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Drum Switch Wiring, Split Phase Motor

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Ulma Doctor

Infinitely Curious
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I purchased a beautiful Hercus ARH lathe a few years ago.
photo (1).JPG

https://www.hobby-machinist.com/threads/hercus-9-workshop-lathe-model-arh-serial-15548v.24143/

i love this machine, but the original owner didn't wire the drum switch for direction.
it only ran in the spindle CCW direction ,whichever direction the drum switch was switched.
being a threaded spindle, the direction of operation was just fine for turning.
i didn't see an urgent need to make the motor bi-directional.

Something changed in me the other night,
Suddenly i felt the necessity to correct the problem that didn't really bother me before. :cautious:
but whatever it was, the dragon had to be slayed before i could rest easy once again.

I went to the shop and took the drum switch off the lathe, noting the wiring arrangement
to my surprise, the drum switch was just being used as an off/on switch,
there was one jumper wire installed, but no other wires were present.

the drum switch is a Square D Class 2601 Type:AG-1

IMG_3188.jpg

the motor is a Dayton - thermally protected, split phase, 56 frame, 1/2 hp, 115v single phase, 8.4Amp, 1725 rpm motor

IMG_3187.jpg

i am glad i got this bug in my head,
the old wire insulation from the drum switch to the motor was crispy and crunchy.
as i removed the wires the insulation mostly flaked off :eek:

IMG_3197.jpg

After seeing this, i was determined to do things differently....

there are many ways to achieve the end.
this is the way i did it.

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
if you are not comfortable with electrical circuits, consult qualified personnel before attempting service of any type of equipment


The 1st step:
was to construct the control circuit wiring diagram to make a unidirectional motor, bi-directional with a drum switch
here is what i came up with...

the control circuit consists of 6 conductors and a ground wire.
the motor start leads are in effect brought back to the switch for directional control, then the wires are returned to the motor terminals.
by swapping the M2 and M3 leads in relation to the start leads, reverses motor direction.

HERCUS ARH DRUM SWITCH WIRING.jpg

The 2nd step:
was to figure out what wire to use for the project.
working with the given parameters, the motor pulls 8.4 amps by the nameplate.
I chose 14 gauge THWN oil resistant White wire, here is why..
i went to the local box store and looked at the different selection of wire, and cord
they did't have 7 wire 14 gauge SOW cord.

i had some liquidtight fittings and flex conduit already at home, so i figured i'd just use THWN, instead.
i looked at the wire selection and the pricing was ridiculous, to be mild.
here is what i found,
50 ft feet of 14 gauge THWN was $20
100 ft was $28
500 ft was $40
i ended up buying 500 ft of White THWN, just out of principle- now i have plenty :grin:

White wire can easily be marked with permanent markers for easy identification.

Note: Stranded THWN wire no matter the color, is made to the same specifications- the only difference is the jacket color.
you may choose any color, as long as you mark or otherwise identify the individual wires
(i would not recommended using green stranded wire for power circuits- it could too easily confused with a ground wire)

The 3rd step:
was doing the work (my favorite part!!!)
i cut the liquidtight conduit to length
i cut the wire into 7, 3 ft lengths and pulled the wire through the conduit
i marked all the wiring with colored ink bands for easy identification
i wired up and mounted the drum switch

IMG_3191.jpg

then secured the conduit and fittings into the switch and motor

IMG_3189.jpg IMG_3190.jpg

IMG_3198.jpg


i made the connections as per the diagram
it was tight work getting all 6 conductors and the ground under the cap, but it all fit!

The 4th Step:
i plugged the power in and gave her a test run.

Sheila now runs forward and reverse ;)

thanks for reading!
 
Last edited:

middle.road

Actively Learning...
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Well we know you won't be sending that machine to LA County. Has to be color coded down thar.
On the ordnance production plant I worked on near Van Nuys airport, back in the '80's, the manufacturing engineering group, bought (6) Mitsubishi Machining centers, and (6) Mazak turning centers. The Mazaks passed but the Mits failed LA County inspection because they were 'black' wired.
Mitsubishi had to bring in six techs and a truckload of crates, and they spent six weeks re-wiring them.

And speaking of tax dollars at work, I never caught on as to why, on an American Defense plant project, they were able to buy all imported machines.
The ME Manager even tried to force us in the QA group to purchase Mitutoyo CMM's. I bought Sheffield Cordax's from Ohio.
And then it came out that the ME mgr was visiting relatives in Japan, when he made his trips over there to check on the machines. . .
 

Ulma Doctor

Infinitely Curious
H-M Supporter - Gold Member ($25)
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Messages
507
Betcha it took you longer to write this up than it did to re-wire Sheila....
surprisingly, no.
truth be told, i filled up the swear jar trying to figure out how to get 7 wires tucked in under the end cap!
what i didn't express earlier is that i had to change 4 terminations from push on connectors to ring terminals
before it would all fit.;)
Nice clean wiring job Mike, the wiring is my favorite part too
mark
Thank you very much Mark.
flicking the switch for the first time is the best feeling, especially when it works as intended.
 

markba633csi

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I never could do this stuff for profit, it always takes longer than I planned; I'd starve LOL
It gets less exciting (no arcs and sparks) as you get older, but that turn-on thrill is always fun
 

middle.road

Actively Learning...
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I have a similar motor on my bandsaw, but... I need yet another lesson in electrical 101.
What's the difference between a 'Split Phase' motor and a 'Capacitor Start' motor.
1545705214957.png
1545705251308.png
 

markba633csi

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Technically I think they are both split phase but I believe the term usually refers to a motor with a start winding but no start capacitor
mark
Just like Apple and IBM compatible computers are both "PCs" (personal computers) , the term usually refers to the latter
 
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