Steel frame cnc router design/build

[CraftyGeek]

It may be a little premature to start a build log - but I think it makes more sense to be asking questions regarding my design/build in a single thread rather than scattering questions across the forum.

I built an MDF CNC router a few years back using a design modified from the original buildyourcnc.com plans. We moved house a couple of years ago - the machine has sat unloved in (warped) pieces in the garage since.

I was planning on building a modified FLA-100 using aluminium profile - but i've already been talked out of that approach (see this thread).
I'm now instead designing a machine from scratch using 50 x 50 x 3 steel box bolted together. I'm aiming for a cutting area of 1200mm x 600mm. The machine will mainly cut MDF & wood - but plastics & aluminium are also a distinct possibility.

I have all the electronics from the previous build which include:
3x Nema 23 motors
all control boards, breakout board, 24v power supply (to be upgraded in the future) & dedicated PC at the ready.
Spindle will just be a trend router for now - another part to upgrade later.

I now plan on using supported rails from Chai/ebay.
Leadscrews are, as yet undecided.

I'd like to use 2 X-axis leadscrews - but the financial side of things may keep this as a single leadscrew for the initial build...then move to 2 as an upgrade later.

I've started drawing up a design which is far from complete. The board on the curtting surface is sized at 1200mm x 600mm for use as a guide only. In practise the lower shelf surface & full table would be covered with MDF. There's no diagonal bracing anywhere either..that can be added in later.

At the moment i'd like some feedback on the general approach & layout. I have a few minor concerns at the moment one being am I over engineering it?

I've also started wondering about bolting the frame together - there's a lot of holes to drill/tap & bolts to buy which will be time consuming & more expense....which leads to me to wonder whether its worth buying a cheap arc welding starter package (£60-75) & weld the frame instead?

Be gentle with me ;-)