View Full Version : Barely Convex


SteveS
01-21-2004, 01:59 PM
I was setting the initial edge on a new knife and ended up doing something a little different - for me at least.

I was using Norax belts and a platen - which have a little give compared to waterstones. I also had some graphite belting under it, which added more 'give'.

The result was a convex edge. I expect that to happen somewhat because of the less than hard surface. But based on the way light reflects I see more convex than I expected. Still less convex than a slack belt.

So, I finished up with a 5x and then a leather belt.

I think I'll call the results - barely convex. Kinda fun because the look has a pretty definiate edge like like a flat edge (I like that look), but not a solid reflection.

Dang that sucker is sharp and slices stuff like the dickens! Haven't run any durability tests yet, but I expect it will do quite well.

Steve

See Jerry - I listen!

berettaman12000
01-22-2004, 11:50 AM
Hey Steve, does Norax make those belts in 1x42"? I really like a convex edge for heavy cutting, otherwise I like the v-grind.
Thanks!

shgeo
01-22-2004, 12:07 PM
I recently tried shaving my face with two of my knives with thin blades that have convex grinds. One is a warncliffe blade in S30V and the other a small drop point bird and trout knife in D2. Both are 3/32" thick and sharpened through polishing with translucent Arkansas stone and then stropped with CrO rouge.

With three days growth, the S30V shaved cleanly and the D2 a little less smoothly, but still did the trick. There may be some bias here as I am right handed and did the right side with S30V and the left with D2. Faces are a lot harder to shave than arms, but these convex edges performed better than I thought they might. I don't normally shave with a straight razor and wasn't sure I could pull it off.

The point is that I don't think convex edges are only good for hard, tough applications. Using thinner stock for lighter blades, you can get very fine edges with shallow angle convex grinds.

SteveS
01-22-2004, 05:04 PM
Steve,

Shaving - like the face? and neck! Don't have the guts myself.

But I feel challanged - I'll try it.

Actually I'm a a bit suprised too. Thought a convex wouldn't do that so well.

How thin was the edge before you sharpened it.

---------------------------------------------
I posted this without a question. But had one in mind for Jerry:

When you are talking convex, just how convex are we talking? I mean I can start with a .040" edge and use a very slack belt and get a nice round edge. The other extreme is what I was talking about where it is slightly convex right at the edge.

So, just how convex for the that high-performance hunting knife?

Steve

PS No I don't have a clue how to quantify convex. Flat ground is easy you have angle, but convex?

shgeo
01-22-2004, 07:44 PM
I start these knives with 3/32 stock, grind distal taper and pretty close to a full convex grind. They are very thin at the edge. I start with an almost flat grind on the platen, gradually slightly round it and shape the smooth curve with the slack belt. There is a wide range to slack belt grinding, depending on belt tension,belt grit and type and pressure applied.

I have to admit that I chickened out on the neck with the D2. It was on the wrong side and discretion kicked valor's butt. The S30V was very smooth-not good enough to give up the three blade cartridge though.

Jerry Hossom
01-22-2004, 09:13 PM
For about a year now I've been using a rotary platen for my sharpening because I can adjust the amount of slack I want for each edge. It allows better control than the slack belt and is less likely to make the final edge too steep.

TJ Smith
01-25-2004, 09:24 PM
Yeah I think barely convex sounds right.
I use a thin cotton pad on my 5160 platten. It's a piece of and old outboard motor cover. very little flex but enouch to stop the belt join from making noise.
I flat grind and blend in the edge grind and then sharpen with the pad on the platten.
Holds and edge real well.
Take Care
TJ