Re-Wiring Lathe Switches

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Re-Wiring Lathe Switches

This topic has 27 replies, 8 voices, and was last updated 11 February 2017 at 14:55 by Roger Bettaney.

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28 October 2016 at 20:04 #263484
Brian H
Participant
@brianh50089
I'm hoping that someone on here can help me rewire my lathe.

I have a Boxford AUD that was wired for single phase, probably by a former owner.

The motor is wired to a MEM No Volt Release (NVR) switch marked 84ADS using Live into L1 and Neutral into L3 with the output to the motor using A and C connections.

I want to now wire in a forward/stop/reverse switch and have a wiring diagram but am unsure which terminals to use in the NVR switch.

I also want to wire in a coolant pump with its own switch but again, am not sure which terminals to use in the NVR switch.

Naturally, I want the mains power to go through the NVR switch first.

Can someone advise or should I get an electrician in?

Many thanks, Brian
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28 October 2016 at 20:04 #38375
Brian H
Participant
@brianh50089
How?
28 October 2016 at 20:25 #263488
Emgee
Participant
@emgee
Brian

You should find a wiring schematic inside the cover, shows remote stop/start wiring details.

To ensure the overload works disconnect the motor feed from term A and connect on B, wire a link between term A and L2.

Best to use a separate starter for the suds pump so you have correct overload range device.

Emgee

Edited By Emgee on 28/10/2016 20:27:04

Edited By Emgee on 28/10/2016 20:44:20
28 October 2016 at 22:27 #263515
Brian H
Participant
@brianh50089
Posted by Emgee on 28/10/2016 20:25:15:

Brian

You should find a wiring schematic inside the cover, shows remote stop/start wiring details.

To ensure the overload works disconnect the motor feed from term A and connect on B, wire a link between term A and L2.

Best to use a separate starter for the suds pump so you have correct overload range device.

Emgee

Edited By Emgee on 28/10/2016 20:27:04

Edited By Emgee on 28/10/2016 20:44:20

Many thanks for the reply and yes, there are a couple of wiring diagrams inside the switch cover but they don't tell me where to take the feeds from for the two additional switches, unless they are simply tagged on to the existing connections?

Edited By Brian Hutchings on 28/10/2016 22:28:25
28 October 2016 at 22:59 #263522
Emgee
Participant
@emgee
Brian

Just read your post again and see you want to insert a reversing function, sorry if I misled you in my earlier post as I didn't allow for the reversing function, the starter is not suitable to reverse your single phase motor but you can connect to a Dewhurst or similar FWD/OFF/REV switch between starter and motor, only use the switch when power is off to the motor or you may cause damage to the switch contacts.

Emgee
28 October 2016 at 23:51 #263527
Steve Pavey
Participant
@stevepavey65865
I added a fwd/rev switch to my Boxford, which also had a single phase motor. The complete wiring diagram is in my album, **LINK**

operating the switch will knock out the nvr, so it is impossible to put go straight from fwd to reverse – important on a Boxford as the chuck screws on and you really don't want it to unscrew. Reverse is only really used for screwcutting odd threads at low speed so the screw on chuck is not a safety problem, just something you need to be aware of.

Wire the coolant pump seperately – if it is a small motor say < 1/2 hp, then you may get away without an nvr
29 October 2016 at 14:35 #263613
Brian H
Participant
@brianh50089
Many thanks Steve for the useful info. I was hoping to tap into the nvr switch to get power to the 1/3 HP coolant pump so that, in the event of power failure, the pump couldn't restart. Is that a possibility?
29 October 2016 at 16:19 #263627
John Rudd
Participant
@johnrudd16576
Anything wired after the nvr switch will remain unpowered until the nvr switch is reset..just piggy back the suds pump onto the other wiring to your main motor..
29 October 2016 at 19:50 #263661
Brian H
Participant
@brianh50089
Thanks John, that's what I hoped, despite having no expert knowledge of electrickery, as its known on the austinsevenfriends site!
29 October 2016 at 21:24 #263681
V8Eng
Participant
@v8eng
Posted by Brian Hutchings on 29/10/2016 19:50:48:

Thanks John, that's what I hoped, despite having no expert knowledge of electrickery, as its known on the austinsevenfriends site!

Nothing to do with "Catweazle" then?

