Thank you Kingcreaky

I was really lucky to ran into this forum just before I was about to start ordering parts. I can't judge Joe's cnc as I don't have the knowledge to do so but I will trust you all on that.

Yes the idea is for a machine accepting a full sheet of ply (2.5 χ 1.22 ) so the cutting area should be slightly larger for clamps etc.
Can anyone tell me the size of the base so I will not come short in the y(gantry) axis?

As per suggestions in other threads 80 x 80 x 5 steel tubing is a good option. Adjustability on the top rails and epoxy leveling is the initial plan.If the rack and pinion is the preferred way for the long axis, will the racks be bolted on the side of the top rails? Any extra consideration for the top rails then?

Help please