what do i set my 'velocity' to in Mach3?

[effimos]

i'm about to test my cnc machine this week.

i've set the stept per turn to 160 (because i have a ballscrew that moves 1.25mm per turn -> 200 steps / 1.25mm = 160 steps per turn when not using microsteps).
-> question 1: is this O.K. or is microstepping with 1/2 or 1/8 better?

also i'm using these motors: "57BYGH56-401A Single-Shaft Stepper Motors 1.26Nm/175oz-in 2.8A" and this controller set: http://www.benl.ebay.be/itm/18084063...84.m1423.l2649

-> question 2: so i'm wondering what to set the 'velocity' to without overheating the motors or controller?
this probably also depend on the material i'm cutting or not? i am about to use the machine mainly for cutting PVC plates...

thanks in advance!!

[louieatienza]

i'm about to test my cnc machine this week.

i've set the stept per turn to 160 (because i have a ballscrew that moves 1.25mm per turn -> 200 steps / 1.25mm = 160 steps per turn when not using microsteps).
-> question 1: is this O.K. or is microstepping with 1/2 or 1/8 better?

also i'm using these motors: "57BYGH56-401A Single-Shaft Stepper Motors 1.26Nm/175oz-in 2.8A" and this controller set: http://www.benl.ebay.be/itm/18084063...84.m1423.l2649

-> question 2: so i'm wondering what to set the 'velocity' to without overheating the motors or controller?
this probably also depend on the material i'm cutting or not? i am about to use the machine mainly for cutting PVC plates...

thanks in advance!!

You mean 160 steps/unit, or 160 steps/mm. The velocity is only the max for rapids. I don't think I've ever overheated my motors by selecting a high velocity though you'll come to a point where they'll stall, then you should back down about 10%.

You'd probably need to check the torque chart of the stepper to see what rpm the torque drops off, then multiply that by your lead to get a starting point for your velocity. So if you had decent torque at say 1000rpm, then your velocity would be 1125mm/min. Normally however, you'd figure out the velocity you need first, then calculate the size of the motor based on the screw you're using and approximate force needed to move your axis.

[effimos]

You'd probably need to check the torque chart of the stepper to see what rpm the torque drops off.

Thanks, but i cannot find this anywhere, not a single chart tells this

Ps: is 160 steps pet mm (my units are set to mm)

[ger21]

Velocity and acceleration are typically set by trial and error. As Louie says, find out where the machine stalls, then reduce by 10%-25%.
Velocity has no effect on motor heating.