So after playing around with the spine calculator I have learned that adding a footing to my shaft actually stiffens or raises the dynamic spine. I thought it would lower or weaken it being I'm was adding weight up front. I guess  adding tip weight  is different than adding a footing up front.
Why is that?

Unless the footing is overly long it will weaken the spine, mine always have. Shawn

I tried both 1&2 in. Footing according the the spine calculator it stiffens not weakens the shaft substantionally.

IMHO the calculator is wrong . I have added up to 5" and it made the dynamic weaker. Just acted like added weight to the tip.

The calculator is a good tool, but not perfect

A 1" footing is only a fuzz longer than a standard insert and the shaft is not bending there anyway, plus your only adding 10-15g of weight which shouldnt effect a carbon shaft.

Eric

This is an intriguing thread. I would like to see more opinions about this. Reason being, just on a hunch, I have "retired" my Foooted shaft arrows to be used only on an Archery Target range. My suspicion is that I have found the footed shaft a little more challenging when it comes to tuning them with broadheads. I strongly suspect that the paradox behaves differently with a longer footed shaft over the usual all wood one piece shaft. Too many variables when it comes to tuning broadheads, why add another one to it. Just something I feel a little stronger than just a hunch.

QuoteOriginally posted by Prairie Drifter:
IMHO the calculator is wrong . I have added up to 5" and it made the dynamic weaker. Just acted like added weight to the tip.

The calculator is a good tool, but not perfect

Do you shoot bh with a footed shaft? Did you still get a weak reaction? Are you shooting carbons or wood.
I wonder if there is a difference on what a aluminum footing does for a carbon vs a wood.

QuoteOriginally posted by WESTBROOK:
A 1" footing is only a fuzz longer than a standard insert and the shaft is not bending there anyway, plus your only adding 10-15g of weight which shouldnt effect a carbon shaft.

Eric

X2

Not saying it will not change the Dynamic spine in some minuscule way, but for a trad hunter, if you can notice a difference with a 1" inch footing, then your better then the best we'v ever come across.    

I can say without doubt, it will make for a stronger hunting arrow though.

My take on this is "it depends."  If you are footing a carbon shaft with a 1" aluminum foot, you aren't changing much since the insert is about that long, so you are adding weight to the point and not changing the original "bending" properties of the shaft.  But, if you add a 2 or 3" footing, you are effectively shortening the length of the original shaft and thereby increasing the spine of the shaft (it is acting as though it is shorter.)

What is the trade off?  I'm not really sure. Where does shortening the bending length of the shaft and therefore increasing the spine of the shaft balance with the increase weight that weakens the shaft?

Here is another thought. Take a wood shaft that is spined about 50# (for example) at 28".  Now put a 2 or 4 dart wood footing on that shaft.  That footing would add weight to the end of the shaft but at the same time effectively shorten the overall length of the "bending" part of the shaft.  What is the net effect?

Dynamic spine decreases as point end weight increases but increases as shaft length decreases.  So there will be a trade off that I think can only be "figured out" by experimentation.

I, for one cannot recall any "rule of thumb" that addresses this question.

Arne

QuoteOriginally posted by Mr. fingers:
 

QuoteOriginally posted by Prairie Drifter:
IMHO the calculator is wrong . I have added up to 5" and it made the dynamic weaker. Just acted like added weight to the tip.

The calculator is a good tool, but not perfect

Do you shoot bh with a footed shaft? Did you still get a weak reaction? Are you shooting carbons or wood.
I wonder if there is a difference on what a aluminum footing does for a carbon vs a wood. [/b]

I did it on carbon shafts. I wanted to add weight to the front of my arrow. The calculator said the longer the footing, the more weight I could add. I put a 3" footing and bare shafted it.It acted weak. I had to drop point weight almost 50grs to get the bare shaft to fly straight.

This result got me curious. I put footings  from 1" to 5" on . I had to reduce point weight the approximate same as the footing weight ie; footing weight 75grs, I had to reduce point weight 75grs to compensate. I shoot a short arrow ,27", so they are very "touchy" about tuning.

These are just my findings from actually doing it. Mosy people talk theory, this was in practice.

Mike.. I am shooting Woodies, but all things being equal regarding weight, your analysis I believe helps confirm my hunch. I also have a hunch that the behavior of a footed shaft wooden arrow has to be different than an all wood arrow in terms of recovering from paradox.

A very small part of the bending of an arrow happens at the very end.  Short footing not much longer than the insert will only add weight.  Once the footing gets a lot longer it will start to add up in what it will do to the shaft, but I think even some of what probably happens for long footing is due to the footing getting on the shelf and moving the arrow center out from the riser. I shoot brass inserts most of the time with 1" footing and don't get it on my rest.  I see no change I can really quantify other than maybe a hair weaker.  I see much less effect with  the short footing than I see changing from heavy insert and light point to light insert and heavy point where the leverage of the point weight is moving around.

QuoteOriginally posted by Prairie Drifter:
 

QuoteOriginally posted by Mr. fingers:
 

QuoteOriginally posted by Prairie Drifter:
IMHO the calculator is wrong . I have added up to 5" and it made the dynamic weaker. Just acted like added weight to the tip.

The calculator is a good tool, but not perfect

Do you shoot bh with a footed shaft? Did you still get a weak reaction? Are you shooting carbons or wood.
I wonder if there is a difference on what a aluminum footing does for a carbon vs a wood. [/b]

I did it on carbon shafts. I wanted to add weight to the front of my arrow. The calculator said the longer the footing, the more weight I could add. I put a 3" footing and bare shafted it.It acted weak. I had to drop point weight almost 50grs to get the bare shaft to fly straight.

This result got me curious. I put footings  from 1" to 5" on . I had to reduce point weight the approximate same as the footing weight ie; footing weight 75grs, I had to reduce point weight 75grs to compensate. I shoot a short arrow ,27", so they are very "touchy" about tuning.

These are just my findings from actually doing it. Mosy people talk theory, this was in practice. [/b]

Thanks for the info what I'm trying to achieve is  lowering my dynamic spine by raising my point weight by 25 grains.  I thought instead of buying new points and bh I could  kill two birds with one stone by adding a 2in. Footing 2018 raise my tip weight by 24.6. And strengthen my arrows for stumping and stick with my existing broad heads  and field points.
I know that actual experimenting is the way to go no matter what the spine calculator comes up with. I was just puzzled when I filled out the footing section and saw my spine go way up instead of down like I thought it would.

I just measured my brass inserts 100gr. They measure 1,75in plus they are recessed .5in. Down the shaft. So a 2in. To a 2.25in footing should not effect  the spine.....yes?....no?

Axis/MFX shafts? footing with a 2018 or 2020 alum of 2" will not stiffen the shaft but you will add 25-30g of weight to the front. You may see a slight wekening of the shaft, very slight. What you see will depend on if you are currently on the stiff or weak side of perfect.

Eric

OK while we are talking about footing woodies and the effect on spine here's what I discovered when I was trying to get FOC.



I footed many arrows with varying lengths and types of hardwood. The group here has 7" of Cocobolo up front with the splice almost reaching the middle of the shaft. The static spine was relatively unaffected, but the dynamic spine was weakened as though I had added about 50 gns up front, the shafts had gained about 100 gns. Anyway eventually I would run out of spine and so quit worrying about FOC-now I just consider proper flight.

QuoteOriginally posted by Mr. fingers:
I just measured my brass inserts 100gr. They measure 1,75in plus they are recessed .5in. Down the shaft. So a 2in. To a 2.25in footing should not effect  the spine.....yes?....no?

It will weaken it a little. Lowering your brace height will get them back in tune(if it needs it).