I was asked this question again, and this was my reply:
Disclaimer: The calculations were done quickly on a calculator and may have slight rounding errors – but not to a factor of 10!
The large wheel radius is 75mm making circumference = 471mm
The pulley on the motor is typically T2 20 or T2 16: 40mm or 32mm
Ratio is thus 11.78 or 14.72
Given a step size of 0.9deg, and 32uStep an electronic step is 0.028125 degree
With the ratio, that becomes 0,002387521 or 0,001910666 degrees on the large wheel.
Lowest possible resolution would be at full arm extension 90degrees to the extended direction, which is less than 150mm+150mm from the SCARA tower, but for simplicity let’s make it 300mm.
Circumference of that symbolic circle would be 1885mm, making the single step lowest resolution movement 6.282mm*0,002387521 (40mm pulley) which is 0.015mm. This is smaller than the effect of filament variation or room temperature variation on your print…
Morgan Pro has a advertised specification of 100micron resolution – which means it will definitely pass the specification and will probably achieve more by a factor of 9 or 10 in terms of movement alone
With the smaller pulley this is even higher….
Enough calculations for now 😉