Hi Graham and Welcome.

First let me say would forget using MDF to build from you'll be wasting your time. It's not really suitable material for building any decent machine from and esp a larger machine.
You'll see there's recently been some debate on forum about using wood to build machines from and while it's possible it's not easy and very few succeed to build a good machine.
Most nearly always end up building another machine using better suited materials like aluminium profile or steel.

If your uncomfrtable using or working with steel which is by far the cheapist and strongest material then perfectly good machines can be made using aluminium profile which mostly bolts together.!. . It just costs much more money.

Best advise is do plenty of research and ask questions until you are satisfied you have a full understanding of what your about to take on.!

Good luck.