So I read about this technique on this here forum, seems to really help. I get less warping and in the event the raft has begun to warp I can kill the print before I waste more plastic.
I'm not sure who the original credit goes to but thank you.
I have one small addition which you may be common sense, but I haven't read it here:
when you re-start a print if it has been idle for too long it will take a second to push out its initial bit of filament. This means it misses the first 10cm or so on the resumed print, to get around this if you unload and then reload the filament before you resume it will be primed and ready to go.
Above comes with the caveat that my hotend might be in worse condition than yours and you may not actually be having this issue at all!
p.s. For those who haven't seen this, it simply involves adding a pause at 0% to allow the raft to root itself down to the bed.
I'm still experimenting with this, but I tend to give it about 15mins+.
It isn't a cure all by any means. If the raft hasn't gained good adhesion to the bed then it doesn't matter how dry it is it can still be pulled off by a part that wants to warp as the raft itself is very flexible if not properly stuck.
It would be nice to have a 'pause after print for X minutes, then prime the hotend/nozzle and continue' - This would also allow more scientific analysis of how long to pause.