Optimum Angle for Broadheads?

[Rick Wiltshire]

Working from the assumption that a broadhead only needs to maintain its sharpness for a single shot, into/through a critter, and with the understanding that bone as well as soft tissue will likely be encountered  - what is the optimum angle for the edge of a double-bevel  head?

[Rick Wiltshire]

TTT for the Saturday crowd.

[Charlie Lamb]

Rick... don't know how this one went unanswered for so long.

20-25 degrees will get you what you want.

Now you'll get a ton of answers letting me know I'm full of horse pucky.  

[**DONOTDELETE**]

what Mr. Lamb said:readit:

[Rick Wiltshire]

Charlie,

I figured there would be some back and forth between the merits of 20 vs 25 as well.  Oh well, thanks.  Rick

[Deadbolt]

do most prefere it in that range for durability?  why not go as low as like 11-15?  

only reason I would think not to is upon impact the blades may bend rather then cut b/c they are so fine...would I be safe to assume this?  I way playing with some sharpners last night on a sasquatch and I got a scary edge with the 11deg.

[oldskool]

IMHO 20to 25 is more durable,easy to touch up in the field. You can get 11 to 15 sharper but it dulls easier and harder to touch up.

[Deadbolt]

Originally posted by oldskool:
IMHO 20to 25 is more durable,easy to touch up in the field. You can get 11 to 15 sharper but it dulls easier and harder to touch up.

when i shoot at an animal i consider that arrow gone...ill never use it again.  thats just me so im never to concerned with how well the broadhead will repair afterwards.  I consider the arrow a loss the second it leaves my fingers.

if when i find it its still good sure ill use it again but i dont set my gear up in hopes of saving an arrow...id rather have a better shot at killing the animal then keeping the arrow.

so why not get it as sharp as possible to make sure you get maximum cutting?

those are just my views and how i come into the whole picture dont take this as me contradicting anyone or making waves.  im honestly trying to learn here.

[Charlie Lamb]

You are the only one you need to satisfy about blade sharpness, but I have no trouble getting a hair popping edge with 20-25 degrees.

If there wasn't a distinct possibility of bone contact I'd be all for the 11 degree edge. Much better chance of the razor edge being wiped dull by ribs and such.

Most all broadheads as pretty dang soft in the steel department and a frail edge can be turned easilly.

Having said all that, you'll probably never have a problem with the 11 degree angle.
 

[Terry Green]

What Charlies said.....and I'll add to your original comment.

"a broadhead only needs to maintain its sharpness for a single shot"

Actually the ideal sharpening angle  is one that will remain sharp for a SECOND shot....that means it ran its course through an animal and had a killing cutting edge all the way though and didn't get dull while doing the job it was intended for.  If it comes out dull, then where did it get dull?  Hopefully not the entrance side!!!

I can sharpen one REAL sharp that will roll at the 1st sign of a rib...and sharpen one REAL sharp that will still be sharp after it slices a rib going in AND comming out. Which edge do you want?  Which edge is more leathal from entrance to exit.

I've shot through plenty of deer and hogs  and could have knocked the dirt off the head and shot it again at an animal.

and Deadbolts comments.....

Read above again.

I don't care if I find my arrow or not either, but I sure hope its still sharp where ever it is!!!

[Sharpster]

Originally posted by Terry Green:

Actually the ideal sharpening angle  is one that will remain sharp for a SECOND shot....that means it ran its course through an animal and had a killing cutting edge all the way though and didn't get dull while doing the job it was intended for.  If it comes out dull, then where did it get dull?  Hopefully not the entrance side!!!

Well stated Terry!    

We may need only one time cutting performance from a broadhead but the stresses that the head undergoes when making that one cut at 180 fps are much greater than a knife gets from 100 cuts. Add any bone contact and the edge is likely to fail if the angle is too low.

IMHO 20 degrees is realy the minimum angle for broadheads. 25 is better and I prefer 30 for exactly the reasons Terry stated. Sharpness is only part of the equation, durability of the edge is also critical. Coarse filed or honed and stropped, the sharpened edge has to be tough enough to stand up to anything and everything that the broadhead encounters from the moment of impact till it cleanly slices though the off-side skin on it's way out.

It's only marginally more difficult to get that blazing sharp edge at 25-30 degrees but well worth the minimal extra effort required.

Ron

[Dr. Ed Ashby]

I agree with Terry and Ron; the BH should still be sharp AFTER the shot. That the only way you'll KNOW it was sharp during the entire course of penetration.

There is an advantage to having the edge as thin as possible, while still retaining its edge during a heavy impact with a bone. How thin (how low a sharpening angle) can be used depends on several factors. The type of steel and its hardness are obvious factors. The slope and profile of the blade are also factors. The more effecient their design, the more efficiently they use the arrow's force during penetration. This efficiency also means the BH encounters a lower peak resistance force - reducing the pressure trying to roll the edge. So, both BH material and design affect how low a sharpening angle you'll be able to use.

The great advantage of a very thin edge (as well as the TYPE of edge) is not one of 'measured sharpness', it is one of the degree of SLICE that it can produce at a given level of pressure against the tissue. Let's consider two broadheads, each "shaving sharp". One has a thiner edge (lower sharpening angle) and one a thicker edge (greater sharpening angle). At any given level of pressure of the tissue against the edge, the thinner edge will slice more deeply than the 'equally sharp', but more abrupt edge. This is because of the edge bevel's MECHANICAL ADVANTAGE (MA): it can do more 'work' (slicing) at a given amount of force.

At a given blade thickness, both the angular degree of the edge bevel and the TYPE of bevel will determine the MA of the edge. A fast look at the formulas for both the MA of a simple inclined plane (which is what a single-bevel edge is) and for a wedge (which is the double'bevel edge) will show the marked advantage a single bevel has. The double-bevel 'lifts' the load (i.e.; spreads the tissues) during a 'lift distance' equal to the length of one edge of the 'wedge". The single bevel "lifts the load" the same amount, but in twice the 'lift distance'. This is the basic difference between the MA of a wedge and that of the simple inclined plane - when both have the exact 'same angle'.

To put that another way; though both will have a total edge angle of 25 degrees, a 25 degree single-bevel edge has a higher MA than if sharpened at 12.5 degrees on each side. That means it can slice more efficiently than the double-bevel edge (at any given level of tissue pressure).

Bottom line: on any BH of a given profile; when 'equally sharp', the edge having the higher MA will create a deeper (more efficient) slice than an edge of lower MA. The lower the sharpening angle you can use, the better; as long as the BH's quality allows it.

Ed
TGMM Family of the Bow

[Deadbolt]

Thanks for the replies...I understand wher eyou guys are getting at!  I was always under the impressing the sharper and lower degree the better...I'll play around and see what kind of endge I can get at 20-30 now!

And that sure makes it easier to sharpen...11 deg is a pain!