Correcting a badly sharpened convex edge?

[tetra_neon]

I have acquired a used Fallkniven F1 and Wetterlings axe which some numpty tried to sharpen as if they were flat grinds.

Being unfamiliar with convex edges, please tell me the best way to rectify the damage

I just read about using a spongey mousemat & different grit sandpaper to create a convex - would this work on both the knife and the axe?

Cheers!

 

[Stew]

Yep.

If you're not siure how to do it, I think the best search term is 'hoodoo hone'

 

[Chainsaw]

+1 it's how I sharpen my F1 not that it needs it much!

There's also BRs legendary how to sharpen an axe thread and the £5 sharpening kit thread.

Cheers,

Alan

 

[steven andrews]

I use wet-and-dry (180,400,600,1000,2500 grit, depending on the amount of work required) on a thick soft-back book (phone book or such like), followed by stropping in my palm with stropping paste.

 

[MSkiba]

whats this stropping in your palm? do you mean you bend the leather in your palm, or you actually apply paste to your hand and strop ?

 

[bushwacker bob]

whats this stropping in your palm? do you mean you bend the leather in your palm, or you actually apply paste to your hand and strop ?

I dont think he has any fingers.

 

[MSkiba]

Now I have a convex blade Im wondering if the normal strop process is still best and stumbled a few people who mention they stop in their palm, wondering what this process is?

 

[steven andrews]

whats this stropping in your palm? do you mean you bend the leather in your palm, or you actually apply paste to your hand and strop ?

I rub the paste onto the pad of my hand:



..strop with that, then wipe the paste residue off and strop on the bare skin. You get "feedback" from your hand and can feel the very, very slight final burr being removed.

 

[Robbi]

now that looks a strange way to use a sharpmaker !

 

[steven andrews]

Slightly off topic in this thread that is dedicated to convex edges.. but I use that system for flat/sabre grinds. Coarse wet-and-dry cable tied around a rod for rapid back-bevelling at 30 degrees (combined), the white rod for the edge bevel at 40 degrees (combined). Palm stropping to finish.

 

[PREPER]

I had to re sharpen an old F1. The knife had been flattened at the edge nearest the handle. I like my knives shaving sharp.
After some research on convex edges I decided to use the mouse mat method. I went through all the grits and found I could only get half the edge ‘scary’ sharp. It turned out that I hadn’t spent enough time at the 240ish grit stage on the ‘flattened’ edge. I had another go from scratch, now the edge is truly ‘scary’. Also worth noting is that the knife makes a distinct ‘sound’ when sharpening at the right angle.
I hope early mistakes help.

PREPER………..

 

[MSkiba]

whats the correct angle for f1? 13 degrees?

 

[PREPER]

It depends on how soft the mousepad is.

Try this thread:

http://www.britishblades.com/forums/showthread.php?100308-Fallkniven-A2.-Good-or-Bad-Sharpen

There are some good videos on youtube too,

PREPER.........

 

[ged]

whats the correct angle for f1? 13 degrees?

It depends on how soft the mousepad is.

Or whatever you're using.

The 'included angle' at the very edge is twice the effective sharpening angle (assuming it isn't a chisel edge). The included angle is very different from the angle of the bulk material of the blade, by which I mean anything further from the very edge than a small fraction of a millimetre.

This article, despite its title, is concerned mainly with stainless razor blades. In places it talks about an included angle of less than 40 degrees being too small even for a razor blade.

 

[MSkiba]

Thanks guys. I have read so many guides its unbelivable! F1 hasnt been used yet but I want to be prepared. So im making myself new strops, etc.. Im stuck on 2 things that these guides do not mention.

1 - which mouse matt? I know not the hard back, but still there are different softness. Anything that is an alternative that is guaranteed to be right? Any links?
2 - where do I get such sandpaper from? I went to BnQ and they only go upto 350, I would love 2000 or even higher to practice on (not to take too much off just to check if Im hitting the right angle).

Many thanks!

 

[MSkiba]

Also, Im making a strop, i see some people use the smooth side up for final finish. The leather Im using is thin, and treated (coloured), is it OK to use it face side up still?

 

[MSkiba]

Will these do the job?

Wet & Dry Waterproof Silicon Carbide Resin bonded paper sheets ?

http://www.axminster.co.uk/hermes-wet-and-dry-waterproof-silicon-carbide-sheets-prod19877/

 

[ged]

Will these do the job?

Wet & Dry Waterproof Silicon Carbide Resin bonded paper sheets ?

http://www.axminster.co.uk/hermes-wet-and-dry-waterproof-silicon-carbide-sheets-prod19877/

Sure they will. I don't use the stuff a great deal so I don't have much experience of the various makes to know how long they last and what kind of abuse they'll take, others here might be able to comment on that. I would say that the products in the link you gave seem a little expensive. That might or might not be a good thing.

You probably aren't going to be using an awful lot of any material to sharpen a couple of blades now and again so the cost probably doesn't matter too much. How long things last is usually more important to me.

Here's another source: http://www.toolbox.co.uk/wet-dry-paper-4382-0000
they only seem to go up to 1000 or 1200 grit but with most of the smaller suppliers it's worth giving them a ring to see what they can do. I know Silverline (cheap end of the spectrum) do at least a 2000 grit and if they have one silverline product they can probably get any of the others.