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Author Topic: Sharp vs. gradual recurves  (Read 7046 times)

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Offline upstatenybowyer

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Sharp vs. gradual recurves
« on: March 11, 2017, 09:19:30 am »
Hi folks. I was just looking at bubby's bows he's got in the works and it got me wondering. When is it wise to employ longer gradual recurves that work some and when is it better to go with short, sharp static bends at the very end of the limbs? I've got some ideas but I'd like to hear from some of you more experienced PAs. Thanks :)
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"Even as the archer loves the arrow that flies, so too he loves the bow that remains constant in his hands."

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Offline bushboy

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Re: Sharp vs. gradual recurves
« Reply #1 on: March 11, 2017, 09:48:35 am »
I think long recurve lend themselves better in lever type bows.statics need more meat to prevent tourquing .
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Offline willie

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Re: Sharp vs. gradual recurves
« Reply #2 on: March 11, 2017, 10:50:58 am »

Quote
when is it better to go with short, sharp static bends

different designs for sure, are you asking about the merits of one design over the other?
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Offline PEARL DRUMS

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Re: Sharp vs. gradual recurves
« Reply #3 on: March 11, 2017, 10:52:53 am »
I like to make what my eyes enjoy at the time, that's just one benefit to making your own rigs. Sometimes its just some nice reflex and sometimes its static tips. As far as design, stave length plays the biggest role. If you want to pull a 62" bow 28", you'd be best suited to make a short static section or short working reflexed section to save working length. If you have a 65" bow you can do either with great results. Whatever makes your eyes happy. I have no chrony, but have shot and built a few bows. Only a few out of hundreds and hundreds really stood out in the speed category. In the end most 50# bows are 50# bows give or take 5-8 fps. That's why I lean towards pleasing my eyes.
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Offline Badger

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Re: Sharp vs. gradual recurves
« Reply #4 on: March 11, 2017, 10:55:51 am »
 I agree with Pearlie. I have a hard time keeping the long hooks stable.
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Offline bubby

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Re: Sharp vs. gradual recurves
« Reply #5 on: March 11, 2017, 11:39:28 am »
Quote from: PEARL DRUMS on March 11, 2017, 10:52:53 am
I like to make what my eyes enjoy at the time, that's just one benefit to making your own rigs. Sometimes its just some nice reflex and sometimes its static tips. As far as design, stave length plays the biggest role. If you want to pull a 62" bow 28", you'd be best suited to make a short static section or short working reflexed section to save working length. If you have a 65" bow you can do either with great results. Whatever makes your eyes happy. I have no chrony, but have shot and built a few bows. Only a few out of hundreds and hundreds really stood out in the speed category. In the end most 50# bows are 50# bows give or take 5-8 fps. That's why I lean towards pleasing my eyes.

Pretty much what Pearl said :BB
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Offline bjrogg

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Re: Sharp vs. gradual recurves
« Reply #6 on: March 11, 2017, 12:32:13 pm »
Those curves you got on the ones you posted today bubby are very much eye pleasers :OK
bjrogg
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Offline bubby

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Re: Sharp vs. gradual recurves
« Reply #7 on: March 11, 2017, 01:07:10 pm »
Thanks bj
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Offline upstatenybowyer

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Re: Sharp vs. gradual recurves
« Reply #8 on: March 11, 2017, 01:09:50 pm »
Thanks to all for your responses.

bushboy, that certainly makes sense for sure.

Willie, I guess I was kinda getting at that. I like PD's explanation that a 50# bow is a 50# bow give or take a few fps.

PD, I had a feeling that length of working limbs had a lot to do with it. But I'm glad to hear you say that ultimately it's what's pleasing to your eyes at the time. That's pretty much how I've been making design choices at this point. That and what the particular piece of wood looks like it wants to do.

Badger, with you and PD in agreement, I'm inclined to agree with just about anything (within reason of course)!

bubby, I agree with bj. Those curves are eye candy for sure.  ;)
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"Even as the archer loves the arrow that flies, so too he loves the bow that remains constant in his hands."

Nigerian Proverb

Offline Pat B

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Re: Sharp vs. gradual recurves
« Reply #9 on: March 11, 2017, 01:13:51 pm »
A gradual bend is a lot easier to accomplish successfully.
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Offline upstatenybowyer

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Re: Sharp vs. gradual recurves
« Reply #10 on: March 11, 2017, 07:41:46 pm »
Quote from: Pat B on March 11, 2017, 01:13:51 pm
A gradual bend is a lot easier to accomplish successfully.

Agreed. Every successful sharp bend I've ever done has been with steam and I go at least 60 minutes per 1/2" of thickness. Probably overkill but it's worked so far.
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"Even as the archer loves the arrow that flies, so too he loves the bow that remains constant in his hands."

Nigerian Proverb

Offline Mo_coon-catcher

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Re: Sharp vs. gradual recurves
« Reply #11 on: March 11, 2017, 08:24:49 pm »
I'm curious if there's a different drae force curve between the two between the string starting to lift off and finally on just the nock. One that has no real transition just jumps from on the hook to the nock . Essentially a sharp kink recurve. vs one that is more curved so there is a gradual lift off.im sure it's been tested a bunch. If just like to see side by side graphs. I might just have to do so myself. I feel like they would feel different on the draw too.

Kyle
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Offline PatM

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Re: Sharp vs. gradual recurves
« Reply #12 on: March 11, 2017, 08:30:51 pm »
The Bob Kooi papers address this. Sharper angles store more energy but lower angles are more efficient. Clear? ;)
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Offline upstatenybowyer

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Re: Sharp vs. gradual recurves
« Reply #13 on: March 11, 2017, 09:37:04 pm »
Quote from: PatM on March 11, 2017, 08:30:51 pm
The Bob Kooi papers address this. Sharper angles store more energy but lower angles are more efficient. Clear? ;)

Man those papers are way over my head  ???

dy
ds
= cos θ , dx
ds
= sin θ , 0 ≤ s ≤ L . (2)
The moment M(s) is caused by the tension force K(b) in the string, we find
M(s) = K(b)h(s) = K(b)
¡
b cos α − x(s) cos α − y(s) sin α
¢
, 0 ≤ s ≤ sw ,
« Last Edit: March 11, 2017, 09:42:17 pm by upstatenybowyer »
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"Even as the archer loves the arrow that flies, so too he loves the bow that remains constant in his hands."

Nigerian Proverb

Offline Mo_coon-catcher

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Re: Sharp vs. gradual recurves
« Reply #14 on: March 11, 2017, 09:37:47 pm »
Makes sense to me. The the higher efficiency of the lower energy design, they probably fling and arrow at comparable speeds. Probably just feel a bit different during the draw cycle.

Kyle
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