Grizzly Broadheads and the HARD steel!

[Sharpster]

I just had to tell you guys about this:

As many of you know, I've been trying to get this pre-sharpened thing up and running for a couple of months now with mixed results. I bought all the Grizzlies as unground blanks and have many rejects and half-ground heads laying around the shop. Some are rusting from sitting around unprotected. (fairly damp shop).

A couple of days ago I was going to try a new grinding set-up and needed a head to experiment with. I found an El Grande that had been fully ground and fine sharpened on one blade but, the opposite blade was still blank. This head had been sharpened some time ago and was visibly rusting on the exposed bevel. I checked and sure enough, it still shaved hair cleanly. I thought to myself "that's way too sharp to be experimenting with, better dull that blade some before I start messing around with it".

So, I picked up a block of solid 6061-T aluminum and while pressing pretty hard on the blank blade, I made 3 deep cuts into the aluminum with the sharp blade...checked the edge- it still shaved hair! So, I made 4 more slices into the block, pushing even harder on the blank blade... It still shaved like it had just been sharpened!!! Finally, I had to run the cutting edge over some sandpaper in order to dull it.

I'm still in awe. I know of no broadhead that can take that kind of punishment and would have bet my last dollar that the Grizzly couldn't either. Ed is right. There is something about the steel used by Grizzly that makes the cutting edge extremely durable.

Oh yea, one other thought: doesn't this experience directly counter/disprove the myth that a honed and stropped edge is less durable than a coarse sharpened one???

Ed, can you add to this? Any knife makers out there who can explain the how and why of it?


Ron

[UCBerzerkeley]

hah shave testing with a rusted blade    

do you know what steel they use in their grizzs? its obviously a carbon, so like 1055 up to 1095, 5160 or something else entirely? edge retaining might point to an upper carbon steel, like 1085 or 1095?

[Doc Nock]

Ron,

Thanks for the tutorial in basic sharpening and compound or whatever name the multi staged edges carry!

so much to learn..already so darned old!    

I might just have to see what my winter tinkering can get me in EFOC and if I can get up to the big Griz head weight!

[Dozer]

I've heard that when steel rusts it gets harder. CZ Arms allows there rifle barrels to rust before machining them. They say it increases the strength of the barrel. This may help explain it... or maybe I'm wrong.

[Sharpster]

Dozer,

The head was only superficially rusted, I'm sure that I could have hit it with some oil and a rag and removed most of it. Besides, as much as I love carbon steel over stainless, I know that any carbon steel broadhead I sharpen today will be less sharp tomorrow just because of oxidation. That's why we coat them with vegetable oil or chapstick or whatever. I really think it's the steel but, my knowledge of metallurgy is pretty poor. Kinda waiting for Ed to chime in here and set us all straight.

Ron

[Chris Lantz]

The only information provided from the manufacturer states they use high carbon steel, I would bet it’s 1095. I think Dr. Ashby mentioned that grizzly broadheads range in hardness from 50 – 55 rc with the el grande usually testing closer to 55 rc then the standard grizzly. 55 rc is harder then many other broadheads out there but isn’t all that hard compared to some high quality knives.

Technical data aside I know the 145s I have seem pretty darn hard. I spent a long, long time trying to grind the initial bevel on one using a KME and a coarse India stone. Eventually I was able to get the bevel ground enough to raise a burr using the coarse stone but it took a long time. Even when using a bastard file it takes a fair amount of time to grind the bevel. The grizzly broadhead steel definitely feels harder then any other broadhead I’ve tried to sharpen.

[Dr. Ed Ashby]

Ron, you raise one of the points I've been trying very, very hard to get across to folks for a long time.

Though the harder steel does take more effort to sharpen, it resist edge damage and stays sharper longer; especially when hard bone has been hit. Ideally, on every single hit, and regardless of what tissues are hit in the animal, the broadhead should still be truly sharp AFTER penetrating through the animal - just as sharp as it was at the time of impact. That's the only way you can be assured it did the absolute maximum damage to every single artery, vein and capillary it touched throughout the entire course of its penetration through the tissues. On a poorly placed all soft-tissue hit, such as a gut shot or one that’s into muscle tissues only, the level of retained broadhead sharpness often makes the difference between a clean kill and a wounded and not-recovered animal.

