Thread: Spine thickness , and angles

At the risk of sounding nitpicky , I want to clairify how spine width relates to blabe angle . I took a Joeseph Smith & Sons 6/8+ blade , and found that if I lay the blade on a flat surface , the line going from the edge of the blade , and across the top edge of the spine is 15 degrees . Meaning , that if you have the blade flat on your face , you're already shaving at an angle of 7-1/2 degrees . If you lift the blade 1 spine width (15 degrees) , the blade will be at an angle of 22-1/2 degrees . If you lift the blade 2 spine widths , you will be shaving at an angle of 37-1/2 degrees . Not 30 degrees , which I've seen stated on several posts . My general "rule of thumb" is 1-1/2 spine widths , max . YMMV

Hone the spine down and you'll be fine.

Originally Posted by AFDavis11

Hone the spine down and you'll be fine.

I guess I should start on the Norton 220 .

Dave,

I, like you, am driven by precision and that's why I shave with an inclinometer. It took forever to hone and has a regretably rotten edge, but I can hold it at 30 degress until Lather freezes.

You guys are killing me ! Actually , all I wanted to do is tell everyone that 2 spine widths is a good bit over the 30 degree recommened max . I've found that my lather freezes faster if I keep my blade at around 20 degrees .

Just for the sake of continuing the nitpicking, many razors are not consistent in proportion and, to make matters worse, have been altered by previous owner's honing practices. I have a W&B that is pushing 20 degrees and a C.Mon. that is closer to 12. So while you have outlined a good rule of thumb, some thumbs are fatter than others and will give different results.

So, I think anywhere between 1.125 and 2.1875 spine widths ought to do it.

Or, one could purchase a nice set of micrometers, then measure the spine (y) width and length from the back to the edge (x), then just calculate the included angle (A): A=2*[arctan{(.5y)/x}]

And then just shave at an angle (A', "A prime") where A'=30degrees, which in spine thicknesses (n) would be: A'=30=[.5A]*n, or n=60/a. Which will be a simple process of maintaining the correct value of "n" as the three dimensional surface contours change with the differential (\/F=dXx+dYy+dZz) of the governing modeled equation of your face, one just has to find the tangent plane to that differential function along with the correct rate of change (derivative) of the tangent plane with respect to the path of the razor at the "i-th" point in the motion and precede as per usual.

And a scything cut would give the utmost comfort, so just translate all of those figures onto a skewed set of cartesian coordinates... and ...and ...and












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Originally Posted by Russel Baldridge

measure the spine (y) width and length from the back to the edge (x), then just calculate the included angle (A): A=2*[arctan{(.5y)/x}]

And then just shave at an angle (A', "A prime") where A'=30degrees, which in spine thicknesses (n) would be: A'=30=[.5A]*n, or n=60/a. Which will be a simple process of maintaining the correct value of "n" as the three dimensional surface contours change with the differential

ACCKKK!!! I didnt know I had to be a math wiz to straight shave If you had seen my grades in a college algebra class you would know that I am now doomed to looking like I got into a fight with a ticked off badger every morning


Bob

Oh, gawd, yes!! Finally, the company of fellow retentives!

Over analyzing is fun.