Trad Gang
Main Boards => The Bowyer's Bench => Topic started by: williwaw on January 14, 2021, 09:22:39 PM
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A nice discussion is going in a parallel thread regarding alternative lams materiels where carbon or glass is typically used on the back or the belly. https://www.tradgang.com/tgsmf/index.php?topic=174583.0 (https://www.tradgang.com/tgsmf/index.php?topic=174583.0)
Foam is mentioned as an alternative to wood for cores, but my understanding is that its primary benefit is temperature and moisture stability. Arrow speed improvements attributed to core selection are said to be nominal.
Some comments suggest presently used glass and carbon lams are not utilized as fully as they might be for performance gains. Are there better core materiel's out there to build with? Can anyone share their their understanding of what materiel properties would be required to make a better core for a faster bow? Or maybe reference or comment on any previous development attempts?
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First thing is good design. I have never tried it but I see several people mention walnut edge grain. Have used Yew edge grain it is pretty stiff. The old standby Elm edge grain.
I think the actionboo is used because it is real consistant and pretty decent core.
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Ive had this wood on my mind for a while. Paulownia.
From the wood database:
Comments: The other Balsa. Paulownia is used in applications where a lightweight (yet proportionately strong) wood is needed. It’s widely used in Japan for construction of the koto (a stringed musical instrument), as well as other household items, where the wood is referred to as Kiri. Paulownia is one of the fastest growing trees in the world, capable of growth rates of well over seven feet per year as a seedling! But while it’s highly appreciated and cultivated in Asia, Paulownia has come to be considered an invasive species in the United States.
Paulownia was named after Queen Anna Pavlovna of Russia (1795-1865), and is sometimes called Royal Paulownia or Princess Tree.
I might track some down and try it. The more I figure out about this bowyering thing the less im focused on the search for the ideal core wood. The amount of weight saving from core to core doesn't seem to have much bearing on performance. This was brought home to me when I did an experiment with a 66" ASL. I chronographed the bow and then continued to check speeds as I added more and more weight to the tips. I would have to check my notes for sure, but I think it got up there to more than an ounce on each tip. The loss of speed was way less than i expected. Since then I don't give hardly any thought to the weight of tip overlays! :)
So, my conclusion was that the effect of weight is the most noticeable at the nocking point and progressively less noticeable as it moves out the string to the nocks and then continues down the limb to the fades.
That area from nocks to fades is the area that is influenced by the weight of the core material. And based on my observations, it is the least important area to try to save weight. That's what has gotten me off the search for lighter core woods.
But none of that addresses the possible return rates of the various core materials and maybe it's inconsequential when dealing with the performance of the most common and proven core woods. Most of the work is taking place in the first .050 to .100 of the back and belly surfaces so, how important are the return characteristics of the wood or whatever that is making up the rest of the limb?
It's interesting to see the loyalty that many archers have for the various core materials. Every possible core has a following and many professional bowyers seems to represent that certain cores are superior. That's smart marketing.
It might be worth paying more attention to the weight of the string serving.
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I'll say it again... Your best bet for a fast bow is a recipe with a great bow design... With that and standard wood core and glass you can reach speeds of 186 to 193 @10gpp and possibly faster... After that and you still want to increase speed try tapering your glass and trying lighter core materials... To me it does not make sense to go with exotic materials and/or tapered glass on an inefficient design... Plus straying from the standard layup could be opening up another can of worms... There could be an exception or you could get lucky but this is how it usually works... You spend months and go through about 15 to 20 bows to widdle down a very efficient recipe to get you 186 fps, now you decide to taper the glass and go with a lighter core... You get all excited... You are gonna break that 190 mark... Guess what?? Your bow shoots 180 fps... Why?? Because you changed the recipe... Now you have to start all over again... Maybe not go through as many bows as last time because you have most of the kinks ironed out but you will probably have to make another 5 to 10 bows just to find out you broke even or gained 2 fps... You may gain 4 to possibly even 6fps but I doubt more than that... But then I have not gone to that extreme yet so I don't truly know... Then there is the possibility of only gaining 1 to 3fps if your design is only shooting 175 fps to begin with... A lot of trouble and less stout bow for 1 to 3 fps... Better to perfect your design with standard lay up before you start getting funky...
