Would you like a square 90 drgree sharp spine?

blgoode

blgoode

Knifemaker / Craftsman / Service Provider
Joined
Oct 3, 2003
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Dave McIntyre send me some interesting photos of what he can do with the sharpened or rather a 90 degree spine. The drawback is the the spine is rough on your thumb or fingers when choking up on the blade. Take a look at what he has used the spine for and let us know your thoughts. What about the last 3rd of the tip having the 90 degree spine?
 
From my perspective, a 90 degree corner is about the last thing I wan anywhere on a knife, especially the spine. IN fact, after using knives with fully rounded spines, i.e. Livesay, Reeves, etc. it is one feature I often request on a custom knife.

A rounded spine makes the knife *much* more comfortable to use and increases durability by reducing a stress risor, whereas a squared spine induces a stress riser, though on a soft, thin, long knife like the tramontina flexibility is not really an issue. ON a smaller, harder knife ths could lead to gross failure when lateral pressure is applied, i.e when prying.

It does make a nice scraper, especially for fire steels. But for that, the spine of the SAK saw works really well.

For me, the disadvatanges outweigh the advantages. I know that others feel just the opposite and while I respect their view and opinion, I respectfully dissent.
 
I don't like sharp edges on the spine under my thumb, but use the edges of the spine of some knives to scrape with, and often as a field expedient steel for another knife or hatchet, but why not have both? Round or bevel it the first couple of inches ahead of the handle, and blend it in.
Maybe round it the last couple of inches toward the tip on a big fixed blade, too, so it doesn't tear up a baton as bad.
Or have a rounded spine with a "band cutter".

I'm all for making whatever changes suit you to any knife. I buy tools to fit the uses or needs I have for them, not to tailor my use around. If anything changes it will be the tool, not what I use it for.
 
I ease the top of my spines just for comfort. I am intersted in what other guys think about this so its good to be getting some discussion going ;)
 
Brian, what about a sharpened part about 2-3" in the middle? Or, one edge of the spine sharp and the other radiused?
 
that sounds good to. Wrap a cloth over the tip and edge, hold the handle and scrape away.
:)
 
You can do the same thing with the primary edge if you angle it so it doesn't bite into the wood. However if you want to avoid it dulling in that manner, then use the section in front of the handle which is usually not sharpened as a scraper. If you sharpen it to an obtuse angle like 25-35 degrees you can also use it to cut bone / metals. The edge of a scraper is just set at 45 degrees.

-Cliff
 
Owen
Round or bevel it the first couple of inches ahead of the handle, and blend it in.
Maybe round it the last couple of inches toward the tip on a big fixed blade, too, so it doesn't tear up a baton as bad.
Or have a rounded spine with a "band cutter".
Click to expand...

THat is an interesting idea. IN the past, I have added a small swedge to some machetes, not to add penetration ability but rather isa a rough working area. Whacking off dried small branches, cutting sod, roots, etc.

Since I don't really batin with a machete class blade, any impact on baton ability is a nullity. On large fixed baldes like the BAttle Rat I think your idea would very useful. Similiar to how the Becker Brute has that anvil thingy only sharpened a bit.

I can see where a band cutter type edge on the spine could be useful for scraping as well. I find that the Awl on a Alox SAK like the Solider makes a great scraper, but I guess that is not something everyone will always carry. In fact, I usually use a plastic handle SAK, so I lose that great awl. Not a huge loss for me since I don't find myself doing mucg scraping.

I wonder if that type of edge would make a knife "double edged" for elgal pruropses. It is already absurd how many knife laws interfer with good tools. I don't carry a machete in my truck or a large fixed balde for that reason, but have no problems with an axe.

Cliff
However if you want to avoid it dulling in that manner, then use the section in front of the handle which is usually not sharpened as a scraper.
Click to expand...

Yeah, the Martindale Golok is really ideal for something like this.
 
So far I’ve only done this mod on my Tramontina machetes and Mora SWAK knives. On the knives it was done to spark a ferrocium rod only, trying to shave wood in this manner with such a short blade is a recipe for a slashed hand. The edge on the Mora doesn’t hold up to the ferro rod too well but the 90-degree back throws showers of sparks.

