Help designing my next bows

[arachnid]

Hi guys.

I plan on making myself a new target/field/roving bow but have enough woos for a couple a'bows. So I really want to make an ELB since I never made nor shot on.

I have ipe for the belly. Right now it's not cut or ripped and it's about 20mm thick. I want to rip it to get 2 bows out of it.

Next is maple. My fried can give me a board, 50mm wide and 50mm thick. Haven't seen it yet, only a picture, so I don't know if the grain is as straight to be used as a backing. If it's not, I'll use it as a core and back it with bamboo.

So, I want 2 bows-
 a R/D longbow, about 64-62" long (for my 26"draw). I want to use KennyM's form (he's a great guy from Tradgang that has a good r/d form plans).
Ans, as I said- an ELB.

Target weight for both- 45-47#@26". Both out of the same materials (ipe, maple, boo).

So, if you laminated experts can land a hand to fellow bowyer and help me design these bows' it'll be most appropriated. I want to plan and design carfully, for best results and I want get as close as possible to my target weight so I'll have to do as little tillering as I can.

P.s
If I rip the ipe, I'll probably need to make a power-lam ti stiffen the handle. So please consider it in the design (I never made a power lam before)

Thanks in advance
Dor

[BowEd]

You don't learn anything about designing and tillering that way.Doing a search on this site might help.Still I'm sure someone will chime in for ya.I mostly do staves.

[arachnid]

I do mostly wooden lam bows and I have some experience. I've just never done an ELB and never used that particular r/d profile before, so I'm asking those with more experience.

[PatM]

Wouldn't KennyM be the guy to ask since it's his form?

[bubby]

Wouldn't KennyM be the guy to ask since it's his form?

It is probably a glass bow form as most of the bows on tradgang are glass

[arachnid]

Wouldn't KennyM be the guy to ask since it's his form?

It is probably a glass bow form as most of the bows on tradgang are glass

Yup, it`s a form for a glass bow. But I`ve seen wooden bows made with similar design. It`s just a r/d longbow form... I just like the shape.

Since I have some experiance making r/d bows (and by "some" I mean "little"), that`s my secondary concern. My main question is the ELB design since I never made one.

[GB]

I can't help you on the design or thickness and taper.  I would think that you'd want to build up the riser area of that form 1" or 1 1/2" because your wood lam bow is going to take some set, unlike a glass bow.  That way, after shooting it in, you'd have a better chance of your tips being forward of the handle or at least even with it.

[mikekeswick]

elb - cut your ipe to 1 1/8th wide. Cut a backing to suit - hickory,ash,maple,white oak,bamboo etc 3/16th to 1/4 thick. Make a 12 inch powerlam to bring the total thickness at the handle to 1 inch. thickness taper - clamp the bow to a straight form and mark out a straight line taper from edge of handle to 7/16ths thick at the tips.
Width taper - center 12 inches leave 1 inch wide, taper to 3/4 wide 8 inches from the tips then from there into 1/2 wide at the tips.
Tiller for an elliptical tiller. Simply watch the set to show you where is too strained etc. Use the faceting method and only round the belly after fitting horn nocks.
fit horn nocks at about 24 inch draw and narrow the tips to 3/8ths.
Whatever you do don't make the tiller arc of a circle.
As for the Kenny M form just shorten the riser for a wooden version. About 12 inches would be right. Increase the taper rate to around 0.008" per running inch.

[arachnid]

Great info Mike. Thanks a lot.
A few quesitions....

 you didn`t mention the total lengh of the bow.... My draw is 26" so I guess 72" is well enough?

you wrote "cut your ipe 1 1/8th wide"... did you mean "thick"?

3/16 and 1/4 is pretty thick for bamboo, is it not? won`t it cause the belly to fret? I know that bambboit usually worked to 1/8 thick.

Do you recomend gluing the lams straight or should I lift the tips to get some reflex?

[loon]

I've drawn my 72" hickory bow to 32" and it has a ton of grain violations, also around 40#. it's held together, has 2-3" of set if going that long for that draw and lighter weight, make it whip tillered..

I would just make a 60" bendyish 'ELB' with perry reflex, haha. ipe/maple/bamboo? dunno. since it's perry reflex, may want something harder for the core i.. guess..? but still supple. Still, a long whippy bow should be fun..

[mikekeswick]

A 26 inch draw would only need a 70 inch bow, even a bit less. I normally made mine 72 inch for a 28 - 30 inch draw.
No I meant 1 1/8th wide for the glue-up then narrow to 1 inch through the center section. 1 inch total thickness is plenty to start tillering.
I meant that thickness if using a wood backing but if using bamboo then keep it thin (1/16th - 1/8th). The thickness of a backing doesn't really affect its 'ability' to chrysal a belly. If a backing is overly resistant to tension for the belly I would trap it not make it thinner. Most of the 'work' done in a bow is by the outer few mm only therefore width has more of an effect on evening out tension/compression properties of different woods. IMO....

[arachnid]

A 26 inch draw would only need a 70 inch bow, even a bit less. I normally made mine 72 inch for a 28 - 30 inch draw.
No I meant 1 1/8th wide for the glue-up then narrow to 1 inch through the center section. 1 inch total thickness is plenty to start tillering.
I meant that thickness if using a wood backing but if using bamboo then keep it thin (1/16th - 1/8th). The thickness of a backing doesn't really affect its 'ability' to chrysal a belly. If a backing is overly resistant to tension for the belly I would trap it not make it thinner. Most of the 'work' done in a bow is by the outer few mm only therefore width has more of an effect on evening out tension/compression properties of different woods. IMO....

Thanks for the explanation. I guess you learn something new every day... never knew that evening out tension/compression is done by adjusting the width.

So, if I use bamboo backing, I should start with a 1/8" thick boo and 7/8" ipe? currect?
What if I want to use maple core to make a tri-lam, how thick should I keep it?

[mikekeswick]

Yes that is correct and if using a maple core I would make it an 1/8th thick and remove that thickness from the ipe.
Good luck.

[bubby]

For the boo thickness I thin it to near knife edge then cut the profile and again thin to near knife edge this basically gives you a tapered boo backer

[loon]

I wonder, black locust vs maple for the core? Someone used black locust for the core of a hornbow & it worked great..
if you wanna do tri-lam, perry reflex, sounds more annoying than just 2 lams.;.