"JW, Unless very long I believe 1.5" is too narrow to make a pyramid bow."
I agree with ryoon, I think it should be 72" at least to take low set, as it is already not wide enough to not take very much set. At least if I make one it will be around 72".
"Unless of course you have a particularly dense piece."
Red oak timber does seem to vary alot in density, sometimes it is hard for me to find a good dense piece, but it is always better to look till you find it, then settle for those light weight ones... as I have found out recently... I had two cut out to the same exact dimensions recently. One was a light weight pinkish board, a molly that came out at 30# @ 28", if that. The other one was a nice dense whiter colored piece, I still haven't done anything with it yet, it will barely bend. LOL