Electricians

[Deleted User]

At the end of the motor is a small cover plate. Underneath the plate are three terminals. No 1 terminal has a black wire from the capacitor and a red wire into the motor. No 2 terminal has a red wire into capacitor and the white wire from feed cable No 3 terminal has a green wire into motor and the red wire from feed cable and finally the blue wire from the feed cable is fixed to the body of the motor (earthed?)

[Deleted User]

@Roger Hulett wrote:

At the end of the motor is a small cover plate. Underneath the plate are three terminals. No 1 terminal has a black wire from the capacitor and a red wire into the motor. No 2 terminal has a red wire into capacitor and the white wire from feed cable No 3 terminal has a green wire into motor and the red wire from feed cable and finally the blue wire from the feed cable is fixed to the body of the motor (earthed?)

OK! That makes sense!

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I fink! ❗ 😉

Terminals 2 & 3 are the connections for the run windings.
Terminals 1 & 2 are the connections for the start windings, the condenser and centrifugal switch.

If you connect the mains supply to terminals 2 & 3 the motor should run.

The blue does indeed appear to be an earth connection.

As it is currently wired the motor is non-reverable. It can be reversed by moving one of the capacitor wires to terminal 3. If foreward & reverse is required, then the introduction of a Dewhurst switch with some small wiring changes will do the trick.

[Deleted User]

Excellent. Thankyou all for your input. Wired it up as suggested and it works perfectly. Now David,is it difficult to incorporate a Dewhurst switch for reversing the motor, and is it worth it ??

[Deleted User]

@Roger Hulett wrote:

Excellent. Thankyou all for your input. Wired it up as suggested and it works perfectly. Now David,is it difficult to incorporate a Dewhurst switch for reversing the motor, and is it worth it ??

‘Tis a long time since I ‘Dewhusted’ my Southbend — me memory ‘aint wot it used ter be, 😳 gotta go boxfile digging for my wiring diagram.

It is an exercise well worth doing. Sooner or later for example you’ll want to cut a thread, maybe a new spindle, now depending on how your lathe is set up, (Norton gearbox? Threading dial indicator? Leadscrew metric or imperial?), you are going to want/need to leave the half-nut engaged to maintain register and therefore run the saddle back under power to the start for the next cut.

If your lathe experience is limited and even if not I can recommend a little book entitled “How to Run a Lathe” originally published by the South Bend Lathe company it is now available in a facimile edition, it contains just about all “man-in-a-shed” is likely to need.

Now I’ll go look for that wiring diagram . . . 😯

[Deleted User]

@Roger Hulett wrote:

Excellent. Thankyou all for your input. Wired it up as suggested and it works perfectly. Now David,is it difficult to incorporate a Dewhurst switch for reversing the motor, and is it worth it ??

Short circuit — pun intended ❗

Have a look at https://www.instructables.com/id/Wiring-up-a-Brooke-Crompton-single-phase-lathe-mot/step4/Dewhurst-drum-switch/

In this application I don’t think the comment about “arcing & sparking” is anything to worry about, my one has never given me any cause for concern.

[Deleted User]

Thanks David. Very good article. Regards Roger

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