Thread: How Bevel is Affected by Taping

Originally Posted by honedright

Icedog, this is what I think: you're an animal! Kinda crazy too - to go through all that, but a great idea.

I also believe that as the spine wears down, coincidentally with the edge (under normal honing) that the angle remains constant for a correct shaving edge. Can you figure a formula for that? Eh?

Or how about this: (and maybe your above data aready has some of what I'm about to suggest)

Assuming a brand new straight razor, the spine has a certain thickness, blade certain width, equals a bevel of X. That bevel would be the intended thickness for shaving for that razor. Yes? Now add the tape. How far off is the bevel with the tape (I guess that is your Delta above), and how would that affect shaving?

Also a rate equation: under normal honing (define) how long will a straight razor blade last before the edge/spine wear will no longer produce a shaving edge?

All in fun, of course.




Scott

Okay Scott, Seraphim has answered your question, correctly. If the thickness of the spine is reduced in direct proportion to the width of the blade, the angle will remain constant. However, that will not be likely. The reason razors (and other cutting tools) are hollow ground is to expedite stock removal at the edge. Therefore, because of the grind of the blade, the edge is removed much faster than the spine.

Your second question regarding how long a razor can be brought back to usefully sharp is loaded with too many variables. Hey, I see 200 year old razors being used to shave. How many times have they been honed? How have they been honed? Who knows? But they probably haven't been taped for most of their lives.

I happen to be ambivilant on the taping issue. On old razors I've seen with badly honeworn spines, I believe that honewear has likely been caused by gents with little pushcarts equipped with handcranked grinding wheels that used to stroll from block to block sharpening anything that needed an edge. These guys would sharpen scissors, axes, cleavers and razors all on the same stone wheel. The razors would be held against the side of the wheel and ground merrily away with a quick finish on a strop.

Glen has voiced his opinion regarding the durability of an edge. Again, theoretically, I agree that a more obtuse edge is less likely to be damaged (rolled, chipped, whatever) however, when looking at the actual delta between taped vs not taped, we see an average difference of 0.59 degrees. Personally I think that is negligible. But that is a guess.

Hoglahoo,

I used a plastic scale to measure the width to the nearest 1/16th inch and I used a Mitutoyo Absolute Digimatic caliper to measure the spine width and I rounded to the nearest 1/1000th inch.

Brad