Blade/bevel angle question

Ok, so I've read according to Bart that the bevel angle should optimally be between 15 and 19 degrees (my understanding of his post.) Is this bevel angle the measure as if one side was laying flat, and you measure the angle from one side of the spine to the other (total bevel angle)? Or is the angle he speaks of the angle from the CENTER of the spine to one edge of the spine (effectively HALF what the total bevel angle would be)?

Just trying to make some sense of the whole bevel angle thing, but from my searches, I could find anything to clear it up.

Thanks!

There is a thread "fun with Verniers calipers" in which all of that is discussed in great detail. There is also an Excel chart which you can use to calculate the number of layers needed to achieve a certain angle.

However, while there were lot of razors that fell into the 15-19 degree range, there is apparently no hard and fixed rule.

Regards,
Robin

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Originally Posted by avatar1999

Ok, so I've read according to Bart that the bevel angle should optimally be between 15 and 19 degrees (my understanding of his post.) Is this bevel angle the measure as if one side was laying flat, and you measure the angle from one side of the spine to the other (total bevel angle)? Or is the angle he speaks of the angle from the CENTER of the spine to one edge of the spine (effectively HALF what the total bevel angle would be)?

Just trying to make some sense of the whole bevel angle thing, but from my searches, I could find anything to clear it up.

Thanks!

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It's the entire angle from side to side. I think the knife guys use the angle for one half of the blade (the angle of the bevel from the centerline of the blade). Not sure why we use the angle for the entire edge, except that the numbers are a little bigger so the differences appear a bit more significant. And maybe because we hone the razor with the blade flat on the hone.

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Originally Posted by BeBerlin

There is a thread "fun with Verniers calipers" in which all of that is discussed in great detail. There is also an Excel chart which you can use to calculate the number of layers needed to achieve a certain angle.

However, while there were lot of razors that fell into the 15-19 degree range, there is apparently no hard and fixed rule.

Regards,
Robin

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Where can this link be found at for the excel chart and having fun with calipers?
I cannot find it on wiki or using the search function.
thanks,
Bill

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Originally Posted by turbine712

Where can this link be found at for the excel chart and having fun with calipers?
I cannot find it on wiki or using the search function.
thanks,
Bill

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Here is the fun with calipers and tape.

Some extra background.

In normal cases you should not worry about the bevel angle. All "modern" razors (roughly from the 1930's till now, probably even earlier) are produced with a bevel angle between 15 and 20 degrees, centering around 17.
Where that angle comes from, I don't know, but it seems safe to assume that the manufacturers found with vast trial and error that an angle in this range delivers the best shave qualities/durability.
As you know, the angle is pre-defined on a razor by the thickness of the spine and the fact that spine has to rest on the hone while sharpening.
You can add a layer of tape to the spine if you wish. In general, this does not alter the bevel angle enough to make a significant difference to how the blade feels on the face.

However, when we start sharpening old wedge-style razors, often produced before the aforementioned period in razor history, we get a different story. Some of these old wedges, when placed flat on the hone, develop a bevel angle that can significantly deviate form the 15-20 degree rule. Were these old wedges not ment to be honed with the spine touching the hone? Did the razormakers from that era not really bother about bevel angles that much? I haven't got a clue.

In any case, when placed naked on the hone, some wedges have an bevel angle of 10 degrees and others have one of 21 degrees. That's why I always measure and calculate before honing a wedge. On the 10 degrees wedge of our little example here, I can add 3 or 4 layers of tape to the spine, to produce an edge with a relatively narrow bevel. This looks good, it hones easy, does not microchip, shaves great and offers good longevity. Honing the same razor without tape, causes wide uneven bevels, introduces all kinds of problems while honing, and leaves a weak edge that chips upon impact with hard whiskers.
At the same time, people have send wedges to me, honed with 3 layers of tape that carried perfect bevels, passed the HHT, but could not shave without a pulling at the whiskers. Honing such a wedge without tape, which is more challenging because of the wider bevel that has to be developed in this case, can turn a lousy shaver into a premium one.

That is why I am a strong proponent of knowing the bevel angle whenever you need to hone an unknown wedge.
This has nothing to do with trying to write things in stone, but we are talking about physics and certain ranges do apply. 15-20 is a pretty comfortable landing zone. I wouldn't panic if it was 14 or 21, but if the shaving results of such an edge are not satisfactory, it should be considered as a possible culprit.

Best regards,
Bart

Perfectly clear and well written Bart....