Thanks Washout - I might have to have a more in-depth search for sources of wider double sided for a try. Over on cnczone I posted the same question and dogsop suggested using blue tape to the back of the wood-to-be-cut and then gluing that to some hardboard with 3M spray adhesive which seems like a good idea too - it might be easier to remove than double sided too?

Cheers Jazz - It's wood I'm looking at the moment but I did wonder about that problem of breaking through. I've experienced the machine not quite cutting far enough through because of places where the natural flex in the wood has it standing slightly proud of the bed (unbeknownst to me at the time).

Out of curiosity what kind of feeds and speeds are you using to cut aluminium and brass? And do you use single flutes and coolant? I think it would push my machine too far but I wouldn't mind the experience of having a go.