It is on a shot that hits both bone and non-thorax soft tissues that the ability of your broadhead to retain its sharpness under all conditions becomes of HUGE importance. A hip hit comes to mind as a common one of this type or, even more critical, a shot through the hip joint or leg bone and angling into the gut. There the broadhead must be able to stand up to a hard bone hit and still retain it full level of sharpness if it is to do maximum damage to the blood vessels found in the soft tissues that it encounters after the bone impact.

I view having the maximum broadhead sharpness you can possibly attain as a 'given' - something you MUST have if your arrow is to be effective to the greatest degree possible - but I view the ability of the broadhead to HOLD that level of sharpness throughout penetration as being even MORE important. A truly sharp broadhead that loses it's sharpness during penetration can be a disaster; and MANY broadheads loose sharpness, or roll their edges far to easily on bone. Very, very few of the commonly used broadheads exhibit equal sharpness BEFORE and AFTER the shot - even on all soft tissue hits. You can do a great deal with arrow design to increase arrow penetration, but regardless of arrow design your broadhead has to be truly sharp; and STAY truly sharp during penetration; for you to gain maximum benefit from the advances in arrow penetration.

The EDGE-RETENTION ability of the broadhead they use is something every bow hunter should be paying attention to. After each shot into an animal, and whether the animal was recovered or not, they should be examining their recovered broadhead to see how well it’s after-the-shot sharpness compares the sharpness before the hit. If it isn’t retaining its sharpness throughout penetration then a lot of whatever effort they used in getting it truly-sharp initially is being wasted.

I don’t know the specific steel that the Grizzly is made from but whatever its steel is, it’s darned good.  Regardless of whether of single or double bevel design, and ignoring all other design features, as far as their quality of steel and the broadhead’s ability to retain their sharpness after tissue penetration; among all the broadheads I’ve tested six stand out as  the best. In a dead-tie for the very best are the German-Kinetics Silver Flame and Alaska Bowhunting Supplies’ Nanook and Ashby broadheads. Right behind those comes the 190 Grizzly and the newer, higher R Hardness, 160 grain Grizzly broadheads. I’d place the Abowyer heads as a near-equal to Grizzly.

The important bottom-line is: It’s not about how sharp your broadhead is when you shoot it. It’s about how sharp it is where you really need it to be sharp - while it penetrates the tissues.

Ed
TGMM Family of the Bow

[Doc Nock]

Ed,

Ron gave me a tutorial just the other day on the same said thing! I know for sure that my broadheads are nowhere near as sharp after burying 3" in the dirt as when they left the bow!

I tended to get too thin an edge to try to get it "sharp" nd consequently, it was way too delicate.

One of these days, when the Gods of Jobs smile on me again, one of KME's sharpeners will be in my poke and I'm going for the compound angle edge!

[Ray Hammond]

I've done some RH testing on some of the grizzlies I use...and they are harder than 55. Some are 59-60.

Every type of steel has different characteristics related to alloy content...

You will absolutely wear OUT hand files if you are changing the blade angle on these things with them.  You will, unless you scrupulously quench the heads in water every few seconds, change the temper on the heads while doing it on a belt sander.

If you will use an AUTO BODY RASP(Thanks,Ed!) (14 inches long or so, 3/16th thick by 1 1/2 or so wide, with about 8 curved teeth per inch) mounted to your table or like I do it, to a piece of wooden moulding just larger than the file itself and use that to change the blade angle, using the ferrule as a guide and just barely lifting the ferrule off the file as you work it back to front, you will be way ahead of the game.

5160, 1095...whatever it is...once you change that blade angle it will sharpen quick...use a big Nicholson or a Grobet and work that edge at the same angle, file held at perhaps 15 to 20 degrees off perpendicular to the blade working back of blade toward tip, using just the weight of the file itself to cut the blade.

One of the most important things to remember is you have to hold that head still while you are doing this, to avoid rounding off if you know what I mean.

I use the edge of a table to rest the head on..or the corner of a wood railing on the porch.

then lay your big file FLAT on the table, and draw the flat side of head across the file FLAT to remove the burr. Now you are done, except for one easy pull on the angled side away from you across a leather strop-and one push on the flat side toward you. STOP you are done. Don't test on your arm, please. Try it across your thumbnail but not your arm.

