laminations for all wood R/D longbow?

[KC Jr]

Hi. I'm just starting to plan an all-wood version of a KennyM R/D longbow. I'm planning on the 64" at around 45#. The plans indicate lam/glass thickness of .355".

One thing that I haven't figured out how to compensate for is that I have a 31" draw.

If I'm using all wood how would this impact thickness? And are there any suggestions for combinations of lams to try and get close to these targets specs?

thanks!

[Pat B]

Just like with a glass bow tri-lam bows have to be engineered as far as what materials used for which lam to go along with your bow design. Of course you want tension strong backing material and compression strong material for the belly. The core is important too so you will want a core that has strong shear properties, is light in physical weight and takes glue well.
 You could start with a 1/8" backing. Both boo or hickory fit that bill(as do other woods). For compression strong woods, osage, yew come to mind although there are others. I'd go a bit thicker for the belly lam because that is where most of the wood removal comes from while tillering.
For cores probably hard maple, ash, elm, and others will work and probably 1/8" there will be plenty.
 When dealing with an all wood tri-lam you are dealing with natural materials and consistency is hard to come by with natural materials unlike with a glass bow.

[KC Jr]

Should I try to get the same overall thickness (.355")

If I do....

.125" back
.125" core

this leaves about .10" for the belly (gets me close to the .355")

And I'm assuming that there is only one belly lam (like the osage)? The core lam would then go up the back-side of the riser?

thanks

[LittleBen]

No the stack thickness may he different for wood. Are you planning on an 18" riser like the glass version?

I think it's going to be tough to get to 31" but you might since the weight is relatively low..

If you're going to try and hit weight using a calculated stack thickness, you need to taper the lams. I would recommend you taper each lam .002 and I would probably shoot for a stack thickness of about .400" or so.

[passion for knowledge]

I can only give you what I've found with the wood I've used.

The last bow I built was a tri lam but not a recurve.

hickory back - hard maple core - ipe belly.

The hickory and maple are in front of the riser and the ipe runs up the back of the riser. I had to taper the ipe to conform to the riser as the curve became steeper.

Shoots really well.

1/8in hickory back

1/8 maple core

ipe belly 1/4 in at the handle with about 1.5in fade into the limbs.

.433" thick mid/outer limbs

69" ntn 1.25in wide at the fades down to about 7/16 tips

Just for reference, your design is very different in terms of limb profile, I would think.

Hope this is helpful in some way.

 http://tradgang.com/noncgi/ultimatebb.php?ubb=get_topic;f=125;t=014061;p=1

[KC Jr]

Thanks everyone.

I have access to some black locust which I have read is similar to hickory in terms of its properties.

I'll do maple core followed by ipe or black walnut belly.

I'll taper all lams

[Roy from Pa]

For a 31 inch draw, I would make the bow 68 inches long.

[Pat B]

...and use the ipe for the belly.
If you are going to use black locust for the backing I'd use a continuous ring and not a sawed out board. With hickory it doesn't matter.

[Jon LOW]

I'm building a t/d recurve right now, and I have almost the same question as KC.  
I am about to glue the lams together and it sounds like you guys have knowledge that could be helpful. I already have the wood prebent and ready to be glued. I was planning to have the front (target) maple, the core hickory, the wedge dark walnut, and the belly bamboo does that order sound good or should I switch it up?

[Pat B]

The boo isn't strong enough in compression. Something like osage, ipe or yew would be a better choice. IMO, hickory would be the better backing.

[Jon LOW]

So would it be better to have the bamboo on the front then maple core and hickory back?

[Pat B]

Is the bamboo processed or is it raw bamboo?

[Jon LOW]

Processed

[Pat B]

I don't think I'd use it for the back. Too much chance of it lifting splinters. Maybe hickory back, boo core and maple belly...or hickory back and belly.