Howmuch weight does trapping remove?

[Johan van Niekerk]

'Nother question  

How much weight does trapping a limb remove? I kind'a "over engineered" and need to drop a lot of extra weight. Problem is I'd like to trap the limbs as well but don't know how much weight that'll take off. So if I trap after removing more width I might end up under weight...

[walkabout]

i dont know that there is any given number really as far as how much weight you will lose when trapping, its more of a technique of doing a little then checking weight, and so on. as far as the "over engineering", a piece of wood that is twice as wide is twice as strong, and a piece of wood that is twice as thick is eight times as strong, so you may want to reduce the thickness if it is very much over your intended draw weight, then save the trapping/narrowing for fine tuning later. also the kind of bow makes a diference, is it a glass lam or all wood?

[Johan van Niekerk]

Its a reflex/deflex glass lam...so reducing thckness is not an option. I'll have to make it lots narrower

[walkabout]

yea your only option is to narrow the limbs. id go slowly, using the whole width to strength principle as a rough guide, always leaving a little more just to be safe.

[kennym]

I just took 4# off mine with a not too rad trap job. I did mine on the back ,only reasoning was that the limbs were narrow and I didn't have much room to lose on the string grooves on that side.

[Swissbow]

How wide are your tips ? If you have a lot of weight to loose I would narrow the limbs over the whole length as much as possible. If you narrow the limbs until you're at 3/8" at the tips you can loose some pounds and as a bonus you gain more speed since you have less mass on the tips. If this is not enough I would start to trap the limbs. There has been another thread not so long ago where this topic has been covered in detail.

 http://tradgang.com/noncgi/ultimatebb.php?ubb=get_topic;f=125;t=003640#000000

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Andy

[Johan van Niekerk]

Thanks Andy!

The previous link helps quite a bit  

[Johan van Niekerk]

Sadly I ended up messing it up.  :(
I basically took of more and more width till I got it down to just more than 60#. At this point the bow started twisting and unstringing itself very easily due to the fact that the tips was equally likely to bend sideways as it was to bend up or down  :(  Next time I'll take EXTRA care to ensure I don't make the tapered lams too thick. I think I had about 0.4mm too much on each of the lams...which quickly added up to WAAAAYYYY too much in total. *sigh*

[Jason Scott]

Been there and done that! What a heart breaker. You are a much smarter builder now. You know what not to do in stack height and of shaping limbs. Think of it that way.