Recurving on a knife

I've got a knife thats been pretty well used, and I've recently been noticing that its gotten a slight recurve, about half an inch from the bottom edge. Its causing some accordioning when I'm cutting.

I want some advice how would be best to remedy it, and also how to avoid it happening in the future?

Pics please?

I'm off today, and the knife is at work. If I remember tomorrow I can get a pic, but there isn't really much to see. Its really only just forming and you can't see much, but I can feel it when I'm cutting

just needs more work to flatten the part that's getting the belly to flatten it so when you cut it doesn't accordion.

=D

Is it a German/French knife with a full bolster?

That can be caused by many things, including putting too much pressure or spending too much time on the affected area.

No bolster, got it from someone here. I think there was a very slight issue when I got it that I've exaggerated over the time I've had it. Is the best way to fix it to sharpen infront of the affected area, or behind, closer to the handle?

Need pix to see whether it is a protruding heel, a neglected fingerguard, an oversteeled section, or an overgrind, and act accordingly.

As I said I'll get a pic tomorrow, but the knife doesn't have a fingerguard, and I'm pretty sure given the knife that it won't have an overgrind from the maker. I believe that it may be from steeling, or maybe neglected getting the final area when sharpening.

Belated pictures

If you can get a picture of the blade perpendicular to the cutting surface (touching the cutting board) it would be easier to see.

It's from not spending enough time sharpening the heel. Maybe my imagination, but it looks like you're not spending enough time on the tip either, and might be headed for a bird beak. It's a common mistake and most people don't realize how much extra attention the heel/tip needs until this happens.

Fix it by sharpening down the heel, keep checking the gap between the edge and a flat surface to make sure you don't over do it. You could also sharpen directly on the edge, like you're cutting into the stone - use the side of the stone and make sure it's flat first. It's faster, but at the same time kinda extreme, and easy to remove too much metal.

About the heel: sharpening at some 70 or 80 degree instead of a purely oblique steel removal will make further bevel restoring much easier -- and save some steel. After that, still a lot of thinning will be involved.
It's not exactly a small recurve profile I see, though.
From the photo I would say the belly and tip do look weird. I would tend to agree with spaceconvoy.

Benuser said:

About the heel: sharpening at some 70 or 80 degree instead of a purely oblique steel removal will make further bevel restoring much easier

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Absolutely. And I'd say that spaceconvoy is completely correct about the heel. I think this is a good opportunity to give the knife a good thinning, as well.

The knife does need thinning, I've gradually being doing it but I need to find time to really get at it. I've also been slowly working at the heel, because I thought that was where the issue was. I can give it some work now that its been confirmed.
I guess that the tip is funky because its been dinged once or twice, and poorly repaired. I've noticed it looks weird, but it doesn't affect the way I can use it so I don't worry about it.
What would be the best grit to get this done on? Would I be okay using wet and dry to get the groundwork done, then refine on my stones?

In my experience, sand paper is terrible for knife grinding. DMT XC is my standby, for serious work, followed by coarse water stones, then medium WS, then sandpaper for re-finishing.

EdipisReks said:

In my experience, sand paper is terrible for knife grinding. DMT XC is my standby, for serious work, followed by coarse water stones, then medium WS, then sandpaper for re-finishing.

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As someone who does this with every knife that passes through his hands, I whole heartedly agree. Grinder, then XC (the XXC is just too much), then stones (or higher grit diamond plates, depending on the damage). I only use sandpaper above 600 grit anymore, because below that on good steels, its virtually useless...and while its not much less so above that, its the only thing that will provide a decent finish.

Sandpaper is fine if you may find the one with a linen backing. Quite common in continental Europe, made by Robert Bosch. I would start at P120, followed by 180, 240. Use edge trailing strokes only. Take care not to overground. What kind of coarse stone do you have? After all the sandpaper work I use a Chosera 400.

Benuser said:

About the heel: sharpening at some 70 or 80 degree instead of a purely oblique steel removal will make further bevel restoring much easier -- and save some steel.

Click to expand...

Good idea, haven't heard that one before

It'd be best to send it back to the maker for refinishing.

Hoss

looks like it's been spotted

I've restored a good few vintage knives now. My process...

I do actually go at a xxc diamond plate at a 90 degree angle. This makes very quick work of reprofiling the edge. I then thin it on the belt, followed by course diamond, and 500 grit shapton. I usually do scratch removal with sandpaper. 320, 400, 600 and 800 work well after the shapton. I then follow up with the full stone progression to reset the bevel.

This is done on flea market finds, mind you....

That knife could use a good overhaul. I'd prob just put it to the stone at 90 deg and reprofile it. Then I'd thin/regrind it on a grinder or a coarse stone if I was really feeling like punishing myself. Then install new bevels.

Gave it some quick attention today, I think it's a little better. What do you guys think? I'm pretty short on gear, the lowest grit stone I've got is 1k. I'm just working on the profile right now, thinning will be done later.

chinacats said:

If you can get a picture of the blade perpendicular to the cutting surface (touching the cutting board) it would be easier to see.

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still very true

I tried to get a pic of that but there really wasn't anything to see. Maybe I was doing it wrong, but when I took the pic it seemed pointless to upload it.

RDM_Magic,

What we are looking for with the perpendicular blade on the board is to see light coming through the bottom where the recurve is.

Looks good, although I'd have a hard time not taking Hoss up on his offer!

I probably will take up the offer, im just biding my time because there's going to be over 100$ shipping involved for me!

Used the knife at work today, it's much much better. Still not perfect but getting there in terms of profile. Now onto the thinning, something which I fear won't be as easy..

What kind of knife is that?