Design Build Input

[Wolftrail]

Here is what I'd like to build if possible. The limbs are about 31 1/2" long but I want to build a one piece bow using the 2 limbs glued to a handle. The limbs cannot be spliced in the center as this will reduce the working limb area. Hopefully the final outcome would make a bow 63-65" NTN. I'm thinking if the fade transition's in the center are done right the bow should survive.  Or is this a mad Idea or complete catastrophe waiting to happen..    

[1] Can the area B be filled in with a filler piece then apply a couple short lams on the back.
[2] I'm thinking area A would be about 4" for gluing onto handle section.
[3] area B, The length between the 2 limbs would be about 6" - 8"
[4] To increase the overall stability I'm thinking of drilling a dowel hole for the limbs where they attach to the handle.

   

[mikkekeswick]

No you would simply make a large stress riser (not a bow handle 'riser'....!) in the angle between the limbs and the riser ends. Any internal angle concentrates stress that is why bows are made with fades. If you tried to glue a limb wedge on it would delaminate (being on the outside of the stack).
stress concentration
[′stres ‚kän·sən‚trā·shən]
(mechanics)
A condition in which a stress distribution has high localized stresses; usually induced by an abrupt change in the shape of a member; in the vicinity of notches, holes, changes in diameter of a shaft, and so forth, maximum stress is several times greater than where there is no geometrical discontinuity.

My advice is to start again!

[Wolftrail]

Thanks for your input. My diagram is quite vague,  its done in Windows paint. Also I do not show a wedge or any taper.
What if I join the limbs with spliced in lams.? There would be 3 scarf joints on each side of the handle.

If you look at these bows and I have seen others there is no continuity in the limbs, the handle area is shaped having no limb structure.
I think its all how its executed having a long smooth transitional fade.
 www.blacktailbows.com

[Jon in North Idaho]

Do you have limbs already made that you are trying to mount on a riser?  Or is this a build from scratch?

Basically - it's a 3 piece look, but a 1 piece bow?  I would build it as a one-piece to make alignment easier, then grind through the riser section to make the gap shown in the top of your pic.

[Roy from Pa]

Looks like an explosion waiting to happen.

[Wolftrail]

The Diagram does no justice as far as what I'm trying to accomplish.

The limbs are already cut and tapered at 31 1/2" long.

[Wagstaff]

Build it and let us know what happens!..

If your limbs have a built in wedge that places the fades beyond the hinge point at the end of your riser section, the limb might be fine.  

The part about glue and dowel connection is the iffy part to me..

[PEARL DRUMS]

Catastrophe waiting to happen is my vote. Glue alone wouldn't be trustworthy holding the limbs on.

[monterey]

I tried that with a simple board bow.  Was trying to make it 4" longer.  I put a spacer between the two plus a thin overlay.  It was about a 28# bow and was shot by one of the grandkids for about a year.  

It gave out without any major drama.  It was glued with TBIII.  It probably would have held with smooth on.

[jsweka]

There's probably a good reason why you don't see any bows of that sort of design.  I wouldn't risk it.

[Wolftrail]

Oh I will be doing it, already have it figured out on paper, like I said the diagram does not cut it. For one thing the handle will be 14" with a gradual transition with 2 lams on the back and the center piece will be cut at an angle.

[passion for knowledge]

I have a terrible tendency to have to learn things the hard way, but at least that way the lesson normally sticks.

I tried something similar using limbs made from 2 quarter inch thick oak lams each steam-bent on the same form and glued together.

I made the riser thinking of making a takedown then decided to glue it up instead.

I did put a bit of a fade on the limbs as they came off the riser.

Long story short, it broke. Had it at full draw a few times, then bang.

When I look at the break, I see glue failure, but people with more knowledge at this stuff than I have disagreed.

There's probably a good reason you never see bows of this design anywhere!

My successful bows, all 3!! of them are very conservative in design, but they shoot!