Geometry for different blade styles

R

RantNRave

Joined
Dec 29, 2015
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Ok, I'm sure this is hanging around in some thread, but on a couple searches, nothing jumped out at me.

Can someone point me to a link, thread, or answer that explains blade geometry for the various styles? For example, what would the edge thickness be of a drop point hunter with a 3 1/2" blade, 1/8" thick steel? I'm also looking for camping, bowie, fighters, etc.

Thanks
 
The most fundamental and ignored topic in knifedom.

Edge thickness is hardly ever discussed, even though it is the most fundamental aspect of a blade's performance.

Most knives are ground too thick behind the edge twice over. A rare exception for fixed blades being Randalls.

A big chopping fixed blade, if the steel is good, should be as thin as 0.020", and it will be plenty strong. 0.030" is slightly too thick even for a big knife, and most are a terrible 0.040". Many even go to 0.060", which is basically la-la land...

For a folder, I think much thinner is possible and even a minimum: I would say 0.010" is plenty thick enough, and on flat ground folders a flat zero edge can be desirable. Any blade under 6" should offer a premium of sharpness for its lack of chopping power...

Gaston
 
Gaston444 said:
The most fundamental and ignored topic in knifedom.

Edge thickness is hardly ever discussed, even though it is the most fundamental aspect of a blade's performance.

Most knives are ground too thick behind the edge twice over. A rare exception for fixed blades being Randalls.

A big chopping fixed blade, if the steel is good, should be as thin as 0.020", and it will be plenty strong. 0.030" is slightly too thick even for a big knife, and most are a terrible 0.040". Many even go to 0.060", which is basically la-la land...

For a folder, I think much thinner is possible and even a minimum: I would say 0.010" is plenty thick enough, and on flat ground folders a flat zero edge can be desirable. Any blade under 6" should offer a premium of sharpness for its lack of chopping power...

Gaston
Click to expand...

You forgot to mention hardness and type of steel , next important is style and purpose of knive .... Not every steel have same toughness ......But if you ask me any steel above 62-63 HRC should be convex ,the mother and father of all grinds ..... :thumbup:
 
Ok, here is a question I have not found a "good" answer to regarding measuring thickness. How far back from the edge should it be measured? Both with and without a secondary bevel. I imagine with a secondary bevel it out to be measured right behind the secondary bevel? I prefer convex grinds because I don't have to fool with a secondary at all.
Without saying how far behind the edge you are measuring the measurement doesn't amount to much at all.
 
A good way to get a fair reading on the edge thickness is to use a set of feeler gauges. The good thing about this test is that it cam be dome anywhere with just two things.
On an unsharpened edge you can guesstimate withing a few thousandths. Place the feeler gauge along side of the blade edge, holding them tight together with your thumb and finger. Look at it under magnification. A cheap 10X hand loupe will be fine. Compare them and switch the gauge until you find one that seems the same as the edge width. On a sharpened edge, it takes more skill, but with practice you can see the line where the bevels meet as a comparison width to the gauge.

If using calipers or a micrometer, you need very good ones that are accurate to .001 or better. They need to be hardened steel. Place the jaw tips as close to the very edge or bevel junction as possible while trying to keep things aligned. Be aware that any twist or misalignment will read much thicker than it actually is. If you have a height gauge that is the best way. Place the blade flat on the surface plate and hold/clamp the bevel down solidly against the granite surface. Lower the height gauge tip until it contacts the exposed bevel where you want to read the thickness.



I personally think everyone makes too much of these measurements. The same with the angle of the bevel. Just grind the bevel to a near zero edge and sharpen at the desired edge angle. If the edge is too frail, resharpen and it will be sightly thicker. No matter what you make the edge originally, it will thicken every time you sharpen the knife. Best to start with the very minimum that will hold up.
 
This was very enlightening thing to read :)



I personally think everyone makes too much of these measurements. The same with the angle of the bevel. Just grind the bevel to a near zero edge and sharpen at the desired edge angle. If the edge is too frail, resharpen and it will be sightly thicker. No matter what you make the edge originally, it will thicken every time you sharpen the knife. Best to start with the very minimum that will hold up.[/QUOTE]
 
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