If you are gonna go for a lighter core I suggest a nice piece of Douglas Fir for the whole limb in a bow under 35# and a maple/fir spliced core for a heavier bow... To go much lighter than fir I believe you are taking chances... Kenny has a cool way of splicing a core lam, I forgot what he told me... Maybe he will share that with us... I would like to hear it again to take note of it...
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In reference to Longcruise's post...
I have talked to bowyers that swear that certain wood cores shoot faster and smoother and talked to other bowyers that say the core does not really matter and seen no difference in performance between different woods...
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Yup. There are endless internet conversations on the topic but no supporting evidence that i know of.
Smooth??? What is "Smooth"? You nail the answer with your reflections on design versus material performance.
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Kenny has a cool way of splicing a core lam, I forgot what he told me... Maybe he will share that with us... I would like to hear it again to take note of it...
hopefully he can.
Tapering glass is worth a thought. How much of a taper have you experimented with? I hope I am not asking about something that has been covered in previous threads. Have you seen much written about this online elsewhere?
thanks
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As I said I have not gone to that extreme so I have not tapered glass yet...
Just a note... I have hit 193 fps with standard lay up... If I get to 196 and I feel that I have hit the wall, that will be one of the few times that I might go exotic just to break 200 and just to say I did it... Anything over 184 is plenty fast enough and really no need to go much faster unless you got reasons to... I got mine... :goldtooth:
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I tapered glass on one bow, didn't seem to make a diff, then it was pointed out that you are cutting glass fibers on the tapered side ...
The only cool spliced lam I can think of was one I made with maple and walnut using tapered lams , seems like about .004 or .005 " per inch .
Thick end of maple to riser and thick end of walnut to tips. Hoping for a lam that was lighter at tip end. Wasn't my idea tho, read it somewhere.
Thad Soy got that bow in a swap and told me later it was the fastest one he had. I think he was just being nice tho.
As for core materials, here is a test I did long ago...
http://www.tradgang.com/tgsmf/index.php?topic=143549.msg2519680#msg2519680
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I've found 1/4 sawn elm to be the best for my BBO bows.
Not speed bows but one that I made for fujimo hit 175 fps, not bad for wood and boo.
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I've just been reading about foam cores. Fascinating stuff. There are quite a few patents regarding the material. Here is a excerpt from a Hoyt patent, circa 1987;
"It has been found that a substantial reduction in bow limb inertia resulting in a substantial increase in arrow velocity is achieved by reducing the weight of the core strip. Applicants have substantially reduced the weight of the core strip while retaining adequate physical properties for the purpose by constructing the core of a material known as "syntactic foam" which consists of a plurality of hollow micro spheres of less than 100 microns in diameter in a matrix of hard synthetic resin. The relative volume of hollow spheres is such as to attain a density of the "syntactic material" which is substantially less than any solid or composite hardwood core.
It was also found that in addition to reducing the weight of the core strip and therefore the inertia of the bow limb in this manner, that the hollow micro spheres in the core material also function as microscopic shock absorbers to dissipate energy of impact and therefore the syntactic material has a relatively high resistance to impact which renders the material peculiarly suitable to bow limb construction. Archery bow limbs in normal usage are subjected to relatively high impact stress every time an arrow is shot and the bow limbs approach a braced position.
In the case of heavier hunting bows it is contemplated employing, in addition to the hollow micro spheres, reinforcing fibres for further enhancing the physical properties of the syntactic material while maintaining a density substantially below that of any solid or laminated hardwood. Moreover, when molding the cores the rolling action of the spheres helps distribute evenly the hollow micro spheres and fibres in the very thin tip ends of the tapered cores."
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I've just been reading about foam cores.
The fancy target limbs use foam cores these days. They claim better performance, but I haven't seen any testing that confirmed that. They should offer the ultimate in consistency for production manufacturing, though.
Applicants have substantially reduced the weight of the core strip while retaining adequate physical properties for the purpose by constructing the core of a material known as "syntactic foam" which consists of a plurality of hollow micro spheres of less than 100 microns in diameter in a matrix of hard synthetic resin. The relative volume of hollow spheres is such as to attain a density of the "syntactic material" which is substantially less than any solid or composite hardwood core.
I've never seen or handled the foam, but I have seen comments from bowyers that the foam they used is pretty much the same density as maple. I assume there are many different densities available if you can find them, but have never looked. It's good to have the correct name for the foam, I had looked for it but had little luck without knowing what its trade name is.
