Recurve stack help please

[Pago]

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.

[JamesV]

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

[Pago]

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

[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?

[JamesV]

Pago...............

How are you measuring the .080 taper or is that the butt thickness?

[Pago]

That is the butt of the lam, two tapered lams total taper of .002.

[mikkekeswick]

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!

[Pago]

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.

[Mike Mecredy]

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.

[Pago]

Thanks Mike I'm estimating .256 at the fades not counting glue lines.

The input is great, thanks for taking the time to help.

[Mike Mecredy]

...So did you nail it?

[Pago]

...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.

[Crooked Stic]

Your bow will be a bunch better than that Sage thing.

[Pago]

Thanks for saying so, I sure hope you are right.

[Mike Mecredy]

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.

[kennym]

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.....

[Mike Mecredy]

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.

[Pago]

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!

[Brett Leinmiller]

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.?

[Pago]

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.