Thanks for reply. I understand the principle now (and the geek in me is finding it facinating). I kind of feel I need to make a bad machine to find the pitfalls before making a proper one or one that suits my preferences.

Sorry, when I said wood, i meant i'll just be cutting wood using the machine. It'll be aluminium profile with a steel frame. Broadly speaking at this point I can see it looks like it could be a catch 22 in terms of weight. The heavier the gantry, the bigger the frame supports, the bigger the mechanicals/motors and around we go again. Feel like I need to overthink the gantry design/weight/speed as this will dictate the size and cost of everything else. With that being said, it looks like you could build a solid machine for C. £2.5k. Not bad considering retail price of these things.

Thanks for the help. Really appreciate it.