How thin of steel can I hollow grind?

[Timy]

I have a 12" contact wheel. How thin of stock can I use without making the hollow for lack of a better word too thin. I understand I can feather and move the hollow up and down. Im more asking from a theoretical sense. I saw a lot of older makers use 3/16 and 8" wheels. Very interested in say I never move the wheel up or down, what is the limit for each wheel in terms of how thin.

Appreciate your time.

 

[Mike Martinez]

Timy, it all depends on your skill lever. By the Grace of God, I've been grinding razors down to .005 on a 2" wheel and they have been fine. You can use this calculator to give you some idea of what a grind will look like. http://bimjo.com/free/widget.html

 

[Timy]

Mike, thanks for chiming in. I have that widget saved, definitely a good reference. Im more curious of specifications then skill level. Ie, if the stock is 3/16, I can grind it at 4.5 degrees and the grind will be roughly 1 inch high. Just an example, but is there anything like that, or does anyone know? The above widget is what made me curious. Like a 12" wheel will give me a 1" high grind on 5/32 with a .020 center, so does that mean the steel is thicker above where its scribed after being ground? I tend to over analyze things but still this is a subject(knives) I could be obsessed with for the rest of my life and still not be bored of it.

 

[Fellhoelter]

I am confused about what you are after.

You have mentioned 4.5 degrees, AND hollow grinding.

4.5* is pretty typical on a flat grind, but there you actually have an angle.
The relative angle between the center plane of your blade, and the bevel.

There is no such thing in a hollow grind.

That widget tells you everything that you need so you can decide if your wheel/stock combination is right for your application.
It is designed so that the tangent point of your hollow is at the edge, so yes, as with all typical grinds, the steel gets thicker from the edge to the spine.

The only way to avoid that would be to have that tangent be somewhere between the spine and the edge.

Here's a drawing to illustrate.

The top shows a section view of a hollow grind, as defined by the widget.
So does the middle, but it also has lines drawn in, representing the offset centerline planes that you defined as your .020" edge thickness, and a vertical line at the intersection of the 2.
This is what that widget tells you.
And, as you can see, the blade naturally gets thicker as you move towards the spine.

The only way you grind would get thinner behind the edge would be if you shifted that point back, like the bottom drawing.
No widget out there is going to give you numbers for that.
The trigonometry to figure it out is relatively complicated for those not well versed in the math.

 

[Timy]

Fel I was merely using the 4.5 degrees as an example. Thank you apex that's what I was looking for so gets thicker from the edge. Thanks for taking the time to post man