Thread: The perfect bevel..

I would like to throw my hat in the primary/secondary bevel discussion.

If anyone has not read "The Complete Guide to Sharpening" by Leonard Lee it is a great book in understanding the aspects and theory of sharpening. Granted it doesn't talk about razor sharpening since it is mainly a book on sharpening woodworking tools but the concepts are solid.

Leonard talks about the double bevel in pretty good detail. Many times it is coveted because of the strength it adds to the edge, reducing sharpening time and also the cutting ability of the secondary bevel is increased because of the primary bevel given that the width of the secondary bevel is shorter than the object being cut.

Now when working with woodworking tools the technique for producing the double bevel is say you want a 25° angle, your primary will be either 23° or 24° using only a course stone and then add the remaining degrees after the primary bevel is set and it is only this secondary bevel you hone to the finishing stone. This as long as the width of the secondary bevel is shorter than the item being cut will produce an edge that has the strength of a 25° bevel but will have the finer cutting ability of an edge as if it was a single bevel of around 23.5 if the promary was 23°. (I'm just throwing out the number 23.5, because I don't know the actual number. What I do know is that the upward force used in the splitting of what is being cut is reduced because of the lower primary bevel.)

Now about razors. Since we have only a fixed primary bevel because of the fixed spine width, we will only be increasing the cutting angle ever so slightly when producing a secondary bevel by adding tape. However if the secondary (microbevel) is shorter in width to the hair being cut, then the hair will be cut at an angle that will "feel" like more than the primary bevel but it will not "feel" like it is cutting a the full angle of the secondary bevel. This is the reason why a secondary microbevel may shave just as well because the angle increase is only a fraction of the small angle increase of the secondary. In other word you will not feel the full increase in angle produced by the secondary bevel.

Problem though is that, as mentioned earlier, the secondary bevel will eventually become a primary bevel. Thus the cutting ability of the secondary bevel will decrease and you will start to feel the full angle of the secondary bevel unless the primary angle is reestablished. Which since we are using tape, over years the primary bevel will slowly creep up in angle in fraction of a fraction in degrees. But we may not see any adverse effects of this in our lifetime.

Like I said, I just wanted to throw my hat in and mention what I have learned on double bevels.

One or 2 bevels doesnt make much of a difference IMO. Look at cotis, unicot or dilicot. Whats the difference besides saving a little time? Nothing IMO. Now 1 degree change in the bevel one way or another means nothing. Unless it changes 1 degree every time you hone it. Now im not saying micro bevels or multi bevels are bad, are they good? Sure either or, Ive gotten 80 shaves plus off of razors with clean linen and leather off plain old carbon steel. Im not done with that one either! But its still shaving great with no tugginess at all. And the one i got 80 shaves from is a simple one bevel, no micro bevel, no tape. Its academic, but IMO if you can micro bevel it, you can refine the edge on the same bevel. And you can do it without tape if you want by altering how you hone it.

I think what throws people about bevels sometimes when honing is that the bevel reflects the current wear of that particular razor. In many cases especially when new guys hone is that we have razors with wavy bevels, uneven pressure applied to the spine or bevel, more pressure applied to the spine than the bevel on one side or both and a myriad of other things that come with the learning curve. In some cases the razor will lay flat on the stone and in others not.

The exercise then becomes more about establishing a bevel that meets equally on both sides at the edge. You can't put metal back on the bevel and pretty much take it from it's current condition. With small bevels and new razors, this is usually not problematic. On older razors with a lot of wear it can be.

So the keys are how you approach what you want the result to be and for me, that is usually simply to make the razor a good shaver. Tape can be the solution, but usually with a razor that has significant wear, one layer will not alter the damage done already and clearly establish a nice micro bevel or secondary bevel. There is always the rolling X stroke as an alternative or even starting off with a very abrasive stone and removing metal until the razor will lay flat on the stone which can really be a chore sometimes. On a razor in good condition, deciding to use tape and create a secondary bevel is usually not problematic. It is just a matter of preference.

Originally Posted by pinklather

....excerpt... The range of angles that successfully shave is pretty broad. This is perhaps illustrated by all the old heavy Sheffields that show little or no spine wear. The absence of wear has to mean something was placed on the spine while honing. Sixgunner had a thread a year or so back on. As a default position - always believe a face. It the shave's good - all the other stuff is just vanity.

