Repairing Beat Up Knives

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Rob Babcock

Head Chef
Joined
Dec 23, 2004
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Last week one of the guys on the line asked me about a certain knife I have. I opened the case and pulled out my Hattori HD 150mm petty to show him and the new guy's eyes lit up. "Cool, I've got three of those!" he said. Well, it's not every day that you meet a cook that has even heard of Hattori, let alone actually owns some. At least where I work, that is.;) He said they were in rough shape, having been bunged up by some previous coworkers, and the tip was broken off of his santoku. Then he mentioned that he'd heard thru the grapevine that I sharpen...you see where I'm headin' with this?:rolleyes:

"Sure, I'll take a look" I told him. After all, how bad could they be, right?

Well, here's how bad:
hattorisantokubrokentip.jpg




My photos suck and it doesn't show up that well, but maybe you can see the edge is chipped and bent/rolled:
hattorigyutochippedroll.jpg



I could have worked on these all week on my DMT, but I decided this called for my 30x1" HF belt grinder; it just doesn't make sense to keep fixing badly damaged blades entirely by hand. I started with a reeeal course one for the tip. I've fixed broken tips before but not one quite this bad. For a first effort it came out pretty well.

Before:
hattorisantokubrokentip.jpg



After:
hattorigoodasnew.jpg



The gyuto was in such bad shape that I decided I'd use the belts on it while I had the HF set up. This is the first time I've ever used powered gear on a J-knife, so I was very, very careful. Switching to a 15 micron 3M & getting a pitcher of cold water for dunking, I let 'er rip.

The results:
hattorigyutocleanedupon.jpg



It would have been better had I not got a tad careless and cut my belt. While I was doing the grinder work I started soaking my Shapton 320 & a slew of Chocera stones: 1k, 2k, 5k & 10k. I sharpened the santoku first, starting with a 15 degree bevel cut by the 320 Shapton Pro. Once I achieved a good, solid bevel & an edge that would cleanly shave, I went thru my progression all the way to 10k, deburring on felt between each stone. At this point it practically falls thru food and will easily cut a tomato in half with just the weight of the knife.

The gyuto was pretty easy after my HF grinder did the "heavy lifting." With all the chips and bent/rolled spots ground out I went thru the same stones, hanging a 15 degree edge on it as well.

I returned his knives today, and "pleased" would be an understatement! He was thunderstruck, I think...for a moment I don't think he believed they were the same knives. The best part- I had him pay me by making a donation to The American Red Cross, earmarked for the relief effort in Haiti.:)
 
Excellent work. Especially on repairing the tip of the santoku, I had to look at the 'after' photo about 6 times before I worked out what you'd done to get it looking so right. Did you give any thought to rounding the tip off rather than have it come to a point? I find my nakiri much easier to handle once a gave it a rounded tip.

Although it does remind me why I generally prefer French knives with their soft steel that dents but doesn't chip.
 
Excellent work. Especially on repairing the tip of the santoku, I had to look at the 'after' photo about 6 times before I worked out what you'd done to get it looking so right. Did you give any thought to rounding the tip off rather than have it come to a point? I find my nakiri much easier to handle once a gave it a rounded tip.

Thanks! To be honest, I like it better "after" because I prefer more of a gyuto-like, pointy tip to the blunter "sheep's foot" that it came with. In case he uses it for work it's nice to have a sharp tip for opening things like IQF fish portions. And since it already lost a little length I didn't want to turn it into a nakiri. Call it artistic license!:LOL: The owner didn't mind- I don't think he expected me to fix it, just sharpen it.
 
Rob, I have a friend who is a sous/prep/something chef and has this "thing" that looks like a cleaver for his "i love it knife". I told him I would check at the local flea market and see if there was a "sharpener dude" to get his knife blade horizontal again instead of a "rocker". He's always at work when the flea market is open and cannot do it himself. What do I look for in a "sharpener dude" and what do I ask him for? Must I specify the degree of bevel? And my buddy Alex has a hone block with the thousands grit from Harbor Freight. Soooo sharpen and he can maintain?
 
