Trying to learn "edge geometry".

B

burnera

Joined
Oct 21, 2006
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I'm wondering if there's an FAQ or guide out there about edge geometry.
I want to get into knifemaking, but i'm doing the research first before diving in.

i don't have any interest in forging, i don't want to spend 10 years getting competent.
So i'd rather buy tool steel plate, and go from there. (thats 'stock removal' right?)
Oh, and whats 'hallow ground' mean?

I've read through the newbie FAQ, and googled a bit. I still can't seem to find fully fledged guide about ideal angles for the blade, or techniques on how to get there.
Is this like welding, where its 10% science and 90% art?


ps: i am competent in the shop, from carpentry to machining. I've never made a knife before though, and i prefer to do things well.
 
The only ideal angle is the one that you choose. It depends on the primary grind, edge thickness, etc. I shoot for around 25 degrees on the secondary bevel (edge) with a full flat grind. Edge thickness prior to sharpening depends on the use of the knife (chopper, hunter, skinner, etc.). Choppers have thicker edges while skinners have a very thin edge. When I say thick, it maybe only be 1/32" and thin may be 1/64" (or less). You may not have a secondary bevel, the grind may be a 0 degree (like on a straight razor).

It's not "hallow", it would be hollow grinding. It is using a round wheel to create a primary grind as opposed a flat grind using a flat platen.

My suggestion is you buy the $50 Knife Shop (book) and go from there.

And, as far as the statement"i don't have any interest in forging, i don't want to spend 10 years getting competent. ", that's just gonna piss a lot of folks off here. I have been a stock removal guy primarily as I've found I don't like / enjoy forging as much, nor do I have the room for a good setup, but that's just me. It has nothing to do with a time investment. Either way, it's a long journey that many of us may never "master". I am 200% better than when I started, but I have sooooooo much more to learn. There is no easy path but if you truly have an obsession (as most of us here do) you will grow in leaps and bounds.
 
Get the revised edition of $50 Knife Shop, it's got more info and jigs in it. The Wonder of Knife Making by Wayne Goddard is a good book, too.

Mike
 
TekSec said:
And, as far as the statement"i don't have any interest in forging, i don't want to spend 10 years getting competent. ", that's just gonna piss a lot of folks off here.
Click to expand...

It's a compliment actually. Thanks for the book recommendations.
 
On KnifeList this morning there was a note about $50 Knife Shop-revised. I asked Wayne if he has "The Wonder of Knife Making" available, too, but haven't gotten an answer yet.

Here is the conversation:

Eric wrote: “Wayne, one of the other knife forums I'm on is having a discussion about your $50 knife shop book, and there are a lot of beginners there wanting to pick up a copy. Most are probably planning on ordering off of Amazon etc... Is there a place that I can direct them to (your website etc...) where they can buy a copy for the same price, but you'll get a larger cut of the $$$?”

First they need to determine if they are getting the revised $50 Knife Shop, which is in color and a bunch of new pictures, some of it updated. They will be getting the new version if they check to be sure it is the revised book. Or by the cover; the original had a wood handled ball pein on the cover, the revised version has a yellow fiberglass handle on the ball pein hammer. I get the same royalty from the publisher no matter where a book was sold. I make the retail mark up if they buy from me, plus they get it autographed. (
) to get ordering information.

Wayne

I still read both of these books (five years). It amazes me that I can reread them once a year and always find stuff in them I didn't get or didn't get all of in the previous readings.

Wayne also has DVD's he has made... knife making... cable damascus

Mike

Edit: Wayne has both of the books available...

2nd Edit: One DVD and it has both cable damascus & knifemaking on it...
 
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Under ideal conditions the edge geometry would be determined by what and how you want to cut, however tools and skills will not always make for ideal conditions, this is where the steel and its best condition will heavily affect the edge geometry.

The overall strength of the edge will govern the shape and thickness of it. The less strength the steel has the thicker the blade will have to be imediately behind the edge. Embrittlement problems will also effect this however going thicker will not have as large an effect as it will with lack of strength. I have found that the higher the hardness, within the accepted range, and the more homogenous and refined the internal structure, the thinner you can go on the edge. One can do funky things to get segregated conditions with mixed microstructures and make a toothy aggressive cutter but the edge geometry will require more meat to it in order to compensate for the overall lower strength.

In short... I know, too late... your heat treatment will allow finer geometries and if you have total controll over it you will have a much wider lattitude to work out what cross sectional shapes you want to use for the intended task.
 
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