On May 15, 2007, at 3:13 PM, Andy Holcomb wrote:
Does anyone know the price an encoder that would work on this
machine with emc and not made out of gold?
Of course, the first thing to do is make certain that you have
resolvers and therefore need to to something about this.
http://web2.automationdirect.com/static/specs/encoderld.pdf
These encoders are $80 + change and seem to work OK. They are not
IP64 so you may want to isolate them from the
environment a bit.
US Digital also makes encoders that are not too spendy.
Dave
Will the geckos run these motors? and are they good with emc? I am
trying to get an idea of the cost to retro fit it.
Andy
Ray Henry wrote:
I started servicing CNC machines a couple years before this
machine was
made. I never saw a stepper used for axis positioning until much
later.
They were used to pace the tape through a tape reader during that
time.
Let's assume that you've got servos. Next issue is the nature of the
position feedback. Many of the machines from the the seventies and
eighties used resolvers rather than pulse coders. A resolver does
not
produce pulses that can be counted.
A resolver uses ac rather than dc power. They take two ac
signals, sine
and cosine to each other and return the rotor position as a phase
shifted signal. My experience suggests that one way you can tell a
resolver is that the six wires from it were twisted in pairs. If
it was
placed in a can with a plug, good luck figuring it out. (This is
where a
wiring diagram would be a real help)
Assuming resolver feedback there are a couple things you can do. The
first is get a resolver to quadrature converter box. With such a box
you get the signal generator to power the resolver and a fixed
number of
pulses per rotation of it. You could also replace the resolver
with an
encoder. This is what MattS and I did with a Hardinge lathe. He
had a
little spindle built that matched the size and arrangement of the
Harosun(sp) resolver and mounted a shaft encoder on top of it.
Okay. Let's say now that you've got quadrature feedback of axis and
spindle position. Now you need a way to get those signals into
the PC
running EMC2. Several board makers have devices that can do
this. EMC
has HAL driver modules that can read these. In alphabetical
order, some
of these include. Mesa, Pico, Pluto, STG, Vigilant, Vital.
You'll find
links to these companies at www.linuxcnc.org.
And lastly you will have to produce a velocity signal of the sort
expected by the motor's drive amplifier. In that age most of the
drives
used an analog signal that varied between -10v and +10 volt.
Again the
board makers will usually have that ability as well.
HTH
Rayh
On Tue, 2007-05-15 at 15:19 -0500, Andy Holcomb wrote:
I am just looking at it, I wanted to know what the task of
changing it
to emc looked like. It does have the crt. I don't think he has the
books. If this is a servo an encoder machine what equipment will be
required to talk to it?
Andy
Ed wrote:
Andy Holcomb wrote:
Has any buddy messed with any old Pratt and Whitney CNC
Lathes? This
one has a fujisu fanuc controller, it is a turn mate 1981 model.
Does it run steppers of servos?
If it is Servos what would it take to get emc running it?
Andy
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Does this machine have a CRT or is it a single line display? I
have one
that was built in 82 that has a CRT and uses servo motors with
encoders,
I bought it to do a retro with EMC but it turned out to have been
"disabled" so the machine would be replaced with a new one. Do
you have
the books with it? They have good schematics. Ed.
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