Re: Servo driven router table

--- In CAD_CAM_EDM_DRO@y..., "omikse2000" <omikse2000@y...> wrote:

> I have 90vdc pm servo rated at 6000rpm with no load.
> I am using a US DIGITAL E2-1024 encoder and a GECKO 320 con-
> troller . My power supply is 46 vdc. I am using Dancam runing
> from a 486dx-66 computer. I amtrying to get at least 2000 rpm
> with no load. The max I can get is 1233rpm. Fiddled with pulse

rate

> multiplier and pwf ,but can't improve speed. Any ideas as it really
> moves when hooked direct to the power source?
> Question #2 What is the best hole size and layout for a 4 x 8
> vacuum clamped router table?

Lets see if I can do the math. The encoder is a 1024 (1,024 pulses
per rev) multiply that times 4 for quadrature output so we have 4048
ppr. Now to spin the motor at 2000 RPM (33.33 Rev per sec) you would
have to supply 134798 pulses per second....that's a lot. Using a 10X
multiplication you still need 13,479 PPS to get 2000. A lot of
Controller programs will not put out that kind of pulse rate.

Sounds like the limitation could be the controller output. Also
remember that the output to the motor is PWM (pulse width modulation)
And probably will not go to 100%. Measure the DC voltage across the
motor when you are running at the 1200 RPM and see how close you are
to the raw powersupply voltage. If it is less than 80 to 90% then
you might have to raise the raw DC voltage closer to 70 volts to get
the RPM. I am not sure about how dampening from a load will effect
the feedback loop so unloaded performance may not be a true
indication of what the motor will do under load in RPM.

Most PM DC motors are pretty linear with respect to voltage and RPM.
A 6000 RPM @ 90 VDC rating should provide somewhere around 3000 RPM
at 45V.