Re: NEW member Suitable conversions?

"D.F.S." wrote:

> First is an electronics manufacture Glue dispenser.
>
> It is a rather general purpose units, about 2.5' square.
> It is a flat bed Plotter type unit with a Z? or Y? axis tool holder
> that has about 4" travel.
> The question about the axis, is how they are defined.
> I would call it Z looking down at the bed, I've been told the
> "Correct" axis is defined looking at the machine from the front,
> making it Y.

The table motion should be called X and Y, and the glue dispensing
head's motion should be Z.
That will make it most compatible with software that will produce
coordinates for the glue dots.

> Overall the usable area on the bed will be 18" Square.
>
> In a quick and dirty test, I rotated the steppers, and counted the
> full revs, it takes ~11.3 to travel the entire width or length of the
> bed.
> The bed travel is about 18" or ~457mm
> The steppers are 1.8 Deg units for 200 steps/Rev.
> Half stepping them would be easy, that would give 400 steps/rev or
> about 4520 / full stroke of about 457, I'm hoping real measurements
> after things ar up and running will show it to be calibrated at
> .1 mm / 1/2 step. that would make life easier.

Not terribly important, as EMC uses floating point aritmetic EVERYWHERE,
so rational
step sizes are not needed.

> The intended use is plotting etch resist on circuit boards, and
> drilling them after they are etched.
>
> The unit contains all the electronics to drive the steppers, and I'd
> like to use the driver ICs, they will take the usual direction / step
> inputs.
>
> Does this sound reasonable?
> Any red flags or problems at the outset on making something like this
> work?

No, it sounds fairly straightforward.

> The second project is a Wasino Gangster.
> It is a CNC Gang type lathe.
> IE. to the right of the lathe chuck is a table like on a mill.
> The tools are bolted down on the table like work is on a mill.
>
> The controller is as large, and 5 times as heavy as a refrigerator.
>
> The lathe itself has a 4 speed induction drive motor, not a variable
> speed CD one.
> There is an absolute encoder on the spindle.
>
> I don't know anything about the drive motors for the table.
> I think they said DC on them and I don't recall much else aside
> from the fact they were probably 1 foot long and 6 - 8" in diam.

Most likely DC brush servo motors.

> This may be too general of a question, but how are such motors
> "Usually" encoded to determine rotation?

No specific type is 'usual'. There could be linear or rotary inductosyn
transducers, rotary or linear
optical encoders, or something else. The rotary type could be inside
the motor, or external.
There may also be a DC tachometer.

> Are the more likely to be optical step or absolute encoders, or
> analog resolvers of some sort?
>
> The controller is a Fanuc 5T if I remember.

You may be able to determine encoder type by looking for the module in
the
CNC control that reads it. It may be clearly labeled with the type
encoder
it is meant for. If not clear, you can try to find the encoder reader
module and
trace the cable back to the encoder.

> The motor controllers appear to be somewhat modular, and may be
> usable seperate from the rest of the controller.

Yes, except on the latest controls, the servo amps were pretty much
separate
modules, with very simple and pretty standard interfacing to the CNC.
+/- 10 V analog DC was the most common standard for velocity command.

> I'd REALLY like it if I could get the info on driving them directly.
>
> I rather not get into hard core heavy duty electronics any more
> then necessary. I can if necessary, but these are very large,
> high voltage, and smoking something could be pretty serious I
> would imagine.
>
> How good would EMC be at running a lathe?
> Everyone seems to be dealing in mills.

Well, I'm pretty sure about 2 years ago, a turning center was set up
with a much
earlier version of EMC, and it DID do threading, so EMC knows how to
handle a spindle encoder - or at least it still should.
Other than that, the only difference is to be able to display the X
position as radius or diameter, which could be completely handled
in the user interface. Otherwise, there is no difference in the RS-274
commands or the motion planning.

One other thing, on electronically variable speed spindles you might
want to have spindle speed controlled by X position, to maintain
constant surface speed. That is not currently implemented, I don't
think. It should not be hard, however.

Jon