New build.Stell frame cnc 1500X1000.Ball screw and gearing calculations

So jazzcnc you sujest

Y axis: 2 X 2010 ballscrews 1500mm long with 2:1 gear
X axis: 1 x 2010 ballscrews 1000mm long with 2:1 gear
Z axis: 1 x 2005 ballscrews 350mm long with 2:1 gear

15mm HTD timing belts
Is that correct?
All three axis will be moved with 3 Yaskawa sigma II 400 watt ac servo motors

No point using a 20mm diameter screw on Z as it's so short that the critical speed of a 1605 screw is plenty. Use 1605 for Z and you'll get better acceleration.

For the other axes I agree with the choice of 20mm screws if you want to get the highest speed from your servo motors. However if you want the best acceleration then using 16mm screws would be better, but this will of course lower the top speed.

Agree with Jonathan regards the Z axis screw 1605 is correct choice.

Regards the 1610 on X & Y then I don't agree it's the correct choice at this length. Yes it will allow slightly better acceleration than 20mm but with using servos you'll have plenty enough anyway. 20mm screws will handle whip better and give a good balance of both allowing higher speeds if needed, with 16mm higher speeds will be limited due to potential whip.!!

Both would work but given servos not steppers then really think 20mm are the best choice at this length.