On 2008-05-22, Ignoramus12247 wrote:
On 2008-05-22, Pete C. wrote:
It's a Bridgeport mill. No drum switch will remain and there will be no
speed pot. I'm quite comfortable with entering the speed and run stop
using the VFDs keypad. Rather similar to the Sxxxx M03 deal on a CNC.

BP drum switch is kind of hard to rewire.

Why? -- The internal wiring of the drum switch is as follows:

LINE MOTOR
o----------+-----------o (L1)
L1) o--------o-------- |
o-------+ |
| /|\
o-------+- | ----------o (L2)
L2) o--------o-------- |
o----------+

o--------+
L3 o--------o-------- |
o--------+-------------o (L3)

And all you need to do is connect the one which I have marked
(L1-LINE) to the common on the VFD, and (L1-motor) to FWD, and
(L2-motor) to REV. Totally ignore all the rest of the terminals on the
switch. If you can't figure out which is which, use a multimeter to
find a terminal on the switch which is connected to another terminal
only in the FWD position and to a third terminal in the REV position.

If you want an "ABSOLUTELY OFF" position, hook L3-Line to one
side of the line, and L3-motor to one of the line power inputs of the
VFD, but I personally would not do that for two reasons:

1) I don't like mixing line power voltages and control voltages in
close proximity.

2) I don't like dropping line power from the VFD's input when
switching to "OFF", which will deprive you of the controlled
ramp-down in speed.

If you want to be fancy, you can add a limit switch where it is
hit by the arm of the back gear selector, connect that switch (SPDT)
common to the common on the VFD, and connect the two other terminals (NC
and NO) to the L1-LINE and L2-LINE terminals of the drum switch, so your
switch will always use "FWD" for forward and "REV" for reverse, whether
you have the back gear enabled or not.

Enjoy,
DoN.

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