Oh well! You live and learn. I thought 4.55 E was lot of money per bit. The priciest in Bricomarche (yes, yes, overpriced - but with 1 hour to go on a Saturday before the shops shut and a 10 mile journey, what is one supposed to do!). I though SDS referred only to the chuck type, i.e. 3 flat sides to the bit rather than round. Anyway, I think I've been drilling too fast - max revs at the highest speed - with hammer action on. So next time it'll be slow speed and expensive bits - I'll leave the SDS until I need loads of holes doing. By the way, putting up and aligning the dish was a piece of cake. If you've never done, or are worried about trying it, just please give it a go - it's so easy...10 minutes and we were watching the football.