Problem knives

E

ericnpeterson

Joined
Nov 18, 2013
Messages
209
Hey Gang,
I've got two knives in my collection that I hardly use at all, only because the don't stay sharp for vey long.
First is an AG Russell white bone scales, spear-point Zulu. I'll take it to the stone, feels good and sharp, passes the paper test.
Then, all I need to do is two or more cuts of ANYTHING (usually cardboard" then it's as dull as a butter knife... all it does at this point is rip the cardboard... then it needs sharpening again, repeat. The steel on it is 12C27, stainless... it's a cool pocket knife, but I can never use it.
The other knife is by Henry Bros. a camel-bone, carbon steel Damascus. Very cool looking knife, same issues as the other one.
I use my knives hard, every day, cardboard, plastic pallet straps, packing tape etc... and all of my other knives don't have this issue. I can get them razor sharp, and the edge will last awhile before I need to sharpen. My Case slim-line trapper, Case large Stockman, Case full-size trapper, Mercator 555, Otter Messer bone, Northfield Autumn Jack, and Tidioute 72 African blackwood, and Douk Douk... these are my main rotational work knives, never an issue with any of these.
My Aitor Castor knife has similar issues, but it handles food prep, so I tend to use it for that only.
Anybody had similar expeiences with these problem knives I mentioned?
 
Maybe it's a heat-treatment issue?

In the case of the Castor, I think Aitor run their steel a little softer. I use a pocket-steel for mine :thumbup:
 
From the sounds of it, it seems like you're getting a wire edge.

What types of stones are you using and what grit stones are you using? What do you use to finish your edges?
 
NJBillK said:
From the sounds of it, it seems like you're getting a wire edge.

What types of stones are you using and what grit stones are you using? What do you use to finish your edges?
Click to expand...

I'm using a Smith's Diamond 4" Fine one side, heavy the other. I'll strop on a leather belt to finish. Like I say, these are the only knives I have a poblem with.
 
I had that happen once with a chipped knife. I ended up destroying the edge, 90 degrees on a crystolon and then started the edge over. Came out great.
 
Yea, it is possible that the HT on the very edge was damaged during final grinding from the factory. I would bring it down to flat and remove 1/32" or so and rebevel.

If you don't want to do that, contact the manu' and see what they say.
 
Do you have other knives in those steels? Some steels are more prone to holding a wire edge than others.

I would sharpen your knives as you do, then drag them along a 2x4 against the grain (once or twice at most) to strip any remnants of a wire edge and then try the paper. If it catches then you have your answer, if it isn't as bad as it normally is, then it likely is the abrasion resistance due to the HT possibly being off.
 
NJBillK said:
Do you have other knives in those steels? Some steels are more prone to holding a wire edge than others.

I would sharpen your knives as you do, then drag them along a 2x4 against the grain (once or twice at most) to strip any remnants of a wire edge and then try the paper. If it catches then you have your answer, if it isn't as bad as it normally is, then it likely is the abrasion resistance due to the HT possibly being off.
Click to expand...

The thing is, both knives sharpen with a good edge. When I finish (strop) I give the paper test and they cut real clean, no catching. Problem is, they dull VERY quickly. I'll do a few cuts on a cardboad box and they're dull again.
 
I'm still thinking that Bill is correct and it's a wire edge. When I have that problem I brush the edge back and forth across my pant leg, first one way, then the other, about a dozen cycles. That breaks any wire edge and produces a usable edge for me.

Of the three knives you have mentioned which you have this problem with, two are known to run their steel a bit softer. The Henry Bros, being toll manufactured in China, is an unknown. Softer steel is more prone to a wire edge.
 
The wire edge is the effect, not the problem!
If you can sharpen, and you can since the other knives work ok, the problem is in the steel treatment.
The first thing to try as suggested is to remove enough metal from the edge, hoping it was simply overtempered by motor driven grinders or a failure in the athmosphere control led to a loss of carbon from the blade surface.
Use water stones (or watered diamond plates) to reach fresh steel.
There is also the chance the heat treatment has been totally botched and there is a lot of retained austenite or skipped altogether (annealed steel).
 
