Comments on my first attempt at a design (if you would)

[John11668]

I wonder why you felt you needed such column height relative to your X and Y dimensions . What height of components do you envisage .

One of the most difficult machining tasks I remember from my early days in industry, was a tall titanium columnar forging which needed double curvature machining onto its top face. It cost a fortune in fixtures to fix and support it and the machining had to be extremely slow to keep cutting forces within bounds. It was done on the table of a triple headed Bridgeport copy mill ( pre cnc days) So machining time for the op was 300 hrs although we could produce 3 in that time, and we needed a pair for each airframe. Prima Donnae in the drawing office would not consider a design change which could have cut the time to a tenth.

The point here is that columnar components are seldom machined standing upright on the table so large throat clearance is seldom needed .
It detracts from rigidity in the column and also in the component , so you get a double dose of flex in response to the cutting forces .

What is the maximum height of your proposed component? Work from that taking into account the Z positions for clearance and depths of machining operations , spindle retraction etc . Tall components will need to be braced from the table so add to the need for table width and extra rigidity.

Looking at your design I see an X / Y table sitting on a flat base . You could save yourself some time by buying one of those and adding the ball screws and motors which was the route I chose to take. OK so mine may not be the prettiest in the world but I wanted to get quickly to the eletronic/ software stage and start to play.

Hanermo mentioned Deckel Aciera and Shaublin , all good examples of well designed column mills from which design lessons can be learned .
I used my Deckel FP1 as a base , but as they say on the BBC , other makes are available . You will not find anything more rigid upon which to base your build .

My project is here http://www.mycncuk.com/threads/13746...802#post117802