starting from scratch- router 1st project

[idefix]

I really appreciate the sharing of experience of the community through this forum.
I've been following the various projects exposed here for some time already and have decided finally to step in by myself. My english is not perfect (sorry for that) but I will make all my best to explain my project.
For sure I will have many questions... but I'm here to learn :) from all your experience. So please don't hesitate to comment and give me advice to avoid letting me going in the wrong direction.

First, I already own a lathe and a little milling machine (round column type) plus a big column drill (1.90m heigh with 30mm drilling capability) salvaged from srap... and totally refurbished. Let's say they are my basic tools.


I'm planning now to design and build a CNC router/milling machine able to machine light material but also aluminium. I already start from an existing welded frame (50x50x3 tubes) which needs some reinforcement; but however this gives me the overall size of the future machine: 1100mm x 650mm.

My first investigations are giving the following axis travels: X 750mm Y 350mm Z 150-200mm
The distance under the spindle attachment and the table will be adjustable to accomodage eventually the use of a milling wise or the use of a horizontal axis divider

Here are some pictures of the project :



Screw ball types are 1605 for Y and 2005 for X (maybe 1605 sufficient ?)
Next question is the use of simple or double separated screwball nuts or dual screwball nut (combined type). what should you recommend as I want to be able to machine large holes with H7 accuracy...

The main beam of the steel gantry will be filled with concreat and same for X axis support beams.
The steel tubes sections are 50x50x3, 50x50x4 and 100x50x3
Currently the axes guides are round types (diam 20 and diam 16 respectively for X and Y axis)

The Z axis will be fixed on the Y box (made of 20mm machined aluminium)

Thank in advance you for all your future comments.

Philippe