# fixing a knife with a "frown"



## gic (Nov 15, 2016)

I like refurbishing old knives for friends and just for fun as it is a good way to improve my grinding skills as I slowly work up to making my own knives by stock removal (not there yet!).

If they aren't really good knives, I tend to use a combination of a vertical and horizontal grinder which is (a)really much more pleasant than dealing with abrasive resistant steels on my stones or diamond plates. Also (b) if it is a crappy knife to begin with, used by someone who doesn't really treat knives "delicately", the convex edge you get with a slack belt grinder is, I think the best edge for them.

Anyway, one of the most common repairs I need to do on a vintage knife is removing a "frown" caused by a sharpening steel. What I have been doing is grinding a *lot* of steel away (see the image), ending up with a butterknife on the part of the knife near the heal. Then I thin relentlessly, put a new edge on from heel to tip and what I end up with is a cross between a chef knife and a slicer. 

My question is: is there something better I can do or basically these knives can only be converted in a suji crossed with a gyuto and I am doing the best that can be done after years of abuse.

The image I attach shows with the line how much I would grind off on a typical example of this


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## Benuser (Nov 15, 2016)

Not so sure whether that has been caused by steeling only. Have seen that profile with NOS Sabs as well.


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## Pensacola Tiger (Nov 15, 2016)

> My question is: is there something better I can do or basically these knives can only be converted in a suji crossed with a gyuto and I am doing the best that can be done after years of abuse.



That's the best that can be done.


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## Dave Martell (Nov 15, 2016)

There's not much you can do with the loss of height from repairs made to the edge, however, you can re-profile the belly to minimize the low ass end syndrome you get on the heel repairs. 

My technique is to hold the blade (positioned lengthwise down the platen) but at a 45 deg angle (like you're going to sharpen at 45 deg) but then grind down the bolster first (keeping the rest of the blade off the platen) and then (while lowering the blade to the platen in a smooth motion) connect up to the frowned area and grind that out and then onto the (if necessary) belly reshaping and tip. Do 1/2 of the work needed from one side and then do the other 1/2 of the work on the other. At this point you should have the profile desired and all repairs complete. I use the 45 deg from both sides method because it leaves me with a bevel on each side that's only another 20deg from complete. If you try to do this type of repair not using the 45 deg method you end up with a great possibility of screwing up your profile again while sharpening in the new bevels....sort of chasing your tail until you have nothing left but a petty.

My method is especially helpful on newer (like the last 30 yrs construction of) Wusthofs and Henckels.

BTW, this repair is the most common thing seen by a professional knife sharpener and it's the most daunting to master when new on the job.


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## senryu (Nov 15, 2016)

you can file down the tip of the knife to a gyuto form. then once you take that thick metal shoulder off, you can just go at the butter knife section with a file at a thin angle before you go the stones. you might not even need a belt grinder, and then you won't have to worry about temperature. i did my crappy stainless Sabatier in a vice with a file and it came out OK. a 250mm French chef's knife turned into a 225mm gyuto.


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## WingKKF (Nov 16, 2016)

You might not even need a file to re-profile - you could always scratch out your gang affiliation on a convenient pavement nearby :>.


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## skewed (Nov 16, 2016)

Dave thanks for the nice detailed description! Makes so much sense. I will remember it for sure. 'Chasing your tail'...


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## gic (Nov 16, 2016)

yes thanks Dave, very useful!


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## Benuser (Jan 21, 2017)

Thanks you very much, Dave. Especially these 45 degrees works wonderfully. At a much higher angle you indeed see much to often the old problem reappear again and again. I just don't understand why.


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## psfred (Jan 22, 2017)

I suspect the "frown" is pretty much a characteristic of that knife design. The thick bolster almost always results in a tapered section just in front of it, and using a steel will quickly "raise" the edge in the thinner section further out. Sharpening without re-grinding the geometry of the cross section will always result in a "dropped" section near the bolster. Most knives with this design are drop forged, so there isn't really a good way to prevent that thick section right in front of the bolster. Ground knives don't have that problem if done well, but the bolster will still "grow" as soon as you start sharpening and still has to be ground off. Not a problem in a bush or hunting knife since they aren't used on boards, but for kitchen knives a big pain sooner or later.

Another reason I don't like them.

The only cure, as noted, is to remove the steel at the heel to restore the proper cross section so the blade is the same thickness from end to end. Really a manufacturing "bug" rather than defective sharpening, hence my personal preference for gyutos. 

Peter


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## Benuser (Jan 23, 2017)

Benuser said:


> Thanks you very much, Dave. Especially these 45 degrees works wonderfully. At a much higher angle you indeed see much to often the old problem reappear again and again. I just don't understand why.





Dave Martell said:


> My technique is to hold the blade (positioned lengthwise down the platen) but at a 45 deg angle (like you're going to sharpen at 45 deg) but then grind down the bolster first (keeping the rest of the blade off the platen) and then (while lowering the blade to the platen in a smooth motion) connect up to the frowned area and grind that out and then onto the (if necessary) belly reshaping and tip. Do 1/2 of the work needed from one side and then do the other 1/2 of the work on the other. At this point you should have the profile desired and all repairs complete. I use the 45 deg from both sides method because it leaves me with a bevel on each side that's only another 20deg from complete. If you try to do this type of repair not using the 45 deg method you end up with a great possibility of screwing up your profile again while sharpening in the new bevels....sort of chasing your tail until you have nothing left but a petty.
> 
> My method is especially helpful on newer (like the last 30 yrs construction of) Wusthofs and Henckels.
> 
> BTW, this repair is the most common thing seen by a professional knife sharpener and it's the most daunting to master when new on the job.


Even free-handing this works very well. I've used much higher angles for this kind of repairs but indeed, the problem tend to reappear once I thinned and sharpened afterwards. Can you explain what makes these 45 degrees to work so well??


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## Benuser (Jan 24, 2017)

Thought about making this a stickie?


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## Smashmasta (Jan 24, 2017)

Re: 'files' for major reshaping and thinning - are they really a realistic/practical possibility? How long are we talking to reshape the knife in the pic with files and not an electric sharpener? Are there certain files best fit for this work for other 'regular' metal files?


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## merlijny2k (Jan 31, 2017)

Smashmasta said:


> Re: 'files' for major reshaping and thinning - are they really a realistic/practical possibility? How long are we talking to reshape the knife in the pic with files and not an electric sharpener? Are there certain files best fit for this work for other 'regular' metal files?



Exactly what i was thinking. Some knives can be filed without instantly ruining the file, but it is no joy in my experience.


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## GorillaGrunt (Jan 31, 2017)

I did some of these a little while ago with only hand tools, almost, but not quite, as badly "frowned" (great term) as the one in the picture. I found Bahco saw sharpening files worked just fine even on the stainless Wusthofs, and I used a thin, round chainsaw sharpening file for the curved areas by the finger guard. I had a minor issue in two instances with the corner of the file gouging the metal, but I'd attribute this to my lack of skill and practice in metalworking.


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