Mark
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I had a pair of limbs for my ILF bow that were carbon limbs with foam core.
They were noisy and the speed did not impress me at all.
Sold them.
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Thanks for sharing again Kenny...
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http://www.tradgang.com/tgsmf/index.php?topic=143549.msg2519680#msg2519680
Just got through this thread. What a great amount of info, thanks for all your work on that one Kenny.
I had a pair of limbs for my ILF bow that were carbon limbs with foam core.
They were noisy and the speed did not impress me at all.
Sold them.
Were they noticeably lighter than wood core limbs? I think they are mostly a marketing exercise and maybe an improvement from the manufacturing side, but no real improvement in terms of performance.
Mark
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Kenny, can you tell us about Loren Piper and "Pipers Bowtuff"
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Physical weight wise, not much difference than my other wood core limbs.
Both my limbs and the carbon limbs were the same exact draw weight.
The Bear archery glass with wood core was noticeably faster.
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Kenny, can you tell us about Loren Piper and "Pipers Bowtuff"
If memory serves me correctly, that is the guy who made his own glass and was making solid glass limbs?
He wanted me to be a dealer for it, but never sent me the sample to test, then he kinda disappeared...
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I recall the failure of foam described as being dramatic with an explosion of foam bits. Belker used to sell it but he got out of bowyer supply with the change to Bivouac.
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Thanks for all the replies. Quite a bit to digest, especially the earlier testing by KennyM.
As with most tech developments, improvements come slowly and incrementally. One in a while a game changer comes along, as we have seen happen a few times with the wheelbows.
A bit about Fred Bear copied from the 3rivers website.
He found that the fiberglass, currently in a crisscross pattern, worked great on the back of the bow, but did not work well on the belly. This prompted Bear to begin manufacturing bows with fiberglass laminated backs and aluminum bellies. Interestingly, the aluminum was scrapped from B-17 bomber airplanes of WWII.
However, Bear found that the aluminum caused too much handshock when shot and there were also a large number of bows returned because of delaminating, which was caused by the large amount of shock. This warranty problem caused a substantial strain on the company’s finances; nonetheless, Bear insisted that all bows be replaced if returned broken.
This prompted Bear to begin developing a unidirectional fiberglass and, in 1951, the aluminum belly bows were discontinued entirely.
Two years later, in 1953, Bear patented the working recurve limb, which is the design that almost all modern recurves use today. The next year Bear began marketing their new fiberglass working recurve – the Kodiak II.
If Fred were still with us, would he think 250 FPS @ 10 GGP is doable?
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Loren Piper posted with some unusual ideas back in 2009. he was 83 at the time according to his profile.
https://www.tradgang.com/tgsmf/index.php?action=profile;u=18128 (https://www.tradgang.com/tgsmf/index.php?action=profile;u=18128)
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Interesting
I read his post.
What is S-glass?
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13% stiffer. specs in last column of table posted in flems thread. not sure if kenny can get it anymore.
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Don't have a place to get S glass ...
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can anyone say what stabil-kore is made from? I read it is a graphite 'replacement", so maybe not any carbon in it? I read what it does, and what it is supposed to do, and the comments that it does not add any poundage when incorporated into the stack.
if you try to light a piece on fire, does it burn? what does it leave behind besides smoke?
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You want a lighter core wood try eastern red cedar.
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Sassafras.
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Yes, Sassafras is another good light snappy pretty grain wood.
I've used that also.
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This is all I could find with a quick search, if you can get anything from it...
http://bearpaw-blog.de/bilder/bearpaw-stabilcore.pdf
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How about some Kevlar honeycomb? It's lite and strong when sandwiched.
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How ya gonna keep glue out of the voids? :dunno:
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How ya gonna keep glue out of the voids? :dunno:
Packing tape... :biglaugh:
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Would a stiff, snappy wood be a good alternative to going lighter in the core? Such as tempted edge grained black locust. Once tempered that stuff gets incredibly snappy for its thicknesses. Essentially to get the core assisting a bit with the return of t he limbs as opposed to being a neutral spacer for the outer layers. The stiffness may make up for the extra mass of being a more dense material. Now I know very little about making glass bows, but it’s just a thought I’ve have running through my head.
Kyle
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How ya gonna keep glue out of the voids? :dunno:
Torsion box construction, but to quote something I read recently;
"I have time to think about, not to do it."