Edited By V8Eng on 29/10/2016 21:25:05
29 October 2016 at 22:12 #263691
Emgee
Participant
@emgee
Anything wired after the nvr switch will remain unpowered until the nvr switch is reset..just piggy back the suds pump onto the other wiring to your main motor..

Not a good idea to connect the 2 motors on the same starter/OL output. The starter has an overload device which should not be set greater than the spindle motor plate FLC to provide overload protection. You can check the setting on your overload by reading the scale setting at the top right of the contactor, adjustment is by turning the green (or red) knob.

Althought the Suds pump will have quite a low current demand the additional load could be sufficient to cause the overload device to operate and thus stop the lathe spindle and pump. If the O/L is adjusted to allow for the additional current less protection is given to the spindle motor, this could lead to the motor windings being damaged in the event of an overload.

The suds pump will not be protected against it's plated FLC overload so the above would also apply.

Emgee
30 October 2016 at 07:32 #263724
Brian H
Participant
@brianh50089
I see what you mean Emgee, thanks for that. Now back to the drawing board.
4 November 2016 at 20:47 #264795
Brian H
Participant
@brianh50089
Me again! Still struggling with rewiring. I have bought what I thought was an 8 contact forward/reverse switch but no that it has arrived I find that it is a 16 contact forward/reverse switch.

Can I just use the first 8 contacts?
4 November 2016 at 21:36 #264806
Emgee
Participant
@emgee
Hi Brian

Sorry but it's not that simple. Did you get a drawing showing contact arrangement with the switch ? or even a connection diagram ? Is it a 2 position switch with no centre OFF ?

Maybe it has 8 switched pairs, you need to know which pairs make/break in the different switch positions.

Emgee
5 November 2016 at 07:51 #264839
Brian H
Participant
@brianh50089
Hello Emgee and many thanks for your input.

The switch is a 3 position one with centre 'OFF''. I have mapped out the connections and give the first four below;

In 'Forward' In 'Reverse'

1 No connections 1 connects to 2 & 4

2 connects to 3 & 4 2 connects to 1 & 4

3 connects to 2 & 4 3 No connections

4 connects to 2 & 3 4 connects to 2 & 1

The following blocks of 4 have similar results.

Brian
5 November 2016 at 09:28 #264846
Les Jones 1
Participant
@lesjones1
Hi Brian,
FIRST CONFIRM THAT WITH THE SWITCH IN THE OFF POSITION THAT THERE IS NO CONNECTION BETWEEN ANY TERMINALS ON THE SWITCH. If this is not so then do not proceed. We will call the blocks A, B, C, & D.
Link A1 to B3 and connect it to one end of the start winding on the motor.
Link A3 to B1 and connect it to the other end of the start winding on the motor.
Connect A4 to one end of the run winding.
Connect B4 to one end of the run winding

Connect the live feed to A2
Connect the neutral feed to B2

Where I have said start winding I mean via the start capacitor and centrifugal switch.

If forward and reverese are the wrong way round then swap over the wires between A4 an B4.

You do not need to use the other two blocks. (They are normaly called wafers.)

Les.
5 November 2016 at 09:37 #264848
John Rudd
Participant
@johnrudd16576
Did I infer that the suds pump be wired after the overload? Oh my bad….

I thought I wrote it could be wired downstream of the NVR switch?

The nvr and o/l are 2 completely different items in terms of functionality…..but then this already known among us…

Enlist the services of an electrician….

Edited By John Rudd on 05/11/2016 09:40:27
5 November 2016 at 12:56 #264895
Brian H
Participant
@brianh50089
Posted by Les Jones 1 on 05/11/2016 09:28:29:

Hi Brian,
FIRST CONFIRM THAT WITH THE SWITCH IN THE OFF POSITION THAT THERE IS NO CONNECTION BETWEEN ANY TERMINALS ON THE SWITCH. If this is not so then do not proceed. We will call the blocks A, B, C, & D.
Link A1 to B3 and connect it to one end of the start winding on the motor.
Link A3 to B1 and connect it to the other end of the start winding on the motor.
Connect A4 to one end of the run winding.
Connect B4 to one end of the run winding

Connect the live feed to A2
Connect the neutral feed to B2

Where I have said start winding I mean via the start capacitor and centrifugal switch.

If forward and reverese are the wrong way round then swap over the wires between A4 an B4.

