footing & spine????

[roughneck3]

I'm playing around with Stu Miller's Spine Calculator because I'm going to foot some carbons with aluminum. When I do the calculations for adding a 2" footing at a total of 24gr it increases my spine by 6.4 pounds. I'm confused by this, I figure adding 24gr up front should weaken the spine and I don't see how only 2" of footing could cause any increase in arrow stiffness, due to the fact that I don't see those first 2" having any flex to begin with.

What is everyone elses thoughts on this?

[don_h]

The added weight would weaken the spine, but 24 grains shouldn't matter much, and a 2 inch footing shouldn't make any difference either. Except give you a pretty tough stumping/small game arrow.

[roughneck3]

don,
 Those are my thoughts also, but the calculator show an increase in spine by over 6 pounds.

[Reaper TN]

Why not foot a bareshaft before fletching and see how it compares to the same bareshaft with no foot? I use just a one inch piece of aluminum on my carbons and they shoot the same as the non-footed arrows fletched. I would be interested in your results compared to Stu's chart.

[Ragnarok Forge]

Send Stu an email and ask what he thinks on the question.  I believe the calculator is wrong.  I have used 1 inch thru 4 inch footings and have seen no real appreciable difference in spine for the same arrows.   The added weight weakens them a bit as the foot length increases.

[Troy Breeding]

I've had the same results. No noticable change in spine either way.

Troy

[AKCrazyhorse]

I think the "theory" is that by sleeving the front 1 inch or 2 inches or what have you, you are making that portion much stiffer therby effectively shortening the shaft by that amount.  Now instead of a 29" shaft flexing upon release you have a 28 or 27 inch shaft flexing upon release.  I don't know if it makes a difference or not.  I foot mine prior to starting my tuning and take length off the back end and play with point weight to dial it in.

[xtrema312]

It is weight added to the end so weaker acting arrow.  If the footing is real long and gets on the rest that, could change things a little moving the center of the arrow out a little.  

I would think the last few inches of a shaft bend, but so little I do not think you can even measure it without some very sophisticated equipment or measurements.

I have seen some noticeable change due to footing, insert and point changes where the combination was the same weight as a light inserted, no footing and heavier point, but the insert and  footing moved more of that weight in back of the end of the shaft.

[JamesKerr]

I think it increases the spine a little because there is that much less arrow to flex when shot therefore even though you are adding weight it is also like shooting a shorter arrow.

[Rob W.]

I just footed some 55-75's with 2" of 2216. I can see no difference in flight whatsoever. Most of the footing is over top a stiff glued-in insert anyway.

I like Stu's calculator but dont understand the footing part.


Rob

[Prairie Drifter]

I tried a long (4") footing. Just acted like extra weight. Made my arrows shoot weak.

[SuperK]

I tired some 3 inch footing on my carbons also.  When I bare shafted them, it made my arrows shoot weak; just like what Prairie Drifter said.

[Jim Wright]

the only way footings could inhibit the shaft's ability to flex would be if it were longer than the internal inserts which on the Easton/Beman Axis/MFX and others with the H.I.T.system would mean pretty long footings. These "calculator" systems sometimes are off by more than a little.