testing sharp vs using sharp

[beyondmyken]

Curious as to what you guys think about best sharpness test for a broadhead. For those who do not hunt, a broadhead must be propelled through hair, hide, soft tissue, and sometimes bone and still be able to cut vital organs and blood vessels. A lot of bowhunters favor shaving hair off their arm but that is a push cut rather than what a broadhead does by slice cutting. Thanks in advance.

 

[MaxTheKnife]

I'm trying to understand your question. How sharp does the broadhead need to be? The indians used flint for centuries. Is there a science to this that I was unaware of? A broadhead needs to be about as sharp as a butterknife when propelled from a compound bow from this century. I think you already have an idea about how sharp a broadhead should be. Tell us what you think and we'll all have a better idea about the whole thing. And yes, I have bowhunted before. It is an art, I know. Nowadays we have guns that are much more efficient at cleanly killing our prey. So, it's kind of like asking how sharp a bullet needs to be.

I had a good friend who was an awesome bow hunter. I lived in Michigan at the time and really looked up to this guy. He went to great lengths to sharpen his skills at bow hunting. He practiced with his bow in every situation he could ever hope to have to use in hunting. But every year he wound up losing several deer while bow hungint. Most times it was when his arrow would pass completely through the deer. Now that's an indication of a sharp broadhead. I helped him track many deer way into the night with very little success at recovering the deer. Hell, he got me into bow hunting. But I figured out early on that gun hunting was far superior to bow hunting. I have never, spelled NEVER lost a deer that I shot at and hit while gun hunting. Oh, I came close a few times to be sure. But that had to do with using a scope I wasn't used to. There's a lesson in that as far as I'm concerned. Use superior means to take game. That's how sharp your broadhead needs to be.

 

[beyondmyken]

Maxtheknife, a broadhead has to retain enough sharpness to cut vital organs and blood vessels after it has passed through the other tissues I stated on my earlier post. Some people like to shave arm hair or cut rubber bands as a test of sharpness. I would propose that they may be getting a wire edge that cuts well for those tests but becomes dull after going through hair, hide, and or bone. I have read that there are different degrees of sharpness, ie polished edge that have better utility for some purposes than others. Please understand that a steel broadhead will not have the love and care put into it that a custom knife will. Many have a Rockwell of 46 - 50.
I enjoy bowhunting with a recurve or longbow for the challenge of having to get close, ie 20 yards or so. You very rarely get more than one shot and it has to be in the heart/lung area as a broadhead kills by causing hemorrhage. A dull broadhead could go completely through a deer or elk and not cause enough hemorrhage to cleanly kill. I can't speak for your friend's experience but it sounds atypical for most bowhunters that I know or have conversed with about wounding losses. There have been some studies on this as well.

 

[knzn]

beyondmyken

I too hunt with recurves and longbows and have since 1988. Many bowhunters using two, or maybe three blade sharpenable broadheads have great sucess using a file instead of a hone. A single cut bastard file will leave a broadhead shaving sharp, while also leaving very small serrations that do a great job of cutting hide and arteries, while having an edge that will resist rolling over.
Good hunting.

Bill

Bullets and Broadheads have nothing in common

 

[MaxTheKnife]

Let me try this one again. My post wasn't very constructive was it?

I too prefer a longbow or standard recurve bow and have a few sitting around that need restoring. I look at bow hunting as more of a survival type of hunting because I've just never been much good at bow hunting. So, for me it's just a last ditch survival tool, not a normal hunting weapon. But that's just me. Your question was sincere and I let my sour grapes interfere with my answer.

There are so many different types of broadheads out there with different steel and number of blade inserts. I agree with Bill on the file trick but I also have an idea for sharpening broadhead blades to get that rough, sawtooth edge on a thin steel insert. I use diamond hones from DMT for all of my sharpening besides initial edge grinding while making a knife. If you work the grits properly you can get a real nice 'working' edge on any blade. And thinking logically you'd want to sharpen a broadhead insert just opposite of a knife blade. In other words you'd want the saw teeth to face into the flight path of the arrowhead. That way the saw teeth would rip and tear a path through the animal and do the most damage. The sawteeth should act like serrations in that as they impact hard bone they would fracture and become even rougher while still being sharp.

The hardness zones on the inserts would play a part in that too. If the entire insert was fully hardened it would most likely shear off or simply break against a mass of bone. But if it was zone hardened much like a knife blade then it would have a tendency to roll while maintaining the hardened edge. And even if the hardened edge did break off the exposed steel should still do some serious cutting and tearing because of the tendency of thin metal to fracture instead of breaking off blunt. Sort of like glass if you see what I mean. I'm no bow hunting pro so my experience with bows is limited. But I've been playing with steel for years and that's my take on it. I hope this helps answer your question. Then again, I never even touched on testing the edge.

One test I would try is a push cut test on some heavy scrap leather. Clamp one edge of the leather in a bench vise and hold the other with one hand. With the other hand push the broadhead into the edge of the leather and see if it will cut the leather cleanly without too much downward pressure. That should tell you if your blade is sharpened correctly. For edge toughness the old brass rod test should tell you all you need to know. Clamp a brass rod (1/4" is fine) into the vise horizontally with at least 1" sticking out of the jaw. Lay the edge of the insert on the brass rod and push down gently until you see the edge deflect. Now push or pull the entire edge along the brass rod with the same pressure making sure the cutting edge doesn't 'grab' the rod and spoil the edge. If the insert will maintain it's shape or spring back to it's original position without developing a 'curl' then you should be good to go for a tough edge.

 

[Jeff Clark]

For bloodletting efficiency I recommend cutting yourself and measuring the pain and rate of blood loss. Trying to sharpen something as small as a broadhead this is surprisingly easy to do. To be systematic you need to hold your injury over a measuring cup an see how long it takes to bleed an ounce or so. In my experience nothing beats a file sharpened edge for stubborn bleeding and severe pain.

If you are impatient and not willing to wait for fate to strike you could test your method using thick rubber bands or leather. Try cutting thick rubber bands or leather shoe laces with the material NOT under tension. Just lay them on an old towel and try and cut them with a forward stroke. They will give, bunch up, roll and otherwise act like arteries and sinew in a deer.