Whats this talk about foam in limb cores

[**DONOTDELETE**]

I have shot Ron's foam core Shrew's, they are nice. But then I like the way ALL of the Shrew's shoot.

I would THINK that the foam would absorb some noise and vibration, am I right?

[KrEn]

foam would absorb some noise and vibration

Why, wood is a decent absorber of vibration, anyway, i dont know, absorption = hysteresis.
It might MAKE less vibration if it is lighter.


K

[hunt it]

I have a 75 pound Morrison Dakota with wood limbs. I also have a new foam core and carbon set of same limbs which are 72 pound. The new foam & carbon limbs draw way smoother than the wood and shoot the same arrow about 4 to 6 FPS faster over the 75 pound wood limbs. In fact several of my friends can only draw back the 75 pound wood limbs about 6 to 8 inches max and can draw 72 pound foam limbs back to 28 inches no problem. Both limbs are identical length and models. So, from my point of view foam & carbon is way to go. Many people should beable to increase weight five or six pounds without having problems if desired.

[Wampus]

What about them nanotubes I'm seeing advertised on limbs these days?

[Hattrick]

There it is!! I`M SOLD     Those limbs are smooth  

[bentpole]

So is the added expense of foam core limbs worth the extra 4 FPS? Only an individual can make that decision I guess. hunt it says with foam core and carbon  limbs an archer should be able to increase their bow poundage weight by 5 to 6 pounds!!?? My bum shoulder just smiled at me!

[Huntrdfk]

This is purely subjective, so take it for what it is worth.....at the Shawn's Bunny Hunt this weekend Larry and I both had Shawnee Dakota's, both 47@28, and both 62" long. Mine have bamboo cores, Larry's were foam cores and carbon. We each shot some arrows out of the others bows, and to be truthful, neither of us felt that one bow was smoother than the other.  As for speed, with the naked eye we couldn't tell the difference.  Again, take it for what it is worth....

David

[SERGIO VENNERI]

Hi dave;
           With all due respect , how can one pair of 70+lb limbs be smoother than another?? a force draw curve would show if there is any difference, but "feel"!!?? 75# @28 is 75#@28, if they both have a build up of say 3#/inch, how can one be smoother than the other?? Maybe i just trust only in science too much !? I totally agree with O.L , send them to Norb or Blackie . The speeds that he is claiming would make it faster than the ACS, Predator, Swan ???
     Sergio

[bayoulongbowman]

Just a  guess but I bet guys that pull heavy weight bows could tell the difference...

[Jason R. Wesbrock]

I wouldn't be at all surprised if Bob Morrison's getting 4 fps more out of his foam core limbs. The man makes amazing bows.

[hunt it]

SERG AND DAVE,

I also have a 64 pound set of Dakota wood limbs and a 63 pound set of foam & carbon limbs identical specs. The difference on the lighter limbs is not near as noticable as with the heavy limbs. I cannot answer as to why but I can say I checked the weight of 72 pound foam & carbons with scale and they are on. There is a very noticable difference as to how smooth and easy they draw compared to the 75 pound woods. As I mentioned earlier several guys have compared the two that could not draw back the wood limbs but had no problem drawing the foam carbons to anchor. For me this is a noticable and great difference. So much so that it has me now considering an 80 pound set. As for the scientific reasons I`ll leave that to OL and Krister but the above has me sold for now. The other major reason for myself going this route is the moisture concern. Serg, you know what 14 days of rain and snow can be like in our north country. I leave my bow hanging in the tree sometimes three or four days straight and sometimes its raining for all those days. The fact that there is no wood in this bow is somewhat comforting for those reasons as well. The above limbs are all mounted on 100% phelonic riser. You guys buy one and send it to Blackie, perhaps you need to know Blackie tests bows that are given to him and he keeps em! Some bowyers prefer not to send Blackie free bows.

[Lewis Brookshire III]

I have had only one set of carbon/foam limbs. They were Sebastion Flute Shorts and they were by far the smoothest drawing set of limbs I have had, and they didnt quite feel the weight that they scaled. They were 52# and "felt" closer to 48#'s.

[SERGIO VENNERI]

Dave;
        I was by no means trying to be offensive or disparaging about Bob or his Bows, his Bows are a work of art and i understand that he is a very nice person. But I still maintain that 75# is 75# and the only thing that will change that is Bow design.I went through this with bamboo versus action wood. I have a recurve that i have 2 sets of equal weight limbs, 1 set with bamboo core and one set with action wood core. This particular Bow has a 2 thousandths of an inch taper , so the last 8 inches has hardly any core wood left I can feel no difference in the draw or speed of either of these limbs and bow the draw force curves are the same. However on a thick cored long bow there probably is a difference with either bamboo or foam , these bows i know nothing about as I am strictly a recurve shooter.
             Also Dave I know as you do what our Moose seasons are like and leave my Bows in a tree over rainy nights and have no problems with hunting weight Bows. Feathers are another subject. I will quote what the late Earl Hoyt told me many years ago concerning foam cores " Sergio the reason i use foam and carbon in my recurve bows is for consistency only ie; using a 41# fita Bow at 80 meters in a humid climate one day and a dry climate a few days later could result in a 1-1/2 lb difference in Bow weight, this is very significant in a 41# Bow at 80 meters,but  in a hunting weight Bow like yours @65# do not waste your money , there is no significant gain!"
     As for Blackies tests, yes i'm aware that Blackie gets to keep the Bow and so does Norb, however Bob is very generous as i've seen in the past so I doubt that it would bother him to give a Bow away in the interest of Science . I know many others that have not had their Bows tested and can only wonder WHY??? I give a lot of credibility to both Norb and blackie and find both there tests very unbiased.
      Again I mean no harm , but feel that if we are basing things on opinions then i am entitled to mine also.

