Does anybody have a schematic for the 3-position switch
(Reverse-Off-Forward) for the South Bend Lathe? I can probably figure
it out with a continuity meter. If so - I would greatly appreciate
getting a scanned copy or pay for xerox copies and postage.
It's time to replace and upgrade the motor on it. It smokes in reverse.
Thinking about replacing it with at least a 1 HorsePower, maybe 1.5
horsepower motor. Any suggestions?
Thanks for your help,
Joe
What kind of switch is it, a three pole, center off, three postion
drum controller? That is typically what sb shipped with their
machines as a rule.
Jim
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The most common types seem to be six terminal switches, eight
terminal switches, and nine terminal switches.
Six seems to be common, and of these there are two types
which look the same but are wired differently, the ones that
cross the contacts closest to the handle to reverse, and the
ones that rotate them from across to along the axis. If you
are lucky, you'll have a schematic glued inside the cover of
your switch.
For a single phase 220 motor, use the straight through
terminals to operate the start winding, and the reversing
terminals to reverse direction of the run windings.
This allows you to avoid wiring "hot" straight through to
the motor, where a short or bad ground would allow it to
keep running even with the switch off. I got the idea for
this from some previous RCM poster who I cannot properly
credit without spending a lot of time digging back through
archived posts.
For my lathe, I ended up with this for a 110/220 reversing
motor, set for 220:
/
+--o o--||--+
3 |
3 S |
3 |
+-----+ |
| |
+----------------+
3 | | |
3 M2 | | o o---- L2
3 | |
+-----o | o o-+
| | | |
+-----+ +---o o---- L1
3 |
3 M1 |
3 |
+---------------------+
Where S is the start winding, with capacitor and centrifugal
switch, M1 and M2 are the run windings, and L1 and L2 are the
220 lines coming in.
This is with a switch which operates this way:
Fwd Off Rev
o--o o o o o
| |
o--o o o o o
o--o o o o--o
Note the jumper on the bottom left on the circuit above.
For the type of six-terminal switch that crosses the
top two sets instead of "turning" them, the jumper would
go from the left side of the bottom contacts to the
right side of the middle set, and the output to the
bottom of the run windings would come from the left of
the middle set. Also note that my use of left-right-
top-bottom are from the reference point of the schematic,
and your switch may be mounted differently.
Also note that the green safety ground isn't shown, but
gets tied to the line, switchbox, and motor housing
straight through, so you'll actually need 4 wires from
the switch to the motor.
And lastly, your motor may be set up differently as
well.
A wander through google groups looking for "metalworking
drum switch" will get you a bunch of info for the variants.
But anyway, hope that helps.
--Glenn Lyford
One thing to check is the block which the wires hook to. Mine had the
screws loosen up and the reverse position eat up the contacts with each
activation until it quit all together. I have South Bends Original paper
work for the various switches and how to wire them to a particle motor
type. I'll fire up the scanner a see if it can pick up the details.
Regards
Jim Vrzal
Holiday,Fl.
Joe Comunale wrote:
I'll try to keep these here as long as possible. Copy on to your own
media for future reference or move to a more permanent web host.
Regards
Jim Vrzal
Holiday,FL.
Mawdeeb wrote:
Because the start winding in a 240 volt configuratin is
frequently tied to the center of the two run windings
(dual voltage motor) this is easier to implement than
the same setup for 120 volts. See:
The 240 volt version has one fewer wire from the motor to
the switch, then the 120.
Jim
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please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
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While we are on the subject- where can you find a new switch? Mine was
damaged and the cover is gone and one of the bakelite terminal blocks is
broken.
You can probably get then from industrial electrical suppliers,
or from places like MSC or Grainger.
I picked up a spare from an eBay auction -- though it is of the
format more often found on Bridgeport spindle motors (bar knob, instead
of a lever shaft with a round knob at the end, but electrically, it
still works the same.
Cutler-Hammer is one of the many brands out there, I think that
Allen Bradley is another, or at least used to be.
But if you wanted to try your had at repairing the original
switch, you might be able to machine a good terminal block to fit out of
Delrin. The cover is a different matter, and perhaps a more serious
one.
Good Luck,
DoN.
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