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How ya gonna keep glue out of the voids? :dunno:
Torsion box construction, but to quote something I read recently;
"I have time to think about, not to do it."
:biglaugh:
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Torsion box construction, but to quote something I read recently;
"I have time to think about, not to do it."
Ah come on Flem...
You can doit...
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This is all I could find with a quick search, if you can get anything from it...
http://bearpaw-blog.de/bilder/bearpaw-stabilcore.pdf
thanks Kenny,
that helps with some specs. not all that informative about what it is really. I read somewhere bearpaw sources some of its materiels from composite suppliers that serve the ski industry. maybe it is repurposed from a different product line.
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Would a stiff, snappy wood be a good alternative to going lighter in the core? Such as tempted edge grained black locust. Once tempered that stuff gets incredibly snappy for its thicknesses. Essentially to get the core assisting a bit with the return of t he limbs as opposed to being a neutral spacer for the outer layers. The stiffness may make up for the extra mass of being a more dense material. Now I know very little about making glass bows, but it’s just a thought I’ve have running through my head.
Kyle
kyle, I wish i could try lots of different stuff. we have very few hardwoods here. birch maybe the best. i guess if I have to depend on the ups truck, I am focusing on things that might remain the same from batch to batch. Not to say your idea would not work. I think I know littler than you about making glass bows, but learnin....
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You want a lighter core wood try eastern red cedar.
certainly some lighter woods out there, but haven't the guys tried them all? most come back to maple when its all said and done.
Im looking for a game changer :)
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Eastern red cedar has a strong following in ASLs built by a fellow named Johnson I believe.
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Cedar grows wild on my place 160 acres, no telling how many I have, most are full of limbs to the ground but some in thick places that could be limb free.
Mine should look like this, scalloped at the base only and milk sap wood.
I have 3 or 4 boards in the barn.
Vertical or flat grain?
(https://i.imgur.com/0xBc9WD.jpg)
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Pretty...
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I think they are Juniper
Google
We go with the common name of Eastern Red Cedar, but they actually are junipers, Juniperus virginiana to be precise. There are indeed true cedar trees in other parts of the world, but the only true cedars in Mississippi are Asian imports grown as landscape trees.Oct 20, 2018
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I used flat grain juniper in a d/r longbow many years ago for a buddy of mine. It had those blonde streaks all through it like juniper has sometimes. I put deer antler overlays on it. Probably the prettiest glass bow I ever made. Twenty years later and he still tells me how pretty it is when I see him.
I made a juniper d/r longbow for myself. It's 90# @ 28" and has a Kingwood handle. Pretty, but I don't shoot bows that heavy nowadays.
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Give it to me Jeff, I can pull 90#...
How bout a picture?
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Damn! thats a nice stack of logs. You could mill that into some useful lumber. I wish our Rocky Mt. Juniper got that big. Apparently ERC and RMJ have similar qualities.
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Give it to me Jeff, I can pull 90#...
How bout a picture?
Probably only if it's on a dinner plate! :biglaugh:
I have an 83# R/D that I can't figure out what to do with.
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There is a thread in powwow about heavy weight bows, couple guys wanting to buy them.
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Hmmmmm...
Haven't visited there in a while.
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You want a lighter core wood try eastern red cedar.
Eastern red cedar has a strong following in ASLs built by a fellow named Johnson I believe.
ERC is up there in elasticity with some of the best bow woods. curious if the ASL usage is to reduce set or mass.
yew of course has been used as a core also. Are there claims made for increased performance or is mainly a cosmetic usage?
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My guess is good edge grain Yew would be hard to beat for core material
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Some pretty wood.
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You want a lighter core wood try eastern red cedar.
Eastern red cedar has a strong following in ASLs built by a fellow named Johnson I believe.
ERC is up there in elasticity with some of the best bow woods. curious if the ASL usage is to reduce set or mass.
yew of course has been used as a core also. Are there claims made for increased performance or is mainly a cosmetic usage?
Every ASL bowyer has a special claim about their bows and all have a following that appreciate those bows. Dave Johnson uses the red cedar and builds beautiful bows.
http://davejohnsonlongbows.com/2011/08/bows/
Yew is forever a desirable bow wood. It's self bow legacy alone guarantees it.
