"Tree felling" knives - can we make them better

idaho

idaho

Joined
May 5, 2005
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I was recently thinking about large chopper knives, their function, design and producers.
And I came to a question, can we make better designs, more functional?

Lets say we want a knife that will work in wood of unknown hardness, but also will be used in other functions as well.
But hard chopping action is primary concern.

Firts lets analize sources of failures in such knives (no makers/companies will be named).
1. 90° notch from tang to hidden tang - most obvious flaw.
2. serrations, and blade stamping - stress contentrator.
3. agresive distal taper leading to weak tips. There are pictures of some survival knives used by military, all ended up with broken tips.
4. full tang with two mounting holes. This CAN lead to creating leavrage on first hole - there were instances of breakege there.
5. More obvious - thin edge/grind ending with broken out belly.

Do you see anymore? I would love to hear more suggestions about flaws and possible faliure sources.


Ok, lets say we build a knife without such flaws.
And we use some lower carbon alloyed steel, in which breakage instances are extremely rare. 1095 and 52100, although very good, are not equaly dependable (based on my own google search "statitic" :D :D ).

Our limitations are.
3/8 inch thick.
2 inch wide
about 15 inches long.

Where to look for optimalization?
Should it look like a competition cutter?

Full grind, convex grind, saber grind? If we have moved away all weakspots, and we use tough steel, shouldn't we go with as aggresive grind as possible?
But wont thin full grind stick to the wood?
If too thin, knife would act like an machete, which often bite deep into wood and stays there...
How about weight distribution. Maybe a parang/bolo shape, not the conventional straight top straight bottom?


I would love to hear your opionions and ideas.
 
A chopper should have a handle that allows the user to "aim" the knife into the wood easily. It should not have a cylindrical handle(Crk one peice knives, kabar usmc). With a cylindrical handle, there is no feedback as to what angle the knife is. This can lead to stress if the knife is at an angle at the moment of impact.
 
I think I've got it!

A tree felling knife:
zim1yo.jpg
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:p
 
For serious chopping weight should be 16 ozs to 24 ozs like my kukri [similar to military version ] .Convex grind. No finger grooves.If the grooves fit your fingers maybe not too bad but if they don't it's terrible.If the 24 oz kukri can't chop it , it's time for an axe !!
 
I'm more a fan of the big knife with limited heavy chopping ability, but with added light brush clearing usefulness. ESEE Junglas and lighter khukuri falling into this category. With these a tip is very useful. But, if you're wanting a true heavy hitter designed for pure chopping, I think a point is not very useful at all. It would just interfere. IMO, a big belly is really your area of concern and you want it out as far as possible. Bolo machetes seem designed this way for this purpose, to add mass where leverage will make the most of it. Differential heat treating can also take care of the tip damage issues. Big, blunt khukuri and some parangs may be exactly what you're thinking about. The khukuris, for instance, often use no rivets for handle attachment. It's held by epoxy and peened on the end. The tang is also not hardened making breaking less of a concern. They also offer some ergonomic enhancements by adding curves in the right places. Just a thought. Take care.
 
idaho said:
Should it look like a competition cutter?
Click to expand...

Basically, yeah... except not ground nearly as thin at the edge, and with a full convex grind.

3/8" stock at full thickness all the way down the blade is going to make for a very heavy, very forward-balanced knife. It will be very powerful, but hard to control, and will wear out the user quickly unless he's a real hulk with wrists made of steel and titanium. Using any high-toughness steel, 1/4" stock is fine, and even 5/16" is a bit much.
 
james terrio said:
Basically, yeah... except not ground nearly as thin at the edge, and with a full convex grind.

3/8" stock at full thickness all the way down the blade is going to make for a very heavy, very forward-balanced knife. It will be very powerful, but hard to control, and will wear out the user quickly unless he's a real hulk with wrists made of steel and titanium. Using any high-toughness steel, 1/4" stock is fine, and even 5/16" is a bit much.
Click to expand...

How about convex then hollow grind? Like axes grinds are made?

We do not chop deep with knives, so no risk of wedgind, and we would benefit of optimal "hitting part", thick, stiff spine, and reduced weight in the middle...
What do you think?
 
Optimal design:

Handle that easily accepts two hands in a baseball bat type grip
Weight just forward of the main chopping belly
Convex edge with minimal shoulder

Basically, just an axe.

I've chopped down trees with my TGLB, and it didn't take too much effort. I knocked the shoulders off of the edge, and that made a noticeable difference.



 
Oh, TGLB is a good example, but I was thinking about something more radical.

Like this.
COLBBladecutaway3.jpg
 
Cypress said:
Optimal design:

Handle that easily accepts two hands in a baseball bat type grip
Weight just forward of the main chopping belly
Convex edge with minimal shoulder

Basically, just an axe.

I've chopped down trees with my TGLB, and it didn't take too much effort. I knocked the shoulders off of the edge, and that made a noticeable difference.



Click to expand...
Now why did you do that? With a sharp ax, used properly, you would have nailed the tree lower on one side with a bite that went 1/4 way in, switch hit from the other side, four licks later the V would have met in the middle, TIMBER. It wouldn't take ten minutes of chopping around it that looked like a beaver knawed on it. :p
 
Blackie Scantling said:
Now why did you do that? With a sharp ax, used properly, you would have nailed the tree lower on one side with a bite that went 1/4 way in, switch hit from the other side, four licks later the V would have met in the middle, TIMBER. It wouldn't take ten minutes of chopping around it that looked like a beaver knawed on it. :p
Click to expand...

To see if I could do it :D
 
i made a chopper/knife from some 3/16" 1075 and i have chopped down several trees with it. i sent it off on a private passaround and let others chop with it. i sent it to a member that is in the army and he trains pilots how to survive, escape, resist and evade. he said for a 13" knife, it would make a good survival knife for pilots to carry. after he was done playing with it he sent it on to unit. here is a vid of unit chopping with it http://www.youtube.com/watch?v=8q_eMwRaHYg
 
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