You do not need to use the other two blocks. (They are normaly called wafers.)

Les.

Many thanks Les and yes, I can confirm that there are no connections with the switch is the 'off' position.

I am intending to rig up the connections using a 6 volt battery and light bulbs so that I can see what happens.

I'll report back on here in case it helps someone else.

Edited By Brian Hutchings on 05/11/2016 12:57:15
5 November 2016 at 14:16 #264901
Brian H
Participant
@brianh50089
First of all, apologies to all, I've just tested connections again and found a broken wire in a multimeter lead.

Even with the switch in the off position (as well as forward and reverse), there are connections between 2&4, 6&8, 10&12 & 14&16.

Even more confused!!

Edited By Brian Hutchings on 05/11/2016 14:17:28
5 November 2016 at 16:56 #264928
Les Jones 1
Participant
@lesjones1
Hi Brian,

Link A1 (1) to B3 (7) and connect it to one end of the start winding on the motor.
Link A3 (3) to B1 (5) and connect it to the other end of the start winding on the motor.

Link C1 (9) to C3 (11) and connect it to one end of the run winding.
Link D1 (13) to D3 (15) and connect it to the other end of the run winding.

Link A2 (2) to C2 (10) and connect the live feed to one of them
Link B2 (6) to D2 (14) and connect the neutral feed to one of them

The numbers brackets are your numbering system from 1 to 16

If you test it by connecting a 6 volt battery to terminals A2 (2) to + and B2 (6) to –
With your meter connected between C1 (9) and D1 (13) you should see 6 volts in both the forward and reverse positions of the switch The polarity should be the same in both positions. You should not get a reading in the off position.

With your meter connected between A1 (1) and A3 (3) you should see 6 volts in both the forward and reverse positions of the switch The polarity should reverse between forward and reverse positions. You should not get a reading in the off position.

Les.
5 November 2016 at 18:13 #264943
Brian H
Participant
@brianh50089
Many thanks Les, I'll give that a whirl and let you know.
6 November 2016 at 19:52 #265163
Brian H
Participant
@brianh50089
Les, I'm afraid that it's me again.

Your instructions regarding the testing with a battery and multimeter were spot on!

I am having problems with the first part about connecting the motor though. I have taken pictures of the plate on the motor, the wiring diagram inside the terminal cover, the actual wiring (obviously done by a works electrician with only a single reel of red covered wire) and a picture of the MEM NVR switch that only appears to have Live & Neutral in and out.

If you can help out on how this should be wired up I shall be eternally in your debt!

Brian
6 November 2016 at 20:54 #265170
Les Jones 1
Participant
@lesjones1
Hi Brian,

Remove the red wire with the green stripe from terminal U2. (Can you confirm that this goes to the capacitor ? If
it does not then these instructions will be wrong.)

Remove the blue wire from U1

You will now need a two position connector strip (Also known as chock block.)
Connect the two removed wires to separate terminals on the chock block. These two points now require connecting to the points on the reversing switch labled for the start winding. ( You may be able to use two of the
three unused terminals in the motor but you would have to make sure that there was nothing connected to them
on the underside of the plate.)

Remove the two red wires that come into the motor. They probably come from the MEM contactor. (Check) tHese
will be the existing live and neutral feed to the motor. Connect these to the live and neutral in connections on the
reversing switch. (It does not mater if live and neutral get swapped over)

Now connect U1 and U2 to the points on the reversing switch marked run winding. (it does not matter which is
which at this point. If they are wrong the reversing switch will work the wrong way round. If it does just swap
over these two wires. You will need some lengths of wire.

Les.
6 November 2016 at 22:25 #265190
Brian H
Participant
@brianh50089
Thanks Les, I'm going to get a couple of yards of the correct coloured cables, especially the earth which is currently in red (the one one the extreme right in the last picture.) It's confusing enough as it is.

I ll get the wire and them follow your excellent instructions and let you know how I get on.

Again, many thanks.

Brian
14 November 2016 at 13:27 #266546
Brian H
Participant
@brianh50089
With the very kind help of a fellow MEer, I have my Boxford lathe with reverse and coolant facilities.

A much bigger job than anticipated as I'm more used to 3ph and am now on 1 ph.

Useful in other ways as I found the primary drive belt about to break.
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