Ok, so I stayed up to the wee small hours trying to figure out what size ballscrew and stepper I should be using on the X-axis but there's some things I don't think I'm understanding. I'd like this machine to be able to cut aluminium so my calculations are based around this. My thinking is that if it can cut aluminium then wood shouldn't be a problem (hope that's right).

In the post describing the motor calculation it says that for cutting aluminium a speed of 1800mm/min or better is desirable but the best I can achieve, even with the largest Nema 34 motor, seems to be about 1600mm/min. In this post though Jazz talks about cutting at around 700mm/min which is well within the realms of possibility. What speed should I enter for Max linear speed (B22) when cutting?

From trial and error I've found two setups that appear to work
Click image for larger version.  Name: MotorCalcs RM1610 Nema 23 - 1.png  Views: 551  Size: 62.2 KB  ID: 7313Nema 24 (Zapp, SY57STH76) + RM1610

Click image for larger version.  Name: MotorCalcs RM2510 Nema 34 - 2.png  Views: 587  Size: 62.7 KB  ID: 7314Nema 34 (Zapp, SY85STH80) + RM2510

I wasn't sure exactly what Screw Fixing (B19) meant so I left it as supported-supported. Would bearing blocks be considered fixed though?

What I don't understand though is why changing from a 1610 ballscrew to a 2510 nearly triples the total torque but doubling the mass of the gantry to 70kg makes only a small difference (in fact in the scenario with 24's is still ok with a super heavy gantry but the 34's are out of the safe range).

Am I doing something wrong here? The smaller motors and ballscrew seems to be a much better choice which feels totally counter intuitive to me.

Cheers