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Discussion Starter · #1 ·
I've been reading the opinions at various sites about which core archers prefer on limbs. To summarize what I've deduced from others:

Wood core is more stable, less vibration, less susceptible to release mistakes, and more durable.

Foam core is faster, lighter in weight, with more feedback from each shot.

Reading at the Border site, I saw this: "[synthetic core limbs] offer more arrow speed than their wood equivalent. This difference is roughly equal to 1lb to 2lbs of bow weight performance."

That doesn't seem like enough to give up the stability of wood core if 4 fps or so gain in speed is the only advantage foam offers, so I'm thinking there must be other reasons people choose foam core.

I noticed the MK Korea top limbs (Vera and Mach) are wood core, and Win & Win's best, the Inno EX, are offered in wood. In other words, obviously a lot of experienced archers prefer wood core.

The limbs that interest me most are Border, but any experience with top of the line wood vs. foam core limbs would be good to hear about.

Thanks.
 

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I have no direct experience but have heard that foam cores are more temperature stable (consistent speed) on a given tournament day going in and out of the sun. 1 or 2 fps variation would make a big difference at 70 and 90 meters and require a sight change.

Rasyad
 
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Ask Any bowmaker this stupid question. "What poundage would the core alone make if you tillered it up without any composits slapped on either side".

Id guess about 1lbs for a modern ILF recurve limb.

So, lets take a guess. lets say that there is 100% difference between cores. meaning a core can deliver 2lbs from exactly the same spec.
This means that you can reduce the core thickness by less than a sheet of paper thickness to get back to the same weight (assuming the conventional 0.002" core per pound of bow weight)

Well. Did that do much to the bow? it saved mass... but the taper is still the same... so the bending relationships are still the same...

SO there must be more to this core making business. Well yes, Mass.

Core mass can change the limb weight and our experience is about 20% lighter mass core will result in about 2-3fps.

So that leaves you with a dialema.

Why choose a wood core.

Well, back to the bowyer question. Ask them if the core sizes they use for a bamboo core changes for a Wood core. and if all things are equal, id guess there wont be a difference. (we don't get one with Elm, maple, Bamboo, Superflex and Hyperflex)
So if the same core size and same laminate deliver the same bow weight, then there is not much of a difference in the DFC as the same result at 28" is delivered...

so if I were thinking one limb is smoother than another, and they have the same widths, and same profile, then it MUST be a different taper. (and you can measure this at home)

so what other differences can their be. Well, We have seen foam cored limbs that have a set in them after time. While the new ones don't, so I would say that some foam core limbs (AND I SAY THIS WITH CAUTION as not all show this) have a set near the fadeout as they get older. and this to me means that the foam has been made light, to the point where its turning delicate.
Syntatic foam is a foam filled with glass microspheres. More spheres the less mass.
but a lot of foam cores are not that light, and don't demonstrate a set at the fadeout. as they are more dense. I wouldn't say that W&W foams are the same as Hoyts for example. and not all cores in W&W range are the same either, from Kevlar fills, to Titanium structures in there.

Its possible to find comments of "My limbs seem to have lost cast..." well, yeah, look down the limbs edge and look for a rearward bend near the end of the fadeout and that will explain why.

but in the mean time. The only other thing I can think of is wood cores being durable (yes, if they don't take a set)


one Caviat. our cores are not foams. but this same data, same thinking still applies. do the cores take a set... (demonstrated over time with any particular limb design) do the cores provide a mass difference in the holistic limb design.....
other than that the string lift point shows you how the taper and profile work to deliver smoothness.

hope this helps...
 

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I have no direct experience but have heard that foam cores are more temperature stable (consistent speed) on a given tournament day going in and out of the sun. 1 or 2 fps variation would make a big difference at 70 and 90 meters and require a sight change.

Rasyad
would warm weather also provide small thermal uplifts. and a change in Air density...

Would a warm day also provide a change in muscle reactions. as well as change fatigue in the human.

I think there are more things to blame than a patened foam concept that removes skillfull core selection in the construction process.

Take this one for example.

Carbon shrinks with heat
Glass expands with heat
Resin Expands with heat.

Carbon and resin remains a constant.
Glass and resin expands with heat.

cant advertise that if you don't have a glass less limb.... but who started this "temperature is effecting your core"? and has anyone managed to identify its source for real. anyone tried a solid glass limb in heat? to see if this changed?

im a sceptic of the core being the source of movement.

and BTW. they don't make Machines chassis (mills and Lathes) out of Alu because it changes size to quickly... Cast iron is more stable?

there are too many other variables for me to be convinced, but I haven't gone to a hootershooter in a controlled environment to test out atmospheric pressures, with all glass limbs vs all carbon limbs to test some of this... if you see what I mean.
 

