Ruined Cleaver?

Joined
Feb 26, 2006
Messages
3
My mother recently sent her heirloom cleaver to a local sharpener and it returned with two beveled edges :eek:. When he returned the next week, she pointed out the problem, and asked if he could fix it. She knew that a significant amount of grinding would have to be done and was prepared for a blade that was somewhat less wide. When the knife was returned the second time, it was evident that the sharpener had used a belt sander on the surface of the blade, and had not only taken off about 1/4" of the curve, but changed the shape so there is no longer that wide, satisfying rectangle that separates you from what you're cutting. There is discoloration on both sides and some small black patches on the bevel that look like they are eating it away. Also, it rusts quickly, despite oiling. I can just see the sparks flying. The poor knife is painful to look at but my mother still uses it. Is there any hope of restoring the surface or is this knife damaged beyond repair?
 
Not knowing exactly what cleaver you're speaking of, shape, size, metal, hardness etc, makes it very difficult to offer more than my wild guess.

Obvisous by the rusting problem that you're not dealing with stainless steel or something more than just his grinding has occurred.

IF the cleaver is carbon steel you may be in luck, carbon is more forgiving to drawing out the temper, the blade could then be reshaped (the problem there is that removed metal can't be put back) and then be re-hardened/tempered.

You would need an understanding knife maker/blade smith for all of that.

A "good" sharpener should be able to have a look and tell you if there is hope over time of reshaping the cleaver. Ie. The burn from grinding may not be overly deep and may not have affected temper/hardness beyond the immediate edge. The first goal would be to get beyond the burn area and start to reshape the blade. Over successive sharpenings a bit more shape could be restored at each sharpening. This would take time, years probably, of progressive sharpening. Recovering from a 1/4" is a whale of a grind out.

If it is HORRIBLE I would take it to someone with skill and knowledge and a water cooled low speed grinder and TRY to clean it up or skip that and find a local bladesmith willing to do a full rebuild.

If the cleaver is a Chinese or Japanense clad type, hard core with softer outer iron/steel covering, you are very probably out of luck unless the value is such that you can send it back to the factory that made it and they would probably just sigh and send it back unless they were very understanding.

Meanwhile I'd make sure the grinder: A) Didn't get paid. B) Paid for all attempts to "fix" the cleaver. C) Got reported to the better business bureau. D.) Got all the attention his "skill" (lack of) deserves. In other words let every one know what a hack he is.
 
I wouldn't worry about it. Just let her use it and take care of any issues the next time it needs sharpening. With a heavy blade like a cleaver it is unlikely that the heat treatment is compromised anywhere except right at the edge. If it is damaged the economical way to fix it is with careful work using a belt sander. It sounds like the sharpener responded to her original complaint by trying to put a wide convex bevel on the blade. There is nothing wrong with doing that (it will actually improver cutting performance compared to putting on a wide flat bevel), but it sounds like he overheated the edge in the process. Just use it for now and take it to someone else next time. I would expect the next guy to use a belt sander as part of the cleanup process. I have often had to use my belt sander to pretty up a blade that has been crudely ground using a bench grinder. Carbon steel will get a little surface coloration very easily if you get it hot. It looks particularly alarming if you are used to working with stainless steel. To damage the heat treatment while grinding you need to get the apex of the edge up to around 500 degrees fahrenheit. You would really be sparking by then.
 
It sounds like the edge which was chisel ground was then v-beveled, and instead of grinding the blade flat and removing this and then applying another chisel grind, an attempt was made to taper the bevel back into the primary grind which basically took off the patina and now it rusts quickly, possibly even after the grinding. In addition the dropped blade was also rounded off.

If this is the case, then there is little you can do to restore the dropped blade other than squaring it up again which will require a rehandling. The patina will come back gradually with use and the blade will naturally darken. If the edge overheated, which seems likely considering the way it was ground and carbon steels have low temperature resistance, you can have the whole thing rehardened, but likely as Jeff noted it is just the very edge which is burnt so after you sharpen it on benchstones a few times it will be eliminated.


A picture would eliminate some of the guess work.

-Cliff
 
thanks for the quick replies, this is a great community! I will post a picture soon- didn't have access to a camera at the time of my first post.
 
This is basically the shape it USED to be:
cleaver.gif

This is the knife now:
e924re2.jpg
7a74re2.jpg
5128re2.jpg

We've cleaned it up a bit by oiling, the edge no longer looks pitted, but you can still see the discoloration where some rust seems to have made permanent residence. Any further comments/suggestions would be most helpful.
 
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