't ever make a statement like below 14 degrees you have diminishing results nor the other way around, of over 20 degrees is too steep...
Without a doubt a razor will come along and prove you wrong...

What we are finding is that most vintage razors fall between 11 and 22 degrees with many falling at 16.. Do not make the assumtion that 16 degress is perfect either, it does not mean that, it just means that seems to be the center...

IIRC much of the data that I have seen of DE's and Feathers elude to higher angles and then some have a double bevel on top of that ... Some of the Feathers were measured at 25 degrees you have to dig for that info yourself I dont have the link handy...

My research so far has me thinking that I would not call any angle the sweet spot as of yet, or the standard....

Interesting, Glen. Have you gotten any word on guys that have had a razor that held up nicely over a long period of time with an angle under 14 degrees? I've never heard of one, but you've got more experience than me. In fact, the angle of 13 degrees was very publicly blamed for the failure of some razors that I've seen. On the other hand, I've had a pretty nice shaver at 25 degrees... Sooo

 

[leighton]

Haven't done much testing or measuring of bevel angles. But my best shavers have an angle between 15 - 17 degrees. Best shavers in terms of smoothness and sharpness.

As for edge longevity, I defer to MParker. He's the expert on those things.

 

[gugi]

Haven't done much testing or measuring of bevel angles. But my best shavers have an angle between 15 - 17 degrees. Best shavers in terms of smoothness and sharpness.

Measure the not so good shavers too, otherwise that's pretty meaningless.

 

[leighton]

Measure the not so good shavers too, otherwise that's pretty meaningless.

Sorry that I have better things to do than measure bevel angles with each razor that comes through my hands.

This is a discussion thread on the bevel angle. I have contributed what information I have. If the info is worthless, I'm sorry for wasting the 30 seconds it took you to read it.

 

[GsSixgun]

Interesting, Glen. Have you gotten any word on guys that have had a razor that held up nicely over a long period of time with an angle under 14 degrees? I've never heard of one, but you've got more experience than me. In fact, the angle of 13 degrees was very publicly blamed for the failure of some razors that I've seen. On the other hand, I've had a pretty nice shaver at 25 degrees... Sooo

Everyone is loading in measurements from users (razors that work)....
Gugi will even do the clacs for you in that thread...
We even explained how to do the measurements so we would have the most accurate info....
I have a couple dozen more razors to measure out myself..

All we can do is to continue the collection of data, I don't think there will ever be a definite conclusion... Like I said earlier, once you make a claim there will be an exception or even multiple exceptions... The only conclusion I would go out on a limb on right now is the 16 degrees seems to be the center point...

If I were going to make a razor myself, I think that is what I would target as a bevel angle... Is it the best???? I would not go that far...

Also the razor you are referring to Paul, (I think I know which one) if you read my review you will find the one I shaved had a significantly higher angle so I think the real problem in that razor is the inconsistencies more than the angle... If you start at the same place with a blank, and one grinder gets a 11 degree angle, and the other gets a 15, to me that means that there are other contributing factors to the edge failing (thinner grind) than just the angle...

We are measuring some of the customs in the thread also, but I would not use those numbers in the averages myself.....

 

[richmondesi]

That was going to be my next question, if the angle isn't to blame what is? Could you go into more depth on your thoughts on that? I don't quite understand the difference in how changing the intended grind would cause failures in the edge but a designed 13 degree edge would be fine. I'm not being argumentative, just trying to gain understanding.

 

[gugi]

Sorry that I have better things to do than measure bevel angles with each razor that comes through my hands.

This is a discussion thread on the bevel angle. I have contributed what information I have. If the info is worthless, I'm sorry for wasting the 30 seconds it took you to read it.

OK, let me use a stronger but more precise qualification then. It is not just meaningless, but misleading, so it's not a matter wasting 30 seconds reading it, but actually inferring wrong conclusions.
It is indeed a thread about bevel angles, but this particular one is not about gathering statistics, rather about discussing the role of different bevel angles.

The way you phrased your post it sounds like there is a correlation between the 15-17 degree angle and how smooth and sharp a razor is. And this is contrary to my own experience. The smoothest and sharpest edge I've used has 25 degree angle, well above the majority of straight razors.