Anyone else have problems with convexed edges?

C

cgebhard

Joined
Dec 26, 2005
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I love my sharpmaker, use it on most my knives except the ones with the convexed edge. I do the sandpaper on mouse pad thing for convex. I can never seem to get a decent edge on my convex blades. I have watched the videos, read the how-to do's, etc. Just can't seem to make it work for me.
I like a shaving sharp edge and can get that on my non-convex blades with the sharpmaker. Anyone have a shaving sharp convex edge? I know the convex is supposed to be more durable, but is it as sharp?

I'm about ready to get rid of my convex blades.:thumbdn: Any suggestions?
 
I'll take them! I don't do the sandpaper/mousepad thing. I do the freehand sharpening thing and let the convex edge form itself over time. And when it does it is very easy to keep sharp with stones.
 
Are you working a burr up on each side before changing grits? If not you're probably not even hitting the edge.
Are you using too much pressure? That will round the edge right off.

All of my convex knives are crazy sharp but it took a lot of practice and patience to get there.
 
The one thing helped me the most was the use of a sharpie. color the edge with a marker. The ink will show you if you if your hitting the edge properly. Convex sharpening takes practice just as the V grind does. I personally prefer the convex edge. With the V grind I was continually chasing the "burr" back and forth. With the SP, MP, and then leather strop I have been able to get the "hair popping sharpness" that seemed forever out of reach. Practice, Practice Practice. and use your sharpie.

RP# 169
 
seems easy to have it shaving for me. Sounds like your maybe using too gritty of paper or maybe pressing too hard
 
I find it extremely easy to get a shaving edge on a convex edge using the sandpaper method. What convex edged knives are you trying to sharpen?

A couple of things that may help:

1. If you press too hard when you are using a soft backing the sandpaper can be pushed up too far on the edge and actually begin to dull it.

2. Make sure you are actually contacting the edge with the sandpaper. You might try coloring the edge with a Sharpie and seeing if you are removing it as you sharpen.

3. Make sure you are raising a burr before you move onto the next grit.
 
My convex edges are RAZOR sharp. Be sure not to press too hard or you will actually dull your edge. Once you go convex you never go back!
 
or the angle is too steep. you want to barely raise the spine of your knife off the paper. it takes a little practice, but they can be made shaving sharp. it's easier than maintaining a bevel freehand.
 
I'm with you. Don't care for them. Got rid of a ton of Barkies because I was tired of fighting with the edges.

I guess most of my blades end up having a ghetto-convex anyway, but it's done with stones, freehand.

I know that convexed blades excel at alot of things and I've seen Richard J do insane things with them but if I can't fix up the edge quickly in the field, forget it.
 
the sharpest knives I have are all convex. personally, I can't find sandpaper higher than 600 from the stores around me so I've taken to stropping with a compound to finish the edge and that really helps.

in fact, I got bored and shaved my face freehand with one of my small convex edged knives and it worked great.
 
100eyes said:
the sharpest knives I have are all convex. personally, I can't find sandpaper higher than 600 from the stores around me so I've taken to stropping with a compound to finish the edge and that really helps.
Click to expand...

Try your local auto parts store. They should have 1500 and 2000 grit.
 
dont get rid of your convex edges. some of my sharper knives are half convex chisel grind edges. i just made a skinning knife that has a convex edge just like the one i made for cjpgeyer. both knives are convexed on both sides.
http://www.bladeforums.com/forums/showthread.php?t=641839&page=3
there is also a picture of a busse scotch dispenser that i convexed the edge on. i work up a burr on my belt sander and remove the burr with a paper buffing wheel.
 
I think the main problem people have with the sandpaper method (or stropping in general) is getting the angle right. It took me a while to get it. What I learned to do (from the straight razor experts) is to lay the blade flat and turn it up slowly while allowing the blade to slide forward; when you reach the correct angle, the blade will stop. Actually, I turn it back down a little after I reach that point, and it seems to work well. Also, I originally sharpened heel-to-tip, but was later advised to do it tip-to-heel. You get sharper points that way.

BTW, it doesn't take much pressure. In fact, with large knives, I tend to just let the weight of the blade do the work.
 
I can't seem to get my convex as sharp as I want either. They get pretty sharp and lets face it, pretty sharp for this crowd is a razor blade to most folks, but not where I want it. I'm thinking about just putting my convexed edges on my sharp maker. In fact I did that with a Gossman PSK I have and it turned out better on the first try than I could ever get it with sand paper. If you don't get the convexed sharpening down, I would recomend just using your sharp maker rather than get rid of your good knives. RAT knives are 20 degree V-grinds and people love them so I don't think you can go wrong.
 
good advice above.

It took me a few days to figure out the correct method, then bingo, not just sharp, hair jumping sharp. I have a fixed angle sharpening system, and I have not touched it in ages. Even on my obtuse edges, that I have specifically left thick and sharpen at a very high angle are still not just shaving, but hair popping sharp.

big thing find the right angle, and almost no pressure.
Don't give up on them.
 
Thanks for the "convex" pep talk I'll keep trying. Also a few questions asked.

The current knife I'm trying to use is a Falkniven F1. As far as a burr I don't know, but will try the sharpie. It's amazing what your forget when your frustrated, I should have thought of the sharpie myself. I'm using 220 grit paper, I''l pick up some finer stuff today. I tryed less/vareid pressure trying to get results.

I'm sure angle is an issue, I just need to find what works.
 
Shotgun said:
I can't seem to get my convex as sharp as I want either. They get pretty sharp and lets face it, pretty sharp for this crowd is a razor blade to most folks, but not where I want it. I'm thinking about just putting my convexed edges on my sharp maker. In fact I did that with a Gossman PSK I have and it turned out better on the first try than I could ever get it with sand paper. If you don't get the convexed sharpening down, I would recomend just using your sharp maker rather than get rid of your good knives. RAT knives are 20 degree V-grinds and people love them so I don't think you can go wrong.
Click to expand...

I do this most of the time and often tune my convex on the sharpmaker using just the white rods and 40 degree angle guides. Basically putting a v-grind microbevel on the blade. Gets it shaving sharp quick enough. The main benefit of the convex is the lack of shoulders IMO not the edge itself. A convex bevel with a micro-V grind edge is the right compromise for me.

When the V-bevel starts to get a bit too pronounced after several sharpenings go back to mousepad/sandpaper.
 
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