Wire edge sounds right.... A 30X, handheld, lighted, microscope might help you really see what is going on. It really helped me out when learning to sharpen.
 
Last edited:
As these are potentially softer steels drawing the edge at 90 degrees a few times should be able to get that wire edge off. If that doesn't do it I would remove some steel off the edge just as everyone had mentioned.
 
But if the knife slices paper just after stropping, and then goes dull after light use, is it a wire-edge problem?
And if the blade is just losing its edge but not chipping, is it an over hardened edge?
Assuming OP is right that it isn't a wire edge problem, what's left but under-hardened?

I'm just asking, not claiming any expertise. I still don't know what my shop teacher meant when he said "When you guys learn to use a burr, [some sharpening advantage would happen]".
 
A wire edge will slice paper just fine, since what is left is a very thin edge (of steel) that is still bound to a wedge. Those two circumstances will slice just about anything, with the only restriction being which gives first, the wire edge or the material being cut.

In this case, it slices paper fine, but an abrasive material is causing the edge to break and the apex to be unpolished and not profiled correctly leading to a short life span.
---------
I notice I produce one one my 1095crovan with ceramic, so I have to go Very steep for 2 (or so) light passes to cause it to fracture and clean the apex. If I feel that the edge isn't where I want it to be, I will go back over the edge a bit with a spine trailing pass a few times.
 
scrteened porch said:
But if the knife slices paper just after stropping, and then goes dull after light use, is it a wire-edge problem?
And if the blade is just losing its edge but not chipping, is it an over hardened edge?
Assuming OP is right that it isn't a wire edge problem, what's left but under-hardened?

I'm just asking, not claiming any expertise. I still don't know what my shop teacher meant when he said "When you guys learn to use a burr, [some sharpening advantage would happen]".
Click to expand...

Perhaps your shop teacher was thinking of sharpening cabinet scrapers where a burr is the cutter.

I am thinking that since you have NO other problems sharpening your other knives, then it is the knife.

I have that model of AGR knife with different scales on it, and have no problems with the knife or its steel. I have another AGR from that same series with the same 12c27 steel, and I had to knock off all of the evidence of factory grinding, rebevel, then sharpen to get a decent edge. For point of reference, I rebeveled with my Lansky setup, and maintain the edge with a 1200gr diamond rod.

Personally, I like the 12c27 and found it to be a good performer. But it took a bit to find its sweet spot for me. My little Queen whittler in the same steel gets the strop as it is a very small knife with very small, thin blades. It will take a scalpel edge and do just fine because I only use it to cut my cigars. But the AGR's are large enough for some work, and I have found that in my use, an ultra fine edge doesn't serve the steel well. I get good service when I stop at 1200gr, which is great because it is a really nice little knife.

On the other hand, you know if there is a problem all you have to do is contact AGR and they will figure something out with you. I have bought several knives from them and only had a couple of problems, and they resolved them right away. It is possible that one slipped through the cracks...

Robert
 
scrteened porch said:
Assuming OP is right that it isn't a wire edge problem, what's left but under-hardened?
Click to expand...

My guess is that the already heat-treated blade was over-heated when the final edge was put on (softening it). I've had a couple like that, and have often seen cutlers over-heating blades when grinding.
 
Thanks NJBill and Midnight.
And thanks Jack. I should have thought of that- the reason why we don't put thin blades on dry wheels, duh. I can't even claim it was too early in the morning.
 
scrteened porch said:
Thanks NJBill and Midnight.
And thanks Jack. I should have thought of that- the reason why we don't put thin blades on dry wheels, duh. I can't even claim it was too early in the morning.
Click to expand...

In my experience, it really doesn't take a great deal of heat to soften the edge slightly (or worse). I can recall one experienced Sheffield cutler, who used to grind with gloves on, heating the fixed-blades he was sharpening until they had colour in them! :eek: The knives were sharp, but they didn't retain an edge well.
 
You must log in or register to reply here.
Back
Top