What's new

Bevel angles

I wanted to get a better feel for different bevel angles, so I did a head to head shave with my 18.0° bevel angle Titan ACRM2 and 16.7° Boker 5/8 ebay rescue. I did a full pasted balsa progression to each blade before my shave, and they were both treetopping leg hairs like crazy about 1cm off my skin. I use my leg hair for tree top tests because it sticks out while my arm hair lies flat for some reason.

With 48 hours growth, I shaved the left side of my face with the Titan and right side with the Boker. My first pass is WTG and the Boker did a noticeably better job removing stubble. I’d say it was probably SAS level all over, while the Titan left a mix of SAS, seemingly untouched hairs, and stubble reduced to about half its original length. I really had to force the Titan while the Boker slid through the stubble like it wasn’t even there. Not a great start for the big bevel.

2nd pass is XTG and here there was very little difference between the two. The Titan again took a little more force to cut through the stubble that was left, but nothing like the first pass. After the pass both sides of my face felt about the same. I noticed that the Boker felt more likely to bite so I had to be a little more careful.

3rd pass is XTG the other way it was much the same as pass #2. At the end of this pass the 16.7° Boker side of my face was closer than the 18.0° Titan side, but both were very good. Not quite BBS, but definitely DFS to DFS+.

So what did I learn? I learned that I get a better shave with a smaller bevel angle, but it’s a little touchier and needs to be treated with care. I also learned that I like a round point much more than a square point. It’s much easier to get into my neck hollows with the round point.

How low can a bevel angle go before it’s too delicate to shave with? Is there any difference in honing a large vs. small bevel angle?

IMG_7375.JPG
 
Very interesting.

I learned that I get a better shave with a smaller bevel angle, but it’s a little touchier and needs to be treated with care.

This echoes my experience. Easy choice for me; I don't mind the extra focus on using the razor with care.

I also learned that I like a round point much more than a square point. It’s much easier to get into my neck hollows with the round point.

You may want to try a French or Spanish point. Amazing for neck hollows and other detail areas.

How low can a bevel angle go before it’s too delicate to shave with?

That depends entirely on the steel. Get too low, and it will start chipping during the shave.
 
I wanted to get a better feel for different bevel angles, so I did a head to head shave with my 18.0° bevel angle Titan ACRM2 and 16.7° Boker 5/8 ebay rescue. I did a full pasted balsa progression to each blade before my shave, and they were both treetopping leg hairs like crazy about 1cm off my skin. I use my leg hair for tree top tests because it sticks out while my arm hair lies flat for some reason.

With 48 hours growth, I shaved the left side of my face with the Titan and right side with the Boker. My first pass is WTG and the Boker did a noticeably better job removing stubble. I’d say it was probably SAS level all over, while the Titan left a mix of SAS, seemingly untouched hairs, and stubble reduced to about half its original length. I really had to force the Titan while the Boker slid through the stubble like it wasn’t even there. Not a great start for the big bevel.

2nd pass is XTG and here there was very little difference between the two. The Titan again took a little more force to cut through the stubble that was left, but nothing like the first pass. After the pass both sides of my face felt about the same. I noticed that the Boker felt more likely to bite so I had to be a little more careful.

3rd pass is XTG the other way it was much the same as pass #2. At the end of this pass the 16.7° Boker side of my face was closer than the 18.0° Titan side, but both were very good. Not quite BBS, but definitely DFS to DFS+.

So what did I learn? I learned that I get a better shave with a smaller bevel angle, but it’s a little touchier and needs to be treated with care. I also learned that I like a round point much more than a square point. It’s much easier to get into my neck hollows with the round point.

How low can a bevel angle go before it’s too delicate to shave with? Is there any difference in honing a large vs. small bevel angle?

View attachment 1467897
If you give up some of the apex width you can get away with a really small inclusive bevel angle. This will give you a more comfortable egde with increased cutting efficiency.
You will need a convex stone and a leap of faith in the process. The key here is to bend the bevel in the thinning process. The edge will be a little more delicate, but more flexible.
An Aransas stone is in my opinion ideal for this last step.
 

rbscebu

Girls call me Makaluod
@Seelector thank you for the results of your comparison shave with different bevel angles. Your results are very similar to what I have found.

