So my 3500 rpm rated motor at 180vdc would be 2916 rpm at 150 vdc and 2333 rpm at 120vdc?
If my ballscrew is 5tpi then at rated voltage i would get 700 ipm at 150vdc 583 ipm and at 120vdc 466ipm feeds? If i keep the amps at the rating of 9.1 I should keep my 31.3 IN-LBS or 2.6 FT-LBS? So 2.6 / .0813 would be 81.76 lbs of linear force? So if my table weighs 200lbs my acceleration would be .41 G? I'm wondering if I've done a calculation wrong or is this a good setup? ________________________________ From: Jon Elson <el...@pico-systems.com> Sent: Monday, July 20, 2020 9:14 PM To: Enhanced Machine Controller (EMC) <emc-users@lists.sourceforge.net> Subject: Re: [Emc-users] Need help with Bostomatic BD18-2 to linuxcnc On 07/20/2020 09:00 PM, Tom Smart wrote: > I forgot to ask how would I calculate the loss of abilities of the mill if i > don't drive the servos with their maximum rated power and amps? If I were to > get drives that weren't rated to 180vdc what losses will i have and how do i > calculate the loss? > > First, find the rated speed of the motor. If the motor is rated at 1800 RPM and directly drives a 5 TPI leadscrew, then it will give 360 IPM linear speed at rated voltage. If you then run the servo amps at half the motor's rated voltage, you would get half that speed, or 180 IPM. Then, if the motor has a peak torque rating at some amperage, but your servo amp can only deliver half the rating, you would only get half that torque. if the motor only shows a continuous torque at some current, you can guess the peak rating is 2-4 times higher. I'll use those horrid imperial units, as that's what my cheat sheet was done in. If the motor is rated in oz-in, then you can convert that to lb-ft by dividing by 12*16. So, a 100 Oz-In motor provides 0.52 lb-ft or torque. A 5 TPI leadscrew advances the axis 0.2 inch per turn. This is equivalent to a spool with a radius of 0.0318". So, that 100 oz-in motor (0.52 lb-ft) would produce 0.52/0.0318 = 16.35 lbs of linear force (neglecting friction). You can plug in your own numbers to calculate it for your own motors and servo amps. So, if your machine has a 200 Lb table, and the leadscrew were to produce 1000 Lbs linear force, it would accelerate at 5 G. Jon _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
