Warco Lathe problem

[AndyMParticipant @andym11566]

HI,

I hope I'm posting in this in the correct place and someone can offer some suggestions.

Started my Warco WM240B lathe and it no longer latches on when the green button is pressed. Any ideas what may cause this?

The safety switches all work i.e. if the emergency stop button is engaged, or the guard is up, or the cover is off it will correctly fail to start. If all are closed, the motor will run when the start button is pressed, but will stop as soon as it is let go. While holding it, it it tries to kick back.

Andy

[AndyMParticipant @andym11566]

[mechman48Participant @mechman48]

Have you made sure the emergency stop button has been released correctly? give it a twist to see if it pops up…

George.

[AndyMParticipant @andym11566]

Thanks for the quick response.

Yes – if the emergency stop is pressed the mortor will fail to start. It it is twisted and pops up, the motor will run – but only if the green started button is held down. The green button is "kicking" while it is held down and the motor stops as soon as you remove pressure. It used to "latch" on when it was pressed.

[David JuppParticipant @davidjupp51506]

A couple of possibilities, corrosion on the pole faces of the contactor or dirty auxiliary contacts that should give the latching action. In either case cleaning up with abrasive should help.

There could be other explanations.

[AndyMParticipant @andym11566]

Thanks David.

Can you describe what the contactor will look like (is it like a relay?) – is it likely to be inside the switch unit or seperate?

Andy

[Neil WyattModerator @neilwyatt]

Welcome to the forum Andy.

Someone had a similar problem and it was that the forward/reverse switch was in neutral so the lathe was in 'jog' mode, i.e. it only runs when you press the button.

But if the button is forcibly trying to disengage, that might suggest an overload.

Neil

[AndyMParticipant @andym11566]

Thanks Neil,

I've tried the fwd/reverse switch and the swicth operates as expected (fwd = fwd, Rev = rev, middle = stop) so it's not that.

I've located the contactor – a telemacanique LC1K0910 but it appears to be a sealed unit.

Only experienced the problem tonight so will play around a bit more but probably ending up calling warco tomorrow although by now it's probably out of warranty.

Andy

[VicParticipant @vic]

It's likely the starter switch from many similar threads I've read on a variety of machines made in the Far East.

[AndyMParticipant @andym11566]

Thanks Vic.

There only appeares to be 4 components –

1. The switch assembly (sealed) containing start stop and fwd/rev,

2. The Contactor (Telemacanque LC1K0910)

3. A transformer

4. The Motor.

As it runs ok when the button is held I;m assuming 3 and 4 are OK.

I'll let you know how I get on.

Andy

[John RuddParticipant @johnrudd16576]

 

my money is on the contactor, one of its auxiliary contacts is not holding it in…..after the go button is released…

Is there a drawing of the wiring in the manual?

What is your location Andy? Maybe some one nearby could help….

Edited By John Rudd on 16/12/2015 21:49:27

[VicParticipant @vic]

Posted by AndyM on 16/12/2015 21:28:38:

I'll let you know how I get on.

Andy

Yes do. It may be helpful to someone else.

[Bodgit Fixit and RunParticipant @bodgitfixitandrun]

I had the same problem on a clarke clm500. It was a fault on the reverse switch which had burned out. They are easy to change. I got a replacement from Fleabay. No problems since. Just make sure you get a high enough amperage switch.

I think the switch units are all very similar on these machines.

[AndyMParticipant @andym11566]

HI,

turns out the switch unit isn't sealed Removed back casing and it looks like the switch behind the green button is made up of a metal contact and a coil a bit like a relay. when pressed the contact is made, the coil energises and I suspect is intended to hold the switch closed, but it appears to be pulsing rather than staying on – it may even be pushing the contact away rather than pulling it – bit hard to tell. I'll investigate further tomorrow and possibly post some pics. I don't have a circuit diagram and I'm not familiar (yet) with the way these are intended to work.

To answer john's question, I'm based in Doncaster.

Andy

[John RuddParticipant @johnrudd16576]

Andy,

The red/green button assembly is an nvr switch by your description…..no volt relay…..which potentially changes my diagnosis….if the coil isnt energised when the green button is pressed it wont hold in and give rise to your problem…

[AndyMParticipant @andym11566]

Progress Update..

Spoke to Don in Spares at Warco – his suggestion is that it is the switch unit although he has never had one go wrong. They have had 2 spares on the shelf for ages – they are £54 for the complete switch unit. Don was unable to suggest any tests that woudl conclusively prove the switch unit is the item at fault.

I have "poked" around a little more. The picture below (if visible) is the front of the switch unit (upside down)

The following picture is the workings behind the red/green button.

The green button pushes the silver button in, making some contacts and energising a coil that holds the silver plate behind the button down (or is supposed to) The red button pushes on the yellow cover, levering the plate away from the solonoid and breaking the circuit. I assume this is what John referred to as a no volt relay in the post above.