                Respectfully
           Sergio

[Orion]

I don't have a dog in this race, but it seems that the comparisons being made are confounding variables, making it impossible to say which most contributes to the discussed effect, the core -- foam vs wood -- or the backing -- carbon vs glass -- because foam-cored carbon backed limbs are being compared to wood cored glass backed limbs.  An apples to apples comparison would involve foam cored carbon backed limbs to wood cored carbon backed limbs.

[hunt it]

Sergio,

No problems here bud. We are both just saying what we think is the case, and as you stated we boyth have different opinions. Hopefully one of the engineers or testers will show us the exact difference at some point. All I know is I love my new limbs.

Orion, good point!

[Bill Howland]

I don't have any stock in this foam so I'll add what I saw when I laid up a set of prototype limbs using the Syntactic foam that Old Master Crafters sells. Yes, it's bluish gray. Yes, it's very light in comparison to boo and or wood more to the weight of Yew. It's very brittle and that scares me. I actually accidentally knock one lamination of my table saw and the .002 lamination's tip EXPLODED into a bunch of little bitty pieces! Being a clumsy person I've also dropped wood and boo cores and they normally do not explode. I laid up the limbs with 2 to 1 ratio/two parts core, one part glass. At the same time I laid up a set of limbs with the same ratio with old stock "Maple" Actionwood. Not the white birch sold today. The wedges, glass and tip material were all the same, out of the same batch glass or piece of wood. Laid up all four limbs in a single press. I built one riser using Old stock Maple Actionwood. Squared everything to 1-5/8" wide through my Performax at the same time. Drilled all holes using a my mill. Everything was kept to the same tolerances as possible. Rough shaped the limbs using the same template, cut to nocks to the same depth using my mill. These limbs are pretty much identical dimensionally.

Mounted the foam limbs on the riser, grabbed a 62" string and these limbs were weighed on my digital scale 48# @ 28". The limbs were dead straight and tiller was zero. I removed a slight amount of the glass off the belly at an angle on the upper limb to tiller to 1/8". The limbs were finished sanded and the edges of the glass rolled over slightly. Trying not to expose the cores to much. Because I feel the foam is brittle and could fracture easily with a side impact. The limbs finished out at 46.4 pounds at 28".

Went to the wood glass limbs mounted, strung and weighed. They were 56# in the rough. Eight pounds heavier in draw weight. Also the tiller was already at 1/8" but upside down and the lower limb was twisted a little to the left. Flopped the limbs around and straightened the limb by hand filling the opposite side nock until the limb laid straight. Finish sanded, rolling the edges over as normal. These limbs finished out at 54# @ 28".

Performed a draw force curve on both sets of limbs and yes, the foam was smoother. At its lowest increase per pound it was 1.9 pounds increase per inch. Where the wood cored limbs lowest was 2.25 pounds increase per inch. SE/PDF for the foam cores .910. SE/PDF for the wood cores .921.

I did shoot these limbs over a chronograph using a shooting machine drawing the bows to 28" and using as close as I could 9 grains per pound. The wood limbs were faster by 3 fps. But the foam limbs were quieter by perception only.

Now to be truly fare the limbs should be the exact same weight. But I was not going to remove that much material of the wood limbs to reduce it to the foam limbs.

Conclusion: I can see an advantage for a manufacturer to use foam. Simply better consistency over wood. Easier to tiller. Cut the limbs out straight and they are straight. Unlike wood. Higher core ratio should also produce better lateral stability because of the greater separation between back and belly skins.

The only hesitation I have with the foam is "HOW TOUGH IS IT?" We'll find out. Over time I think you'll see more and more foam limbs hitting the Traditional bow market. I can say this though I don't believe at this point that I would suggest a foam cored limbs to guys that hunt in extreme cold temperatures.

[amar911]

Bill,

You are always a wealth of information. Thanks for contributing to this thread. I hope your arm is healing well, and not just because I am waiting on my Non-Typical! How are you coming on the static tip recurve design? I am eager to see it in production. If I remain down the list when you get the new bow design ready to produce, I may have to change my order.      I know it will be hard to beat a Quest, and I say that as the owner of 6 of them, along with about another 8 or 9 other Bracks.

I have a number of foam core bows by various bowyers and have been very pleased with all of them. The foam is more brittle, but so is carbon fiber and glass fiber. I don't think it is a problem in a finished limb.

Take care,
Allan

[Bob Morrison]

Lots going on here??? I have been using the foam cores for over a year now, I'm very happy with it and the only core I will use for my personal bows. We still use actionboo cores in our bows as always.We are using some carbon also.. As long as I can see useful improvements in my bows I'll keep doing what I'm doing, and look for new materials, designs, glues what ever I think may work better. We make custom bows to what ever your needs are, we just give more options..I really don't care if someone bow is 2 fps faster than my bow, and there is a difference in feel at the same poundage and if you can't feel it I guess you need to try more and different bow materials.I could give Norm a bow and find out what? My bow is plus or minus 2fps against youever thinks there is fastest.... It just doesn't matter, there are much more important things in life. I choose to give my bows to different groups to auction off to benefit them, seems a better way to help out.

[mooseman76]

Bob, have there been any durability issues with hunting weight bows (say over 50#)?  I know foam cores have been around a long time in the target sects, but they normally shoot light weight bows???  Thanks...Mike

[Bob Morrison]

Mike, We have had some failures none from the use of the foam cores, always different issues. WE have had less with the foam that with any other core material we have used.
We have some heavy weight stuff out there and so far all is good. The only trouble we normally have is long draws trying to use a short draw limb.