Knife Test on Some Tough Stuff

Steelhed

Steelhed

Joined
May 21, 2001
Messages
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While walking the beach in Yakutat, Alaska, I came across a twisted pile of washed up hawser. It appeared to be made of a synthetic material, probably polypropolene, that was approximately 4 inches in diameter. I was carrying an S30V Sebenza, and so I decided to do a knife cutting test to see how long it would take for me to cut through the hawser. I keep all my knives shaving sharp and the Sebenza was no exception. When I started cutting the blade sliced down about a half an inch and then would not cut anymore. I tested the edge against my thumbnail and was amazed to discover the edge had been completely blunted by the hawser. I mean blunted to the extent that it would not catch on my thumbnail at all.

My first thought was that Chris Reeve's S30V blade material was not all that it is cracked up to be. I ran back to my truck and grabbed a Busse Steelheart-E made of INFI. I tested the edge against my thumbnail and it caught and held as it should with a high degree of sharpness. I then started slicing the hawser again and quickly repeated the performance degradation I had experienced with the Sebenza. What was going on? Two high quality steels had been blunted in very little time by this waterlogged and sun degraded material.

When I examined the hawser in more minute detail I found that it was not only waterlogged, but that beach sand had become distributed throughout the big rope's strand structure. In essence, the hawser had become a cylindrical matrix of highly abrasive sandpaper, and trying to cut through it was like trying to slice through a stack of 1000 grit SiC sandpaper. I have never cut anything that pliable that dulled a blade so quickly. I think the only way I could have cut through the hawser was to have had a diamond hone with me to touch up the blade edge every few slices, or perhaps a ceramic bladed knife would have worked better. A larger blade, even the Steelheart, might have been able to chop through the hawser, but not without some edge blunting.
 
Sand ( Silica [SiO2 ])is extremely abrasive , that's why they make SANDpaper. I've had to very carefully explain to production engineers that , yes indeed, their carbide dies wore out because the parts were contaminated with sand. And of course there are those who reload ammunition without cleaning the sand from the cases and wear out the carbide dies.
 
When cutting trees or wood that is near the ground (especially on beaches or arid climes) this can also occur.

The only thing that woulda cut that in one swipe would be an axe, or khukuri. Basically the chopping cut over the sawing cut is required.

I've cut braided steel and copper conduit in this way with the khukuri, with little edge damage. I'm sure a sawing cut would've dulled the khuk, but it relies on its mass for cutting rather than a razor edge, which sometimes makes me think of the khuk as a rather sharp edged hammer.

Keith
 
Yes, I think chopping through the hawser would have worked better, but I was mainly testing the edge holding using a sawing or slicing motion because I could not have chopped well with the Sebenza, and to be fair in my comparison I had to use the Busse in the same manner. And yes, I am careful to remove all sand and dirt from my shell casings before I reload them.
 
That is a cool experience...
Frustrating as hell!!!!
When you were about it.
You can laugh at it now.
I'll take your experience with me tho as I pick up stuff here and there
Thanks
Tom
 
I once had a similar experience while cutting very old barn rope. I was trying to do a cutting test of my own similar to the one Jerry Busse did for his testing(I was using a BM-e). I posted my results of the test prematurely and subsequently to eat my words and put my tail between my legs because old barn rope is full of dirt and dust and other particles that dull knives really fast. No matter how good a steel is(and INFI and S30v are certainly some of the best steels out), they can't stand up to hard abrasives similar to what is used to grind them to shape.
Luke
 
If you don't have a chopper handy you can try :

1) using a serrated edge, it will cut such material far longer than a plain edge, or else a *really* coarse ground plain edge

2) make a serrated edge by chopping the knife into a rock a few times

3) use a baton and simply pound the knife through

The baton method also only blunts one section of blade.

-Cliff
 
There's certainly limits to any knife steel....if you decide to use a knife to cut a Concrete Block....then you're relying on things other than edge retention. ;)
 
Cliff - Actually I found another way, although I used an old knife I didn't care about that much, not the Sebbie or the SH. I built a little fire next to the hawser and heated the blade of the beater knife. Once I had it pretty hot I simply melted my way through the hawser. It took a couple of heatings but it worked. Of course the blade's heat treatment is probably all messed up now. This would probably not have worked on manilla or hemp, but it did on the polypropylene.
 
Yeah, I have a couple of old books on knot tying and this is how it is often described to cut the ends of rope neatly. If there is anything metal lying around it can serve as such a knife, provided you can grab a hold of it, stick a nail in a piece of wood, or just try to burn the rope directly if you don't need a neat cut.

-Cliff
 
I'm glad some other people are suffering the same fate I did! I cut a lot of 3" hauser from lakers and on a thin edge blade (Spyderco-Moran) the edge actually chipped as well as dulled on the first cut. Now I like to use a big blade and cut the stuff free-hanging, though it scratches the heck out of fine finishes.
 
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