i posted earlier today about my microstepper controller having 1\2 1\4 1\8 and 1\16 settings on a dip switch,hood suggested using 8 steps.ive been playing around with the steps per unit on mach and measuring the movement until it matched the dro and found i need 640 steps per unit with my 1:1 drive and 5mm pitch screw.so i assume it must be 1\16 steps.QUESTION is ok to use 16 steps and whats the advantages and disadvantages of this.i dont want to try to alter the dip switch because i dont no what im doing.THANKS FOR ANY ADVICE.

i posted earlier today about my microstepper controller having 1\2 1\4 1\8 and 1\16 settings on a dip switch,hood suggested using 8 steps.ive been playing around with the steps per unit on mach and measuring the movement until it matched the dro and found i need 640 steps per unit with my 1:1 drive and 5mm pitch screw.so i assume it must be 1\16 steps.QUESTION is ok to use 16 steps and whats the advantages and disadvantages of this.i dont want to try to alter the dip switch because i dont no what im doing.THANKS FOR ANY ADVICE.

As long as you can get the rapid speed you want, there's no real down-side to using the higher microstep rate.  It will double the step rate requirement from your PC, but if it can keep up, go for it.

Regards,
Ray L.

You have arrived at the correct answer by a long route.

Calculating steps per unit is easy - your motors need 200 steps per rev, and therefore your 5mm pitch leadscrew gives you 1mm movement for every 40 steps (1/5 of a rev).

Your drives add micropulses to give smoother operation, and as Hood said, and good number to try is eight which seems to  give good performance.

If you used 8 then your pulses per mm would be 40 x 8 = 320 - and this is the figure you would put in the motor settings.
You appear to have stumbled upon 16, which is obvoiusly 40 x 16 = 640 steps - which is clearly what the drivers are set to.

It doesn't honestly matter. If you run with that and performance is satisfactory, then use it. Ray mentions rapid speeds - i.e. the speed you want your machine to traverse on a non-cutting move. Yes if your computer and drives will run at that speed so be it. If you find you set your rapid speed, and the axis starts missing or stopping (it stops moving and there is a big whine from the motors) then you may have to alter the DIP switches to the 1/8 setting, and alter your steps per mm to 320. The effect will be the same, it is just that the electronics will not have to operate as fast to give you the actual speed on your table.