Contact wheel diameter size guidlines for hollow ground bevels

V

Vulcanite

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Jan 16, 2009
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I have one of these:
00910354000


It has been made clear to me how much of a benefit hollow grinding is in terms of giving more times that a blade can be sharpened without needing to re-grind or discard the blade.

I have a few ideas of how I can replace the contact wheel w/ a patten or wheel, at least after having done the bevel grind flat...

Anyway, what are some diameter/radius guidelines for different grind heights/blade thicknesses?

As to making a rounded patten, the only things I can think of are cutting a wood block and beating some sheet metal on it for the belt to ride. Or, maybe some sort of flexible slick polymer material I can glue on. Any ideas?
 
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Thbe last thing I would worry about is how many times you can sharpen it. You need a round wheel or get something made so you have a platen with a radius.
 
I looked at my grinder. I can dangle an adjustable taught line w/an extension spring hanging from it above my grinder. Attaching that spring to the tension release lever result in a reduced net spring tension. That will give the belt the slack for the rounded protrusion and will reduce belt load and patten friction.

For larger radiues I would have to use a patten since it is easier to fit that than a wheel in there.

What are some typical radiuses or diameters for different grind heights? THx
 
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http://bimjo.com/free/widget.html

Plug in the numbers and it will give you the height of a hollow grind.
For example, using a 10" wheel on .25" stock, and having a .030" scribe line ( the unground section where the edge will be), you will find that the hollow grind will go about 1" up the bevel. Chang the wheel to 14" and the grind is 1.25" high.

Most folks only have one large wheel, so if you are making a modification, just use whatever wheel you have. A 10" wheel is sort of standard for hollow grinding.

In radiused platens, 36" and 48" radius are good choices.
 
To clarify, the 36, 48 and 72 Nathan platens are actually 18, 24 and 36 inch RADIUS. they are designed to replicate 36, 48 and 72 inch diameter wheels. the effect is pretty subtle even with the 36 incher unless you have a wide blade.
Stacy E. Apelt - Bladesmith said:
http://bimjo.com/free/widget.html

Plug in the numbers and it will give you the height of a hollow grind.
For example, using a 10" wheel on .25" stock, and having a .030" scribe line ( the unground section where the edge will be), you will find that the hollow grind will go about 1" up the bevel. Chang the wheel to 14" and the grind is 1.25" high.

Most folks only have one large wheel, so if you are making a modification, just use whatever wheel you have. A 10" wheel is sort of standard for hollow grinding.

In radiused platens, 36" and 48" radius are good choices.
Click to expand...
 
Brought back from the dead thread.
 
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