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My ford lathe problem!

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John Vickery22/12/2018 09:25:57
10 forum posts
1 photos

Hi guys, currently recently retired and undertaking Allchin 1.5 build. My problem.... my Myford lathe switched itself off, will restart in both forward and reverse but refuses to stay running, switch reverts to off position. The current switch from single phase supply is.a Kraus and Naimer CA 10x. Please can anyone help? Is the switch the problem? If so, can anyone suggest a reasonably priced replacement? Thank you

Brian Wood22/12/2018 10:23:50
2154 forum posts
37 photos

Hello John,

Welcome to the forum, I hope we can help you

Is this a sudden failure from what was a fully functioning switch?



Edited By Brian Wood on 22/12/2018 10:24:21

John Vickery22/12/2018 10:40:44
10 forum posts
1 photos

Hi Brian, thanks for your prompt response. Yes, the lathe was working perfectly until I turned it on after returning from a hospital stay (!)

Regards, John

Les Jones 122/12/2018 10:49:01
2121 forum posts
146 photos

Hi John,
I am not familiar with the Kraus and Naimer CA 10x switch but by looking on the web it looks like just a reversing switch with no overload protection. Does it lookf:0"> like this ?


When the lathe stops do you have to wait for some time before it will restart or will it restart straight away ? Is this switch the only control or is there a push button stop and start switch ? About how long does it run for before stopping ?



Edited By Les Jones 1 on 22/12/2018 10:50:42

Edited By Les Jones 1 on 22/12/2018 10:54:02

Edited By Les Jones 1 on 22/12/2018 10:58:09

Edited By Les Jones 1 on 22/12/2018 11:02:31

Simon Williams 322/12/2018 11:00:27
499 forum posts
78 photos

Good morning John, if I remember right this is a blue cam switch, with a three position knob on the front of a silver fascia plate. I've just tried to lift a picture out of the K & N catalogue but it only comes as a pdf which I can't put in an album.

It's some while since I had one of these switches to pieces, but I think that the detent mechanism is behind the switch fascia, There is a nylon cam and a spring which controls whether the cam mechanism stays put or returns to centre or what, and it sounds as though this has failed or got worn out. Whether it is repairable is a whole different can of worms.

Don't take the black switch body to pieces - there is any number of little bits of brass and things hiding in there waiting to jump on the floor.

If you want to have a go at the detent mechanism take the knob off the front by loosening the little screw in the centre of the knob, don't undo completely it's only a clamp, then pry the silver fascia out of the black surround at the front of the panel. This exposes four screws which mount the switch to the panel. Undo them and push the switch body off the back of the panel. Now you should be able to work out how to take the front off the switch cam to see the detent mechanism. The down side of this of course is - quite apart from the intricacies of getting to this point - it may not be obvious what is missing.

Last time I tried this I managed to get it to bits but gave up trying to put it back together, I needed more hands than an octopus. You'd be better off buying a new one, but be careful to specify the right thing as they all look the same on the outside, but the arrangement of the internals is crucial. I think City Electrical Factors are agents for K & N.

Alternatively this looks like the right thing, **LINK**

and at least you know where you're starting from. I would think you want the 2 pole changeover for a single phase reversing switch so that looks like option CO202 (20 amp 2 pole). It may not be obvious how to connect the new switch to the old wiring, it should come with a diagram which describes what to do.

Good luck, and all the best Simon

Brian Wood22/12/2018 11:05:22
2154 forum posts
37 photos

Hello John,

I have a 4 way switch by these makers that allows me to select different poles for speed control in an old induction motor salvaged from a washing machine that is hooked up to my drill.

These rotary switches don't have any mechanism built into them to return to an OFF position. The only restraint as far as I know is the usual sort of ball bearing click action to hold the switch in position for that particular set of contact arrangements to select a chosen direction of motor running

I can see no good reason at all for it to fail in this way. Current loading on the contacts, even if heavy, would not have this effect.

No, sorry----you have stumped me on this one


John Vickery22/12/2018 13:59:00
10 forum posts
1 photos

Hi again. Yes, I'm at loss to know why this might be happening because lathe was running fine and then switched its self off. As soon as I release the switch it turns off. I've tried, unsuccessfully, to load a picture of the switch. It doesn't look quite like any of the link pictures sent by Les, it does have A401 printed on top of the block? Like you, I'm left scratching my head..but thanks for your support!

BW John

Les Jones 122/12/2018 14:17:24
2121 forum posts
146 photos

Hi John,
Can you confirm that the switch actually jumps back to the off position ? I was assuming it stayed in the forward or reverse position but the motor stopped. I think the type number refers to a range of switches and the "X" will be replaced with some code that gives the number of poles and positions.