I have found that a relatively obtuse bevel angle is more forgiving. It is for this reason that I recommend such for n00bies to the gentlemanly art. Many others recommend a more acute bevel angle but I think some of them have forgotten what it was like starting out on their SR shaving adventure.

As for the point style, it is often stated by SR shavers that a Dutch (round) point is easier for a n00bie to shave with. Again, more forgiving as it doesn't require as much concentration on what the toe of the blade is doing while shaving.
 

rbscebu

Girls call me Makaluod
.... Is there any difference in honing a large vs. small bevel angle?
The main difference is the care needed in honing (not pasted balsa stropping) a more acute bevel angle. They can chip more easily while honing. When this occurs is very dependent on the steel and its heat treatment process.

By more care, I mean being very careful with your pressure and the whetstone(s) selected for the honing. I have found that some whetstones can be more susceptible to chipping an acute bevel angle.
 

Slash McCoy

I freehand dog rockets
I wanted to get a better feel for different bevel angles, so I did a head to head shave with my 18.0° bevel angle Titan ACRM2 and 16.7° Boker 5/8 ebay rescue. I did a full pasted balsa progression to each blade before my shave, and they were both treetopping leg hairs like crazy about 1cm off my skin. I use my leg hair for tree top tests because it sticks out while my arm hair lies flat for some reason.

With 48 hours growth, I shaved the left side of my face with the Titan and right side with the Boker. My first pass is WTG and the Boker did a noticeably better job removing stubble. I’d say it was probably SAS level all over, while the Titan left a mix of SAS, seemingly untouched hairs, and stubble reduced to about half its original length. I really had to force the Titan while the Boker slid through the stubble like it wasn’t even there. Not a great start for the big bevel.

2nd pass is XTG and here there was very little difference between the two. The Titan again took a little more force to cut through the stubble that was left, but nothing like the first pass. After the pass both sides of my face felt about the same. I noticed that the Boker felt more likely to bite so I had to be a little more careful.

3rd pass is XTG the other way it was much the same as pass #2. At the end of this pass the 16.7° Boker side of my face was closer than the 18.0° Titan side, but both were very good. Not quite BBS, but definitely DFS to DFS+.

So what did I learn? I learned that I get a better shave with a smaller bevel angle, but it’s a little touchier and needs to be treated with care. I also learned that I like a round point much more than a square point. It’s much easier to get into my neck hollows with the round point.

How low can a bevel angle go before it’s too delicate to shave with? Is there any difference in honing a large vs. small bevel angle?

View attachment 1467897
Good experiment. Your conclusions are pretty much in line with mainstream thought. The bigger bevel angle can be a good thing for a beginner. The finer bevel of course, as you found, will generally be more responsive and aggressive, and will cut you or over-exfoliate if not used with care, particularly with your shave angle and skin stretching.

Most razor steel will support a bevel angle of over 15 degrees with no problem. Below that, things can get dicey. The edge can become too fragile, and even topple while honing. This is correctible with tape on the spine when honing or at just the finish stage, but that's a PITA. Some steel alloys and hardnesses do better with skinny bevel angles than others. The sweet spot is usually found at between 16 and 17 degrees. At over 19 degrees, even the most meticulous honing can give you a mediocre edge. I had a Henckels 401 that had a bevel angle just over 14 degrees and it was a real sports car of a razor, cutting me because I wasn't expecting that level of performance. I tried a couple of ZY razors that had very obtuse bevel angles and the shave was underwhelming. The bevel angle is important. The geometry is as important as the steel of the razor. Now, I find I can eyeball a razor and determine that the bevel angle is or is not where most razors ought to be, and you can develop this eye for your razors, too. You don't have to measure and calculate, to get a pretty good idea of what to expect from the razor. Your eyes will tell you.
 
I wanted to get a better feel for different bevel angles, so I did a head to head shave with my 18.0° bevel angle Titan ACRM2 and 16.7° Boker 5/8 ebay rescue. I did a full pasted balsa progression to each blade before my shave, and they were both treetopping leg hairs like crazy about 1cm off my skin. I use my leg hair for tree top tests because it sticks out while my arm hair lies flat for some reason.

