| From: marc
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| Date: 05-Apr-17 |
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I just compared an actionboo and foam lams. Both were 30 inches long and both were 2/1 taper with butt end of .079 and the tapered end of .019. As close as can be made. My surprise. The foam weighed 401 grains and the actionboo weighed 370. Actionboo being 31 grains lighter. Next I clamped 1 inch of the butt end of each lam on a flat table with the remaining 29 inches just hanging free. The foam deflected down 14 inches and the actionboo 3 inches. I'm looking forward to building my foamcore longbow limbs to go on the ILF riser I built
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| From: bodymanbowyer
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| Date: 05-Apr-17 |
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I would have guessed, the foam would have been lighter. Hmm... JF
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| From: fdp
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| Date: 05-Apr-17 |
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What kind of foam was it just out of curiosity? That's a huge difference in spine/stiffness.
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| From: RonG
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| Date: 06-Apr-17 |
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I am missing something here, if the foam just dropped 14 inches why would you want a limb made out of such a weak material.
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| From: marc
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| Date: 06-Apr-17 |
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"What kind of foam" I hope to get in touch with my supplier and get more information about the foam.
An inquiring mind makes me do it. I want to see what it does in my limb design. Keep tuned.
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| From: marc of PAW
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| Date: 23-Jul-17 |
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I did make up a set of longbow limbs out of the foam for the 15" ILF riser I made. The limbs are made out of 7 lams which are 4 ply woven carbon, 2/1 taper foam, speed strip 3" past fadeout, .030 uni carbon, 2 parallel foam, and .040 glass. It made a 64" R/D longbow 52# @ 28". Weight increase from 26" to 30" draw is just under 3# per inch. Crono test with many shots using a 481 gr arrow and drawing to 28" averaged 181 fps. For me it was an interesting experiment and most of all I enjoy shooting the bow.
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| From: badger
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| Date: 23-Jul-17 |
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Seeing as how it is just acting as a spacer I don't think the spine and stiffness really make any difference. The foam is probably more precision but hard to say as I have never seen it.
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| From: Hal9000
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| Date: 24-Jul-17 |
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guy here in Iowa a few years back made his own foam lams and put less glass spheres in it as he got closer to the limb tips. He wanted the tips to be as light as possible. Double carbon with an osage riser with a piece of aluminum sandwiched in the riser for stiffness. Touched 198/199 fps at 28" with 10 gpp. There were witnesses and it was documented. Ken of Whippenstick had either wood, or boo cores and nudged 200 fps. Kid from Minnesota had a longbow with hickory cores and glass and hit 195! More the design than the cores.
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| From: Iwander
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| Date: 24-Jul-17 |
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The guy that used to cut lams at old master crafters told me that syntactic foam was just nothing but a gimmick. I don't know if that's really true but I have always wondered if non synthetic material in a limb core could actually change enough due to heat and humidity to change a bow's performance. I don't know too much about action boo, but it's hard to beat good tempered bamboo core for lightweight and stiffness.
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| From: George D. Stout
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| Date: 24-Jul-17 |
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I think a lot of it is the total misunderstanding of the term foam as it applies to limb laminations. It's not at all like Fun Noodles or packing material. Here is a more thorough explanation.
https://en.wikipedia.org/wiki/Syntactic_foam
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