I can't imagine the cost in time and materials that you could invest in exploring the facts of the matter. When you are done you will be both praised and damned regardless of the facts. :biglaugh:
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Yew makes a great bow its one of my favorites and one other
very light and fast core materials is Russian Olive but you have to find it with out knots or you will end up with small fractures in the glass at every knot. Ive used a lot of different things for core including doug fir but the best is laminated bamboo and its not action boo thats something old mater crafter came out with and it was not good .
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thanks guys, no yew here either, but i have a very dense and extremely fine grained piece of doug fir that is worth trying. i think shredd mentioned it earlier, and got me to considering it.
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Willie, do you have Serviceberry up where you are? If you can find some large enough, it is one of the finest, unlikely and unknown bow woods.
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not of any diameter to get a bow from a stave. the woods available in any size large enough to cut a lam from are aspen, alder, birch, willow, spruce and hemlock
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Stave would be nice, but you don't need one. You can make nice bow from a shrub if you decrown it.
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Stave would be nice, but you don't need one. You can make nice bow from a shrub if you decrown it.
I've seen some that would make a stave. It's similar to the fruitwoods in character.
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Stave would be nice, but you don't need one. You can make nice bow from a shrub if you decrown it.
if I could find a piece an inch in diameter and long enough to make a billet I would be calling it a "stave".
not very easy to find either. there are some ornamentals in other peoples yards......
I have been up and down mountains, and what i have found is that there are occasional birch and alder that have very high density. growing conditions that yield a good stave are more of a determinant than species alone. some fast growing trees from protected areas are actually quite soft and weak.
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Do you live out on the Tundra? Sound like you need a ninja suit, headlamp and folding saw :goldtooth:
Oh, and maybe a book on pruning
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Do you live out on the Tundra? Sound like you need a ninja suit, headlamp and folding saw :goldtooth:
Oh, and maybe a book on pruning
I took a look at where 60* North is and I'm thinking things don't get very big there. :)
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Do you live out on the Tundra? Sound like you need a ninja suit, headlamp and folding saw :goldtooth:
Oh, and maybe a book on pruning
I took a look at where 60* North is and I'm thinking things don't get very big there. :)
I'm near the coast. Spruce trees 3-4' diameter, some of the best in the world for building stuff like airplanes and arrows. Might be ok for cores, if i find some with sufficient density.
Service berry, wild crabapple, etc, just not of any size. Tundra if you go up above treeline or further north. Good fishing here though.....
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Has anyone tried hickory yet in a recurve bow?
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I was told it was fast but then I was told by another that cores really don't matter... :dunno:
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Hickory did well in the Walk The Talk
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Kenny, where can i read about it?
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Bill Howland said he made his own actionwood from hickory and used it if a customer ordered a bow and was going to shoot real heavy arrows.
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One of the rules Terry has listed is "no links" to other archery sites.
Had to remove them, sorry guys.
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The site is still there but it appears to be dormant.
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Hickory really did well in WTT!!
From what I recall Ken coached aaron (Feral Donkey) on this straight limbed longbow 65" (NO backset) bow made with hickory which I think was tempered.
This bow hit 179.7 Fps @ 10 gpp which is SMOKIN for that that style bow especially since there was no reflex/backset. I shot this bow at a shoot a year after WTT.
Like Shredd sez design is everything but in a deep core environment the core does matter to squeeze out some extra Fps.
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I would be interested in any info about hickory, but missed the links. Would whomever posted the links be kind enough to pm them?
thanks.
Stagmitis, any pics of the bow? It was a ALB I presume?
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Williwaw kinda ASL profile when strung but wider flatter limb. 18" Handle, power lam, slow limb tapers.
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I would like to check out those photos, but unfortunately photo bucket......... SUCKS!
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I would like to check out those photos, but unfortunately photo bucket......... SUCKS!
2X
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Sorry Roy I wondered about that.
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Williwaw kinda ASL profile when strung but wider flatter limb. 18" Handle, power lam, slow limb tapers.
wider at the fades? I'm guessing if it didn't have much thickness taper it would be more of a pyramid with the best part of the taper being in width? Maybe the flatter limb was thinner than a ASL, and not working the core so hard, it was better able take advantage of a stiffer core made of hickory.
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Much wider at the fades and much flatter limb than a traditional ASL. He also threw out the PL lam another 3" past the fades so about a 21" handle. In effect he had a short working limb while maintaining stiffness in the outer third.
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Stotler longbows are built kinda the same way with a shorter working limb.