Convex edge sharpening recommendations?

H

Hammer2124

Joined
Sep 29, 2016
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G'day, new to the forums here. Recently picked up a Fallkniven A1, and was curious as to how some more experienced convex edge users would recommend sharpening? I was looking around and I'm looking at two options. The first would be the whole simple sand paper on a mousepad method, but I'm also looking at a double sided leather 'paddle strop' with sharpening compounds. More specifically, I've found this one fromt DLT trading; http://www.dlttrading.com/dlt-standard-double-sided-leather-paddle-strop-sharpening-kit do you guys think this would be all I need to maintain and sharpen my convex edge? Also, which 2 of the 3 compounds would you recommend? (the three options are 12,000 grit, 6,000 grit, and 3,000 grit).

Thank you in advance, Hamish
 
Maybe this video can help you..
[video=youtube;UwlPwKnOxCY]http://www.youtube.com/watch?v=UwlPwKnOxCY[/video]
 
I generally start a convex edge with a stone to "rough it in". Then I progress to stropping it on those sand sponges to shape it up a bit. If it needs it, I'll go to the sandpaper/mouse pad thing. I'll go to a slack loaded strop (and old belt with Dremel compound on it) and finish with a flat piece of loaded leather.
 
Thanks for the replies guys, just in regards to the video you've linked scubisino, I take it that the leather strop would be used for a very fine sharpening, and as a finishing touch, but seeing as though my knife already has a relatively sharp and already convex edge, assuming I don't let the blade blunten excessively, could I not just regularly do this fine sharpening?
 
I think there are 3 ways to maintain a convex edge.

The first is strop the blade on a deformable surface. Leather strops, slack grinding belts, or wet/dry sandpaper on a mouse pad use this approach.

Another approach is to use a guided rod system like the Lansky. If you put a back bevel on an edge at 17 DPS and a primary bevel of 20 DPS, then you create a pseudo-convex edge. This pseudo-convex edge can be stropped to convex. I can't find the link but there is a Scandanavian sharpening system that uses "bent" rods to put a convex edge on a blade. You can do this easily by bending a Lansky rod where it leaves the stone. I can provide more details if you're curious.

The other approach is to free hand sharpen on a bench stone. Adding a bit of roll to your wrist will naturally convex the grind. This is how convex grinds have naturally been done for a very long time. My grandfather's hunting knife was hair popping sharp. He maintained it free hand on a scalloped stone. Point your you tube player at videos by virtuovice to see this in action.
 
Hammer2124 said:
Thanks for the replies guys, just in regards to the video you've linked scubisino, I take it that the leather strop would be used for a very fine sharpening, and as a finishing touch, but seeing as though my knife already has a relatively sharp and already convex edge, assuming I don't let the blade blunten excessively, could I not just regularly do this fine sharpening?
Click to expand...

Yes. A few swipes over the loaded strop hone after EACH USE is going to maintain that edge for a long time.

BUT! You are going to want to use one of those methods like the wet/dry on a mouse pad (very close to what I use) for two reasons:

1) Fallknivens can chip until the factory edge is re-established using something like sandpaper and a mousepad. Little bit of that gets rid of the chipping problem.

2) You are going to start convexing v grinds all over the place, and for that you need the more abrasive stuff. SAKs, steak knives, etc etc. Trust me.
 
Thanks for the help everyone, I suppose sandpaper + mousepad followed by a leather strop is the way to go then.
 
Almost forgot to ask, what grit sandpapers should I go for on the mousepad, and which two compounds should I choose for the strop (out of 3000, 6000, 12000)?
 
I'd recommend using wet/dry over a hard surface and induce the curvature by hand. This will allow you to make a nice shallow convex instead of the curvature being dictated in large part by the amount of give of your mousepad. You can do this with a stone as well, preferably something that makes a bit of mud will help with the cosmetics (same principle behind using the wet/dry). Softer waterstones are a good choice but the wet/dry will be more convenient.

For maintenance I'd just stick with a good quality woodworkers compound like Flexcut Gold. If it needs more touchup than that, go back to a 1200-2000 grit wet/dry and give it a few backhone passes before going back to the strop.

The convex geometry tolerates stropping over a much longer period of time before rounding the edge compared to a V bevel, but I'd still limit the amount of work you expect to get done on the compound unless stropping over a very hard surface.

I make a sharpening block that works very well with wet/dry and lapping film, also allows for use of compound over paper for a finishing strategy. The compound I supply it with is approx a 4k finish but can be managed to create a finish closer to 6k.

Here's an older video showing it with a convex edge:

https://www.youtube.com/watch?v=SalomUAvMHI

Even if not interested in the sharpening block, I cover the method I use for convex on a harder surface.

Martin
 
I'd recommend checking out HeavyHanded's method, as it will give a more reliable angle control (and curvature control). Murray Carter recommends the same.

Found this youtube sometime back, neat idea, but it doesn't allow adjustment to already established curvature. Just checked, it seems he has removed the video or making it private: youtu.be/vqU526UtYcU
 
This may not be the thread for it but ill try here anyway. A razor that's been stropped on a pasted hanging strop is already convexed, but i had to replace that. The new one isnt quite flat so instead of hanging it im laying it on wood. Ive got the suede side pasted, will that still convex the edges? Will the edge be in contact?
Another thing i always assumed with straights a pasted hanging strop(convexed) might be geared more towards comfort and a hard-flat paddlestrop (flat bevel) with no give is geared more towards keen-ness?
 
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