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Main Boards => The Bowyer's Bench => Topic started by: Mad Max on December 05, 2020, 09:34:46 PM
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I emailed Bearpaw this question
Will 2 pieces of Stabil-kor (1 under the belly glass and 1 under the back glass) help a High reflex Recurve.
Thanks
Response-- Our Stabil-Core is normally used as the middle layer in the limbs to help prevent twisting over time. It does not have any performance effect on the bow by using it but to stabilize the limbs.
So I edited my question and asked again
SORRY--EDIT--Will 2 pieces of Stabil-kor (1 under the belly glass and 1 under the back glass) help a High reflex Recurve with stability, and where should I put them in the stack?
Response--You can use them directly under the glass which is going to increase the stability and the draw weight of the bow. If you only use them in the middle, you only increase the stability.
So I was going to build a thin unstabil Recurve bow and wanted to know if 2 stabil-core was better than 1
It got me thinking about this topic.
So the Topic that comes up on this forum all the time is where in the stack to put it.
What I get from there answer is next to the back or belly glass is going to compress it or stretch it, dead center (edit--Neutral) and it should do it's job better.
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Interesting. I have until recently always put as close to the belly glass as I could. Lately between the lams for the racing stripe look. I haven't noticed one place being better than the other. Of course my recurves are more moderate. Hope you can shed some light on this.
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I too put mine next to the belly glass but I think I'm going to the center.
I've already told you more than I know :tongue:
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From the secnd response:
Response--You can use them directly under the glass which is going to increase the stability and the draw weight of the bow. If you only use them in the middle, you only increase the stability.
Hmmmm.... So, if we put an extra maple lam of .015 in the center of the stack, it will increase the draw weight. But if we put .015 of stabilcore in the center it won't increase draw weight.
Somethin wrong with that pitcher.
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I have always put StabilKore between the back and belly lams running along the back of the riser. Now I'm considering using two pieces of SK in the center of the stack w/ one passing behind the riser and the other running up the ramps - a forked racing stripe, so to speak.
Thanks for the interesting post Max!
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add .015 you will increase the weight. You got to use the SC as part of the stack.
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How much testing do y’all think Bear Paw has actually done on the placement of stabilkore in stack? I say do your own testing and see what works best for you!
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How much testing do y’all think Bear Paw has actually done on the placement of stabilkore in stack? I say do your own testing and see what works best for you!
Yes to that!
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I exclusively use the Stabilcore under the backside veneer and only in my recurves. On occasion, it has been put under the belly side veneer. I have never put it in the middle and can't see as how it would be as effective in the neutral plane as it would on either belly or back.... I would say that I have good success with it in the back and wouldn't put it in belly unless for some reason you needed extra stabilization.
Having said all this, i have no clue what anyone else's bows like.
BigJim
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The last sentence was to say, "putting stabilcore in both belly and back is unnecessary unless you have a real need to stabilize a limb.. "
I just read my last reply and thought it might be confusing.
Thanks ,bigjim
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The last sentence was to say, "putting stabilcore in both belly and back is unnecessary unless you have a real need to stabilize a limb.. "
I just read my last reply and thought it might be confusing.
Thanks ,bigjim
I think I need to. :thumbsup:
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Since Bue was kind enough to provide a link to ISOSPORT, the manufacture of BearPaw glass and stabilkore, it was worth looking at the tech specs provided. The ad copy from Bearpaw is worthless if you are looking for information of any value.
ISOSPORT makes a number of composites, the Stabilkore looks to be one of their fabric based laminates.
They offer carbon, E-glass and Basalt fiber as reinforcements.
BearPaw advertises stabilkore as a "Carbon alternative" which implies the material being used is similar in its physical properties. This is not true, neither E-glass or Basalt has similar properties to carbon fiber and in fact Basalt and E-glass are very similar to each other. Reading the provided literature, the only laminate to fit the description for Stabilkore is a plain weave Basalt reinforced epoxy composite. The transverse strength info, shows it to have 1/8 the strength compared to its longitudinal axis.