And remember, it is the METAL SHAVINGS in your file that are causing your file to go bad, AND they will damage the edges of your broadhead- think about it...they are as hard as the metal you are trying to cut..and if you are loading up your file with those shavings and pushing them across your blade...are you helping or hurting?

[Dozer]

Dr. if I can get a broadhead to become shaving sharp at the 30 degree angle, instead of the recommended 25 degree angle, should I go with the 30 due to its ability to hold an edge better???

[Soilarch]

I'm not the "Dr." but I can answer that question from a knife-guy viewpoint.  His opinion may be different since he's got the broadhead-doctor viewpoint.

Use the most obtuse (largest) angle you can use to and still be sharp afterwards. For some metals that may indeed mean 30*.  For other you may have to go as low as 15*.  

Here's why:
You have heads that are both shaving sharp and one is set at 30* and one is set at 15*.  Now lets pull a random number out of the air to tell us how much metal is "worn" away from a pass through the animal.  Lets say 10 microns on the 15* edge and 6 microns on the 30* edge. For every micron that's worn off the two edges the 30* edge will increase in "bluntess" twice as fast.  So using our made up numbers the 15 degree edge will be worn to a 2.68 micron edge and the 30 degree edge will be worn to a 3.46 micron edge....even though the wear only went a little more than half as "deep".

Now the trick is different metals have different wear characteristics.  That makes the whole thing impossible, or at least impractical, to "quantify" like that.  Soo.....you either use trial and error and a LOT of time.  Or you pick a happy medium.

I just realized I answered nothing.     :(  

If were talking single bevels also remember that smaller angles will give you less torque to "spin" through bones and flesh.  Kinda like running a shallower prop on you boat engine.

Well, I've done it again...sorry for the long post.

[Dr. Ed Ashby]

John, even a dull, repeatedly used razor blade will still shave hair - it just won't give you a 'perfectly clean on one pass' shave much beyond the first time it's used. 'Shaving sharp' covers a lot of territory. So, let's look at it in terms of the ability of our broadhead's edge to do what we intend - to make the deepest, cleanest, most efficient cut it can.

The thinner you can get an edge, the higher it's mechanical advantage. Why does that matter?  At an equal level of 'shaving sharpness' the edge with the higher MA will slice a blood vessel with less applied pressure. At an equal level of 'shaving sharpness' AND equal pressure between the edge and the tissues, a thinner, higher MA edge will slice a blood vessel deeper than a more-abrupt edge bevel. The thinner your broadhead's edge, the better and more efficiently it cuts.

For something designed to make a single fine-slice, the thinnest edge you can use is desirable but, as discussed above, that edge has to be durable enough to resist damage during that one slice. During any given impact, at any given level of force, the lower-limit of edge bevel-angle that your BH can have and still resist damage is determined by (1) the steel from which the broadhead is made and (2) the overall MA of the broadhead. A third, and closely-related factor can be added also; the bevel's profile. That's the 'compound angle edge' Dave mentioned.

A compound angle edge can be used to permit a lower 'main sharpening' angle by adding a very narrow, more abrupt sharpening angle right along the edge. I tend to refer to it as a micro-bevel, and is the type of edge bevel I routinely use as steel hardness in the broadhead being sharpened decreases.

Though it's double-beveled and and has excellent quality blade-steel, the Silver Flame uses a compound angle bevel; and a compound angle bevel can be used on a single-bevel edge too. Though they do lower the overall MA of the bevel somewhat, on a given blade a compound bevel will give a somewhat stronger, more damage-resistant edge than will a comparable main-sharpening-angle straight-tapered edge. However, whenever the steel quality permits I prefer a straight taper on the edge bevel; at the lowest possible angle allowing edge strength.

So, the bottom line answer is that you want to use the lowest possible sharpening angle that will resist damage; for the broadhead you are using. On the single-bevel broadheads I listed above the minimum angle that RELIABLY holds up is 25 degrees on the beveled side, and zero on the other side. That gives a total bevel-angle of 25 degrees; exactly half as thin (and with DOUBLE the MA) as the commonly-used 25-degree double bevel edge (sharpened at 25 degrees on each side). To get an equal total bevel angle and bevel MA, a double-beveled edge would have to be sharpened at twelve-and-one-half degrees on each side.

