2013/9/5 Gregg Eshelman <g_ala...@yahoo.com> > On Thu, 9/5/13, andy pugh <bodge...@gmail.com> wrote: > > Subject: Re: [Emc-users] Servo motor watts VS torque? > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Date: Thursday, September 5, 2013, 3:19 AM > > On 5 September 2013 05:40, Gregg > Eshelman <g_ala...@yahoo.com> > wrote: > > The old motors were 5.8 amp cont, 30 amp peak. Stall > torque 3NM cont. Max RPM 2400. Max voltage 140 DC > 140V * 30A = 4200W > 140V * 5.8A = 800W > 3Nm * 2400 rpm = 750W > > You probably want at least 750W motors, geared to suit any > difference in nominal motor speed. > > My small knee mill seems pretty reasonable with 750W > brushless servos. > Though I suspect that I am limited by software commutation > at that top speed end. > ----------------------- > > The Servo Dynamics SDF1525-12 is rated at 120 volts so I assume the motors > never saw 140 volts. Still nearly 700 Watts. > > I don't know what your machine looks like, but I think many people believe they need much larger servos than actually needed. My steel router has a gantry weight around 80-90 kg and is driven by small Nidec servos rated at 80 V (really small). I can assure you that my computer is the bottleneck and if I go from max feed to a complete stop the whole table shakes. It's all about acceleration, and I can accelerate pretty fast. If I don't remember wrong I lowered the max_accel value to 2250 from 3000 to be able to cut with the table jumping around. This machine has a belt reduction and 5 mm pitch so I have no problem running alu or steel despite the small motors, it's the spindle that doesn't take it.
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