Adding Draw weight (Wood longbow)

[Wolftrail]

Muffed up on this bow.  It came in at 25# way, way, way under weight.  I was expecting at least 32#.  But would like 38# to 42# if possible.  At any rate its maple with a center power lam.  I want to add an additional lam to add more stiffness.
Is it better to add the lam to the back or belly...?

PS the bow is pretty well tillered and pulling 28" and taken 1/2" of set, and tapered down to 1/2" at the tips. 66" NTN.

[Bowjunkie]

Need more info on it. Is this a trilam or what? Are the back and belly flat as a board? Does it have a deep handle area with fadeouts? Usually it's easier to add a piece to the back, if it's flat.

[Pat B]

...or add a piece to the belly and re-tiller. I did this on a short(60") static recurve a few years ago and it turned out better than I expected. It doesn't take much thickness to get the weight up a pretty good bit.

[Wolftrail]

Originally posted by Bowjunkie:
Need more info on it. Is this a trilam or what? Are the back and belly flat as a board? Does it have a deep handle area with fadeouts? Usually it's easier to add a piece to the back, if it's flat.

Of course it has fades, if it was not a flat back bow I would not even consider adding another lam. The working limbs are roughly 27" inside the fade. I always measure about half way into the fade. 4 1/4" handle 2" fades. 1 7/16" width at the fades. I hope that explains it.  So far the bow feels nice drawing but then again its a wet noodle at 25# .

 

[macbow]

If the back is flat enough for a glue up my choice would be to,add bamboo or hickory to the bacl 1/8" or so.

Do you guys think the belly can handle the bamboo?

[Wolftrail]

Thanks guys, I worked on it today and the belly is flatter so thats what I'm going for. The lams are about 3/32" that should give me about 38# or so after re-tillering.  I'm using the same wood (maple)

[Pat B]

Add a little reflex at glue up. That alone will give you a few extra pounds.

[Wolftrail]

Yes thats exactly what I have in mind,  stay tuned.

[mikkekeswick]

Firstly why did it come in so far underweight?
An added 1/8th of the current total thickness will double your draw weight.

[inksoup]

you can add some Woven Fiberglass on back with epoxy.   one layer will add aprox #5 then you can calculate the number of layers.
do not forget to remove the bubbles with paint roll. and also possible to apply some pressure with fire hose or some other method.
woven glass is transparent so you will still have wood beauty of underlying wood.


best.

[Pat B]

A FG backing can overpower the belly of a wood bow plus the excess weight of even one FG layer can slow down the recovery of a bow. IMO adding wood to the back or belly can add draw weight and performance to an under weight bow without restricting it.

[Wolftrail]

Originally posted by mikkekeswick:
Firstly why did it come in so far underweight?
An added 1/8th of the current total thickness will double your draw weight.

Came in underweight just because, not thick enough.  I'm adding 3/32" but will re tiller so it wont be over 42#.

Agreed Pat will not add extra FG to the back she will go Kaboooomm.

[mikkekeswick]

No it wouldn't go caboom! The fiberglass has much greater resistance to stretching than the wood has resistance to compression.
What would happen would be the belly taking much more set or chrysaling.