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j-san = Jason
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I regularly shoot at 70m and 90m with my Olympic recurve and have tried a variety of wood core and foam core limbs. Most of the time the ambient temp was around 70-80F when I shot outdoors. I never needed to move my sight pin on a warmer day vs. a cooler day, but a 1 mph wind from any direction made a much bigger difference than temp, in my opinion. Really, I am not a good enough shooter to realize the slight differences between foam and wood. I did notice some wood core limbs seemed to be quieter than foam core limbs and could tolerate a slightly larger variance in brace height before getting harsh sounding on the shot.
 

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Discussion Starter · #7 ·
Ask Any bowmaker this stupid question. "What poundage would the core alone make if you tillered it up without any composits slapped on either side".

Id guess about 1lbs for a modern ILF recurve limb.

So, lets take a guess. lets say that there is 100% difference between cores. meaning a core can deliver 2lbs from exactly the same spec.
This means that you can reduce the core thickness by less than a sheet of paper thickness to get back to the same weight (assuming the conventional 0.002" core per pound of bow weight)

Well. Did that do much to the bow? it saved mass... but the taper is still the same... so the bending relationships are still the same...

SO there must be more to this core making business. Well yes, Mass.

Core mass can change the limb weight and our experience is about 20% lighter mass core will result in about 2-3fps.

So that leaves you with a dialema.

Why choose a wood core.

Well, back to the bowyer question. Ask them if the core sizes they use for a bamboo core changes for a Wood core. and if all things are equal, id guess there wont be a difference. (we don't get one with Elm, maple, Bamboo, Superflex and Hyperflex)
So if the same core size and same laminate deliver the same bow weight, then there is not much of a difference in the DFC as the same result at 28" is delivered...

so if I were thinking one limb is smoother than another, and they have the same widths, and same profile, then it MUST be a different taper. (and you can measure this at home)

so what other differences can their be. Well, We have seen foam cored limbs that have a set in them after time. While the new ones don't, so I would say that some foam core limbs (AND I SAY THIS WITH CAUTION as not all show this) have a set near the fadeout as they get older. and this to me means that the foam has been made light, to the point where its turning delicate.
Syntatic foam is a foam filled with glass microspheres. More spheres the less mass.
but a lot of foam cores are not that light, and don't demonstrate a set at the fadeout. as they are more dense. I wouldn't say that W&W foams are the same as Hoyts for example. and not all cores in W&W range are the same either, from Kevlar fills, to Titanium structures in there.

Its possible to find comments of "My limbs seem to have lost cast..." well, yeah, look down the limbs edge and look for a rearward bend near the end of the fadeout and that will explain why.

but in the mean time. The only other thing I can think of is wood cores being durable (yes, if they don't take a set)

one Caviat. our cores are not foams. but this same data, same thinking still applies. do the cores take a set... (demonstrated over time with any particular limb design) do the cores provide a mass difference in the holistic limb design.....
other than that the string lift point shows you how the taper and profile work to deliver smoothness.

hope this helps...
Thanks for the detailed answer. I am embarrassed to say I wasn't able to follow all of it. For example, I don't know what it means for limbs to "have a set in them" as you said.

Of course, you make both wood and synthetic cores, so I know your opinion about which gives what benefits is objective. But from your comments I wasn't able to figure out what benefits one has over the other :eek:

It seems like you are saying the Hex H limbs are lighter, faster, and all things considered, almost as durable as wood. Smoother too? I wasn't sure you said that or not, but I don't think you said anything about which limb is more stable or handles release errors better. Smoothness is important to me.

I've imagined the Hex H limbs are speedy, lightweight and very smooth, probably more than Hex W, but also more sensitive to archer error. I do value stability however, so if there isn't so much difference in smoothness, I might choose wood. As I mentioned in the opening post, there must be good reasons why a lot of top archers choose wood cores.
 

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markliep
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In my limited experience in below freezing temps my Border cvs (carbon-synthetic) limbs pretty much felt the same as in warmer weather - wood based limbs (wood - glass, bamboo - glass & wood-carbon-glass) seemed heavier at below freezing - didn't see abig difference in poi but I was only shooting out to about 30m - M
 

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I have long wondered about the long term durability of the syntactic foams as they age. MY first limb blow up (maybe 10 years ago) was a setoff used 50# Hoyt FX limbs that cracked a tip and delimitated along the foam core all most all the way to the fadeout point. I noted that the foam core was discolored perhaps 1/4-1/2 inch in from each edge. It was kind of a dirty grayish-tan while the center part was a light grayish-white.

I recognize that those FX were probably early-gen tech and that current foams along with current adhesives and finishes have probable made a lot of progress since those limbs were created.

In comparison I have several sets of older Hoyt Carbon-Wood and Carbonwood limbs, while I have reservations about how much the "carbon" used (Isn't wood actually carbon based? ;) actually adds to the limb performance, the limbs are still holding up well with little change in their feel or performance.

FWIW, I latch on to every pair of those old Hoyt CW limbs I can manage, even thought I also have some of the more contemporary near-state-of-the-art limbs.
 
