Reinforced plastic beams for x-axis rails ?

[flanagaj]

im assuming when you say "rails" you mean the frame or rail beds ?

i like the idea of epoxy granite, i dont like the idea of casting around the plastic I beams.... if your going to the trouble of casting a base anyway why go to the bother of using the I beams..... if its about keeping the "volume to weight" ratio down id be tempted to just cast around foam or polystyrene blocks

Sorry, but having reread my post it was not very clear. I was thinking of

a) casting the rails using epoxy granite

b) using the plastic i beams for rails

Both a and b would then have a 50mm * 40mm machined aluminium section attached which has been precision milled to hold the linear guide rails.

The other option and I would love to explore it, would be to make the rails using composite materials. eg foam which has been layered with carbon. Carbon is super stiff and I suspect you would end up with a very stiff and light rail ?

Thanks