The Tramontina blade spine comes from the factory as a rough, unfinished stamping. I only dress it with a file until the spine is uniform. That being the case I don’t think I’m loosing anything in terms of blade strength. In the field it is a very useful mod.

During rainy season there is very little tinder available that hasn’t been soaked by weeks of rain. If you split a piece of hardwood you can scrape out a ball of very high quality tinder in a few seconds. The tinder is so light and curly that it lights up with just sparks usually. Some woods need the help of a little plant wool or pocket lint.

The first photo shows the blade spine, tinder, and ferro rod. Notice that the forward portion of the blade is rounded for comfort. It also works well with a baton. Batoning with a machete is useful when opening hard palm nuts etc. They tend to shoot off into the bush if you chop at them. The rounded spine also works well for cracking dry coconuts. It is more comfortable to choke up on if you want to use the tip of the machete for detail cutting.

The second photo shows one of my students using the technique in the field on a piece of seasoned Candeia wood. Candeia burns very well with a bright yellow flame and tinder made from it in this way practically lights itself. There are several months of the year here where a machete set up this way is a great asset. The same tool will prepare tinder, kindling, and fuel from the same piece of hardwood.

I have a Livesay NRGS that I often use as my small fixed blade. It has a very rounded spine that is comfortable to brace the thumb against when making powerful cuts or little push-cuts. On that knife the choil is sharp enough to spark a ferro rod, saving the edge.

I haven’t modified my BK-7. I carry a Sparklite and prepared tinder with that knife anyway so I’m not concerned. Mac
 
In a tropical environment the machete is indispensable.

NAVIGATION: Cutting trail
SHELTER: Clearing campsites, leveling ground, cutting poles, vines, and thatching
WATER: Digging seeps, cutting vines, opening coconuts, cutting water-bearing plants
FOOD: Harvesting palm hearts, preparing game, cutting and peeling fruits and veggies
FIRE: Cutting firewood, splitting kindling, and with a squared spine making tinder and sparking a ferro rod
DEFENSE: Wherever machetes are in use they are also used as weapons

As I read on Newt Livesay’s site a while back. “You may go into the jungle with your machete in the sheath but you’ll come out with it in your hand.”

The 90 degree spine is one simple mod you can do with little effort that enhances a tool you have to take with you. It allows you to make a renewable supply of dry tinder in a place where nothing is ever dry. Like I said, all that for five bucks. Mac
 
Brian, take a look at a Fallkniviffen F1. Mine is very square. It is sharo enough to produce showers of sparks from any of 3 ferro rods, and sharp enough to scrape wood well, though nothing like a burnished furniture scraper. It has a reputation for being an incredibly strong knife. I have never heard any complaints about them being hard on anybodies thumb, and it certainly isn't on mine.

I had never paid attention to it before this thread, but in looking at my Randall custom, based on a Mod. 12 Little Bear Bowie, the choil and and back of the blade where the thumb knotches are cut is quite acute, but has been 'melted' just enough to be comfortable on finger and thumb. Both will strike rod OK, but not like the F1. Now, the area ahead of the thumb cuts and up through where the spine blends into the sharpened, reverse curved swedge/clip [chisel ground at 50 deg.] is very sharply square, even more so than the F1.

All of my other fixed blade knives are either intentionally round, or melted enough to feel good under your thumb. I have one older Schrade with a choil sharp enought to be uncomfortable.

Of my folders, several of my Benchmades have spines sharp enough to scrape. One is notably sharp: a mini-Abmush so sharply square ahead of the thumb knotches that I have used it to generate piles of tinder in short order from dry sticks, dowels, fat wood, even a cedar pencil, once.
 
This turned out to be a thread I'll need to read again ;)
 
I request all my customs to have a 90 degree angle spines, but then again I use my knives out in the field. I love the fact that I can spark a FireSteel, scape wood or hide, and perform various other tasks.

RM
 
randjack said:
Brian, take a look at a Fallkniviffen F1. ... I have never heard any complaints about them being hard on anybodies thumb,
Click to expand...
Then you got one. I've done some wood carving secession (about one or two hours) with my F1, edge and grind are excellent for that job, but thumb suffer quite a lot because of spine.
 
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