Bart

Modified knife is chipping like crazy

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Hi All,

A friend of mine who has unfortunately lost his right hand in an accident popped in this morning with his hunting knife which he wanted me to sharpen it again.

Eyeballing the knife's edge I noticed that is was massively chipped.

I managed to get it sharp again by using a few whetstones but I still got major concerns about the quality of the blade.

The blade was marked as being a Winchester hunting knife, but googeling the knife makes me think it's a China made blade.... so there's a certain doubt about quality. Besides that the specs of the blade reckon it's surgical stainless steel, and I don't have any experience with that kind of material....i.e. it doesn't ring a bell.

Anyway... the knife's handle has been removed by an orthopedic device maker, in order to weld an adapter on it which fits in my mate's hand prosthesis. 

Could it be that the hardness of the blade has suffered from the TIG welding so that it may have caused the edge to chip that bad? The area of the blade adjacent to where the handle used to be showed some brown and blue discoloration.

Or is it just another piece of China crap?

Just tell me what you guys think...

Grtz, Bart.

 

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If the edge did not discolour it was not affected by the welding.  I do worry that the welder did not take in account the high Carbon metal in his work and so it may be an accident waiting to happen!

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Hi Thomas,

Thanks for your reply.

Like you say, the edge did not discolor and I think you might be right that the welding didn't do the blade any good.

And to Glen, unfortunately I didn't make any pics and started wondering after I've ground the blade. What I can do is await to see what happens with the blade in the near future. It is only used for gutting and cutting rabbits, so there's not a lot of force involved....  I hope to be able to post some more .

I've got some pics from after the sharpening, but they're not telling something very obvious I'd say.

Anyway, we'll see...

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I think it hardly matters now WHY it's brittle. It is what it is. All you can do is deal with it. A secondary bevel, with greater angle, is one way.

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Hi Guys, thanks for your replies and of course a happy and healthy 2019!

Here's some pics from after the rework. It was just to get him going again and we'll see how it's going to wear again.

On the first pic you can see what type of blade it is, the second one shows some dull spots on the edge and on the last one you can still see a bit of the discoloration.

Grtz, Bart.

31fce558-d8e7-4c20-ac60-b5d15cc3dec8.JPG

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That's a cool modification.  As above, chipping implies brittleness.  I wouldn't think welding back where they did would impact the heat treatment of that blade.  My guess is that the knife was just mediocre Chinese work to begin with, and would have had issues even if it hadn't been modified.  About the only thing I see is to keep sharpening it as it chips out, or to modify the edge angle to make it a little thicker.  Thicker edge would increase stability and chipping resistance, although it also will make it not slice as pretty.

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As a side bar to this; people often try something different with the lowest quality/cheapest stuff they can find. Unfortunately you usually have to have the highest levels and experience and knowledge to get low quality stuff to work half way decently.  Good quality materials are a LOT easier to work with.

This is not only in smithing; my wife has remarked numerous times on spinning students whose previous teachers have tried to have them learn on very low quality fibers frustrating them terribly. When she starts them on "good" fibers they learn that the good stuff is easier for a beginner to use! (There is a limit though; some of the best stuff is very tricky indeed---the same with smithing; some fancy alloys take mad heat treating skills to get the best from them!)

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Hi Jason and Thomas,

I do agree with the both of you guys; I did some research on the origin of this particular knife and I found that the blade is indeed made in China which is, in my opinion, very well known for the amount of crap which it delivers.

In the near future I'll might have a go at forging a proper blade with the desired adapter so it can heat treated in one go.

Then I can make a proper size blade which fits the job, as he 's only gutting rabbits with it. No need to have a blade the size like that.

I'm gutting anything from woodpigeon to roe-deer with an Opinel No.9 ......

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Bart: Do you know how hard your friend is on knives? I've known lots of people who don't think twice about using them for pry bars, diggers, or seemingly mundane jobs like chopping veggies on a dinner plate. 

A Chinese blade isn't likely to last long under "severe" conditions but aren't known to be worth much.

Boy, I'm starting to sound like a sour old curmudgeon but I really dislike that particular knife profile. The "gut hook" looking thing doesn't have an edge to start with so unless your friend is too hard on blades it speaks out as junk steel or lousy heat treatment. 

Make him a proper blade and do it right. Hmmmmm? ;)

Heck, you could make the prosthetic connection into one that can connect to different tools, various knives, real pry bar, take requests.

Frosty The Lucky.

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