I have disconnected one of the power leads to the coil. When I push the silver button in everything runs, but it obviously doesn't stay on when released.

When the power lead to the coil is connected and the silver button is pressed, it runs, but the switch vibrates violently (not buzzing) as it tries to alternately push then pull the contact away.

I have checked the voltage across the coil – it is 240v AC. I don't know if this is correct – I would have expected DC in order for the solonoid to work correctly (although not certain). If this is the case, then it suggests that either the voltage is converted to DC inside the swicth (and it isn't any more) or that whatever is supplying the voltage is no longer supplying DC. or have I misunderstood.

There are a number of contacts (3 i think) that are made when the switch is pressed.

 

 

Edited By AndyM on 17/12/2015 14:51:37

Edited By AndyM on 17/12/2015 14:59:42

[modeng2000Participant @modeng2000]

I had one of these switches fail on my WM180 recently.

It was replaced by one of these which is a drop in replacement. At £13.00 it was a good buy.

http://www.ebay.co.uk/itm/Start-Stop-Switch-No-Volt-Release-Switch-NVR-2HP-16A-with-Emergency-Stop-/262190170222?hash=item3d0bc0806e:gEkAAOSwrx5UX~P0

John

[AndyMParticipant @andym11566]

Thanks John.

Did your failure exhibit the same symptoms – I'm happy to swap the switch but i'm not convinced its the faulty item yet.

Andy

[AndyMParticipant @andym11566]

Found diagram below which seems to match my lathe – not sure it's helped me much though

[John RuddParticipant @johnrudd16576]

To help you understand……

SB1 is the NVR switch, 240 v in on pins 6&8. 240 v out on 5&7 going to the motor and the control transformer.4&3 switch a live feed via the LOR switch ( links or recht its german left or right fwd or rev if you like ) back to terminal a, terminal b being internally connected.

Km is the contactor feeding the motor via 4&6. The contactor coil is powered via the secondary of the transformer via the E stop and the two interlock switches. 13&14 on the contactor for a latch for the coil on the stop/start buttons.

If you measure the resistance between terminal 6 on the stop start switch and terminal 13 on the contactor you should read the coil resistance….if it reads ok, the check the contacts on the contactor terminals 13&14…you might have to energise the contactor coil if there is no manual means of closing the contacts via the contactor core

 

I SHOULD POINT OUT THAT ALL TESTING SHOULD BE DONE WITH THE PLUG REMOVED FROM THE POWER SOURCE……….sorry for shouting but we dont want any accidents…..

Edited By John Rudd on 17/12/2015 17:12:14

Edited By John Rudd on 17/12/2015 17:13:15

Edited By John Rudd on 17/12/2015 17:15:02

Edited By John Rudd on 17/12/2015 17:18:24

[VicParticipant @vic]

Thanks for the link John.

**LINK**

My belt and disc sander fails to latch some times so I reckon I'll need a new switch soon and that's not a bad price.

[AndyMParticipant @andym11566]

Thanks John, that helps a lot.

I'd worked out SB1, but coudln't fathom out what KM was doing – you explanation really helps.

Since my last post I have dismatled the switch further and removed the solonoid (see pic)

I have applied 240v to the solonoid and it clicks into place nicely and remains latched, leading me to suspect the problem may with with the supply to it through KM

Andy

[AndyMParticipant @andym11566]

hmmmm…. Put the solonoid back in the switch housing, left the lathe power disconnected and applied a seperate 240 feed to the coil and it doesn't latch – just rattles like before….. investigation continues but I feel were getting close…

[modeng2000Participant @modeng2000]

Andy,

I think it sounds much like mine. I had to hold the run button down to make the lathe run but this only worked for a couple of tries. As I recall it did make a buzzing sound. Took the switch appart and some of the contacts were burnt and beyond recovery so I just replaced it.

From your picture you have a different switch but as I recall there was something like it on the same shopping site.

Vic, glad to have been of help.

John

Edited By modeng2000 on 17/12/2015 19:52:53

[AndyMParticipant @andym11566]

Yay – Solved it.

Please excuse the scruffy drawing.

When the plunger goes in it pulls a switch contact bar out. The plunger wasn't able to go in far enough and was hovering in the magnetic field, on the bring of latching.

To solve it I bent the blue bar above to allow the plunger to go in slightly further.

The stop button has always been very sensitive so I guess it's always been on the cusp – I don't know why it stopped working, whether it's cold in the shed and something shrunk, or whether the coil is getting tired, or whether the switch bar is getting stiff or ……. but it's working fine now – I may have bent it a little to much as the stop button now needs a good press to disengage.

Thanks to everyone for their help and guidance.

Andy

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