........ I think in this case I followed the thin clues in the Shannon video too literally. They said to fire it when it 'was barely bending', so that's what I did. Which I think caused some over stressing as I tested the floor bend after that. Next time I'll wait till it's about done with floor tiller and be more gentle on stressing the bends........
thin clues are not too helpful sometimes. I have never seen the video, but I understand it is an involved process, and would hope the the video shows more about the tillering required before the heat treating session is begun. It suppose it is possible to cook the stave too hard, and conversely, to get the proper amount of treatment on the belly, only to remove the treated wood if the stave is not close enough to dimension after cooking. Steaming the stave to get it on the caul before the heat treat seems to suggest you are being too cautious or still had it too thick.
Bracing too early is an easy enough way to over stress a bow. I think every bowyer can remember one like that.
Learning floor tillering can be a bit of a subjective exercise as it's an acquired skill. The long string and a tillertree can help with developing the feel for how much and where when it comes judging bends.
Without seeing some pics of your stave, its hard to tell. If you are going to build a caul and do another heat treat? why not draw up your new proposed shape on another 2x6 and post some pics also? There are some new guys here recently that I think would also be interested in a thread seeing some simple deflex reflex curves.
Bowmarra's suggestion to get the bow built before fire hardening has merit, so maybe propose a curve, then build to it as close as feasable, then cut your caul, possibly adding some final recurve?