Re: [CAD_CAM_EDM_DRO] Re: EMC Spindle control Help!

paragon032003 wrote:

>Addition info to help clarify things....
>
>What I would like to do is use just two pins from my printer port...
>
>I guess it would be something like this but not entirely sure...
>
>One pin would set increase or decrease speed (hi - low)
>The other pin would pulse hi low hi low etc etc to increase/decrease
>speed
>of motor depending how the first pin was set!
>This would then drive a circuit to supply the variable voltages.
>
>Hope the description above makes sense! ;-)
>
>
>

Well, EMC does not have provisions to do this right now. If you want to
write the software, feel free to do so.

If you just want to bump the speed higher or lower, without any control
of the actual speed, EMC does have a rough facility for that. Of course,
you don't need a computer to do this! Bridgeport BOSS R2E3 machines
and some others had an air motor that drove the mechanical vari-speed
drive. I think the reason for this is that the Series-II was so tall
people needed
a ladder to reach the control. So, they put a button on the pendant to
activate the air motor. EMC has this feature, with on-screen buttons
to raise and lower spindle speed. This is connected by the existing
software
to 2 solid state relay outputs by the bridgeportio option. It would not be
too hard to rig up a DAC, counter and a one-shot to step the DAC voltage
up and down when these buttons are pushed. You could also use one of
the Dallas Semi digital Pot chips to do the same.

The limitation to this is that the computer is not able to set the speed to
a known value, like 2500 RPM. It requires a human operator to push the
button and read a tachometer to set the spindle speed. Really, not a very
good solution.

Jon