Thanks Andy,

I'm trying to figure out whether 2005 or or 2010 ballscrew would be better, or 1605/1610 (which seems to be less available pre machined). I don't plan to use pulleys.
Problem is all calculations seems to lead to other values which I don't know what I'm aiming for!
So filling out a speeds and feed calc for say hardwood @ 20,000rpm spindle I get min/max of 9-11 M/min speed. Assume this is the cutting speed and the rapid people refer to are movement between cuts.
I also used zapp calculator to get critical speed of 20mm diameter ballscrew with 750mm spacing between supports giving 1548 RPM.
From forums someone gives 2010 screw @ 1348 RPM = 2.15m/min, so would the motor need to at appox 6740rpm to achieve that?
But also the motor Voltage driven needs to be known to get an idea of rpm which can be achieved?
I also don't know the final weight of the gantry, I'd estimate say 20Kg based on extrusion weight + spindle and alum plate.

On another note - have I already got off to a bad start using the non-heavy type of aluminium profile. This was from KJN, I intend to add plate/strengthening to make it more rigid.
Just installed fusion 360 to see if I can learn to create my design in diagram form:)

Ryan