Thread: A theory on Over Honing (not mine BUT interesting)

After honing probably 300-400 razors and starting after 2008 when it was all about the bevel, I can honestly say that if I can set a good 1k bevel I will get a shave ready razor. Any crumbly edges I've had can be attributed to either bad steel on the edge or a spine with to much wear causing to thin of an edge or bad geometry from the maker.

Glen,
Thanks for an IMPORTANT history lesson.
I'm in the information gathering stage before deciding if honing is for me (beyond using a barber's hone).
Like you said, the information pool on honing and straight razors has exploded in the last few years. Those of us late comers/late bloomers really are benefiting from all of you who have been in this since day one.
Responses like yours not only answer the question, but explain how the answer has changed over time.
My sincere thanks.

Originally Posted by gssixgun

Hmmmm..

Although I am also part of the "Overhoning is not an worrisome issue club" and have been since before Tom ever picked up a Straight Razor

http://straightrazorpalace.com/honin...er-honing.html

You have to understand that history of the entire issue first when applied to Straight Razors..


Back in the Dark Ages of SRP Overhoning was a word that got tossed out after near every post that said "I honed my razor on my Norton 4/8 and it won't cut, what did I do wrong??? " That was answered by a statement of "You probably overhoned it"

In contrast that is now normally answered by the statement "The bevel probably isn't set correctly"

What changed ??? Please don't take my word for this simply drop back to 2008 or a bit earlier in the archives and read for yourself...

There was a push from a few of us to prove the "Unset Bevel" theory, it went so far as offers being made to new honers that some of us were setting the bevels on their razors and then letting them simply finish the razors.. The 1k Shaving challenges.. all kinds of threads and pics
You also have to understand that back then it was a challenge to get people to accept that Progressive honing as in 1-4-8-finisher in a row worked, and that you did not HAVE to do pyramids to prevent overhoning.. The honing information for straight razors has come a long way in a short time but then again this hobby has exploded in a few short years.....

Around 2008ish people began to accept that a poor bevel set was more of an issue then an overhoned edge


Ok there was a little history lesson now back to whether you CAN overhone ???

What Tom is saying in the article is true to an extent, but it is not taking pressure into account, it is also not giving enough words to the steel itself (read Oakeshott's post #8 which is a much more detailed way of saying "Carbide Popping" )...

Perhaps it is better said that one can "Incorrectly" hone a given razor and cause a Harsh Fragile Chippy edge that is uncomfortable to shave with and tends to fail quickly...

The real problem is in the Term "Overhoning" because it is used for a host of different problems and is not clearly defined but in defense of the term it came from multiple sources many years ago... Barber's manuals and Barber's Hones often warn of the issue yet never clearly define it..

Originally Posted by jgkeegan

I'm comfortable skipping Einstein, but I am curious what holes you found in the article.

Most of the article is about...
" micro chipping as a result of over honing."

Micro chipping is due to the grit levels affect on the steel. Not over honing.

"the edge of the edge becomes thinner as it becomes more refined"
I think he shoots himself in the foot with this comment as it completely negates his statement..." the thickness of the spine of the razor combined with the width of the blade determines the edge angle.
How can the edge get thinner if the angle never changes?

While I don't find the man completely wrong I think he went off road with the micro chipping issue. You may hone longer trying to get these chips out not realizing that the grit level your at is creating them which is really just a waste of steel. I think 1 of the more important variables not mentioned is the pressure applied to the blade. I would think a wire edge would show up if to much pressure is on the blade forcing the angle to change. This would definitely cause a wire edge by forcing the very edge of the blade off the hone because the top of the bevel has more or less become a fulcrum which will be ground down as you continue honing.Increasing the height of the bevel and extending the edge to a point where it is bent away from it's original point in the overall geometry of the razor as it was.

My 3d drawing of a normal hone angle

Add some pressure and the edge will lift. The top of the bevel will now be honed away thinning the edge.
The geometry has now changed.

As the blade thins 2 things will happen. At the lower grits not only will you have the grains of steel breaking away but also bending away from the surface of the hone. As you move up in grit the impact of grit will decrease and more likely cause the grains to bend away from the hone rather than break them away. The longer you hone (over hone) the longer and more curled the edge will get. Therefore creating the wire edge the author of the article claims can not happen.


In support of my theory I give you the example of rolling an edge with a strop. Here you are bending the grains at the edge because of the angle/pressure of the leather against the edge. Because the blade is traveling in the opposite direction of honing it is less likely to break the grains that make up the very edge and merely bends them.

Thanks for putting this in drawing form!! I've had the "to much pressure" on extra hollow grind razors before especially immediately after honing a wedge or other heavier grind when I get used to using more pressure

Originally Posted by 10Pups

You may hone longer trying to get these chips out not realizing that the grit level your at is creating them which is really just a waste of steel. I think 1 of the more important variables not mentioned is the pressure applied to the blade. I would think a wire edge would show up if to much pressure is on the blade forcing the angle to change. This would definitely cause a wire edge by forcing the very edge of the blade off the hone because the top of the bevel has more or less become a fulcrum which will be ground down as you continue honing.Increasing the height of the bevel and extending the edge to a point where it is bent away from it's original point in the overall geometry of the razor as it was.

Nice read ...but I'm still glade that the closest that I look at my edges is when they have a little magic marker on them and my bifocals on!

Pressure is a whole different deal than "overhoning" and the edge being too thin.
Pressure tears chunks of steel out at any grit.

Originally Posted by 10Pups

Interesting read, thanks. Like every theory I have read, I find holes. Einstein's theory has holes :<0) This is why they are called theorys.

The only holes I know of in Einstein's theory (or theories, actually) are black holes, and they are not only accounted for in his theories but predicted by them.

[a little off topic]

Very informative article but better yet the inexpensive 'USB micro scope' (had no idea of such things) so you can see for your self what is going on.

Many thanks. Being the FNG that I am I have already damaged the edge trying to see it with hand held magnifiers.

DOH!

=(_8^(1)

Originally Posted by Oakeshott

In a razor, this would present itself as areas of increased stress along the grain lines of the martensite. This would make those areas more prone to cracking along the grain lines. The act of honing is an abrasive action, but at the micro level, it is also impact. This would cause any micro fissures present at the edge to propagate along the grain lines and the end result would be a piece of steel popping out.

It seems to me that "chipping" simply occurs at points of sub surface honing damage. So, not the scratch being uncovered, but weak or damaged regions near the apex. During honing, the edge becomes thinner and breaks away, usually in chips or flakes. The edge always has a finite width determined by the thickness of the steel where the flake breaks away.
Here is an image of the same location on an edge, first following a normal Shapton progression to 16k, stopping at the point I recognize as 'done'



Then the same location after another 20 laps on the Shapton 16k.



In the first image, the location where the chip will occur shows some existing damage:

Great shot.. So to put things in perspective for me,,,,If the edge was in the bottom of my thumbprint the surface of my thumb would be 1/2 way to the bottom of the frame ?