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Barefaced tightropewalker
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Hey I'm new to this how to u create a question thanks!
On the forum board (the one with the list f thread titles) there's a button on the top left to start a new thread.



For now, click on the icon above.
 

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I've seen some pretty good archers swear the bamboo sky limbs are the smoothest they have ever shot. I've only had one set of foam cores, they were harsh upon release.
 
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LOL. Well most wood core have a snapper feel to the release. Foam has a less definite ending. Kind a 'thunk' with woods core vs 'whiiink' with foam core. Louville slugger home run compared to a Easton home run. Soft ball foam core vs hard ball wood core? Are is it all in my imagination?
 

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赛
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LOL. Well most wood core have a snapper feel to the release. Foam has a less definite ending. Kind a 'thunk' with woods core vs 'whiiink' with foam core. Louville slugger home run compared to a Easton home run. Soft ball foam core vs hard ball wood core? Are is it all in my imagination?
Something to consider is that wood core is nature's own UDR, whereas every foam/synthetic core I know of is cellular and/or granular in structure. How so? Wood is made up of single continuous parallel strands of cellulose fibre bound together by lignin, which is nature's version of polymer resin. In short, a wood core is a tapered strip of UDR laminate. Synthetic Core on the other hand is a granular structure made of thousands of "cells" that are a skin of the core's material surrounding a bubble of air. The microballons and microspheres that are used to make resin lighter and tougher are similar; tiny spheres of silica filled with air. In that sense trying to compare the two is like trying to compare apples & oranges. I'm not saying that the one is fundamentally better that the other, just that the principles of design for the two are radically different.

And there is a third option, monolithic carbon limbs - again a UDR structure - such as those made by Uukha. Of the three, I've decided on a pair of Uukhas for the riser I'm building as better suited to my purpose than either a wood cored or foam cored laminate limb.

Assuming the riser performs the way I hope, I'll be posting about the build in a couple - three months.

Regards,

Salskov
 
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taking a set.... following the string... or staying slughtly bend in the direction of draw.


but its possible that tiller can effect how the shot feels. limb timing.
string quality of construction and brace height (again controlling closure timing) also effects how the bow feels on the shot.

we are still not convinced that there is a big difference between cores. especially when there are other factors that can contribute to each aspect of the observation
 

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Besides physical weight a core is just a piece of material used to separate the laminates, the greater the separation the stiffer the limb, like an I-beam. But there are other things going on as one side of the limb is under tension and the other compression. This means the core is under a shear forces if it doesn’t compress (squish down to a reduced limb thickness). I have no idea on what this does to a limbs feel but it’s really the only explanation for what others have stated. The smoothness feeling is not the DFC then it must be hysteresis or something like that.

The monolithic limbs like Uukha are intriguing, the core is CF which has some of the same desirable properties that are in the laminates. The issue there is added weight, so do the benefits outweigh this? There is also the question as to why everyone is still building laminated limbs, is this one of those this is the way we always did it things? Or are monolithic limbs just a fad?
 

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hell, us older guys KNEW that compounds were "just a fad" too. LOL
 

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Discussion Starter · #19 ·
we are still not convinced that there is a big difference between cores. especially when there are other factors that can contribute to each aspect of the observation
Interesting. What do you say about wood vs. synthetic core in terms of stability, and issues like lateral movement of the limbs? It seems like you are suggesting there is very little difference between Hex 6 wood and synthetic cores.

Also, I'd enjoy hearing your comparison of using monolithic carbon vs. synthetic foam for limbs. I assume you could build monolithic carbon limb if you wanted to but choose not to.

In short, a wood core is a tapered strip of UDR laminate. Synthetic Core on the other hand is a granular structure made of thousands of "cells" that are a skin of the core's material surrounding a bubble of air. The microballons and microspheres that are used to make resin lighter and tougher are similar; tiny spheres of silica filled with air. In that sense trying to compare the two is like trying to compare apples & oranges. I'm not saying that the one is fundamentally better that the other, just that the principles of design for the two are radically different.
Of course, what I am interested in is what you didn't say, which is there is a detectable difference between wood and synthetic; in particular, are wood core limbs of the same quality and design (except for core) of top of the line limbs like Win & Win, Border etc. more stable than synthetic, but simply just bit slower and heavier than? Or is the wood-stability thing not so true?
 

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IVe owned both the foams and the bamboos I don't believe the average archer is in tune enough with his limbs to know the difference between a limb that sucks or a top notch limb.

Even as much as I shoot and compete at several different disciplines its hard for me to tell much of a difference..

Right now ive got several sets of the SKY double carbon bamboo limbs and they draw smoother than my Hoyt F7 and some of the cheaper Win Wins that ive owned..and my scores are much higher with the TR7 riser than my hoyts...this is on dots..3-D seems to be about the same so far..


Dewayne Martin
 
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