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Hello guys, I may be reading something wrong but what is foam in limb cores. what dose it do or made of and why is it used.... Thank's Cody
-------------------- We as archer's must keep it alive by helping others into the sport WE LOVE. Posts: 2005 | From: Charlotte, michigan | Registered: Jan 2005
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It is very hard foam that is actually cut and ground into core lams for bows. Have not tried it in any of my bows yet but have heard good things about. Might give it a try but I am still stuck on boo.
-------------------- Now then, get your weapons ~ your quiver and bow ~ and go out to the open country to hunt some wild game for me. Gen. 27.3 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Sarrels Archery Posts: 274 | From: Austin, Texas | Registered: Dec 2008
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According to my readings the foam core limb has two advantages, first it is more temperature stable, that is to say poundage is not affected as much shooting in extreme variances of temperature (important to long range shooting like Fita Olympic).Second it is of lighter weight than wood cores so this should make a faster limb. Some have reported foam core to be a little louder than wood core.
-------------------- shoot straight shoot often Posts: 1462 | From: south carolina | Registered: May 2006
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Talked with Bob Morrison about them and he is getting 2 ft/sec speed increases with foam cores over boo. He shipped me a set of foam limbs and they are lighter. They are smoother to draw and quieter. He also just finished testing on foam cored limbs covered with carbon veneers and he is getting a 4 ft/sec increase in speed over boo limbs.
-------------------- "Dog on Point" or "Deer on Ground?" Posts: 6453 | From: Kentucky | Registered: Jun 2007
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Foam core limbs give from 0 (or negative) to 2-3 fps of speed gain. This i have from several written sources, also talked to Sid at Border Archery. Generally foam core cost ~200$ over maple cores, or maybe 150$ over boo.
The difference in feel drawing must be extremely slight, on release shock is possibly reduced due to lower mass.
However, the reason people are paying for this is 70 and 90m FITA competition. Your # of sight clicks is far more constant on foam limbs. This makes a difference, when you shoot a day full from morning till evening + finals @3 different (long) distances. Come sun, come rain, you hit in the same place. On wood you must compensate for temperature. This is what the FITA fellows says. What Sid Ball said, was it was no improvement whatsoever defending the cost if you are not sight shooting @ long distance.
Now on factory ILF limbs the price diff is not what it is on custom limbs. The fastest ILF limbs available are still wood, Samick Masters I hear.
K
-------------------- -You see something, just whack it" Posts: 211 | From: Norway | Registered: Dec 2004
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K, your's and Sid's conclusions are closer to correct then any expresed so far! Much is marketing of properties that can't be measured by the ave***e archer, therefore can't be proven. An example, I had some foam cores used by Hoyt, weighing them, they weighed the same per square inch as red elm. Folks only think they are light cause they call it "foam". Many of the foam limbs are "light" but that's due to the carbon, not the foam....O.L.
-------------------- ---Six NAA/FITA National and World flight records.---- Posts: 2601 | From: Roswell, NM | Registered: Mar 2003
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OL, i'll elaborate, since ive studied this in my process to buy myself superfast recurve limbs, that are ALSO all the other things, result is i have sold and traded and do not even own a complete modern material bow right now
I have a pair of Hoyt 900CX foam limbs right here, i havent weighed them. But i have chroned arrows shot w them, on a Hoyt Helix riser. They are no faster than my own Winacts, and significantly slower than a a pair of old FX-limbs, both wood core.
However, the new Hoyts ARE smoother at the end of the draw, and they have more torsion resistance, and different tiller. They are shot full of crossweave and doodahs to make the shot more forgiving to the archers errors. Such as - bad release - inconsistent draw - inconsistent hand placement - etc.
Point is, you cannot compare directly unless you know what else is in the limb, to achieve other things than speed. Also modern tiller is different, as both better machining makes other tapers than oldfashioned "straight taper" possible, as well as more accurate, newfound (crossweave) torsion stability has also given the possibility to make limbs narrower, and new tiller shapes are seen as well. Do not hang everything on "foam", as in all bowmaking perfect tiller is king.
The main point is, as said before: *Syntactic foam does not vary in draw weight nor cast at anywhere near the extent wood does - mainly in temperature changes. Even this effect is small, but noticeable, at 70 and 90m.
Moisture resistance have been mentioned, but the wood in bows are usually thoroughly sealed anyway.
K
*Since the material in the foam that does the work (the work is to do no work..) is glass usually and sometimes mixed w/ carbon or glass fiber, some (Border) has a foam that supposedly is purely polymer,"strenght" is normally proportional to weight anyway.
The term syntactic comes from tha fact that the "bubbles" in the foam are "made", they ar fabricated from a (usually) different material than the continuous phase. The original syntactic foam was used in the oil industri in the 60s and was glass spheres in epoxy.
-------------------- -You see something, just whack it" Posts: 211 | From: Norway | Registered: Dec 2004
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"what foam", the beauty of syntactid foam is it can be tailored to the specific needs.
Since wood is strong enough, i would GUESS the foam used in bows have strenght properties similar to wood, perhaps somewhat less tension strenght and somewhat higher compression. More isotropic than wood. If you want it stronger, you would need heavier, so no one would use stronger than necessary, and wood is just about as strong as neccesary.
For the current bow designs, that is.
Again, i dont KNOW this, im ass-u-me-eng(ineer)
K
-------------------- -You see something, just whack it" Posts: 211 | From: Norway | Registered: Dec 2004
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Much is marketing of properties that can't be measured by the ave***e archer, therefore can't be proven. An example, I had some foam cores used by Hoyt, weighing them, they weighed the same per square inch as red elm. Folks only think they are light cause they call it "foam". Many of the foam limbs are "light" but that's due to the carbon, not the foam....O.L.![[clapper]](graemlins/xxtaclap.gif)
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