Tree Mill Help

[Gene Warren <gwarren-at-execpc.com>]

Hi Enrique,

Enrique Sanchez Vela wrote:

>   I got a stgII card and it turns out that I dont really need it, well,
> I got it and the mill has servo motors, so I dont have to replace them,
> I guess I would need a driver card to interface the STGII with the
> servos, anyone knows of a good, reliable and not very expensive card
> that works with A/C servos.

     Look no further.  The Servo To Go card is the driver card you want.
It produces plus or minus 10 volts.  0 volts for no speed, plus or minus 10
volts maximum speed, depending on direction.  The Getty N360 sums your
velocity command (from the Servo To Go card) with the Tachometer feedback
(from your tachometer).  The difference between those two voltages is what
ultimately controls the speed of your DC motor.  This is open loop as far
as the Servo To Go card is concerned at this point.  The Getty N360 is
first adjusted with the offset pot, with zero volts input, for no motor
movement.  Next, the Getty is adjusted to match the tachometer output
voltage (3 volts per thousand RPM).  Third,  it is adjusted for your input
scaling, which would be the 10 volt maximum output of the Servo to Go card,
for maximum speed.  Now you are finished with the Gettys Drive.  You have
just done the Velocity Feedback.  I usually do this with a battery box I
made using a 9 volt battery.  (Gets me close and I don't need the
controller.)

     Next, you hook up your encoder to the Servo To Go card and start
adjusting the P.I.D. settings in the software.  These adjustments are
considered, among other things, the Position Feedback.  The Getty N360 does
not have P.I.D. adjustments.  I do not have a clue about these EMC
adjustments because I don't have a Servo To Go card. but I'm sure someone
here will help you. I might be able to help you with the P.I.D. theory.  I
have a BDI v.2.04 EMC box with nothing attached to it yet.

>
>  the servos are from GOULD and rated at 12.5 amp, in the mill there are
> power drivers GETTYS 360, Three phase halfwave controllers., 240 VAC
> and 12.5A Rated Motor Current.

      We (me) will need a little bit more information about your Tree Mill.

1.  What is the volts per thousand of your tachometers?  That information
is usually printed or engraved somewhere on the tachs.  The tachs may be
integrated with the motors.

2.  Do you presently have Encoder feedback or Resolver feedback?  If you
can't tell, post the numbers here and you will receive an answer.  (Posting
all numbers here will be helpful, no matter how distant they may seem.)  I
am going to guess by the age of your machine (20 years old) that they are
resolvers.  If they are resolvers, you will have to include Encoders in
your limited budget.

3.  What is the model number of the Tree Mill?  Does 2UVR-C appear
anywhere?  On the back of the column on that little door?

4.  How many Getty drive packages are there?  Two?  I believe your Spindle
motor is one or two fixed speeds at the most and the Z-axis is not
controlled by encoder or any position feedback.  If this Tree is anything
like the ones I have seen it is a flat milling machine, with preset
drilling  done by a depth-stop micrometer.  The quill comes down, hits a
mechanical stop, and a clutch slips to hold it there.  I would have to go
to our Tool Room to check this out.  (We have well over 150 CNC machines in
our manufacturing facility, and I don't have them all in my head.)  Get all
the numbers from the Spindle motor.

     I believe we could make this Tree Mill Retrofit a group effort.  I
have a lot of experience repairing machine tool electronics and doing drive
setups (Servos), but no experience and less knowledge with EMC.  I have
been reading this list over a year and I recognize lots of expertise here.

     A number of assumptions have been made here.

1.  You have Gettys N360, 3 phase, half wave controllers. (Might be called
a RN136 somewhere.)
     Note:  this has since been confirmed.
2.  You have a 2UVR-C Journeyman Tree Mill machine.
3.  The present controller has a keypad on the upper left of the pendent
that looks like a touch telephone keypad.  If you want, I can send you a
JPG picture of the one we tossed out when I retrofitted it to an Allen
Bradley 8400 in the late 80's.

     If the above is true, I can send you spare manuals of all three
items.  Item 3 would be the Operators manual.  (I am an unrepentant pack
rat.)  Email your Snail mail address to me privately if you want any of
this.  No cost.

Later,

Gene