Rob, I have a friend who is a sous/prep/something chef and has this "thing" that looks like a cleaver for his "i love it knife". I told him I would check at the local flea market and see if there was a "sharpener dude" to get his knife blade horizontal again instead of a "rocker". He's always at work when the flea market is open and cannot do it himself. What do I look for in a "sharpener dude" and what do I ask him for? Must I specify the degree of bevel? And my buddy Alex has a hone block with the thousands grit from Harbor Freight. Soooo sharpen and he can maintain?


Perhaps he has a nakiri? It looks a bit like a cleaver but is smaller and thinner; typically it's used on veggies. Any time you sharpen or repair a knife, particularly a Japanese one, on powered equipment heat build up is a concern. Depending on what the knife cost I'd be a bit leery of having it done at a flea market, unless you know the guy doing it is pretty good. Certainly a belt is the fastest way to reshape the edge, but beware you can't put metal back on nor repair the heat treat if you burn the edge.

Most of the sharpeners that use a belt grinder tend to sharpen on the "slack" part of the belt, not the platen. This means that the angle used isn't quite as important since the slack belt will convex the edge. If the knife is a nakiri the edge should probably be between 12 and 15 degrees per side (24 to 30 degrees included, or total).
 
And my buddy Alex has a hone block with the thousands grit from Harbor Freight. Soooo sharpen and he can maintain?

To answer more specifically, a belt isn't ideal for sharpening J-knives IMOHO, but some expert Japanese sharpeners do it that way. I think the master sharpener at Korin in NYC does most of 'em on a belt. If he wants to do it on a belt I'd suggest practicing on some "beater" knives first. Tell him to keep some water nearby for dunking. Keep the passes short and light, with little pressure. Keep the knife moving- it's very easy to overgrind if you don't. The HF spins at over 2,500 RPM! Metal comes off fast at that speed. Feel the metal near the edge constantly; if it feels warm, dunk in cold water. Then wipe it dry (some belts will dissolve if they get wet).

Remember: Use a light touch, be conservative & be careful. Also DON'T EVEN THINK OF TURNING ON THE GRINDER WITHOUT EYE PROTECTION! Just don't do it!
 
Gentlemen, I will see Alex tonight at church, maybe, and if not tonight, definitely tomorrow night. I'll ask about the Nakiri and jpaulg I figured out why your post was at an ungodly hour of the day.(6:15am) I'll let you both know...
New question? We have a set of "Pampered Chef" knives (cast?) that have
"German Cr Mo V Steel" on one side and "china" in mice-type on the opposite side. I believe is an exclusive and carries a lifetime guarantee. What's the best way to keep them sharp? It comes with an "arkansas style" V stone to dress up the edge, but they get dull quick..
 
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WOW! I just spent 30 minutes lookin up nakiri and all of it's relatives....and I think he has a cleaver...of some kind? I'll maybe post a photo..see ya later!...
 
New question? We have a set of "Pampered Chef" knives (cast?) that have
"German Cr Mo V Steel" on one side and "china" in mice-type on the opposite side. I believe is an exclusive and carries a lifetime guarantee. What's the best way to keep them sharp? It comes with an "arkansas style" V stone to dress up the edge, but they get dull quick..

Just to digress a little on the metallurgy.
Cr - Chromium - makes steel "stainless"
Mo - Molybdenum - a hardening agent for steel
V - Vanadium a hardening agent for steel.

Molybdenum and Vanadium have broadly similar properties, with Vanadium forming smaller crystals that help edges take a sharper edge and Molybdenum having better resistance to shock. Most knife steels are a Cr Mo V steel and the differing % of the components in the alloy giving different properties.

As knives they'll probably do the job in a domestic kitchen. IMO the most practical way to keep them sharp is to use whetstones, but that's a skill that takes time to learn properly. For an easy to use practical system that isn't going to damage your knives the a ceramic rod sharpener, like spyderco's, isn't a bad option.
The V sharpeners I avoid like the plague and the ceramic wheel sharpeners can do real damage to your knives if you don't use them properly.

PS I've usually been at work for 1 1/2 hours by 6:15am.
 
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