A Killer Edge
October 28, 2010
"Shaving sharp" is a longtime bowhunting catch phrase; a phrase forgotten by some of today's archery hunters.
I've seen it in camps from Alaska to Zimbabwe. I observe it most closely while guiding, when more directly involved in the hunt and better able to impart my influence. My good buddy Bob Mizek, head engineer at New Archery Products, recently brought it up in hunting conversation. Too many archery hunters are simply wielding broadheads that are not nearly sharp enough for real life hunting applications. Whether this stems from lack of knowledge, frugalness, or sheer laziness is left to question, but we owe the game we hunt no less than the sharpest broadhead possible.
This issue surfaces in many forms: The archer firing a few practice shots into foam then returning those very arrows to their hunting quiver. A hunter missing an animal and later shooting that same arrow at game. Broadheads that clatter around in a quiver an entire season, slowly but irrevocably becoming dull. Replaceable blades allowed to rattle lose in a gearbox. Even those with good intentions attempting to touch up edges themselves without proper tools or skills. Some simply don't understand what "sharp" really means.
Broadheads should be shaving sharp; they should be spooky, dangerous. It could be argued that a perfectly placed field point will kill a moderately sized big-game animal, but of course, while "perfect" is the goal, nerves, arrow obstacles, jumped strings, sometimes result in less-than perfect hits that call on a super-sharp broadhead to save the day. Broadheads kill by slicing major veins and arteries, short-circuiting vital organs, by spilling blood. I feel silly bringing this up, but these are important points to remember.
A recent Texas scenario drove this home pointedly. I'd stalked a particular herd of wild boars several times, attempting to kill a true monster, one of those you need a winch to load. After a couple failed stalks and a lesser hog taken from the group with my recurve, the group leader had become a tad jumpy. When a strong wind and the terrain finally tipped the odds I had the behemoth broadside at 30 yards. I was already taking the hero shots in my mind. The arrow looked good all the way but at the last possible moment that huge boar whirled to flee and instead of the double-lung hit that should have followed, the arrow buried into a hindquarter up to the fletchings. What followed was a trailing job through riparian tamarisk and mesquite with evening light failing quickly. A severed femoral artery and punctured liver proved too much for even that 400-pound bruiser. I found him on his side after 500 yards of tense hands-and-knees trailing. A dull broadhead would certainly have resulted in a different ending.
There's sharp, and there is sharp, and no one is chastised for carrying heads that are too sharp. Major arteries are rubbery and extremely pliable, allowing a dull edge to roll around harmlessly, turning a potentially deadly hit into a nonfatal flesh wound. An embedded broadhead that is razor sharp, stopped short of full penetration by a shoulder blade, or due to low Kinetic energy, is able to inflict added tissue damage as the animal runs, creating a faster kill and wider blood trail.
Producing a razor's edge is so technically demanding that myriad makers of even the most advanced broadheads in the industry still contract replaceable blades out to firms who specialize in razor edges. Anyone who prefers hand-sharpened cut-on-contact heads understands this. If you aren't using the highest quality replaceable-blade edges, you must resign yourself to the fact that extra time and skill are required to put an edge on your broadheads that matches today's best replaceable blade models.
With experience you might simply feel an edge with a thumb and declare it sharp, but if you find yourself unsure there are several easy tests to employ. One of the fastest is to stretch a rubber band between thumb and index finger, running the broadhead edge across it lightly. A sharp blade should sever it instantly. The dull head might only saw through, or roll across without cutting at all. Jack Zwickey, maker of time-proven Zwickey broadheads, suggests running broadheads across taught packing twine secured horizontally, holding the arrow only by the nock. A sharp head should easily cut the string. He-man types have long used the shaving test, checking edges on the hair of their arm to see if they will shave. I don't recommend this, as you might cut more than hair...
Modern Broadhead Edge
The modern replaceable blade is a marvel of mechanical technology. They are sharper than almost anything man is able to achieve by hand. Bruce Barrie, owner of Barrie Archery/Rocky Mountain Broadheads, says they inspect sample batches of blades under a microscope to look for uniform edges, then evaluate them through a process that measures ounces of pressure required to cut monofilament line stretched by a consistent weight. They graph each batch to assure consistent sharpness.
Bill Henderson, Ballistic Archery/Steel Force partner, says that most manufacturers purchase stripground blades for replaceable broadheads. Cut-on-contact blades, like Steel Force models, are stamped to create individual pieces and then sharpened, more like the creation of a knife. Steel Force manufactures their own blades, heads that are normally good and sharp out of the package. All of their equipment is dedicated to making broadheads, equipment used only for sharpening, all custom-built, including a final process of leather stropping. Steel Force offers lifetime sharpening of their heads.
NAP's Bob Mizek puts it all into obvious perspective. "We've tested all kinds of heads in ballistic gelatin, finding that seldom does a broadhead create the same size hole as its true cutting diameter. They most often make a smaller hole than their actual cutting width. This is a function of material resistance and elasticity. We've found through careful testing that the sharper the broadhead is, the bigger the hole it creates. Test results have shown that a sharp broadhead will produce a 15- to 18-percent smaller cutting diameter in soft tissue than its measured width. A dull head can loose up to 50-percent of its measured cutting diameter. Animal hide, flesh and vital organs are all elastic, stretchy if you will.
