Duoflex bow ?

[Swissbow]

Ronny, a good friend of mine asked me if I could build him a bow like the Duoflex from Willcox. Anybody here ever built one or has a plan how to build one ? I intend to build a glass bow with the profile of a duoflex. I have found a couple of good pictures on the internet but I'm uncertain about the stack thickness and the taper. I know that the stack has to be less than in a regular longbow, because of the recurves that increase the preload in the limbs. But how much ?
On the other hand the recurves should be working, thus the limbs need to be tapered. Any idea how much ?

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Andy

[Pat B]

I tillered out a duoflex glue(hickory backed osage) up a few years ago but don't remember the dimensions. TBI I believe has a write up about the duoflex that might give you some insite.

[NTD]

TBB 3 has some info on it as well.

[John Cooper]

I'm going to be experimenting with a bamboo version of the duoflex, but it'll have to be from scratch since the TBBs don't give much info.  It looks like a fascinating design, but very unstable!

~john

[Swissbow]

Hi John, I've read the article in TBB and also other stuff but there are no indications about the limb shape or even measurements. Do you know if the limbs are shaped pyramidal like a longbow ore more like a recurve ( parallel and then narrowed to the tips ) ?

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Andy

[John Cooper]

I've done a few r/d bows with a pyramidal shape, but the TBB4 suggests full width up to mid limb for that design since so much work is being done at mid-limb.  I like the fact that the pyramidal taper cuts down on the ounces and I haven't had any problems with too much strain mid-limb.  Here's a picture of an old Wilcox fiberglass duoflex.   http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=print_topic;f=14;t=003456   It looks a little clunky for using it as an all-wood design. However, that might be necessary to make it that wide for stability's sake!  It would have to be a delicate balancing act between the extra weight on the tips vs. actually being able to tiller it!  The more I think about it (even as I write) it seems like this might be more like the modern recurve and be a sort of precursor of the Bear working recurve.  Anyone is welcome to come on here and correct me, however!  

~John

[Swissbow]

That confirms what I'was thinking about the limbs being parallel and just narrowed at the recurves. I think with the glass and a proper design the strain mid limbs should not be a problem but I'm afraid that it would be very difficult to keep the limbs/recurves from twisting with a pyramidal shape.

I guess I will try with a parallel shape and a parabolic tiller towards the tips ( kind of like a modern recurve ). The width of the limbs will be 1.5".

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Andy