Always believe the face.. that has been my motto for some time. And, with only a few years of straight shaving under my belt, and half that at honing successfully, my face can't tell the difference with a single or double bevel. It's smooth and close or not.

Originally Posted by rlmnshvstr8

....excerpt... I would like to throw my hat in the primary/secondary bevel discussion.

Thanks.. Though I do want to clarify that my double bevel question was not focused at micro-bevels. I have a few razors that were honed with a heavy hand and/or no tape and had a rather wide bevel. I prefer to hone with tape for a variety of reason and as a result these razors have an obvious double bevel. Not a micro-bevel. I can't see wasting the steel to obliterate the original bevel.

You bring up another good topic.. The idea of setting the first bevel on a bevel setter and leaving it unpolished. That might seem reasonable for woodworking, but I can't see that translating over to razors. I have to think that one through a bit more.

Originally Posted by bill3152

One or 2 bevels doesnt make much of a difference IMO. Look at cotis, unicot or dilicot. Whats the difference besides saving a little time? Nothing IMO. Now 1 degree change in the bevel one way or another means nothing. Unless it changes 1 degree every time you hone it. Now im not saying micro bevels or multi bevels are bad, are they good? Sure either or, Ive gotten 80 shaves plus off of razors with clean linen and leather off plain old carbon steel. Im not done with that one either! But its still shaving great with no tugginess at all. And the one i got 80 shaves from is a simple one bevel, no micro bevel, no tape. Its academic, but IMO if you can micro bevel it, you can refine the edge on the same bevel. And you can do it without tape if you want by altering how you hone it.

Thanks Bill.. I think it really comes down whether it's worth it to waste the steel to get rid of the original, wide bevel. I mean, if the original bevel was reasonably finished and I can set and polish the new narrower bevel, the fact that there are two bevels doesn't seem to impact the shave. Maybe the Bevel Police might feel different..

Originally Posted by Lynn

I think what throws people about bevels sometimes when honing is that the bevel reflects the current wear of that particular razor. In many cases especially when new guys hone is that we have razors with wavy bevels, uneven pressure applied to the spine or bevel, more pressure applied to the spine than the bevel on one side or both and a myriad of other things that come with the learning curve. In some cases the razor will lay flat on the stone and in others not.

The exercise then becomes more about establishing a bevel that meets equally on both sides at the edge. You can't put metal back on the bevel and pretty much take it from it's current condition. With small bevels and new razors, this is usually not problematic. On older razors with a lot of wear it can be.

So the keys are how you approach what you want the result to be and for me, that is usually simply to make the razor a good shaver. Tape can be the solution, but usually with a razor that has significant wear, one layer will not alter the damage done already and clearly establish a nice micro bevel or secondary bevel. There is always the rolling X stroke as an alternative or even starting off with a very abrasive stone and removing metal until the razor will lay flat on the stone which can really be a chore sometimes. On a razor in good condition, deciding to use tape and create a secondary bevel is usually not problematic. It is just a matter of preference.

Thanks Lynn.. I take a few things from your message.

First and foremost, the all important topic of even pressure. It took me a long time to get it right. That's a skill I don't ever want to take for granted. It's easy to blame a wavy bevel on the blade, when more often it's self induced by uneven pressure.

You verbalized what I was struggling to communicate. I am often faced with trying to fix someone else's honing issues and that's what leads to the double bevel. I am fortunate to be getting bevels that are nice, straight, and set properly. Though narrower.

I got in the habit of using tape because early on I didn't want to waste away the spine as I learned. Later I found that many of my razors had decorative spines and or, finishes on the spine that I didn't want to destroy. So the tape stuck. no pun intended..

My take-away from this.. Don't fret the double bevel if the new one is set properly.

Originally Posted by bill3152

The matrix for determining bevel angle asks for spine width and the size of the wear to determine the length of the blade as well as how many layers of tape. It does not however ask for the grind of the blade. So wedge, half, full or extra hollow will have the same bevel angle if everything else is the same.

In razors of the same geometry, the bevel angle will be the same regardless of grind, I agree - however, the width of the bevel will differ according to how much metal is behind the edge. An extra hollow ground compared to a near wedge will have identical angles but completely different appearances.

Edit - this difference is more apparent on razors that have signs of diminished width through previous honing.