"We've taken our sharpening process as far as it can go. We've created edges that are easily much sharper than a surgeon's scalpel. We call our process Diamize, using diamond wheels and a cold-grind process in which the last .005 of the grind never exceeds room temperature to assure we sacrifice no temper."
Maintaining The Edge
A razor is simply two converging angles cut into steel to create a straight and fine edge. It's important to remember that this makes it somewhat fragile, that every cut corrodes a blade's sharpness. Few archers consider this when removing and replacing broadheads held in bow quivers, blade edges dulling ever so slightly each time they cut the foa
m in the quiver head. The easy solution is to rotate the arrow you most often grab when readying for a shot so a single broadhead doesn't receive all this wear. Back quivers like Rancho Safari's Catquiver, for example, hold broadheads only by the tip, but cramming too many arrows into the quiver, or replacing them haphazardly when in a rush, can damage edges with others around it. Even while stalking or sitting, inadvertently bumping heads into vegetation can dull edges slightly. This is not something to obsess about, just factors to keep in mind.
Replaceable-blade heads have become the most popular style because they make creating fresh razor edges nearly instantaneous. If your broadheads have been in your quiver an entire season of stand hunting or a couple weeks of hard mountain hunting, take the extra precaution of replacing them with fresh steel. I know, replacement blades cost money, but in relation to all the other things we spend money on in order to bowhunt, the cost is minimal. Save old blades for practice or small game hunts, marking them with a permanent marker to assure you don't mistakenly use them for big game hunting.
Harsh environments — moist or saltwater atmospheres — can dull blades even while simply sitting. Even modern stainless steel is subject to the effects of oxidation, which moisture (rain) or chemicals (salt) accelerates. Use a trick of archery hunters of old, back when carbon steel and hand sharpened edges were the rule, lightly applying standard-issue, scent-free petroleum jelly to cutting edges. This keeps edges fresh, and even aids slightly in penetration on thick skinned game. I find this especially helpful with mechanical designs, where moisture and grit can accumulate in retention slots to corrode edges.
An issue worth pointing out is broadhead packaging. I won't point fingers, but too many heads come in eye-grabbing bubble packs that make it easy to see what you're purchasing, but also allowing edges to rattle around and become dulled. Never assume heads are hunt-ready out of the box. Test all heads before hunting, touching them up if required, or simply selecting brands that take precautions to protect sharp edges from abrasion. Cut-on-contact, resharpenable heads are often not shaving sharp out of packaging, and should always be touched up before the hunt.
Some heads are simply easier to sharpen than others. Two-blade traditional heads are made for re-sharpening and are generally the easiest. With unfinished edges, or those damaged after a shot, start with a bastard file, taking steel off slowly to create the correct edge angle. This is a subject of debate, too much angle creating a fragile edge, not enough a chopping "ax" edge. At one end of the spectrum are heads like Rocket's Ultimate Steel with Bacon Skinner blades, New Archery Products' Thunderheads, or Magnus Stingers, with low cutting angles in the neighborhood of 20 degrees, which some argue are scary sharp but apt to dull more easily after damaging bone hits; at the other extreme three-edged heads like G5's one-piece Montec or laser-welded Razorcaps sharpened two edges at a time, that some argue don't offer enough sharpness. I've experienced killing results from both approaches so have no opinions.
A Lansky Sharpener or GATCO Sharpening System, with blade clamp and guide rods, gives you some ideas on the former, the latter created by pushing two edges at a time across a flat stone. The Real Deal sharpening system from Ballistic Archery/Steel Force allows you to sharpen across the blade like factory blades, while maintaining the proper angle through a rail system, edges honed with diamond file, leather strop and finishing compound, for an incredibly sharp finished job.
Traditionally, finishing edges of one-piece heads is accomplished on a stone, beginning with a rough surface and working through finer grits. Modern diamond sharpening tools are best, proving more precise; lacking dips and imperfections old-fashioned stones (rock) can develop. Many old-timers argue that filed, or rough "serrated" edges are good enough, but I beg to differ. A surgeon will tell you that a smooth, clean cut will bleed more profusely, yet heal more quickly; while a ragged cut is likely to bleed less, and heal more slowly. This translates into a lethal hit killing more quickly, leaving more blood behind; while a nonfatal hit allows the animal to recover and live a normal existence. There is also the matter of feathered broadhead edges clogging with tissue fiber and becoming less effective. GATCO and Diamond Machining Technology (DMT) make fine examples, DMT Dia-Sharp stones offered in three grits and sizes.
To touch up replaceable-blade heads correctly and precisely look to tools such as Fine Line's Honing Guide (discontinued but still around) or DMT's Diamond Broadhead Sharpener. The first clamps replaceable blades securely, a smooth-running wheel allowing you to run the edge at a repeatable angle across a fine stone, #400- or #600-grit wet-dry sandpaper. The DMT Diamond Broadhead Sharpener offers adjustable honing surfaces that allow archers to simply push heads across its dual surfaces, two to four blade, without disassembling that head.
I recall guiding a respected heart surgeon for trophy elk. He arrived with a popular cut-on-contact head tipping his arrows, rearing to go. I've long made a habit of inspecting clients' broadheads before setting out, leaving no controllable detail to chance. To my estimation the surgeon's heads were sadly dull. I quickly set to work on his edges despite his loud objections. After I'd finished the first I handed it to him to inspect. He promptly cut himself while thumbing the edge. "Yikes!" the man exclaimed, sucking blood from his bleeding digit. "That sucker's sharper than a scalpel!"
That's the whole idea.