one piece adapter, brass or wood?

[sticksnstones]

OK, I've got a really tough arrow but I'm wondering if I could build it even better. I'm currently using carbon shafts with aluminum footing, then I use a 1 piece brass adapter to mount a big single bevel BH. All is well, it shoots great, I get great penetration, etc. I don't have to change anything.

What I'm wondering is this: currently my brass adapter is about 1 inch into the shaft and ends on an abrupt line. With this setup it breaks when I shoot plate steel targets during destructive testing right at the end of the adapter. I've started footing over the shaft with aluminum in an attempt to transfer more energy before hitting the breaking point. Now I do believe it hit's harder, but it usually snaps at the end of the footing in a clean line. Better but not ideal.

What I'm considering is this: what if I put something like purple heart on a lathe and made the section glued to the carbon something like 3" or 4" long, and tapered the end so there wouldn't be an abrupt line to snap the carbon on? What I'm picturing would be something like this.
   

Of course the BH would cover the wood and go cleanly over the aluminum footing as it currently does.

Have I gone crazy in all my time testing and destroying arrows, or am I on to something here? I really think that slow internal taper would give a lot more flex before breakage, but if anyone has done testing like this I'd love to know their results.
Thom

[JimB]

Doc Ashby and OL Adcock did extensive testing on a 7" parabolic,tapered wood internal footing that was glued in behind the insert.I believe the first 3" of the dowel was parallel and epoxied in.The rest was tapered.The internal footing weighed,I think,50-60 grs.Not sure how to find it.He talked about it on Tradgang once,maybe in the Dangerous Game forum.

[Fletcher]

Anyplace you have an abrupt change with little or no radius, you create a stress riser.  That is why your arrows have been breaking at the end of the adapter and/or footing.  I see two risers in your diagram, one at the end of the footing and the other between the purpleheart insert and the shaft.  My SWAG is that the skinny piece of wood is gonna snap pretty easy..  I would try the 1" brass insert with a 2" alum outer footing.  I have also seen some good reports from using a tapered wood insert behind the brass insert.  Troy Breeding may have some insight on that.

Good luck with your testing.  Arrow integrity is an important factor.  Once the head snaps off, penetration is done.

[JimB]

Alright,here it is:
 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=070146;p=1

[sticksnstones]

Man, first two replies are very encouraging!

Thanks Jim I'll keep researching.

Rick, here is a picture of my last generation of arrow with steel tip screwed into brass with 1.5" of aluminum footing, I think 2" would still have the same issue:
   

I guess I should admit that was an 80# longbow vs plate steel. It's not like I looked at it funny and it failed.

I kept thinking of this    and "crumple zones" and I started thinking of transfering the stress over a longer length of the arrow shaft.

Sounds like the distance and taper of the internal footing will make more difference than the material used (brass only, brass/wood/wood, and wood only.)

If I get the internal footing correct, will there still be a need for external footing? Sounds like I could probably skip that if that is the case.
Thom

[sticksnstones]

Originally posted by JimB:
Alright,here it is:
  http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=070146;p=1  

Thanks! Gonna read it now!
Thom

[JamesKerr]

What you are doing now with the aluminum footing and one piece brass adapter is way more than strong enough to bust through ribs or shoulder blades of any animal including Cape & Asiatic Water Buffalo as well as Elephant except perhaps not the shoulder blade on the elephant. I have yet to see any animal that is made of or that is as tough as steel. I'm not trying to bash what your doing it just seems like WAAAAAYYYY overkill to me, but if it floats your boat go for it.

[sticksnstones]

Maybe you're right. I am working up towards larger game and the existing generation of arrow has preformed very well so far. I've got a good tune and I will probably just run as-is for the upcoming season.

I will probably have to try making some 9" one piece tapered hardwood adapters next winter just to see if they work/how they compare just to satisfy my curiosity at this point.
Thom

[Hermon]

Why not just chuck up the brass adapters in your lathe and put a radius on the back end of them? Would be much easier to do. I agree with JamesKerr, overkill.  But have fun and let us know how it turns out whatever you do.

[JimB]

I will tell you,I made some up,similar to those that Dr Ashby and OL used and they made noise with every shot.The noise sounded just like taking a shot with a loose field point.It drove me nuts and I scrapped the idea.I guess my point is,don't glue too many of them up until you are sure it is what you want.

Most that have experimented with parallel footings found as you did,that the break still happens where the footing stops.I don't know much about the properties of purple heart but you might be on to something with the right choice of wood.Good luck with it.Keep us posted.

