Test knife for ABS

David Loukides

David Loukides

Joined
Mar 17, 2006
Messages
1,363
Lately I have been making some "practice" test knives for the ABS. This one is made of 5160. Edge quenched, Double tempered at 350 degs F, and the spine has been softened 3 times. It cuts the 2 by 4s, the rope and still shaves.
Next I will be giving it to a Landscaper friend to clear some saplings. I wanted some work out of the knife be for the bend test. In this lot of knives I am trying to improve on my 50% failure rate on the bend test.
Practice Makes perfect or in my case better.;)
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Dave

Not knowing what your failure was, I'll make a few general comments. Assuming the blade broke, if the grain pattern doesn't look like satin, you need to normalize more. If the grain looks nice and small, keep the blade thin as possible, round the back edge, make sure there is no scratches, dings, pits or any other imperfection which could become a stress riser. When you soften the back, place the cutting edge in a baking sheet with about 1/4 inch of water and let the color run to within a quarter inch of the edge. You can lift the cutting edge up until it just touches the water then drop it into the water just before the color reaches the cutting edge. It takes some practice. At worst you reheat treat and start over.

Jim Arbuckle
ABS JS
 
Dave

Not knowing what your failure was, I'll make a few general comments. Assuming the blade broke, if the grain pattern doesn't look like satin, you need to normalize more. If the grain looks nice and small, keep the blade thin as possible, round the back edge, make sure there is no scratches, dings, pits or any other imperfection which could become a stress riser. When you soften the back, place the cutting edge in a baking sheet with about 1/4 inch of water and let the color run to within a quarter inch of the edge. You can lift the cutting edge up until it just touches the water then drop it into the water just before the color reaches the cutting edge. It takes some practice. At worst you reheat treat and start over.

Jim Arbuckle
ABS JS
 
Hi Dave

Jim gave some good advice. Can you tell us what is happening when you do the bend test? We can give you some better information if we know what you are seeing.

When you examine the grain, look for lines that reveal that your softening did not go all the way through. I have done some experimenting with trying to soften the spine after hardening the whole blade and found that edge hardening is a much easier way to go.

Brian
 
I know that 5160 is the preferred steel for the performance test knife, but do you run a small chance of the part that you aren't quenching air hardening a bit ? I have a rather thin full tang test blade of Aldo's 1084 made up and I am going to try edge quenching that to see if I can get it to work. I would love to use Don's W2 because that stuff is like silly putty when annealed, but I worry about not being able to edge harden it. I don't own any 5160 that i am sure of the quility other than some 3/4 round that i got from Ray Kirk and that is not big enough for a test blade. Has nayone tried to do the test with one of the "cleaver" shaped blades like the guys are using for the cutting comp knives? That would make life a lot easier for me because I wouldn't have to rock the blade in the quench and this might be a good thing if I was using 1084 or W2.

Edit. Do you guys think a full quench with thicker coat of Satanite combined with some spine tempering with a torch leave the back of a W2 blade soft enough to pass the bend test and still get the edge hard?
 
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Hello and good luck. For me on my test knives I used the water method of drawing the spine and edge quenched on both of my blades, 5160 and damascus. Go with Jim's advice and definitely examine the grain structure. With a good spine draw 5160 should bend without a problem. Normalize three times or more.
Joe you can air harden the spine on 5160 because of the chromium, but drawing the spine with the torch to blue should alleviate that problem. For good 5160 try Uncle Al. He has some 5160H, a higher quality run, in
.262x 1.5". The W2 idea should work with the coating and spine draw, but make two knives and test the first one. If it passes do exactly the same sequence with the next one. As for the shape, it is pretty much up to you, but everyone seems to go with the standard spear point and make sure it has a good distal taper to the blade, that helps with the bending.

Brion
 
5160 is a fav for the bend, because of the combination of low carbon and chromium.
It's a spring steel. But I have seen a few 5160 blades snap completely and spectacularly in two.

Any of the above mentioned steels can pass, with the right blade geometry and HT.
Make your blades as thin as possible, this is almost as important as HT for the bend.
A thin tapered blade will bend/flex over it entire length, a thick blade will want to
bend just at the vise and a 90deg bend at the vise will tend to crack the edge. Which will still pass if 2/3rds or less of the width cracked.

Joe, IMO, W2 will make the best cutter but possibly not the best bender. It will pass,
if treated right. No need to draw the spine if clay is used.
 
I don't understand why there should be a need to draw the spine back, if you are only doing an edge quench. Are you annealing your blade after finish forging it? If not, I would suggest getting a bag of vermiculite. It can be found in most nurseries. Completely anneal your finish forged blade in it over night. That should take care of any residual hardening that has occurred. Then I always edge quench 3 times. Then immediately go to the tempering oven 3 times for 2 hours at 350 with 5160.
Try taking a look at Ed Caffrey's website, www.caffreyknives.net. He has a pretty good tutorial on " Passing the ABS J.S. test".

Good Luck


Steve Kelly
ABS J.S.
 
Thanks for your input.
The blade is breaking at the vice and most of the time its because I have quenched it too deep in the oil. How deep should the edge go into the oil???
Some are only cracking to the spine and not breaking fully.
The grain most of the time is very fine.
I Draw the spine because I figure it cant hurt:confused: and I use water to keep the edge cool while drawing the spine.
This latest knife in this post is the farthest down I have ever drawn the spine.
The 5160 is from Admiral steel but If this last batch still gives me problems I will definitely try Uncle Al's
I do use vermiculite. After I normalize 3x's.
When I get the blade back I will show the results in pictures:thumbup:
 
This thread is very interesting as 5160 is my first and favorite steel to work. How thick do they have to be for the test?
 
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