Lamination stack help - First Glass Bow

[NYArrow]

Hi Folks!

It's been almost 2 yrs since I've been around on the board. (due to injury was unable to build / shoot) I'm back to 100% and need some help on my 1st glass bow.

Right now, I'm researching my first glass bow and need some help on the stack to use. It will be a Hill style bow, 64" ntn, 28" draw. My form is desgined after bjansen's build along - less the 3/4" backset. (straght limbs) Anyhow the first bow I want to build is for a friend that wants a 40# bow. I'm just really confused on limb thickness. I can reference binghams and 3 rivers but still seem to be confused. Should I use tapered lams? And when one source states total stack of X...is that at the butt / thicker end (of a tapered lam)?

 I want to use clear glass over some kind of wood lamination. Is the glass be parallel and the wood be tapered? I would like to use curly maple or zebra lams with clear glass. Given this what would you recommend?

Sorry if this is too long - just having trouble fining a good source of info in regards to stack layout. Any help is much appreciated!

[talkingcabbage]

Hey, and welcome back!  
I haven't built a straight Hill style longbow, so I can't help you out on stack thickness.  But I can help you out with a couple other questions.  

First, the glass will be parallel.  Your wood laminations will either be all tapered, or a mix of tapered and parallels.  Your stack thickness will be measured at the butt end of the lams.  You will want some tapered lams to get the tiller right.  I think with a Hill style, you want around a .006 taper, but wait for someone who's actually built one of those to chime in.

And one extra little bit of advise, zebra is really porous.  I've used it in a few bows under clear glass.  Make sure you use smooth-on and make sure it's warm, so it runs a little nicer when you glue everything together.  It's easy to get bubbles under the glass if it's thicker.  I've had to remake a couple pairs of limbs cuz I'm a little slow sometimes  

[bigbob2]

I build HH style bows and mine have 4 lams each with .001 taper. the shortest I make is 66ntn and stack for a 40# bow at that length depending on some variables is .355, plus .030 glass. so for a 64ntn bow could drop maybe 15 thou. to give somewhere in the target range.

[NYArrow]

Thanks for the help thus far - I failed to mention my form and limb width is 1.5" and I plan on my riser being 16".

[NYArrow]

Originally posted by bigbob2:
I build HH style bows and mine have 4 lams each with .001 taper. the shortest I make is 66ntn and stack for a 40# bow at that length depending on some variables is .355, plus .030 glass. so for a 64ntn bow could drop maybe 15 thou. to give somewhere in the target range.

Thanks for your reply to my thread. I just want to make sure I understand you. My plan is to build a 64", 1.5" wide with 16" riser, and a straight taper from fades to tips with tips being 1/2".
According to your reply -
My wood/core stack should be around .355. Then on top of that add my glass stack of .030? for a total stack of .385? And this would  end up about 40#?

[k-hat]

Hey man I ain't got no advice but I'm sure glad to see you back at it!!  I noticed you fell off the face of the earth awhile back and was hoping everything was ok.  Glad it was "just" and injury  

[bigbob2]

Few variables in your bow. Mine are only 1.125 at fades narrowing to 1/2'' at nocks and are 66ntn.My tapers are all .0001 and number 4 of.My riser is the same at 16'' The wood stack using A'boo would be around .355 for my figures, plus .030 glass back and belly, adding up to .415 overall.Because you are planning a wider bow then the outcome would not be the same but at least you have ballpark figures.

[NYArrow]

Thank you for your help! After learning a bit more about this process I think I will narrow the bow down a bit after glue up. I will use the stack recommendations given and hopefully post some pictures soon! I just found the stack calculator - what a nice tool to have! Thanks for all the help!