A matter of geometry?

I am curious...

Why do different width straight razors require a different angle to achieve the best shave (especially if they are all hollow edges)?

I don’t understand your question.

The angle at the bevel is the same, weather it is hollow ground or not. The grind does not affect the angle.

As the blade gets wider the spine needs to be thicker to keep a shaving geometry, otherwise you are shaving with a knife and you would need some type of a jig to get a consistent angle.

I have seen several videos where they say that the angle at which you hold your razor relative to the skin surface is different depending on whether you are using a 5/8, 6/8, 7/8, or 8/8.

The wider the razor the further the spine would sit away from the skin but angle remains constant. Using the same distance would create a shallower angle the bigger the blade got

OK.... It's just a misuse of the word "angle" when they were talking about distance.

It seemed to me that the angle should be constant.

Us engineer types and technical writers can get real persnickety about words... :argue:

(Some of the people responding to messages at Straight Razor Designs have already discovered this about me and I apologize.)

Well do an experiment, hold a 5/8,s razor two pine widths off of a flat surface then measure the angle, then do the same with a 8/8. Se if the angle is the same at two spine widths, but in reality, that's just a starting point usually just lay the blade flat on your face and start raising it till you get good cutting with out scraping. Plus different areas of your face will be different angles of attack. This the reason this way of shaving takes months to learn well.
Tc

Angle of attack on the skin vs the beard hair is actually a combination of two things

#1 the actual angle that you are holding the razor which should be "ABOUT" 2 spine widths

#2 pressure against the skin


You have to realize that when the edge of the blade is "Pressed" against the skin, this can change the actual cutting angle at which the hair is struck by the moving blade, the closer you are to zero pressure the closer you are to an an actual two spine width angle...

This is where the expression "Try to just shave the lather off the face" comes from,,, it teaches to be barely touching the skin with the edge ..

Shaving is the constant adjustment of pressure vs angle vs edge vs hair

Embrace the Challenge :)

IMO the bevel should be flat on the skin (how easy is that to achieve with any razor is another story) , then the edge cuts the hair at 90 degrees . Depending on the size of the razor the spine will be a different distance from the skin.