How much does adding a Aluminum footing to carbon arrows affect spine?  Would a 3" footing act the same as cutting the shaft down?

I got to thinking that I would like to try the Abowyer brown bear screw in heads at 260 grains this year. Currently my arrows are tuned in with a 100 grain brass insert and a 175 gr screw in head.  My tip weight would be really close by going back to the factory insert with the Brown bear.  I am afraid the difference in length between the two inserts will change the spine and tuning of my arrows.  Would it be possible to compensate for this by adding the correct size AL footing to the front of my arrows?  I really don't want to cut my arrows down any further.

Please let me know what you guys think.
Ben

QuoteOriginally posted by Benjamin199:
 Would a 3" footing act the same as cutting the shaft down?

Ben

I think adding a footing would reduce your spine. Where as shortening your arrow would increase it. A 3" footing is similar to adding about 30 grains to your point. From my experiances 30 grains can change the spine about 8-9 lbs.


In your case I don't see how it would make a difference.

I don't think the difference in insert length will change anything so that you would notice,as long as you get that front end weight close.how do you plan to get the brass inserts out?

I used the low temp hot melt glue from 3 rivers.  This really helped when tuning the shafts as I could pull the inserts and cut off my arrows in small increments.  

I do realize I would be adding weight to the front with the footing, but I will also be stiffening up that section of the shaft.

I may have to get the correct size AL shaft to cut down and do some testing with.

Ben

Why are you wanting to add a footing anyways?

Maybe I am just over thinking this.  I am thinking the factory insert is short maybe 3/4" the brass insert I tuned with is about 1 1/4" so effectively when I switch these I will be making the bendable section of my shafts about 1/2" longer. which I am afraid will have a huge change in the spine of my arrows, so I figured if I could stiffen the same section where I just removed the insert from it should even things out again.
Ben

It is not going to effect it enough to tell a difference.   If your form and release was exactly perfect every time and you were shooting 35-40 yards......Maybe but I still doubt it.   You are probably shooting carbons anyways. IMO they recover better from the paradox and I have not been able to really even tell a difference  other than in trajectory in a gain or reductions of 25-30 grains of point weight.  At least not at the hunting distances I shoot.

You are over thinking it, with carbons 30 grains of weight will reduce the spine a tad, not 8-9lbs. As a matter of fact I bet I could take 5 peoples carbons and add weight without them knowing it, say up to 30 grains and not one of them could tell the difference in the flight of their arrow. Use an aluminum insert that is a little longer like Eastons which is at least an inch if it makes ya feel better, but 250-275 you will not notice the effect. Shawn

I would be more worried about a consistent draw and anchor, if that varies by a 1/3 of an inch than it will effect spine a lot more than 30 grains of point weight. Shawn

I added on a few arrow for stum p shooting carbon a 3 inch 2117 shaft with 2117 easton insert and then glued the item to the carbon shaft with 24 hour epoxy. I still used the 125 gr blunt screww in and or can shoot field point as well. What was a surprise was the bemen 500 hunter showed no change in flight at all. I am shooting out of a martin hunter bow at 45 lbs or my checkmate firebird that is 44 lbs at 28 inch and the arrow length is 29 inch and I am draw true draw of 28 1/2 inch. I do love the setup for stumps as they seem to bounch off  trees or stumps and I have not had a broken arrow so far.

Jamesh asked "why?"

I wanted to get more front weight. My arrow weight was up around 620 already and from a 50# bow, that was about as heavy a shaft as I wanted.

Through another "tinkerer" I found the GT Entrada target light-weight shaft. Same .400 deflection, lighter GPI.

Had to mean they were a bit less strong.  Over-footing (my term) w/ aluminum 2117 (3")+ 100 gr brass insert gave me a very strong shaft in that vulnerable front impact area behind the point where 90% of my alum bent when I shot them and previous carbons would break when /if they did break.

I had to chamfer both ends of the over-foot to minimze that bump transition as it draws over my pivot point under my seal skin rest.

At a fun shoot lately, I shot from a hill top to a creek where a tempting Gator 3D was set...didn't realize it was sitting on a large, moss covered ROCK!  :eek:

Hit just that bit low and sparks flew as the arrow recoiled.  I thought, "there goes one time consuming set up!"

Nada! The field tip was messed up, was white most of the tip from the limestone rock it hit, but the nock was there, the arrow was fine... nothing!

That's my "why", Jamesh

I will say it does not make much sense to add a piece of aluminum loner than the insert as it just makes the breaking point(weak spot) farther back. I use a piece the same length as my brass inserts or 16th." shorter. It does make the end of the shaft near indestructable. Shawn

make it a 2 inch foot and you'll be fine,that part of the arrow doesnt flex and don't forget to add the weight of the footing,that's exactly what i did,175 zwickies w/alluminum inserts,but target is brass 100gr inserts w/100gr feild points.

People are different and find different things here is what i tried and it did work for me, Try one, use hot melt so you can remove it if you need to too make length adjustments to the footing..

 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=105381#000000

"People are different and find different things here is what i tried and it did work for me, Try one, use hot melt so you can remove it if you need to too make length adjustments to the footing."

Thanks Pops, finally someone who has tried what I am thinking about, (having it work is a bonus).  My thinking is along the same line as yours.  Even though the end of the arrow "doesn't flex" cutting off a half inch makes a big difference in flight and spine, more than changing weight by 15 to 20 grains.

I will always be a tinkerer, just can't help it.

Thanks for the link to your post, I am going to give it a try to see how it works out.

I have already experimented with this by checking the spine of a arrow with and without 1.750" footing and it doesn't change the spine.

QuoteOriginally posted by Earl Jeff:
I have already experimented with this by checking the spine of a arrow with and without 1.750" footing and it doesn't change the spine.

How did you check the spine?

In Stu's calculator...doesn't it increase the spine when you add a footing?

I don't have the excel model in front of me, but that seems to ring a bell.

I Stus calculator is never close for anything I try it for. I enter everything in right but in real world it always has me well over spine with carbons. I don't mean 6-8#s but 20 plus. Carbons are spine on 14" centers not like woodies and everything changes as they recover so much quicker. As I said there are very few guys on this entire site that are consistent enough with their anchor and release, myself included to notice 20-25 grains in point weight or from a 3" footing to an inch footing, that part of the arrow is not where the spine is measured as said above, it is on certain centers. When shooting it still does not flex a couple inches from the end of the shaft. It is not hard to play with the footings or point weight, why does everyone make it so complicated? Shawn

QuoteOriginally posted by Shawn Leonard:
It is not hard to play with the footings or point weight, why does everyone make it so complicated? Shawn

That's easy, Shawn, season isn't open yet!  

 

I use a 1" aluminum footing on my carbon stumpers...don't see much need for it on hunting arrows as I don't plan on missing with them. I've used longer footings, but didn't notice any change in flight characteristics with up to 3" footings. I also didn't see any benefit. I can foot three arrows with 1" footings and they work just as well.

I also agree with Shawn that few of us are consistent enough to notice any difference there might be...probably fewer than one percent of us...and I am most definitely in the 99 percent group.