A convex edge for the college student.

U

USSR

Joined
Dec 23, 2005
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Hey folks. I want to learn to get a good convex edge on my knives, but I feel I may be limited somewhat by my living situation. I've seen many people state that for around $40 and change you can get a belt grinder and go to town, but my apartment complex has an extremely strict noise policy so power tools are out of the question. Is it possible to learn how to convex and maintain an edge without initially using power tools? I currently have a leather belt and a bunch of cardboard at my disposal, and I can get sandpaper easily. I think I can make my own strop out of these materials, but will it be as effective as the ones you buy? Hopefully this will work as a guide for other people in my situation who want to make their own kit without too much expense. Thanks.
 
with cardstock (cereal boxes) and sandpaper and masking tape (or duct tape or even scotch tape) you can have some very effective stropping boards.

so for all of about $15 you can have several sheets of 3 or 4 different grits (i suggest starting with around 300, then 400, then 600, then 800). this can come from an autobody store or a walmart with an autobody department.

then for a strop you can use the same cardstock or use leather and load it with some compound that you can get a stick of for $6 at Ace. i like "tripoli" listed for non-ferrous metals and plastics. i find it works great for a steel strop and it sticks to a strop pretty well. if you want to order online you can go through knivesshipfree.com and get the bark river knife and tool compound set. this is designed for polishing knives so it might get you farther. i haven't tried it yet but look forward to getting some in the near future.

hope this helps, any further questions feel free to ask.
 
Many like to use the mousepad and sandpaper method. You just lay the wet/dry or cloth backed paper on the mousepad and sharpen using trailing edge strokes. The softness of the mousepad gives you a convex edge as you sharpen. I would want to use something a bit firmer for final honing, and if you can get some thick leather strips those would work perfectly as a backing for both sharpening and finish honing.
 
I am just getting into sandpaper, mouse pads, etc. I have been using stones. Just don't get the edge I want with sandpaper. I find I can get a very good edge by rolling the blade a little when I put it to the stone. Works for me, any other suggestions?
 
Greetings, USSR! Santa Cuz, eh? Go, Bannana Slugs! Or is it Artichokes?

I used to hang out around there decades ago!

Okay, here's the real deal about convex:

If you learn to free-hand sharpen your knives - as in a stone, oil and knife, or diamond stone, water and knife - you will consistently produce a convex edge.

You can't help it - the natural variability of the human hand holding a knife at an "exact" angle will produce a convex edge every time you free hand sharpen a knife.

No magic, no rocket science.

Stropping on increasingly fine grades of sandpaper placed over leather on wood, followed by leather with polishing compounds, will refine the edge.

The only difference is that it takes longer with free-handing it than doing it on a belt grinder.

Once you've got the edge, just strop occasionally, and hte edge will last very long indeed!

Best of luck, and go visit a redwood grove and enjoy those great trees for me! :thumbup:
 
Thanks for the responses everybody! I'll get started with some sandpaper and test on old kitchen knives. Hey Grampa, it's the Slugs. And I will be in the forest soon, hopefully camping with some convexed knives.
 
A college student with 30 minutes an evening (or morning! :thumbup:) to spare can, as Grampa said, do alot to a convex edge. If you're convexing a scandi or v-grind, that'll take some time but you'll sure learn alot about your knife and yourself while you do it. If you already have a convex-edge knife (like a, ahem, Bark River :thumbup:), you won;t have much to do to maintain the edge.

Here's my kit. While I use the 1500 and 2000 to maintain my BRKT edges, the other grits, starting at about 320, will certainly turn a v-grind or scandi into a gentle convex in very little time. Keep your pressure and angle low and your spirits high!

convex-01.jpg

convex-02.jpg
 
michdad said:
I am just getting into sandpaper, mouse pads, etc. I have been using stones. Just don't get the edge I want with sandpaper. I find I can get a very good edge by rolling the blade a little when I put it to the stone. Works for me, any other suggestions?
Click to expand...

Shaping the convex on the mouse pad takes some pressure.
Sharpening on the mouse pad takes a very light touch.
:D
 
USSR said:
Hey folks. I want to learn to get a good convex edge on my knives, but I feel I may be limited somewhat by my living situation. I've seen many people state that for around $40 and change you can get a belt grinder and go to town, but my apartment complex has an extremely strict noise policy so power tools are out of the question. Is it possible to learn how to convex and maintain an edge without initially using power tools? I currently have a leather belt and a bunch of cardboard at my disposal, and I can get sandpaper easily. I think I can make my own strop out of these materials, but will it be as effective as the ones you buy? Hopefully this will work as a guide for other people in my situation who want to make their own kit without too much expense. Thanks.
Click to expand...

Just use a light touch, and some very fine grits. When I rehabilitated a thoroughly trashed Vic Soldier I got cheap, I started at 80 grit and worked slowly up to 2000. It now shaves like a razor and has an edge like a mirror.
 
DcZippo, that's 7-8oz leather loaded with Thiers-Issard white compound (was that you, Siguy, that sent that to me??). That particular compound feels like it's a tad more coarse than the green on the strop far left, but it may be my imagination.
 
$13 got me four grits of sandpaper and a bunch of foam for backing. I'm starting my strokes with the blade flat on the sandpaper and ending with the blade at 90 degrees to the sandpaper. Is this a good technique? Also, how do I know when to move up in grit?
 
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One thing I did was glue 80 grit sandpaper to an empty DVD case. You can see it at this link:

http://www.youtube.com/watch?v=_c9nKerj5SI

I used it to convex the back bevel on my UKPK then applied the microbevel with a standard flat DMT stone.

In all honesty I don't think there's much advantage to a convex edge compared to a thinned out back bevel (6-8 degrees per side) with a more obtuse microbevel.
 
USSR said:
$13 got me four grits of sandpaper and a bunch of foam for backing. I'm starting my strokes with the blade flat on the sandpaper and ending with the blade at 90 degrees to the sandpaper. Is this a good technique?
Click to expand...

I think for convex edges you want to keep the angle consistent at around 13 degrees (doesn't matter so much as sharpening flat grinds because your flexible backing will allow the sandpaper to conform to the edge as it hones, thereby creating the convex edge). Check out the Bark River Knife Collectors Association page on convex sharpening (has pdf you can download too):
http://www.barkriverknives.com/convex.htm

The key is to use very little pressure, use only the weight of the blade in most cases. And if you're ending your stroke with the blade perpendicular to the paper, you are most likely rounding off the edge instead of refining it.
 
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Thanks Rksoon. I had read somewhere that you should end at 90deg. The article you linked shows the process more clearly.
 
You're welcome :) That link was really helpful for me since I recently starting learning how to sharpen convex edges as well. I think whatever source it was that said 90deg probably meant in the x-y plane, as demonstrated in that BRKT page. Like you start the stroke with the blade perpendicular to direction of travel, but if the blade has a belly, you end the stroke with the blade nearly parallel to the direction of travel. So in theory it's a 90deg CCW rotation through the stroke; it allows you to sharpen the tip properly.
 
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Hey StretchNM, your papers are backed with leather right? Does that work better than the mousepad in your experience? I want to make a couple sandpaper strops and have heard some people prefer using leather backed paper to the mousepad backed paper.
 
USSR said:
$13 got me four grits of sandpaper and a bunch of foam for backing. I'm starting my strokes with the blade flat on the sandpaper and ending with the blade at 90 degrees to the sandpaper. Is this a good technique? Also, how do I know when to move up in grit?
Click to expand...

Don't pull up so much. How I do it is to sharpen normally, just let the natural flex of the pad and paper give the convex.
 
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