Duoflex Bow Design

[mmattockx]

I read about this design in TBB Vol.3. It is a reflex/deflex recurve design with large working recurves that substantially straighten out at full draw. The design was produced commercially in the 1930's by Roger Willcox using osage with a thin hickory backing. It was claimed to be a non-stacking, high energy storage design that allowed low(er) draw weights without significant performance losses. I have modelled a couple versions of the design in Super Tiller and it does store very high amounts of energy for a wood bow. I can't say how well it gets all that energy into an arrow, though.

I have noticed few here like to use working recurves, with most favouring static hooks instead. Is there a reason this design isn't used more often by traditional bowyers?


Thanks,
Mark

[Marc St Louis]

It does store a lot of energy but it's a tough design to tiller.  I would be surprised if someone could make one as a selfbow.  I made this one as a composite many years go, it's based somewhat on the duoflex design.  It was a lot of work and took me awhile to finish it but it sure was fast.  The HHB chrysalled after awhile so a more elastic wood than HHB would be better

[HH~]

Made ine very similar out of winged elm. Was a left hand boy for a young man. Was a fast bow and elm is suited to this design. Elm will take the deflexing and reflexing last third then recurving tips.

Had bow out to 15” when i deflexed it. Duoflex bows were very nice.

HH~

[DC]

All my Boo backed Yew bows were made with the Duoflex in the back of my mind. Any time I tried to put that much reflex in a limb it would take set and the reflex would be gone. Inner limbs straightened out. Could have been my tillering talents, I struggled with every one. I never got chrysals but I never got close to the Duoflex reflex either. I think the Duoflex had bent more by the time it got to brace height than a lot of bows have at full draw Beautiful things to look at though

[mmattockx]

OK, I'm getting the impression that huge recurves like the Duoflex had can make tillering a major challenge.

What about smaller working recurves that straighten out at full draw? Does anybody use them to gain some energy storage capacity?


Mark

[PatM]

The original duoflex was more  deflexed in each fade/inner limb  and then a sweeping increased reflex into working recurve.

 The bows were not bent a lot to reach brace.

http://www.broadheads.de/docs/bowdocs/Willcox_Duoflex.html

[Badger]

    The very fist bow I built was a duo flex. I knew nothing about bows and nothing about bow making. I was going by memory from what glass recurves looked like  that I saw when I was a kid. I used 3-1/8" laminations and did no tillering. It came out at about 48" and was later to fin out a duo flex, good shooter but not exceptional. The duo flex design used more working area limb than most designs so tends to loose a lot of efficiency do to vibration or distortion in the limb.

[willie]

The duo flex design used more working area limb than most designs so tends to loose a lot of efficiency do to vibration or distortion in the limb.

Guys were pushing design limits with wood, then other materiels came along and innovators moved on to different directions.

I have been reading a bit at another forum, and was surprised to see designers that use the other stuff coming to understand what Steve says, that it is not so much about energy storage rather than keeping the working limb area down to a minimal size, and creating limb geometries that can make long draws with minimal limb movement.
With some of these designs, the challenge seems to be stability as the limbs get too wide and thin. whereas with wood, we often see stability problems when limbs get too narrow.

[bownarra]

I've made a few and wasn't overly impressed. Just make a holmguaard and marvel how they came up with that design, awesome shootability, speed, zero shock and you can make them with stone tools out of any straight bit of bow quality wood.

[BowEd]

Beautiful lines on that type of bow,but a lot of work to make.