There are some broadheads out there so soft that, even when sharpened at 30/30 (a sixty degree total sharpening angle), they noticeably dull during all-soft-tissue penetration.

Hope that helps,

Ed
TGMM Family of the Bow

[Dozer]

If I get you right Doc, the thinner the edge the better it cuts BUT the thinner the edge the greater the chance it will dull on soft tissue. With that in mind, a happy medium must be found.

[Steve H.]

I had some Grizzly EG's that a NEW Nicholson would just slide over the surface.  I really do think they have a quality control issue on hardness.

[Dr. Ed Ashby]

That's sort of it, John. The best broadhead is one with steel hard enough that you can have a very thin edge and still have the strength to resist dulling during penetration or rolling when bone is hit. During the testing, that has worked out to be steels witha hardness in the R52 to R62 range. Below R52 a thin edge (25 degree total angle) rolls to easily on bone. R62 is the hardest steel I've tested, and it is still not so hard that it shatters on heavy bone impact.

The only drawback to a broadhead in the R52 to R62 range is that it requires more effort to sharpen the first time. Once the edge bevel is set correctly, because they hardly dull at all during penetration they are very easy to resharpen to a true shaving edge.

The point in the above post was that IF you are using a slightly milder steel than that of the 190/160 Grizzly; say those broadheads in the R47-R51 range; then a compound bevel is a better option than using a more abrupt angle straight taper bevel. When the steel gets much softer than R47, you need to start using an abrupt main taper on the bevel (for an abrupt cutting angle). Each time you go down in steel hardness, you have to increase the angle of the edge bevel; but each time you do you also lose mechanical advantage in the edge bevel, decreasing the efficiency and effectiveness of your broadhead's cut.

Steve, that's about the hardness that's right for the El Grande. Most files have a tough time cutting them. As noted above, the biggest drawback to the Grizzly is that you have to do that initial edge regrind to get it down to 25 degrees. Most of the other single-bevel BH's I mentioned in the previous postings come with a 25 degree bevel. It's only because of the initial bevel regrind that the Grizzly seems so hard for most folks to sharpen. The double-bevel Silver Flame has significantly harder steel than the Grizzly (as does ABS's Nanook and Ashby BH's), but have you ever heard anyone complain that the Silver Flame was too hard to sharpen? I've not. Why? Because no one has to reset the bevel.

If I understand correctly, work is underway to develop a grinding machine to put a factory 25 degree bevel on the Grizzly BH's, and Ron (Sharpster) has them available reground, pre-sharpened and ready to hunt with - but might be a bit snowed under with orders at the moment.

Hope that helps,

Ed
TGMM Family of the Bow

Ed

[Bjorn]

I was a Grizzly fighter!    If they know the angles why not grind the blanks to those?
I gave up and went with STOS.
Now I have time for dinner with my wife; and other stuff.  :cool:

[Dr. Ed Ashby]

Bjorn, I think it was just a cost thing. They already had a lot invested in an automatic grinding machine, but it wouldn't adjust down to 25 degrees. They did change from the 40 degrees they were originally grinding, down to as flat an angle as they could get. Now I hear rumors that they are looking at a new grinding machine that will do 25 degrees. I sure hope so. I hate to think how many hours I've spent resetting the edge bevel on Grizzly's. Now, if they would just factory produce the Modified El Grande too!

Ed
TGMM Family of the Bow

[Mike Gerardi]

That auto body rasp that Ray Hammond showed me really works well. I can sharpen a head in less than ten minuets with a 25 degree edge. After the rasp I use the bastard file then strop with leather. Will there be a cost increase if they have to but a new machine?

[Doc Nock]

Once Ron gets all the grinding equipment and hiccups worked out...these BH mfgs should just contract with him to do single bevel and compound bevels for them!

[Steve H.]

Any more details on the "auto body rasp" and where to find them?  I will try my grinder again, may have to get a better wheel cause last time I tried it, it didn't do all that well either and neither did the belt sander.