How much reflex can be put into a D/R bow?

[upstatenybowyer]

I guess the subject speaks for itself. Anyone got any examples of a D/R with a lot of reflex? I'm just wondering what's possible.

[BowEd]

Last one I tried with red cedar @ 6" blew through the ceiling of my tractor shed....lol.No seriously osage would probably be your candidate of wood to do that with I'd say.Heat treated elm or hickory too.Their tricky to tiller I'm sure.As much as you can get away with I'd say.Top view profile would have to be accomodating with extra wood to handle it I'm sure.
A couple of inches was the best I could do with BBH years ago.Starting with 4".Losing 2".

[JNystrom]

If you think adding reflex creates more performance, what i think is more important, how much does the wood take set. If you add 8" of reflex and you end up with 4" of reflex, in my eyes and mind, the wood has broken down pretty much and the performance is a bit ruined. I might be wrong, but what is the most important, is the real set. Not the reflex you end up with.
If i remember correctly, Gardner has been writing about this same topic here earlier.

So i don't make this totally OT, i throw you a number of 4" of reflex for 60"+ bows. I wouldn't personally add more. Even that might be too much.

[upstatenybowyer]

Thanks for the responses.

JNystrom, I hear you loud and clear. I guess I should have titled the post, "how much reflex can be held by a D/R bow." I'm sure more is possible with a sinew back. I've seen D/R "F-word bows" with a lot of reflex, but I was wondering what the best possible outcome with an all wood or all wood/sinew could be.

Ed, your bow from the "Handle Crack" thread got me thinking... I've seen static recurves with extreme reflex, like yours and the ones Marc posted, but not any of the D/R design. You'd think with a little deflex in the handle they'd be easier to brace.

[Badger]

   Just speaking for myself because I know there are guys who can get more. I will on occassion nail one with 5" or so but for the most part about 3" is where I feel good about the bow and I am tickled pink to hold that maybe starting at 4". For my personnal shooters not more than 2".

[Badger]

  Several issues with D/R bows. #1 if you get it bending too much into the reflex area you end up with a d bow shape and defeat the purpose of a d/r bow. #2 if you have more than about 3" reflex and have too much working limb the brace becomes very unstable and it will tend to rock from one limb to the other when braced.

[upstatenybowyer]

Cool Badge thanks a bunch. It's like you read my mind and answered questions I couldn't have put into words. Creepy!

[H Rhodes]

Not creepy....  He has just already plowed these fields years ago!   

[BowEd]

Jeff...I really don't have any problem stringing them kind of bows up using a primitive stringer.

[mikekeswick]

The 'extreme' profiles just don't really work too well with wood. I personally wouldn't go much over 3 inches as a starting profile. As mentioned above a bow with no reflex and very little set will likely shoot better than a more stressed design that has taken a bunch of set. Once wood has taken a chunk of set it goes all mushy and is firewood to me.

[Springbuck]

Depends on lots of factors, but you can put in a surprising amount and have it work.  However, I am not convinced that more equals better performance.  There are diminishing returns.  Here is my thinking and experience.

First, I will say that a little deflex goes a LONG way as far as eliminating problems, both with overstraining wood and with stability issues.  I have pulled off some LARGE, high angle recurves by deflexing the handle a little.  People were mocking me once about how big and stupid my recurves were, but that bow (boo backed BL, 64", 2" wide limbs, deflexed 2" to the deepest bit, and recurved back to 2.5" ahead of the handle with tips almost curved to 90 degrees.  With string bridges6" down the limbs that bow was a screamer, baby-butt smooth draw, and dead quiet.  I used a 10" kid's bike wheel rim as a form to steam bend the lams.

A Perry reflex/deflex that was pre-deflexed at the handle (look at how Marc. St Louis does it) rather than force-glued into reflex can take a LOT more than a R/D stave.  But it sure is easy to just bring the limbs around with heat when you have a deflexed stave.  Other rules still apply; a wide, flat limb and more parallel width profile help out a lot,   skinny tips raise efficiency, a wild profile will not compensate for bad tiller or damaged wood, etc..  This design stores a lot of energy, so you need a lot of inner limb mass and the best belly wood you can get. 

Also, as the profile curves increase, the bow has to be tillered differently.  Big curves have to bend more, sooner by the handle, and have tighter radius toward the tips. The middle limbs bend a LOT in this design, and are easy to overwork.  If they curve a little and bend to "straight", that might be just right, but if they curve a LOT and bend to "straight" that's likely too much, which means you really need the inner limb to do its share, but it's a tricky tiller and hard to see.

I cut my teeth making these with bamboo backs and boofloo or tropical woods, and rarely do them anymore.  But, the only form I kept around is set up for about 2" deflex (or 1-1/2" if I shim the form) and 5" of reflex on a 68" bow. (I measure reflex from the deepest part of the deflex, so limb tips 3" ahead of the handle.)  I lose 1" to 1-1/2" as the bow relaxes off the form (and BTW, TB III relaxes more than Urac used to).  If I tiller well, I end up with tips about even with the handle or a half inch ahead.  For me, this has been the best overall design compromise.   I have made R/D's that started with tips a full 4" ahead of the handle before tillering, and they gave me fits.