I have started on my first Osage bow and been doing a little heat straighting and adding some reflex. It has about 5/8" reflex now. Do you think that will be enough to keep a straight unstrung profile? Sorry about the crappy pictures.
(http://i5.photobucket.com/albums/y166/Magnum2/osage1.jpg)
(http://i5.photobucket.com/albums/y166/Magnum2/osage2.jpg)
Osage wont take very much set at all. Whether it ends up with a straight profile or not will depend a lot on tillering skills, how wide and long it is, and the mc of the wood. So to answer your question, yes it could end up with a straight profile but if you want to be sure you could heat in another inch or so. I've never built a bow from osage that took more than 3/4" of set after shooting it in.
I find that if I add 2" to 3" of heated in Reflex I usually end up flat or with slight reflex. A lot will depend on your tillering skills but also that specific piece of wood. Osage is pretty resilient wood but it is still just wood!
my most recent osage bow, had no noticable set, but then i changed to the "rick welch" method of shooting, where one holds for a full 2 seconds at full draw( i used to be a snap shooter)- then i developed about 1,5" of set- from the original reflex profile.
so i think i am going to heat in a little reflex,
and also heat treat the belly at the same time.
My finding match Pats. Start with 2 or 3 and end up almost straight. If you want to keep the zing in the bow you can heat in 3" of relfex and flip the ips an 1" or so.
...concur with Pat