I think I fell straight into the trap Del was talking about, by making the reflexed limb weaker to match the other. It certainly wasn't deliberate, and I was trying my hardest not to do it, but when looking at it on the tiller I just couldn't trick my eyes into leaving that limb alone before it was really working. If I'm lucky, and with a LOT of heat treating, this bow that was designed to be 100# will finish at about 45# which is diabolical. It will also be massively overbuilt for that draw weight, and having been pulled to around 80# during tillering is of course hugely over stressed.
I always try and take away lessons from each failure to avoid it happening the next time, but apart from the above, I really don't know what went wrong here. I'm still in the dark as to why it suddenly started bending sideways, and really surprised at how much weaker the limb that originally was reflexed the most now is.
I like to think part of it is down to using an adapted Mary Rose design on a bow wood not suitable. I know that ash works well with some heat treating, and especially well with a trapped back. But that bow on the Warbow Wales site has completely thrown me, because it breaks all of those rules and still comes out at an unbelievable draw weight.