Thread: Sharpening convex edges

A few of yiu know that I make knives and sheaths and also sharpen knives and have various different methods of sharpening, until recently I sharpened convex edges on a slightly slack belt on my 2x 48 belt sander, but just recently I purchased a little jig for my Russian made knife sharpener, this little jig puts a 7.2 degree angle on a knife edge, I just recently bought a Svord peasant diy kit and once I had made the knife I used the jig to sharpen it, took a while to get the hang of it, mainly due to muscle memory freaking out from the new shape it makes, but once that had settled in it was sweet, worked a treat.

There is a lot of debate about whether convex edges are any good, well Svord and Bark River use them and all I am going to say is they are stronger that other edges, and I can now do them in a jig, and will do yours too, I took my little Svord to 4000 grit on waterstones and it’s fantastic.

I have a knife I made while in the sth island on holiday a few years ago that has a pretty thick blade,would you be able to put a decent edge on it ?will post a photo tomorrow.

How are you getting the convex edge with stones?

Originally Posted by The bomb

I have a knife I made while in the sth island on holiday a few years ago that has a pretty thick blade,would you be able to put a decent edge on it ?will post a photo tomorrow.

Almost certainly shelley.raskin@icloud.com send me a pic

Originally Posted by Bremic

How are you getting the convex edge with stones?

Takes a while but careful strokes and the jig puts a curve into the stroke, then move it along the width of the stone and repeat, would not want to do it on a machete but a folder is fine.

Originally Posted by Bremic

How are you getting the convex edge with stones?

Plenty of folk out there doing it by hand/eye


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There are plenty of ways to sort a convex edge, but to be fair I have other methods of sharpening that mean it's easier to do straight edges. A double-bevel edge achieves the same result in use as far as I can tell side-by-side anyway, and they are also faster to sharpen when needed.

The performance of the edge for practical purposes from what I've had experience wise is more a factor of the abuse you put it to and what it is made of steel and heat treat wise than the fact of what angles and profiles are on it. The best edge I've used was a poncy ceramic jobbie that was quite heavily hollowed in profile and the thing was unreal in cutting. But, and it's a big but, you can't sharpen the things unless you have fancy diamond wheels and it was soo hard it was specifically stated only for slicing - no heavy work.

more photos of both the knife and the edges please...I can get knives very sharp...and they stay sharp but Im struggling to work out what this convex edge thing is.... MOST knived are a V with a small less angled v right on the very edge...good stone technique takes the edge right back to big V again and its steeling that puts the wee blunter bit back there...cuts well but when gets too dull stone it out again...(I need to wear glasses to sharper/stone well now) convex is opposite on concurve...so the svord is pretty much straight sided with taper towards edge and you have stoned a smaller steeper V to create your cutting edge..correct????the straight bit stops at writing and then long taper down towards edge then little stoned steeper taper

a concurve is sort of like }{ crossed with a V so your final stoned bit doesnt work anything but the last 3-4 mm Gerbers have this
so convex would suggest edges are rounded ?????
I did that on purpose with blade I made so its really strong while staying fat till quite far down blade..but stone it just the same..
actually I do pretty much all blades the same no matter what the profile is...the stone still only works 3-4mm from blade edge and the only thing different is a fat blade is steeper angle the thin blades I like to have rather shallow..like a mercator

so whats the edge on a bacho called??? thats stoned straight for about 8-9mm down to fine edge super sharp and dead easy to keep sharp.

The Bahco is a bevel or straight bevel style, the one you mentioned earlier is the 'double-bevel'. The convex is literally as you say, there is no flat defined taper the edge just curves from the full with to the working edge. There is a mathematical thingy about that gives the length of the curve for the width of blade to get the best edge profile, but what I find with the convex is it can be fine, great, perfect then another lick up and blunt as f***... When it gets to that it needs a full tickle up as the convex curve has gone and worn back to the point that there isn't enough cutting edge to form a cutting edge on again.

The point everyone makes with the convex edge though and fairly made, is that it usually takes longer for that to happen than any other edge profile as the theory goes that there is more edge reinforce closer to the edge with any other profile. Down side, most people struggle to sharpen them and end up replacing the knife before it's needed and moan about it not realising their sharpening technique is creating the issue.

I've had several convex edges, now with a Scary Sharp system I double bevel them all as it's way quicker and easier to resharpen them. Your mileage might vary depending on your kit, but for the cost of a stone that last for a very long time unless I drop the thing (which is when I suddenly find I now have several pocket stones) the cost of mini sander bands etc is just not a goer for me.

Please excuse my poor drawing skills.first five all finish with same angle the last one very sharp but easy to chip or bend. Unless I give it also a wee tickle up often with steel but make sure to change angle to finer.poke tip of steel away from you and look down steel then stroke blade away n down works well for this,learnt that filleting fish

@Shelley which is last photo taken? The grind on that blade looks to be 4mmish in one photo so assumable a fine edge and 2mmish in the other photo so a stronger less fine angle.

I've convexed a few knives and sharpen my BRKs. Always just done it by feel with stones and strops. Had a lot of practice and get good results these days

Originally Posted by Micky Duck

@Shelley which is last photo taken? The grind on that blade looks to be 4mmish in one photo so assumable a fine edge and 2mmish in the other photo so a stronger less fine angle.

Don't think he's still o. Here mate, least ways I haven't seen him post in a couple years