Well, I have just started to go over these drawings. Lots of tapping and bolting.

I kind of have the best of both worlds. I have a heavy background in cabinet making, and my step father has a metal machine shop.

I wonder how MDF would work in place of the aluminium? Dense, pretty damn straight. I could biscuit, glue, and screw parts together. Even the gantry parts. Any comments? Very cost effective!!

Going back to the metal side I think I could use a structural steel angle for the gear rack rails. Really cuts down on the joints, and I am assuming the cost. I think I can get some nice straight stock. As for the gantry pieces, well flashes of mdf still rush through my head. Anyhoot, If I go metal I think I would stick to metal. The aluminium would do fine. I would weld the parts together rather than bolt it all up.

I'm kinda thinking out loud here. I am asking for input.

Next thing I will be researching are the Linear rails, bearings, and lead screws. Sounds like I will have to raid my piggy bank for those.

Well Cam, It depends on the size machine you want and what you will use it for.

Personally I love steel, It is strong for its size, Quick to weld. Easy to bolt, cheap, and hard wearing.
Balsaman ( you will find his posts in this forum) has made a router out of MDF. From all his picture he makes nice stuff from it. I wouldnt want to mill aluminium in a MDF built table though.

There are cheap alternatives to linear rails too.

Why dont you post what you want to make, and its size, and then we will have a better idea how to advise you.

ynneb,
I am building from the cadcut plans. The machine will be able to route a full 4x8 sheet of plywood. You can view the machine in the main of this thread, or at :

http://www.inshorepowerboats.com/cnc%20stuff/CNCROUTER.htm

It's a large machine. Take a peek at it, and see what you think. Nice machine, simple in design, nice quality prints. This is my first at building a cnc. THINK HUGE!

Dave D