Tri-lam question.

[Easternarcher]

Hey guys...HAven't posted much lately...just haven't had time I guess.
I am planning on firing upi the bow-building again soon and have a question.

Let's say I wanna use a raw boo backing right? And my belly wood would be either hickory or Cumaru, maybe Jatoba...I was thinking that to lighten the limbs and improve cast I would use an extra lam of boo flooring (I dunno, maybe a 1/8" lam)...I wonder which sequence to lay this up....
1. backing-boofloo-Cumarubelly, or
2. backing -  cumaru core lam and THEN boofloo belly?

Or is it unnesecary work to do a tri-lam? IE boo backing - Hickory or Cumaru belly with a power lam at the riser?

[venisonburger]

I choose the second layup, only because thats how I made mine, I used a thick enough belly lam of booflo to give me room to take some off if needed for tiller
VB

[david w.]

will cumaru work? i know its really dense though

[Easternarcher]

will cumaru work? i know its really dense though

I dunno for sure....It's an experiment, so we can all learn wether it'll make a bow.
I got it, so I'll try it.

Venisonburger, I assume that the core lam needs to be tapered, starting maybe 1/8-3/16" thickness? and a belly lam about 1/4-3/8"? Looking for 50-55lbs@28.

Length I dunno, maybe 64"ntn. width 1 7/16" at fades straight taper to 1/2" nocks. MAybe it should be narrow like IPE(if I had any)
If I'm carzy on this design, PLEASE stop me now!

[George Nagel]

The properties of the wood should determine the order. You have three planes: 1) Tension  2) neutral  3) compression. It's a given the bamboo is the tension wood, hickory excels at either (so compression, belly) and the camaru or flooring  proly do fine in the neutral plane.

Why not just get a osage board, back it with bamboo and induce a little reflex during glue up?

[snedeker]

I think your idea with the boo flooring as core and cumaru belly is a good one.  I would put some tiller/taper into the cumaru, glue on the boo flooring strip with a little reflex, adn then put the backing on with a little more reflex.  Sounds cool.

Dave

[Gordon]

I spent a day this week at John Strunk's shop and noticed that he likes to use vertical bamboo flooring as a core lamination for his bamboo backed yew bows. He tends to make them about 1/8" inch thick and he leaves them parallel or tapers them depending on the design.

[Easternarcher]

The properties of the wood should determine the order. You have three planes: 1) Tension  2) neutral  3) compression. It's a given the bamboo is the tension wood, hickory excels at either (so compression, belly) and the camaru or flooring  proly do fine in the neutral plane.

Why not just get a osage board, back it with bamboo and induce a little reflex during glue up?

Well Mr. NAgel....I would do exactly that, 'cept we don't have Osage up here in the cold north. Gotta use what's in the shop, before I go buying bow wood....so, I guess I could just do a boo backed cumaru and call it a bow. but I like to try new things....we'll see.

[snedeker]

I'd like to see how the Cumaru works out.

Dave

[venisonburger]

I learned to make tri lams from Norseman(for any of you that remember Paul from leatherwall) his design of which he made 80+ bows was to make a form with deflex in the handle section and reflex in the limbs, the raw boo tapered from 1/8 at center to 1/16 at tips, the core lam was not tapered and mine were about 1/8 thick maple the belly ended up being tapered when you tillered, but was glued up untapered. I guess it would be easier to taper all the lams and eliminate most of the tillering but this method works too.
I think my belly lam was about 3/8 to 1/2 in thick. the width of the limbs was 1 1/4 at fades tapering to 3/8 at tips. the handle was made up of lams also and was long,12- 14in with about  2 inch fades. There may be better ways, but I made quite a few like this and it worked. My picture shows the handle section and the lam thickness
VB

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[Easternarcher]

Venisonburger, what are the lams there...raw boo back? maple core? and looks alot like boofloo belly?
I was thinking og doing something very similar to what Norseman taught you as far as the form goes...and yes, I do remember him from the 'wall.

What were the specs on that particular bow in the pic?