Convex Grinds on a Sharpmaker

Lobo103

Lobo103

Joined
Jul 14, 2003
Messages
645
I don't have a lot of expierience w/ Convex grinds. I do 99% of my sharpening on a Spyderco Sharpmaker, although I can do flatstones and have experimented w/ stropping. The widely accepted view is that stropping is the only way to go on a convex grind, but is anybody using anything else? I'm also curious to know if I could effectively sharpend a Convex grind w/ my sharpmaker (i.e. a Swamp Rat)? Thanks in advance for your inputs.
 
You might be able to, although the edge would become less and less convex over time.

The question is..... Why would you want to? A piece of wet/dry paper costs about a dollar.
 
What happens when you get the edge dull enough to require more than stropping? Is a flat stone the way to go?
 
I'd go with Buzzbait on this one.
The Sharpmaker is pretty mutch designed to prevent a convex edge.
It's all an adventure so grab a cheap blade a mouse mat and some wet and dry.
Best of luck
 
Katanas are convexed (to the median) on benchstones, the blade is constantly turned. Its a difficult skill that wants to be mastered (I think that I do quite well on benchstones, but I haven't mastered convexing on a benchstone). The easiest is probably an old mouse pad covered with sandpaper just as Anarcus said.
 
Stropping on sandpaper (on a foam pad/mouse pad) is the easiest and cheapest way to get a convex edge.

You can do a convex edge on a stone if you practice a loooong time I suppose.

AFTER I create the convex edge on my SAKs, I use the sharpmaker rods at 40 degrees to get the extreme edge of the bevel perfect. And I contunue to use the sharpmaker to maintain the edge until it is time to convex it again (usually a long time). (You could add stropping on leather at the end, but I usually don't bother.)
 
one thing you can do is put multiple bevels, and then sand off the corners with sand paper. it ensures you get the proper edge angle you want (if you dont hit the cutting edge with the sand paper), and how much metal you wanna take off the shoulders.

basic idea = 20 degree at the edge, then 18, then 16, then 14, then 10, and sand the bevels into a smooth transition
 
klattman said:
You can do a convex edge on a stone if you practice a loooong time I suppose.
Click to expand...

it didn't take me that long to learn. If your already good with flat stones itr not really a problem. You just have to get the knack of feeling when your on the final edge point
 
SethMurdoc said:
one thing you can do is put multiple bevels, and then sand off the corners with sand paper. it ensures you get the proper edge angle you want (if you dont hit the cutting edge with the sand paper), and how much metal you wanna take off the shoulders.

basic idea = 20 degree at the edge, then 18, then 16, then 14, then 10, and sand the bevels into a smooth transition
Click to expand...

Good idea, I don't bother with SAKs, but I did a VG10 blade like that and it sure sped up the sanding process.
 
Lobo103 said:
What happens when you get the edge dull enough to require more than stropping? Is a flat stone the way to go?
Click to expand...
This is something I tell my customers who purchase one of my convex knives. Maintain the edge by stropping and don't let it get to that point. Regular stropping with an old belt and 600 grit compund will prevent alot of hassle bringing the edge back. It only takes a few minutes to strop after each use of the blade. But if it does, the wet-dry paper is the most effective way unless you can master it with a benchstone.
Scott
 
Cool, thanks for the great info guys. I'm a bit of a chronic sharpener anyway so stropping regularly shouldn't be a problem. I do a bit of survival style wilderness work occasionally and also certain things that come up in a tactical enviroment are real edge killers and it's not like you can stop to sharpen up. I'll have to breakout my benchstones and practice up a bit on a beater before my new HR gets here :) Tango Victor Mike!
 
I disagree with everyone on this thread. Unless your useing some kind of jig, you are putting on a convex edge freehand with a bench stone. it's easy to convex with a bench stone, the hard part is getting a flat bevel free hand very few if any can do it.
 
once you have mastered the "edge-trailing" technique used in stropping, you can apply it to any grit stone or sandpaper. It's certainly easier if you have a forgiving backing beneath the paper.

Also note - just because your knife has a flat microbevel on it, doesn't mean it can't be stropped. The stropping will give it a slight convex at the very edge. Might be all you need/want.
 
I say as DB.
The big question I think is, why is all knife people are “so extreme” to get a straight edge perfectly sharp (and straight) – and in the same time not bother to make a convex edge with a perfect curve?
Mouse pad and so on, ok, it give you a sort of convex edge, not in any matters perfect, just a sort of convex. It will be variations on the edge, variations you never have accept on a straight edge…or?

If you sharpen a knife by hand, you get about 3 degrees variation on the edge = you get also a sort of a convex edge, not a straight edge. To get a straight edge, you must have a sharpening system of some kind.

I have never seen a perfect straight edge made by hand. I have never seen a perfect convex edge made by hand either, or one made with the help of a mouse pad.
Have you? A perfect one?

Regards
EdgePal
 
There are only two perfect things in this world my friend. Perfect A$$holes and perfect intentions! ;)
 
Hi Lobo13,
in your part of the world my friend? Really?!

I have never been wrong, never! Except one time, and then I tell everybody that I was wrong. But, later it shows that I wasen’t wrong, so that was the acknowledgement who was wrong…
Regards
EdgePal
 
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