Duoflex Bow

[Marc St Louis]

I started working on this bow a few years ago but it was aggravating and I had to leave it for awhile. It's patterned after the Wilcox Duoflex bow he developed in the 1930's and is made from HHB backed with White Ash. The limbs had a serious lateral stability problem that made me nervous tillering it out. Then last month I had an idea on how I could continue, it was nothing more than a matter of shortening the limbs by an inch. This took the reflex down to a manageable amount and this took a lot of strain from the limbs. I still haven't finished with the bow but do have it tillered out and I thought I would post some force draw numbers on it. The bow turned out at 57# @ 28" with a very smooth draw. Here's the force draw on it

10"  =  18#
12"  =  23#
14"  =  28#
16"  =  33#
18"  =  38#
20"  =  42#
22"  =  45#
24"  =  49#
26"  =  53#
28"  =  57#

What created the problem initially was that I had put in about 5" of reflex in the bow. Cutting 1" from the tips reduce the reflex to about 3", this still left the bow at about 60" in length and after tillering to 28" still has a couple inches of reflex. I haven't shot the bow yet as it's not ready for that but I suspect it will have excellent performance. Here's a picture of the bow as it is now

[Justin Snyder]

Nice bow Marc. Justin

[tom sawyer]

Interesting bow.  I'm surprised it has decent early weight, looks almost the same shape braced, as unstrung.  When does the string lift off the limbs?  I'd guess between 18 and 20", thats when your pounds per inch of draw drops a bit.  Your experience is like a lot I've heard about, you get much more than 3" of reflex and its diminishing returns on these natural materials bows.  Really nice work.  Did you glue all the reflex in as forced reflex or did you heat-form it some?

[Tom B]

i've wanted to do one of them.please answer tom s questionas it applies.i'm a newbie comparerd to you all,but ... nice marc. tom

[Badger]

Mark, some of us will be waiting patiently for your chrono tests, at 75% efficient it could easily shoot 10 grain arrows over 190 fps. very good possible candidate for the first bow to hit 200 fps at 10 grains arrow weight. Stored energy is phenominal. Efficiency will be the big challenge from this point on. From appearances it looks like it will be equally efficient. Also congratulations on successfully building an extremely difficult design. Steve

[Dustybaer]

awesome project.  i'm with badger,except i can hardly wait for the results 

[huntersim]

Looks nice Marc. I like  the duoflex. I bet it's tough to get those curves to open up properly. Look forward to see it finished.

[Ryan_Gill_HuntPrimitive]

looks great so far, i look forward to seeing it aswell- Ryan

[cowboy]

Wild looking bow Marc! I still don't know much of anything about efficiency, cast and such - this will be interesting. Am thinking about trying something new (to me) with my next one .

[brian melton]

Marc,

                Very nice love the look of that profile!!!

[Marc St Louis]

It was interesting tillering this bow out. The brace height of the bow is 6"

I think you are right Lennie. I have a picture of the bow drawn to 22" that I took to examine the tiller as I was tillering that I will upload. The string has already lifted from the recurves. I started this bow 3 or 4 years ago so you are asking a lot for me to remember that far back. I think it was a combination of heat and glued in reflex.

I half expected this one to blow on me. I tried one like this out of BL before making this one and it failed violently. It could still blow as the limbs are highly stressed

[Dano]

What a challenging design, you have done well to get it to this point Marc. I hope the wood can handle the stress.

[Gordon]

Wow, that is a challenging design. Did the lateral stability issue ever cause any frets to appear along the edges?

[mullet]

  Cool looking design Marc. It kinda look's like the Bear Kodiak Magnum. Looking forward to seeing the finished results.

[PK]

I'm impressed I think that string angle is less shocking :)I meant that in a good way, nice job.