Reprofiling a Blade

G

Gypsy

Joined
Aug 9, 2000
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When reading arcticles on sharpening I run across the term reprofiling a blade. What exactly does it mean?

This sounds like one of those 'dumb' questions, but I don't know if they are refering to the shape of the curve or re-doing the bevel. They always mention using extra course or course stones.

Thanks in advance everyone!
 
Reprofiling is redoing the primary edge bevel. Most edges have a primary edge bevel (thin angle) and a secondary edge bevel which does the actual cutting (wider than the primary bevel). Some knives have only one bevel. In a zero bevel flat ground blade, there is only one bevel from the edge all the way to the spine of the knife. A full flat ground blade with a convex edge has only the primary edge bevel, and the cutting edge bevel is actually convex, or rounded. Most knives have a primary edge bevel, and a very small secondary edge bevel.

Reprofiling a blade means to make changes to these parameters. Since this often requires removal of large amounts of metal compared to honing (making the cutting edge), the use of coarse stones is recommended to speed up the process.

Some knives (e.g. Benchmades) come from the factory with what some of us think are ridiculously wide primary edge bevels. Sometimes these are not of even thickness along the blade, or are set at different angles on either side of the blade.

Reprofiling simply means using coarse stones to adjust or construct this primary edge bevel. Usually, this means making it thinner and symmetrical on either side of the blade. The cutting edge bevel (secondary) is sharpened with finer and finer grits of stones after 'setting' the primary edge bevel.

Some people use these terms differently than the way I just did. It is important to define exactly which bevel (angle) you are talking about. In Joe's article, he refers to the blade grind as the primary bevel. I just ignore the blade grind altogether. It is hard to call a hollow ground shape a bevel.

So the primary edge bevel (to me) is that narrow strip that you can see along the edge of any blade. The secondary bevel is not necessary, but something I apply with very fine stones in order to strengthen the edge a little without compromising performance. You will probably not be able to see the secondary bevel with the naked eye. I hope this makes sense to you.

For additional help on understanding edge geometry and sharpening, see Joe Talmadge's excellent articles in the knowledge base section of BFC:

Edge Geometry

Sharpening FAQ

Paracelsus

[This message has been edited by Paracelsus (edited 09-15-2000).]
 
Thanks for the info and links. I understand the primary bevel and the second widder bevel, but then this raises another question.

Where does the 'back bevel' come into play that can be had from the Spyderco Sharpmaker?

These questions are because I have an old Buck folder that I can't get "real" sharp on my sharpmaker because it appears that there just isn't enough of a bevel on the knife. Based on your info I think it doesn't have a primary bevel.

Is this a candidate for a reprofile, or should I just keep at it longer with the back bevel option.

Thanks!!!
 
I don't have a sharpmaker, prefering to do my sharpening freehand, but I think what they mean by 'back' beveling is the same as what I call thinning out the primary edge bevel.

With v-type sharpeners, a common problem is not removing enough metal at the thinner angles to reach the edge. This will happen if the back beveling angle is much narrower than the primary edge bevel already on the knife.

A very useful technique is to use a black felt tip marker to color the edge before sharpening. This will allow you to see what part of the edge is making contact with the stone after just one or two strokes. When sharpening a knife with a v-sharpener at an angle thinner than the bevel already on the knife, the stone will not make contact all the way to the edge. Simply keep stroking until the all of the color is removed all the way out to the edge. When this has been done, you are ready to start honing the secondary or cutting bevel.

Read the comments in Joe's sharpening article about the wire edge. This will only be produced when the edge bevel is actually reaching the edge, and a small amount of metal is pushed over onto the other side, forming a thin rolled 'wire'. This should be removed by honing and stropping.

Sharpening with a device or freehand is a skill that takes practice. Some knives are properly ground from the factory, some are not. If you need to regrind the primary edge bevel, it may take some time, but subsequent sharpening will take much less time and effort. Good luck!

Paracelsus
 
Thanks alot!!!

That answers my questions. I read the two pieces you suggested. They were great! I just recently got into this stuff and they answered alot of questions. Plus now it all finally makes sence.

I'm off to the sharpening bench.........
 
All you have to do is.... go try....... get yourself....... try these links...... DAMN!!!! Paracelsus beat me to it! Bastid
smile.gif
 
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