Plain weave reinforcement fabrics are not the strongest in resisting torsional forces, which is what they are suggesting Stabilkore be used for. Triaxial or Biaxial fabric would be a more suitable material for transverse strength. In fact a bowyer could buy them self some fiberglass or even some Carbon fabric ;), add it to their layup and have a superior reinforcement.
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I am thinking a 45 weave carbon fabric would be better. But have no idea what to get.
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Flem
If you don't know, Stabil-core is like a limp noodle compared to fiberglass.
Thanks for the info Bue/Flem
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Flem
If you don't know, Stabil-core is like a limp noodle compared to fiberglass.
Thanks for the info Bue/Flem
True, but stabikore is without resin until you lay it up.
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Flem
If you don't know, Stabil-core is like a limp noodle compared to fiberglass.
Thanks for the info Bue/Flem
True, but stabikore is without resin until you lay it up.
Yep
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Flem
If you don't know, Stabil-core is like a limp noodle compared to fiberglass.
Thanks for the info Bue/Flem
True, but stabikore is without resin until you lay it up.
Yep
Not true, Stabilkore is a composite according to the info provided by BearPaw and all their dealers.
In any case, what I'm saying, is its not the optimum reinforcement for torsional rigidity.
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All I know is that it does the job for me.
I'm making a 1.25 wide recurve with a .215 Stack--25#@28"
5" from the tip it is .163 thick and it is stable. :)
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Not true, Stabilkore is a composite according to the info provided by BearPaw and all their dealers.
In any case, what I'm saying, is its not the optimum reinforcement for torsional rigidity.
It may not be optimum but it does improve stability. It does no work of any kind until it is bound in place with resin.
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And it is a good idea to be sure you got plenty of glue on it. To me it looks like it soaks some glue.
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https://compositeenvisions.com/hexcel-himax-carbon-fiber-fabric-biaxial-45-45-degree-12k-50-127cm-2-95oz-100gsm-t-700-fiber/
One layer of this stuff would be thinner, stronger/stiffer and lighter than StabilKore
It also will add nothing till it is bound in place with resin.
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That's some interesting stuff. Have you used it? The 45* orientation should provide superior stability.
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I have used it, but not in a bow. Only for alpine skis, which are subject to way more torsional stress than any bow.
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How was it for penetration by the resin? How did you cut it?
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Awesome sleuth work there Flem.
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How was it for penetration by the resin? How did you cut it?
It wets out nicely. I was using it in a "by hand" lay-up. I use a rotary cutter, no distortion of the fabric that way. You can cut it with a fresh razor blade or knife edge tailors shears also.
If you were incorporating this into a bow lay-up using EA-40, it would be worth doing a separate wet-out of the fabric first on a strip of parchment and sliding it into the lay-up rather that trying to wet it out on a slippery lam! Might want to heat the EA-40 up to about 90* and use a roller instead of a squeegee/scraper.
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Thank you Flem. Sounds interesting, but perhaps a bit difficult to lay up in a bowlimb?
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If you were to wet-out the fabric by itself, it might add around 5 minutes to the layup.
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Disagree with Flem...4.85 min :biglaugh:
Bue I lay out a sheet of material 72 " long (Cause thats the length of my form) by whatever width I want to prep then use flat aluminum straight edges 1/2" apart and spray with a 3m adhesive. I leapfrog this over ending up with 2" strips of material after I cut down the middle of the adhesive with scissors.
The glue edge on both sides of the strip hold the material intact from fraying. Ill add this to my layup with a roller and like flem said make sure your bowsnot is warm to promote better wetout.
You do waste some material this way so maybe Ill try Flems method using a rotary cutter.
Hope that was clear as mud Lol
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Spray adhesive on the edges is an excellent idea Charles :thumbsup:
Love learning something new! Especially when it simplifies work