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Main Boards => The Bowyer's Bench => Topic started by: Pago on November 20, 2014, 05:58:00 PM
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I have decided, probably unwisely, to attempt a recurve for my first composite bow.
19" riser
58" long
1.5" wide
60-65# target
black glass over osage lams, may do a walnut/maple thing for the riser. (I hate to cover up the osage but black glass is cheaper and will hide small imperfections as I will probably have some)
black glass .050
osage taper .085 @ .001/inch
Stabil Kore .015
osage taper .085 @ .001/inch
black glass .050
Total stack .285
I have tried to do my homework and relying on you guys to help keep me out of the weeds, so to speak. Help/advice much appreciated.
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The bow profile will have a lot to do with the total stack for producing a certain poundage. I have several 58" forms and each requires a different formula. If I were building the bow you describes I would go with an 18" riser, .0035 taper rate and .265 total stack.
Good luck on your build and be sure to post pictures.
James
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I find I am thinking and rethinking everything and your post helped me prevent a huge mistake. I went back and looked at the baselines for the design and am thinking I will back the stack down to .275, .260 is supposed to yield about 55# on this design. I'm switching to action boo on the tapers also.
Thanks for the input, I will post pics. Probably won't be till Christmas time.
black glass 0.050
action boo 0.080 (taper .001/inch)
stabil kore 0.015
action boo 0.080 (taper .001/inch)
black glass 0.050
Total stack 0.275
36% glass
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Isn't it disgusting that a person can by a Sammick Sage take down for less than the cost of materials to build a bow?
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Pago...............
How are you measuring the .080 taper or is that the butt thickness?
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That is the butt of the lam, two tapered lams total taper of .002.
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Originally posted by Pago:
Isn't it disgusting that a person can by a Sammick Sage take down for less than the cost of materials to build a bow?
That's mass production buying power for you.....when you stop and think about the point you've raised for a minute or two it's no wonder the World is in the state it is!
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I agree, its nuts. Do it yourself used to be a way to save money or make a little on the side. I have an old set of do it yourself encyclopedias on how to build everything from a pool table to a boat. I'll eventually get the cost down but with time and opportunity cost I will never come close. Good thing its about personal satisfaction which is priceless.
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don't forget each glue line adds about .002" and it looks like you'll have 4 of them. So once it's done .008" approximately will be added from the glue used.
I have a 1 1/2" wide 58" recurve I made with a 20" riser and the stack thickness is .277", and it comes in right at 60#.
But I measure the limb thickness at the fadeouts.
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Thanks Mike I'm estimating .256 at the fades not counting glue lines.
The input is great, thanks for taking the time to help.
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...So did you nail it?
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...not yet. I have my plan but have to wait to get materials in and then that four letter word W-O-R-K to stop interfering. I drew out for Javelina in January, my goal is to complete the bow and harvest an animal with a bow I built for the first time. Thanks for checking in..more to come.
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Your bow will be a bunch better than that Sage thing.
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Thanks for saying so, I sure hope you are right.
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If you haven't got the materials yet, you'll save yourself some frustration if you just use two wood lams (and also, it'll work well if they are both .002 per inch or a recurve) and the two glass lams.
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I'm not a recurve guy,maybe Mike or someone else can tell you.
But is .004 total taper quite a bit of taper for a curve?
Any stability probs with that much taper?
Just askin for curiosity, I'll never be a recurve guy I'm sure.....
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The 60" recurve I build I use 2 .002 tapers, if you keep the tips ground evenly, the nocks cut evenly, and the string perfectly in the center there isn't a problem.
The 54" recurve I build, I use 1 .002 taper and one parallel lam on the belly side, just because I don't need the thickness on the bow that short.
My longbows all have 2 or 3, depending on length and weight, .001 tapers, but sometimes If I have lams ready, and they are too thin, I'll make a parallel to take up the .050 or so that I'm short.
I make all my own lams, and they are all full length, one piece, so there's no joint in the middle of the riser.
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I am ordering materials tomorrow. You fellows are the experts but with my inexperience I'm going to stay pretty close to the design specs on this first one. I may try something different on the next layup. The only thing different I am doing is the stabil kore which I put in there after seeing lots of positive feedback and finding what I believe is stabil kore in some of the major manufacturers bows. This bow will be a little short for its narrowness so I wanted the extra stability. The only thing I am vacillating on tip wedges which I think this bow needs bud I have no idea how long or how thick.
Thanks for all the help!
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I hope this isn't inappropriate but the op has an excellent thread and I'm learning as well, though far behind the op. Maddog suggests taking.002 per inch off the lams and Kenny questions 2 .002 lams on a recurve tip. Is it coincidence that .002 is the amount taken off per inch AND the final tip thickness of each lam or have I totally misunderstood? Perhaps I have backwards and they're feathered to nothing at the tip, hence the question of stability by Kenny? Thanks guys.?
