Why sharp matters

[Mesophilic]

A while back I started a thread asking which was better a better edge on a broadhead, a polished edge or a toothy edge.  Rather than dig up an old thread I figured I'd start a new one

I stumbled upon the answer in a paper done by Dr. Ed Ashby.  Makes alot of sense.

For the Cliff Notes:  A clean cut takes longer to clot.

When all else is equal there's absolutely no question which type of edge finish makes a cut that bleeds the longest and most freely; it's the one made by the thinnest, sharpest, smoothest edge. That's a medical and physiological fact. Why? Because the thinner, sharper and smoother the cutting edge the less disruption there is to the cells lining the inner wall of each blood vessel cut. What does disruption of the blood vessel's inner cell-lining have to do with the rate and degree of bleeding from a cut?

Disruption of these cells is what initiates the blood's clotting process, known as coagulation. Each vessel-lining cell that's disrupted releases the protein prothrombin. As prothrombin comes into contact with the blood's plasma it is converted the enzyme thrombin. Thrombin acts as a catalyst, converting fibrinogen in the blood into fibrin; the final chemical reaction required for blood coagulation.

Coagulation stops or retards the rate of
hemorrhaging - exactly what the bowhunter does not want to
happen.

The 'rougher' a cutting edge is the more it mangles the
tissues, tearing rather than slicing cleanly. That means more
vessel-lining cells will be damaged, and the amount of
disruption to each damaged cell will be greater. The more cells damaged, and the greater the damage to each cell, the greater the amount of prothrombin released. The more prothrombin released, the more thrombin produced. The more thrombin there is, the more fibrinogen converted to fibrin. The more fibrin produced the shorter the clotting time. The shorter the clotting time, the sooner blood loss decreases and/or stops. The sooner the bleeding subsides, the less the total blood loss.

[JW_Halverson]

Three days and no replies?  Well....shows you just can't argue with these facts!

[Ryan Jacob]

Well I’m not gonna argue but I’m just going to add, what about stone points?

[burchett.donald]

Dieselcheese,
                     That is correct in my findings...I'm not bragging here when I say this but I have been shooting deer with bows over 30 years and have killed quite a few...So, from a guy in the trenches I agree with a smooth stropped razor edge on a steel head gives a wonderful blood trail...


Ryan Jacob,
                   They say under a microscope that obsidian is sharper than a steel scalpel...This deer traveled 60 yards after hit with a stone point...When both lungs are penetrated the deer suffocates before bleeding to death IMO...Most double lung hits for me are dead under 100 yds...A single lung angle shot is a whole different story...


           Hope I didn't get to far off topic, but you are correct in IMO dieselcheese...

[Comalforge]

He might be a doctor but I have to disagree with this one. Having cut myself on many objects over the years, I always found that a cut from a sharp edge heals better - I've slashed myself with razor edges and simply closed the cut to seal.  Conversely a ragged cut takes forever and hurts like hell while recovering.

I killed a hog and a deer a few years apart; while skinning, we found each had a steel broadhead left inside their bodies that had healed over.  Both points were just under the skin on the opposite side of where the arrow had entered - neither had exited but the entry scar was visible on the far side.  Both animals were healthy and appeared no worse for wear.

For the purposes of killing an animal humanely, I should think proper placement is more important than the edge characteristics, i.e., razor sharp broadhead in the hams vs. a stone point in the heart.

[Ryan Jacob]

burchett.donald
Aren’t most stone hunting points serrated, why dont they have a clean edge instead?

[Will Tell]

All edges are serrated even on a razor blade, some you need a microscope to see them. I would think a smooth razor sharp edge would penetrate better but either edge will kill.

[Mesophilic]

This kind of reminds me of the 9mm vs .45 debates on the gun forums 😁  Which usually ends withe everyone in agreement that shot placement is the most important element.

I've read just about all of Ashby's papers at this point and he does make alot of sense with alot of research going on.  Not from the typical researcher angle or a MD or PhD in a lab, but a dude who actually hunts and has shot alot of animals all over the world.

Being a knifemaker I've had alot of cuts, too.  I'd say the bleeding and healing depend on the angle of tbe cut, how deep it went and what did it.  Put my thumb in a bandsaw blade and cut to the bone, hurt like hell but didnt bleed too much, took forever to heal and got a nasty infection.  A similar cut with a razor stropped chef knife, for about 20 seconds I could see all the layers of tissue going to the bone, various layers of skin, subcutaneous fat, meat, etc., then the bleeding started, pouring blood, and took alot of direct pressure to get it stopped.  The sharp cut did heal better, though.  I think two big differences that makes this apples to oranges is that 1) we're generally not running for our life  and 2) we have opposable thumbs and knowledge to do something about our injuries.

