Help With ID Of Contour Issue Of Blade

Whayne Pack

Whayne Pack

Joined
Nov 28, 2019
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32
Can anyone tell me the possibilities of what could be wrong here or what could be wrong? The shape is certainly off here. Thought I would try to get some information before I sharpen this recently acquired “used” ZT 804CF. I do not want to make the issue worse as I am not familiar with what happened previously. Any ideas or thoughts? Oh, this issue came about after a sharpening, not damaged from use. The blade has the same issue on both sides.

 
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Looks like a serious production flaw. A lot of steel would have to be removed to sharpen that out.

That would be totally unacceptable to me. I'd send it back and demand a refund from whomever you bought it from.
 
My guess is uneven pressure applied during sharpening, such that the most force was being applied at that point during the work.
 
killgar said:
Looks like a serious production flaw.....
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Not a production flaw. The issue developed after sharpening.

I would just use it and not worry about it. The blade shape will change gradually as you use it anyway. You have already knocked the “new” off of it so now you can enjoy it without guilt.

n2s
 
Some manufacturers have a slight recurve at the back of the blade like this. Benchmade 710 is like this too. Take a look at some other pictures of the same model on the web and I bet they came like that from the manufacturer.

I have not sharpened my BM 710 because of the same issue.
 
I'm wondering if the placement of that kink in the edge relates to the width of the stones used. If the stone were all the way back against the ricasso, where it meets the rear of the edge grind, I'm wondering if the other edge of the stone lines up with that flaw.

I mention this, because I think I used to do that sometimes with my Lansky sharpener (1/2" wide stones). In trying to sharpen the rear portion of the recurve, one edge of the flat stone butts up against the ricasso at the plunge, and the other edge of the stone ends up overgrinding one very narrow portion of the recurve (about 1/2" away from the ricasso), leaving the edge looking that way. Especially likely, if you're seeing this on both sides of the blade, at the same distance away from the ricasso.
 
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jjg6319 said:
Some manufacturers have a slight recurve at the back of the blade like this. Benchmade 710 is like this too. Take a look at some other pictures of the same model on the web and I bet they came like that from the manufacturer.

I have not sharpened my BM 710 because of the same issue.
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I removed the recurve on my 710 over time by sharpening. Recurves are a PITA.
 
If you sharpen on a system and go from point to tang, then reverse; the middle of the blade gets twice as many passes as the ends. So you end up with a recurved blade.

n2s
 
That's not a designed recurve, it's a result of improper sharpening.

I'd consider that a serious flaw. If it was not disclosed during the sale, you should get your money back.

You have some options: 1) Just sharpen it as if it were a recurve like the Benchmade 710; or 2) grind the edge flat again, although you'd have to remove a fair amount of metal and you'd push the edge back up into thicker steel, reducing its effectiveness as a slicer; or 3) see if ZT will sell you a new blade; or 4) have someone regrind it four you, although you'd lose the blade coating.
 
Twindog said:
That's not a designed recurve, it's a result of improper sharpening.

I'd consider that a serious flaw. If it was not disclosed during the sale, you should get your money back.

You have some options: 1) Just sharpen it as if it were a recurve like the Benchmade 710; or 2) grind the edge flat again, although you'd have to remove a fair amount of metal and you'd push the edge back up into thicker steel, reducing its effectiveness as a slicer; or 3) see if ZT will sell you a new blade; or 4) have someone regrind it four you, although you'd lose the blade coating.
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Any thoughts on how it would have been sharpened improperly to get to this condition? I am thinking that what “Obsessed With Edges” stated could be a strong possibility.
 
Whayne Pack said:
Any thoughts on how it would have been sharpened improperly to get to this condition? I am thinking that what “Obsessed With Edges” stated could be a strong possibility.
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Sure, Obsessed could be right. But there are a number of ways you could get that kind of wear. What's for certain is that the sharpener spent too much time on that portion of the blade, while ignoring the rest. This is a fairly common mistake that you can see with well-used knives.

upload_2021-1-29_10-37-51.jpeg
 
Looks like someone used a Worksharp or similar device to remove a big chip from the blade there. Or that was their practice knife when they got the Worksharp.
 
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