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The way I'm interpreting Maddag suggests 2 tapers at .002 per inch for total taper of .004 per inch. But for a recurve Kenny suggests that .004 is a little much based on his experience. To me this is like two doctors suggesting different treatments based on their experience neither one is wrong. I feel fortunate to have both contributing. In the end I have incorporated advice from both I think and balanced with the original design. The materials have shipped, its all over but the building now. All input is greatly appreciated. I'm super excited (yes its geeky) this is two years in the making for me. It may end in spectacular disaster but I'm having fun regardless.
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So would the tips be .002 by Maddogs suggestion? I understand that was his taper per inch suggestion. It sounded as if that might ALSO be his tip thickness per lam as he refers to his 60" recurve? This is what has me a bit confused. And yes, we are very fortunate to have experienced bowyers being so helpful. Thanks to all.
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Under the Maddog scenario the tips would roughly be .0.155" . The buttv of each wood taper is .080 reducing by .002 each inch towards the tip. So roughly .002 x 30"= 0.06". So 0.08-0.06=0.02". So each lam is 0.02 at the tips, there are two in each limb plus the thickness of the glass and in this case the stabil-kore also. However I am using a total taper of 0.002 which means each taper lam reduces by 0.001 per inch as you move toward the tip. I could also use a single taper lam at .002 per inch and make the second wood lam a parallel. Does that help?
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I think Mike meant .002 " per inch as the measurement of amount of taper, not the thickness of tip.
Usually measure lam thickness at other end, or at fades depending on your method of madness...
I'm not much of a recurve guy, was just wondering if the .004" per inch would make the tips twist a bit easier.
Better listen to Mike, he has built more curves than me I'm sure!!
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Yes. Thanks for clearing that up for me. Pago, I'm glad your 2 year project is closer to a finish, I'd be super excited to! Keep us in the loop on your build.
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Like I said, I normally only use 2 laminations for my recurve bows and .030 glass or .040 glass. Example, If each lamination is .100 at he fades (I don't go with butt measurement because my laminations go full length with no joint in the center.) So from the fade outs to the tips on the 60" bow I make, it's about 20", so at .002 per inch the thickness of each lam at the tip is about .060 each. So with that scenario, at the fades, and using .030 glass, I have .260-.265, at the tips the thickness is .180 total, giving me a recurve drawing around 55# @ 28". I consider the tips of my recurve to be "working" and not static by the way. If I use the same lams but use .040 glass it gives me a stack of .275 - .280 at the fades (I've never gotten .040 glass that was actually that thick, it's usually .038 thick) and Around 60# - 68# @ 28". (the weight ranges I mentioned I control with the total length of the riser, but that's a whole new can of worms)
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Thanks Mike, I'm sure I will reread that post many times in the future. I'm a hands on learner and I'm sure it will mean more to me in the future. Over the past two years I have put together all the equipment I feel I need to make custom bows, I even found a performax thickness sander. But I'm trying to learn to walk before I try to run. Saving up for some taper sleds now. I like the idea of no butt joints do you use a special sled to accomplish that?
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I have some 72" sleds that I made myself, one parallel, one .001'inch, and one .002 /inch. I also have a .002/inch that's 37" long for my youth recurves.
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I have been daydreaming on how to go about that. Several times I have nearly purchased maple from home depot to see if I could make my own. I guess I worry too much about being perfect and thinking I need super high tolerance manufactured sleds. Not that yours are not, I just don't know if I could do it with my current skill level and experience.
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(https://farm9.staticflickr.com/8623/16292394868_9e3ccdb827_b.jpg) (https://www.flickr.com/photos/21955099@N07/16292394868/)
(https://farm8.staticflickr.com/7423/16292395768_6d9b6f618f_b.jpg) (https://www.flickr.com/photos/21955099@N07/16292395768/)
Got the template cut out and the form glued up today. The holidays didn't go as planned but I'll keep chipping away at it maybe I'll have a bow before Easter lol.
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Get that form cut out and get gluing!!! ;)
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It looks like Your making a rubber band form. I have only made "firehose" forms and the top half of form is pretty thick And adds weight to the form. I am using 002/inch total taper in my one piece modified Bingham's design recurve and 003/inch for my 62/64" kennym D/R design bows. I recently made a form for making ILF limbs and I will start off with 003/inch total taper for that one. Good luck with your form and build. A clamp to hold riser centered on form would be a good addition to your form.
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Thanks my plan is to put a strip of aluminum on topof the form and probably use an index pin. I hope it all works out I have been studying Kenny's latest form build along its great stuff.