[sticksnstones]

Well that noise wouldn't do, and I think putting a bevel on that short of a brass adapter wouldn't help much.

Maybe I'll skip the taper section and just do a few inches of parallel on the inside and match up the external footing to the same. At least I'll get maximum punch and know exactly where it will fail if it hits something too hard.

Thanks again for the continued input.
Thom

[JamesKerr]

Any arrow set up no matter what it is made of or how strong that material is can and will fail at some point. My thing against going with that long of an internal footing is it will be hard in my opinion to find a shaft that will tune in right to your 80# bow with that much of another "shaft" inside it, and as I said before I really don't think it will be necessary even if you were to shoot an elephant compared to your current footing operation.

[bamboo]

IMO I think what you are running into is the impact paradox--and moving back the fulcrum [longer adapters] will only cause the arrow to fail further back and /or become too stiff to shoot--lightening the shaft while increasing point weight is the best bet for reducing impact paradox and improving penetration as well as durability--you are most likely asking a bit too much of your shafts -steel plates are hard to beat!!LOL!!I once saw a wood shaft hit a steel plate and the field tip split perfectly in to two halfs!!good luck -I hope you can beat the plate!!!let us know!!!

[2treks]

Thom, about 10-12 years ago I glued a hardwood dowel inside my AD shafts. About 6 inches worth.
I had a square cut on the inside end I am sure. I also left 1" out of the shaft for grinding my taper on.
I never broke a shaft even when I did a test on an old furnace that was removed from my home. The broadhead was wasted but the shaft made it thru fine.
Not plate steel but still pretty tuff. probably a 65#+ bow.
Good luck. Can't wait to see what you come up with.

CTT

[Kris]

I've done it with oak & hickory dowels (3" - 4" long) and aluminum arrows just as your depiction indicates.  I've also made drawings like yours on CAD, just for the fun of it.

I hot glue the dowels in and then turn them down to the 5 degree taper on my Woodchuck tapering machine.  I also include the aluminum with that taper which makes for a very strong footing as the field point or BH ferrule glue over the aluminum as well.

Wood is very strong married to aluminum or carbon.  This is not an extreme idea but a lot of fun and can make for a very strong and effective setup.  No end to the experimentation one can do.

Kris

[sticksnstones]

I didn't know if I'd regret starting a thread like this or not, but I'm really glad I did.

Mike, I agree I'm at the limits of the materials I'm using. I had to move to steel for testing in order to get them to break. My big question now is how can I transfer the maximum amount of energy before that failure regardless of where the shaft breaks.

Chuck, good info! I'm not surprised you experimented with similar ideas. I might have something to show you by GLLI if I get a little more free time. Hopefully I'll have some new string groves on my heavy bow by then too.

Kris, I've got a few dozen odd aluminum shafts so doing some preliminary runs with that is a good idea. My planned process is exactly as you describe.

Should be a fun experiment even if it doesn't work at all.
Thom

[bamboo]

Originally posted by sticksnstones:
I didn't know if I'd regret starting a thread like this or not, but I'm really glad I did.

 My big question now is how can I transfer the maximum amount of energy before that failure regardless of where the shaft breaks.
 
Thom

my opinion--perfect arrow flight!!!hands down--i'm also trying to reduce impact arrow flex by shooting high foc-its hard to push a rope!!ha ha-I like one piece adapter/inserts from vintage archery-and joes heads are fantastic too!!
 
 

[sticksnstones]

Hi Mike, at 200 grains are those solid brass or hollowed out like the lighter ones?
Thom

[halfseminole]

You're nowhere near the maximum for carbon fiber in a general application.  I think what you're seeing would go away with a little support on the inside of the shaft (like the hardwood dowel that was mentioned earlier.)

That buckle is pretty telltale-if that part of the arrow was solid you'd probably have a busted steel plate to show us.

(I know composites very well, though I don't use them in this capacity.  I've been making literally bombproof composites for nearly ten years on and off.  My last test destroyed the gun that shot it.  I completely accept that there are people that will know the arrow tuning bit better than me, but the general strength of carbon is all I'm speaking to.)

[bamboo]

they are solid and longer than most adapters
 http://www.tuffhead.com/
I've adjusted a little--and started using 175g adapters/an inch more arrow/and a double footing
the arrow in the photo is broken just out of the frame-I think by the offside leg-can't build for that and I didn't care because this happened 25yrds from the tree