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Straight razor blade geometry

Posted by bricklayer 
Straight razor blade geometry
December 19, 2016 02:44AM
Hello All,
Im getting into shaving with a straight razor. This subject on the shaving forums is driving me crazy. Tape or not tape the spine when honing. Most everyone believes that the spine is a built in angle guide. Meaning keep the spine on the stone every honing session, and the angle will stay the same through out the entire life of the razor. The best angle for a razor is said to be 14°~17° at push cutting hair.

How can the spine be a angle guide if and when the spine wears the angle decreases. Just say my razor starts out 6/8 in width and the spine is 3/16 in width when new, and my bevel angle is 17°. If i never tape my spine to protect it from hone wear, in just say 10 years of honing. As the spine gets thinner from hone wear, the angle has to get more acute. I dont know the math but with, just a little common sense tells me as the spine thins the edge bevel thins also. So there is no way in 10 years spine wear the edge angle will still be 17°. So IMO if your setting the bevel on a king 1k i would use 1 layer of tape to protect the spine, because thats the most aggressive stone and more likely to cause spine wear. After i set the bevel remove the tape mark the bevel with pernament marker let marker dry,then go 4k norton. While doing this with no tape its going to create a secondary bevel, and thats why i marked my bevel. When all the marker is gone that means the first and secondary bevel has become one bevel. Then moving to the 8k. On the 8k and above im not going to cause heavy hone wear on the spine because they are not aggressive but merely polishers. I do think the spine is a reference point, but it doesnt keep that razor at the same angle through many years of honing as the spine wears.
Re: Straight razor blade geometry
December 19, 2016 01:10PM
Here is some good YouTube's that will have some answers to your questions, as Keith (Tomonagura/Gamma) and Caleb (BlisterSteel) both have a more pragmatic approach to straight razor sharpening (warning: Occasional Profanity):

Keith V. Johnson (Tomonagura on ETSY and his website and Gamma on the forums) Tape or No Tape:

Caleb McCullough
With tape:

Without tape:

Also, reading about the difference between Dillucot Honing and Unicorn Honing:


And Dr. Matt357 has some great stuff, along with TheJapanStone:

Dr. Matt357


The Japan Stone


Another good video with lots of info (fairly long, 1 hour and 7 minutes)

Straight Razor Revoltution!:


"I am still discussing issues of steels and performance at this stage."
--Cliff Stamp

"Cause geometry cuts, .....steel determines the level and the duration"
--Roman Landes

"But in general, I'm all about high performance, Ergos, safety. That's why I've been accused of 'designing in the dark' "
--Sal Glesser

Edited 1 time(s). Last edit at 12/19/2016 02:00PM by jasonstone20.
Re: Straight razor blade geometry
December 19, 2016 09:53PM
if you tape the spine so it cannot get thinner, then using the spine as a guide will result in a thicker and thicker angle.

if you are removing an even amount of steel from the edge as you are the spine then as it gets thinner in cross section, its also getting shorter in distance edge to spine, maintaining the same angle on the guide.

if you push harder on the spine, or softer than the edge then you are also changing the angle

KnivesAndStuff (YoutTube)
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