I don't  have a whole lot of experience putting sharp points attached to a stick through animals, but even bullets dont always behave the way they're supposed to.  Saw an Afghan kid shot in the head and manage to survive, so I know that projectile theory only applies in a general sense as once it is in flight it does what it wants to do.  So I'm relying heavily on research and you guy's experience as I move forwar, with my main emphasis in putting the arrow where it matters.  New Mexico doesn't  allow stone points so my next area to cover is how can I humanely and quickly put down the animal with steel.

[DC]

Is there a width of arrowhead that is optimal? There's going to be a point where penetration suffers if it's too wide. Is it the spacing between ribs that determines that? Obviously if you could get a 3" wide point into the animal it would bleed a lot.

[Mesophilic]

Is there a width of arrowhead that is optimal? There's going to be a point where penetration suffers if it's too wide. Is it the spacing between ribs that determines that? Obviously if you could get a 3" wide point into the animal it would bleed a lot.

Ashby discusses this, I'll see if I can find which one of his papers goes in to the details.

[Mesophilic]

Still looking to see if I can find actual penetration depth measurements based on broadhead width.  But did find a couple of blade profile quotes.

In this initial testing, the 1" wide, modified Grizzly, gave 26% MORE penetration than EITHER the wider Grizzly OR the narrow Grizzly Extreme. For buffalo, there definitely appears to be a 'too narrow' cut width to reduce skin drag on the shaft.

Blade profile: A broadhead having a long and narrow profile will have a higher mechanical advantage than a similar one; either shorter in length or wider in cut. The mechanical advantage of one’s broadhead is one of the major factors influencing penetration; especially in heavy bone.  arrows carry a very low amount of force, relative to the task we ask it to perform; or task it might be asked to perform should the hit be less than perfect. At every stage of
developing the hunting arrow one should chose components
maximizing the arrow’s ability to perform as much ‘work’ as
possible with whatever force it has available to it.
Mechanical advantage is the improvement gained by use of a mechanism (machine) in transmitting force. It is the ratio of the “applied force” required to perform a given amount of
“useful work”. In other words, broadhead design can multiply
the force of the arrow, increasing the amount of work it can
achieve with whatever force the arrow carries at the instant
of impact. Not all broadheads offer an equal mechanical advantage. As with any inclined plane, the longer the slope of the plane in relation to the rise of the plane, the higher will be the mechanical advantage. A long and narrow single-blade (2 cutting edges) broadhead will have a higher mechanical advantage than one of equal length and width, but having more blades. Also, as the profile of a broadhead’s blade(s) becomes shorter and/or wider the mechanical advantage becomes less.

[Mesophilic]

Is there a width of arrowhead that is optimal? There's going to be a point where penetration suffers if it's too wide. Is it the spacing between ribs that determines that? Obviously if you could get a 3" wide point into the animal it would bleed a lot.

After rereading several papers I think optimum broadhead width for penetration has to be considered along with shaft width, arrow weight, and momentum.  Seems to be too many factors to make any kind of a blanket statement that specific  dimensions will give max penetration across multiple platforms.

[Comalforge]

I don't know if they did any research to arrive at this figure, but Texas Parks and Wildlife regulations state a broadhead must have two edges and be a minimum of 7/8" in width.  Any point that opens on impact must also meet this minimum width when fully expanded.

Another thing to consider is whether the point goes thru the animal on initial impact or slashes around inside when the game goes off running through the brush with the arrow swinging to and fro.  Lots of variables take place in the field.

[Hawkdancer]

Not sure if there was any research on the minimum width, but the 7/8" seems to be pretty much standard.  Could be input from the manufacturers, also pushing to sell steel points!  Colorado also sets the mini at 7/8" and requires steel..  Btw, what is the best way to get that razor edge on a broad head?
Hawkdancer

[archeryrob]

Width can definitely be a problem. I shot a buck before and the arrow deflected 15° after hitting the first rib. Went in maybe on the 6th - 7th rib and exited on last rib almost hitting the liver. It was direct broad side and the arrow turned after hitting the rib.

Maryland is Min. 7/8" and steel also