Testing: Success and Failure

Greg Covington

Greg Covington

Joined
Oct 28, 1999
Messages
1,563
This past weekend I built a Combat Special strictly for testing. No final finish, etc....just wanted to test blade strength and handle construction. The handle and guard are all one piece of Micarta, held together with Corby screws and Acraglas.

The 1084 edge was up to shaving sharp and I pounded thru some 2X4's with no perceptible difference in the edge. I chopped thru a few other pieces of wood to test for sore spots on the handle. Cut some rope, leather, cardboard and did some stab testing too. It did real well.

This knife has a medium to fine tip...so I wanted to see if the tip would fail. I stabbed the blade into an old hard 2X4 about 1/2 deep. Gave it a few twists and it did okay so I repeated a stab to the same depth and gave it a sideways pry and lost about 1/8 of the tip. Examination of the break revealed a fine grain stucture....so I figure it was the geometry of the tip that caused it to fail. A tanto it is not.

I figured what the heck so I gave it some more abuse. Chopping into nails on the old 2X4. I expected to see chips but it did not....which I consider a pretty good sucess. The edge was not completely folding over either. Just slight deformation that sharpened out nicely.

I pounded with the spine of the knife against an old metal pole to see if I could damage the handle attachment by shock. Came thru fine here except for dings in the spine (blade is edge quenched so the spine is dead soft.

About 10 minutes on the grinder repaired the tip and I gave the knife the old Bagwell trick of drawing the tip, about 1/4 to 3/8", to a nice blue color with a torch. The result was the the tip held okay when I tested it again, although I cannot fully attribute the success as the temper draw....the tip was slightly thicker. That small section of the tip is also not too hateful on its edge...being softer and all.

Sorry for the lengthy post but I figured ya'll might like to share some info.

Greg Covington
Bladesmith
 
Hello Greg: That is some serious testing! It sounds like the blade did well. Keep thinking and testing and you will find that it becoms habit forming. The first year I started forging I did not complet a knife, just tested and tested some more. Stick With It and Take Care.
 
Well...popping the tip was slightly disappointing but I would have to say that it constituted abuse rather than normal use, especially for the type of blade profile.

Hitting the nails in the 2X4 was a pretty good test though. I have seen plenty of knives blow out dime sized chunks with hits like that. I think that this is a test of one of the things you can accidently do with a knife in use, like banging it off a rock or something else when chopping.
 
Sounds like you're doing the right thing. Not as serious as Ed, but I've only finished two blades in the last year--one was destroyed anyway in the ABS JS test--the rest have been tested to destruction. I've learned alot.

One note on the tip, there may be an intermediate step between fully hard and Bagwell blue. My teacher, J.D. Smith, recommends what he calls an "impact temper" on the tip. Everyone sees/judges colors differently, but if you think of your edge as light straw, the tip is somewhere between pumpkin and light plumb. This can be done with a torch, feathering the flame out toward the tip very gingerly, then waiting a while because sometimes those colors delay a bit before appearing.
 
Thanks John...

I know that color you are talking about.

This weekend I am going to do some tests with 1084 and tips to see what works best.

I would rather have it bend than break.

Tip design has alot to do here too and not every knife would need this special treatment.

Greg
 
You are doing good Greg. sound thinking all alone. To me getting a balance between geometry and the heat treat is the key to a really fine knife. Making that tip just a wee bit thicker, and tempering a wee bit softer will make a big difference. I am fond of chopping through old oak pallet lumber for testing, that's some tough stuff. Its great to be able to tell potnetial cistomers that you test your blades. I add a temporary handle and test the edge on most of my blades at an intermediate stage.
 
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