Help! If I grind 5/32 stock with a 3 inch wheel will my hollows touch & ruin knife?

LARRYZ10

LARRYZ10

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Feb 6, 2010
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I ground my first blade with a 10 inch wheel and got a 1 inch plus high hollow. I next bought a 6 inch wheel and ground a hollow about an inch high but deeper and it looks cool. I now have a 3 inch wheel and would like to grind a 1/2 inch + hollow that is deeper still because I like the looks of a deep hollow grind. Am I in danger of the center of the hollows touching and cutting my blade in half? The stock is 5/32 inch thick. I know this sounds nuts but I don't want to spoil a nice piece of CPM 154 CM.
I have seen Steven R. Johnson in his sub hilt fighter video use a 3 inch on a 3/16s blade and make beautiful deep hollow grinds but wonder about 5/32 material. Some wisdom please! Larry Lehman
 
I could sit down and do the math, but why not just grind a piece of wood, g-10, or plexiglass down to 5/32" and try it. You can hog off the material super fast and see exactly what it would look like once you switch to the CPM-154.
 
Yes, you will grind through the steel if you try and actually get a 1.5" radius hollow to go back that far.

A double ground hollow, ground to a zero edge goes back .478" on paper.
Won't even go back that far in real life.

Now if you have the skill to grind a different radius with that 3" wheel, you can get that to move farther up the blade.
 
Since most guys leave about .025 to .035 edge for heat treat and then use finer grits and finally grind the sharp edge do you think a half inch high hollow with a 3 inch is feasible? I see a lot of thin balde folders with nice deep hollow grinds and I wonder if they do this with a 6 or 8 inch contact wheel. Maybe I should grind a piece of G10 like Jonny Mac suggested. The Steve Johnson fighter I saw had a deep grind ( with a 3 inch) but again was 3/16ths to start. Thanks for your input. Larry
 
Only if you can walk the grind back.

In a perfect world, leaving a .025" edge, a 3' wheel goes back .439"

.487" on 3/16" material.
 
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A lot of the really spectacular deep hollow grinds are actually closer to a thin flat grind towards the edge, because the wheel (and thus the hollow) were walked back toward the spine of the blade. IIRC, the trick is to do the primary grinding with a larger wheel, then come back with the smaller wheel to refine the grind and get the deeper, more dramatic hollow up high.
 
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Thank you. This helps a bunch. I have been grinding taller hollows by moving the grind towards the spine but maybe I should be uising 4 inch wheel or a 5 inch to get the deep hollow I like. Thanks for the calculator. Larry
 
LARRYZ10 said:
Thank you. This helps a bunch. I have been grinding taller hollows by moving the grind towards the spine but maybe I should be uising 4 inch wheel or a 5 inch to get the deep hollow I like. Thanks for the calculator. Larry
Click to expand...

You're welcome!
 
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