John Vickery22/12/2018 14:31:12
10 forum posts
1 photos

Hi Les, if I hold the switch in either forward or reverse, the motor will continue to run, once I release it it 'springs' back to the central, off position. I looked at the Krauser and Namier catalogue online and the X appears to relate to a 'power failure release' component of the switch.

Les Jones 122/12/2018 14:50:15
2121 forum posts
146 photos

Hi John,
I found their 2017 catalogue online but did not fond anything about the power failure release. Is there a coil assembley on your switch ? If so there is probably a contact that keeps that held energised in the foreward or reverse position. If that contact is intermittent it would cause it to drop out and cause the switch to return to the off position, It could also be the mechanism that holds the switch in the forward or reverse position that is faulty. It may only be dirty or needs a drop of oil. If you can post some pictures it may help.


Clive Brown 122/12/2018 15:52:10
405 forum posts
11 photos

Assuming that the switch is goosed and at the risk of upsetting the electricians, for a cheap solution, why not just a 13 amp plug and switched socket?

The reversing function is not very useful on a Myford 7, potentially a liability  with the screwed mandrel nose. (How do I know when I've got a Boxford? That's the reason for the only mark on my lathe bed.)

Edited By Clive Brown 1 on 22/12/2018 15:53:20

Edited By Clive Brown 1 on 22/12/2018 16:01:35

Robbo22/12/2018 17:51:47
1504 forum posts
142 photos

Sounds like John's switch is the one specifically used for Myfords, is in a substantial cast housing, and came with specific wiring instructions for Myford use. I have an unused one "on the shelf", but have never tested it.

These are not like the smaller switches with a cam and spring lock to hold the switchgear in place, but have a built in NVR capability. If there is no voltage flowing then the knob will return to the off position.

Seems like the NVR coil has called it a day, or become disconnected, so the contacts can only be kept closed by holding the knob in place.

A picture of the switch will help identify it

Edit - must acknowledge Mrs Robbo's help in typing this wink

Edited By Robbo on 22/12/2018 17:54:26

John Vickery22/12/2018 18:35:55
10 forum posts
1 photos

Hi Robbo, this sounds exactly the issues I'm having! I have a picture but (even with Mrs V's help!) I cannot upload it to this site. If you could give me an email address I can send the picture, but I don't know if that's something people do on these forums and if it's an inappropriate suggestion.. I apologise!

The unused one on your shelf... is it for sale?

BW, John

Grizzly bear22/12/2018 18:36:25
232 forum posts
8 photos

John V,

You have to create an album, then place your pictures in it.

Search the forum for info.

Good luck, bear..

John Vickery22/12/2018 19:09:22
10 forum posts
1 photos

img_0093 (1).jpg

John Vickery22/12/2018 19:10:25
10 forum posts
1 photos

Thank you Grizzly Bear! MrsV is learning so much this afternoon!

Les Jones 122/12/2018 20:01:23
2121 forum posts
146 photos

Hi John,
I have had another thought. If there are any interlock switches on a chuck guard or cover over the belts or anything else they would be wired in series with the NVR coil. If there are interlocks it would be worth making sure that they show continuity when closed. Is it possible to get the switch out of the box so we can see the underneath of it ? I expect there to be two wires going to the black part at the front of the switch. If there are can you measure the resistance between the ends to see if the NVR coil is open circuit ?


John Vickery22/12/2018 20:35:14
10 forum posts
1 photos

Thanks Les. I'm sure that Robbie has identified the problem for me and I'm thinking that a replacement switch is going to have to be the answer. The coil failure makes sense to me as there didn't seem to be a mechanical lock on the positioning of the switch. Once Christmas is over I will contact the supplier that Simon suggested unless the one on Robbo's shelf is available.

Can I thank everyone who has responded... I've been genuinely amazed by the generosity of your time and expertise! I think this is a 'solved' issue but I will return if I still have problems.

BW John.

Robbo23/12/2018 16:45:17
1504 forum posts
142 photos


After a Doctor visit this morning can manage to do this myself without too many shakes, so have taken a pic of my switch which seems the same as yours. Pics below

If you check out the items noted by Les Jones, who is a whizz at this electrics lark, and still need a replacement, then let me know.

I will send you a message with my email address, pick up the message from your Inbox at the left hand of the green bar at top.


John Vickery24/12/2018 08:43:26
10 forum posts
1 photos

Hi Robbo. Pleased to hear you are feeling better! Yes, this switch looks exactly like mine. Is this switch surplus to your requirements and if so are you prepepared to sell.... and how much? I’m in Devon so it would have to be a postal job.

Regards, John

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