[neorules]

Ok,
I have purchased left overs from someone else's build.

What I have now is lengths of 3030 (3x3 80/20 T slot), lengths of 1530 (1.5 x 3 80/20 T slot).

The motion parts are
4 pcs Hiwin rails HG25-1520mm with 8pcs HGH25CA bearing blocks
1 pcs ballscrews DFU1605-300mm overall length with 1pcs DOUBLE BALNUTS, end machined
3 pcs ballscrews DFU2505-1520mm overall length with 3 DOUBEL BALL NUTS, end machined
1 sets BK/BF12 bearing mounts end supports with locknuts and circlips
3sets BK/BF15 bearing mounts end supports with locknuts and circlips
4pcs ballnut housings/brackets for the above ball nuts.

The Control system I have is,
4 pcs Nema 34 Longs motor 34HS5435C-02B2 (3.5A 1.8 step)
4 pcs Longs 2H Microstep DM860A
4 pcs s-350-60 power supplies S-350-60 (60v, 5.85A)

2 pcs 2x2x.25 6061 square tubing 20' each

So....
I am getting ready for the build.
Don't have a spindle yet but I do have a Hitachi router that isn't doing anything at the moment as an interim solution.

What are peoples opinions on using 3x5x.250 steel a36/a500 tubing bolted to the 80/20 extrusions as opposed to bolting the linear guides directly to the 3030?
I have a bridgeport and can lightly face the steel tubing (big time pain in the butt) or I can purchase a little cold rolled square bar and flat stock and do the epoxy / spacer thing.

1) It was suggested to me that if I make the frame too strong I will have a pain getting the linear guides to line up.
This is scary for me as this is my first build and I don't want an expensive dust collector.

2) As for the ball screws being to slow (5mm pitch) I am thinking about using an overdrive pulley from the Stepper to the screw to get my IPM up a little.
I will be doing some light aluminum and some hardwoods.

3) It has also been suggested that a 4x4 cutting area won't have near the accuracy I am used to with smaller machines.

4) The bed is presently going to be aluminum cross members with an aluminum deck of at least .250 maybe even 1/2 inch if I can afford it.

I have attached a rough drawing of the gantry design (I have a better drawing but it is on another machine)

So what say the masses of CNC masters?
Is just using the 80/20 and bolting the screws and guides directly to it the way to go?

Thanks JC