Re: [CAD_CAM_EDM_DRO] Re: servo vs stepper

jeffdavis516 wrote:

> That is exactly what I thought as well. I'm not an electronic
> engineer so what does it mean "Continuous" and "Peak"? It sounds to
> me that the motor can change it's torque when needed (up to 430 oz/in)

Servo motor torque is directly related to armature current. The motors
have two "fundamental constants", Kt in torque-units per amp, and
Kv, in Volts/1000 RPM. So, you see Kt is a direct relation, amps to torque.
The continuous torque rating is what the motor can do all day long without
overheating. The peak torque is what the motor can handle in short bursts
without demagnetizing the permanent magnets. You have to dig in the
motor specs to figure out how many seconds of peak torque it can take
per minute, ten minutes, etc.

> All I know is I don't have any problem running my Drill Mill. Have
> you looked at my movie on my web site?? In the last part of the
> movie my Mill is running that finish cut at 131 IPM!!!
>
> I machine at standard feed rates that are calculated by my cutter and
> the RPM of the spindle. I can't get real fast cutting feedrates
> because the Drill-Mill does not have a fast running spindle. Don't
> most CNC mills run the spindle at 5000 to 10000 RPM??? I know that I
> have pushed the feedrate too much and broken a 3/8 EM and the motors
> did not stall at all.

There is no such thing as "most" CNC mills. Yes, machines bought for
mold contouring use will often have higher speed spindles than machines
used for hogging out big cavities.

I broke a 3/8" end mill off clean in the spindle with the spindle not turning,
and didn't cause a servo trip, on my system. Calculations that ignored
friction were used to set up the machine for 1000 Lbs of linear force
at the table. I guess it can do it, too! One has to be careful when jogging
around at high speed.

Jon