With 48 hours growth, I shaved the left side of my face with the Titan and right side with the Boker. My first pass is WTG and the Boker did a noticeably better job removing stubble. I’d say it was probably SAS level all over, while the Titan left a mix of SAS, seemingly untouched hairs, and stubble reduced to about half its original length. I really had to force the Titan while the Boker slid through the stubble like it wasn’t even there. Not a great start for the big bevel.

2nd pass is XTG and here there was very little difference between the two. The Titan again took a little more force to cut through the stubble that was left, but nothing like the first pass. After the pass both sides of my face felt about the same. I noticed that the Boker felt more likely to bite so I had to be a little more careful.

3rd pass is XTG the other way it was much the same as pass #2. At the end of this pass the 16.7° Boker side of my face was closer than the 18.0° Titan side, but both were very good. Not quite BBS, but definitely DFS to DFS+.

So what did I learn? I learned that I get a better shave with a smaller bevel angle, but it’s a little touchier and needs to be treated with care. I also learned that I like a round point much more than a square point. It’s much easier to get into my neck hollows with the round point.

How low can a bevel angle go before it’s too delicate to shave with? Is there any difference in honing a large vs. small bevel angle?

View attachment 1467897
Provided the apex width and condition is the same with both razors the change in bevel angle would account for a difference of around 7 percent. In this particular case i think other factors are more important then just the bevel angle.
1654593891190.png

If you get into 20 deg bevel angle you are looking at a 20 percent difference. Now you should definitely feel the difference.
 
If you give up some of the apex width you can get away with a really small inclusive bevel angle. This will give you a more comfortable egde with increased cutting efficiency.
Is apex width the width of the cutting edge right at the edge of the bevel?

Provided the apex width and condition is the same with both razors the change in bevel angle would account for a difference of around 7 percent. In this particular case i think other factors are more important then just the bevel angle.
I haven't sketched it out, but I think your Fv1/Fv2 ratio boils down to a ratio of the normal forces? Where Fv = cutting force = mu * Force_normal? Looking at it this way feels like it's missing a lot of the mechanics of the edge actually cutting through each hair. I wonder what research is out there this subject, I'd find it really interesting to read.
 
Is apex width the width of the cutting edge right at the edge of the bevel?


I haven't sketched it out, but I think your Fv1/Fv2 ratio boils down to a ratio of the normal forces? Where Fv = cutting force = mu * Force_normal? Looking at it this way feels like it's missing a lot of the mechanics of the edge actually cutting through each hair. I wonder what research is out there this subject, I'd find it really interesting to read.
It is just a geometric assessment. The width of the apex is the radius at the tip of the bevel.
How well the razor initiates the cut is much more complicated. I would assume Gillette have some secret research 😉
20220607_174231.jpg
 

Slash McCoy

I freehand dog rockets
I would urge you to not draw too many conclusions from the math. A bevel face is not necessarily flat. The point where an edge width is measured is a wishy washy subjective sort of thing. Also there can be significant disruption of the bevel surface from the scratch pattern, and also "stiction" from a very highly polished bevel. The theoretical, even backed up with math, does not always agree with the empirical. The best way to actually measure sharpness as manifested by actual cutting ability would be to measure the average force required to sever a consistent sample of a relevant substance: in our case, hair.
 
I would urge you to not draw too many conclusions from the math. A bevel face is not necessarily flat. The point where an edge width is measured is a wishy washy subjective sort of thing. Also there can be significant disruption of the bevel surface from the scratch pattern, and also "stiction" from a very highly polished bevel. The theoretical, even backed up with math, does not always agree with the empirical. The best way to actually measure sharpness as manifested by actual cutting ability would be to measure the average force required to sever a consistent sample of a relevant substance: in our case, hair.
Bevel angle is just one of many variables. If all else is equal and you change one variable, you can at least quantify something.
If you compare this with a Feather Pro super at an inclusive angle of 19 deg to a sr at 15-16 deg. I am quite sure the apex radius is smaller and the friction coefficient on the bevel plane is smaller then my sr. So why does it tug more then my sr's?
In addition to the apex condition the bevel angle is one important variable.
 
Top Bottom