So far they haven't budged a bit and the wood was a joy to work with - no knots, burrs or splits (I did spend a fair time selecting the pieces I wanted!!). Did I mention cheaper than 'new' timber?
I've painted mine (4 coats oil based enamel) but left the ends of the blades untreated (built 1" too long, painted up to the end and then cut to length) so that they can 'breath'. Robin - Down Under (or are you Up Over)