Re: [CAD_CAM_EDM_DRO] Replace Heidenhein w/ EMC?

Jon Anderson wrote:

> Jon,
>
> Thanks for the input. The only reason I turned my friend on to this
> machine was the fact that it came with a PC already setup with a CAM
> program and comm link to send/recieve programs to the control. This was,
> in fact, the very machine I looked at late last year. I decided that
> with the huge order I was about to get, I didn't need the hassle of
> trying to figure out the idiocyncracies of a new control. I have seen a
> BP machining center with Heidenhein control that had both Heidenhein and
> standard G-code available but I doubt this control supports both.
> Not sure about the tach vs encoder issue. What's a quick way to tell the
> difference? If the motors have tachs, I assume then, that they'd need to
> be replaced with encoders for a switch to EMC (assuming the drivers can
> be configured to work with encoders alone)?

The machine you described had linear scales, which should be sufficient
for EMC, assuming they have decent resolution. There have been machines
made with both linear scales and shaft encoders, to obtain both high resolution
and long-term accuracy. Sensor fusion of these things can be a nightmare.

A DC tach is quite similar to a small DC motor, fixed magnets, moving coils
and a commutator. Integral tachs often are just another set of windings and
brushes on the same motor armature. If the motor has brush caps on both
ends (possibly 4 on one end, 2 on the other) that is a dead giveaway it is
a DC tach. An encoder needs at least 4 wires (5 if an index channel is
provided). A DC tach should only have 2 wires (3 if a shield ground is
provided).

Some (most older) servo amps need a tach. A few of the newer ones
derive velocity info from the encoder.

Jon