Thanks for the great responses to my questions.

I was thinking of starting with the Z or the spindle as you suggest routercnc. I can see what you mean about everything affecting everything else which was partly where my difficulty starting.
This gives me a good start.
Great tip about setting the height from the bed to the tool straight away.
I will remember Jazzcnc`s comment about starting with the strong base too....

Do you do suggest sort of rough drawing on fusion (or whatever software ) first just using plain rectangles etc, to get the shape and then do a proper one with the profiles of the extrusion and the carriages etc, or just go straight in with the full detail.

I have been attempting to gather dxf files of aluminium extrusions and the Hiwin stuff. does anyone have a source to a library of this sort of thing.


Thanks

Ollie