Concave or Convex

[JBiorn]

I see a bajillion different broadhead designs. Now I am going to build some new arrows and am wondering the opinions of others.

 I am wondering if the concave style blade of the Simmons heads is effective in comparison with equal weight convex style blades.

 And are the Silverflames as good as they claim to be? A shame they don't make them in a glue-on.

[Brian Krebs]

You know; I totally believe in concave being better;and I cannot see how a convex can out perform a concave.
 In the upper penninsula of Michigan there were 'zwickey clubs' where you could only shoot zwickeys; and deltas were the blade of choice.
 You were instructed by these guys who had strong beliefs; to sharpen the point; and back one third; not sharpen as much; then sharpen the back third to perfection.
 the ideal was a concave blade from sharpening; that was dull in the middle.
  I tried this; and what it does; is it cuts with the point 1/3; then the skin and flesh drag on the middle third; and the back third cuts a hole big enough to stick four fingers into.
 I know saying to not get the middle third real sharp is hard to swollow; but it does make logically a bigger hole.
  Then too; any drag on the concave blade causes the same effect.
 Now the convex- it seems like its done cutting a path as soon as its half way in.
 How can it cut further than its farthest point apart; and why would the skin/flesh not ride down the blade in the same place it rode up it?
  I sharpen my deltas the whole blade; but I shoot them plenty into dirt before I sharpen them for the hunt; and it seems from the way you sharpen them it encourages a concave blade.
 I really have made some massive cuts with my deltas sharpened to encourage a little 'concaveness'.
 To measure the width of a cut; you would have to use a material that gives a little; not a hard surface like cardboard; because skin and flesh give a little.
  Do some tests. Sharpen a convex and a concave and see what happens!!

[JBiorn]

A piece of heavy leather maybe?

[Ray Hammond]

It would help to start out with KNOWING the difference, wouldn't it, Brian??? I had it backwards...sorry.

I wonder if to varying degrees the points of concave heads are actually depressing the hide of the animal just fractions of a millisecond prior to cutting, causing a 'dent' in the side of the animal which is then cut before it can flatten out again, thereby making a "larger than the width of the head" cut?

[flatbowMB]

With all the convex heads I've seen, the distance between the 2 blade edges does continue to get wider as you go further back on the blade - it's just that the angle of the sweep gets less and less steep.

Regardlesss of the shape of the blades, the whole blade should be as sharp as possible.  Leaving the middle 1/3 dull will simply increase resistance to penetration and reduce the amount of cutting that the blade does accomplish.

With a concave blade, I would imagine (though have know proof) that the more tough, fibrous structures (eg. tendons, aponeuroses etc...) that MIGHT slide out of the way (along the edge of a convex blade), would more likely get cut by a concave blade.  This may cause some reduction in penetration, but not enough to make any difference on almost all North American size game with legal bow weights & 2 blade COC boradheads.

[SlowBowinMO]

Very interesting discussion.  Markus from Silver Flame has posted some good info on this topic on the past, I can't do him justice or remember half of it though.

They both seem wicked, sometimes convex can have a little stronger tip, but pick yer poison and go hunt!