Re: [CAD_CAM_EDM_DRO] Servos for Dummies

WDSmith wrote:

>
> Since I have yet to find "Servos for Dummies" or even "servos 101"

check out http://www.cnckits.com/ on the Tutorial page:

Tutorial 101: precise motion control from a PC
a short overview with sweeping generalizations
on Step & Direction (S&D) CNC control

But to answer your question:

> I checked my motor stash and came up with a Pacific Scientific
> motor with an encoder of some sort. The motor has two wires the
> encoder has a 10 wire ribbon and header plug.

>Here are all the numbers from the dataplate:

>4MV82-004-4 835D20074-01
>Torque Constant: 9.1 oz. in. amp
>Terminal Resistance: .89 ohms
>30 V 7.4 A (rms)

Not knowing anything about those parts except the specs you
show, it should be ok if geared down quite a bit. At 9.1 oz*in/A * 7.4A
thats 67.34 oz*in continuous. For some motors, that spec is a 95+%
continuous rating, with a 1%-5% surge rating of many times that
amount (for bursts of acceleration, etc). Of course you get torque
multiplication with the gearing-down.

Since the Gecko G320/G340 have 18-80V input at 20A, then using
those with a 30V (possibly up to 35V) powersupply should so the
trick.

The one concern is that you are able to output the pulses fast
enough to achieve top speed. For example, if the above is a 2500
rpm motor (= 41.66 rev/sec), and if you were able to emit 25,000 pulse/sec
using your favorite software, then you wouldn't want more than a
600 count-in-quadrature encoder ( 25,000 / 41.66 == 600 ).

If your encoder counts were higher per rev, or your pulse/sec were
lower, then you wouldn't be able to reach the top speed of 2500 rpm.

Doug Fortune
http://www.cncKITS.com
















.