How to hollow grind?

[Leu Custom]

Can someone post some detailed photos on how to HOLLOW Grind? I am very interested in learning, however, don't really know the exact concept in how to do it? Is hollowgrinding always done free hand with the contact wheel? I currently have an 8" inch contact wheel. How does the grind differ vs. a 6 or 10" inch contact wheel in the grind? I know, all very stupid questions, but till now, i've only been gring flat zero grinds in tool steels. Thanks!

 

[richard j]

how about filling out your profile a little more so we know more about you. i dont do hollow grinds or i would help you out. your question isnt stupid either. asking a question is the only way to find out what you want to know.

 

[LRB]

I hollow ground for a number of years just because in the eighties it seemed that the majority of makers were doing it, and at the time, I thought it best to follow their lead. I don't really like hollow ground blades, they are weaker in the edge bevel, and if deeply ground, have a tendency to drag in cutting meat. The most efficient hollow grind is a relatively shallow hollow from spine to edge, which calls for a large diameter wheel.
One starts by creating a lateral groove down the middle, and little, by little, widening this groove by high, or low pressure on the wheel as you make a pass. The more definitive the groove gets, the easier to stay in it. It is really just that simple. It takes some practice, but acually becomes relatively easy. You might practice on soft metal, such as brass, or cold rolled steel to get the feel for it.

 

[David Wesner]

The more definitive the groove gets, the easier to stay in it. It is really just that simple.

Yeah, everything LRB said. Good post. All I can add is that "ideally" you should finish grind (after HT) and end up with the radius coming tangent to your edge (as opposed to a thicker edge than is higher up on the grind).

LRB mentioned, IHHO the ideal hollow grind is " a relatively shallow hollow from spine to edge, which calls for a large diameter wheel " . You can easily figure out just how big a wheel you will need to fill any given height of grind by using this online calculator that was figured out by Rob Frink of Beaumont Metal Works. It is at the bottom of this link http://www.bimjo.com/free/widget.html , just enter the correct data and click on "evaluate grind height" . If your wheel is too small to fill the width of steel you're grinding you can blend or "fudge" the remainder of stock out by tipping your blade forward or back, dependant on your needs.

And I agree with Richard, no such thing as a stupid question

 

[rashid11]

With narrow knifes, it is easy to hand-hold it. With larger ones (kitchen choppers etc), a jig helps. I most highly recommend renting a few videos from http://smartflix.com

http://smartflix.com/store/category/9/Knifemaking

http://smartflix.com/store/video/1041/All-About-Grinding
^^
this one is a good intro to grinding, rather basic

http://smartflix.com/store/video/2025/Making-A-SubHilt-Fighter
^^^^^^
Da Classic ! A+++


And of course, practice makes perfect - so buy a few strips of Lowes/HD steel and practice on it.

Stay focused when you grind. It is real ez to loose concentration and ruin the knife
or spend hour or 2 correcting a nasty scratch or ruined grind line or ruined spine line - you get the picture

 

[Rob!]

One starts by creating a lateral groove down the middle,

:thumbup: Thanks. My Sunday morning kernel of wisdom. I loathe (hate is too strong a word) hollow grinding, but I've always started the grind at the edge same as a flat grind and chased it toward the spine using point of pressure. I've gotta try the groove down the middle as a start.

Rob!