Electrics are definitely not my forte

[sean logieParticipant @seanlogie69385]

Hi, been a bit of a disappointing day on the lathe front , on the bright side I’ve moved it to its new home . I’ve added some photos in my albums of the motor stripped down and it doesn’t look very healthy .

[sean logieParticipant @seanlogie69385]

[Tim StevensParticipant @timstevens64731]

The two first pictures look OK to me, for an elderly motor. What are the symptoms of the problem you need to cure?

The contact device in 3 should be closed when the motor is stopped, but the lever and spring in 4 moves outwards (towards the camera) when the motor starts (centrifugal force) and this opens the contact. The purpose is to disconnect a big capacitor (often fitted outside the motor) which is there to distort the magnetism so the motor starts quickly and in the right sense of rotation. That is why when the motor runs down (switched off and free-wheeling) you can hear a ker-clonk, as the switch is thrown back in again.

If the contacts are dirty or burnt away then the motor will be slow to get going and might need a spin to get it turning at all. If they are sound but don't open, then the capacitor will remain in circuit and everything will soon smell of hot resin. Switch off at once.

Cheers, Tim

[Les Jones 1Participant @lesjones1]

Hi Sean,
The good news is that it is a single phase motor. These are normally very reliable and not too expensive to buy. I would not like to comment on the condition of the motor just from the pictures. If any of the electricaly competent members live near to you they will be able to help you test it. By the way the item in your last photo is an over current trip,

Les,

Edited By Les Jones 1 on 05/11/2016 18:14:20

[sean logieParticipant @seanlogie69385]

Posted by Tim Stevens on 05/11/2016 17:51:42:

The two first pictures look OK to me, for an elderly motor. What are the symptoms of the problem you need to cure?

The contact device in 3 should be closed when the motor is stopped, but the lever and spring in 4 moves outwards (towards the camera) when the motor starts (centrifugal force) and this opens the contact. The purpose is to disconnect a big capacitor (often fitted outside the motor) which is there to distort the magnetism so the motor starts quickly and in the right sense of rotation. That is why when the motor runs down (switched off and free-wheeling) you can hear a ker-clonk, as the switch is thrown back in again.

If the contacts are dirty or burnt away then the motor will be slow to get going and might need a spin to get it turning at all. If they are sound but don't open, then the capacitor will remain in circuit and everything will soon smell of hot resin. Switch off at once.

Cheers, Tim

Hi Tim ,thanks for the reply. Symptoms of the problem is that the motor hums when I turn it on , but when I spin the motor by giving the belts a quick pull normally it starts but lately it getting harder to do this . The power comes into a switch on the side of the left of the lathe from there it goes to the forward and reverse toggle switch and finally to the motor . The cables are all in need of replacing . I took the forward and reverse switch apart today and it had quite a bit of scorched markings on it ,so I cleaned up the contacts but I had a bit of a distraction during putting it back together so I'm not sure I've correctly assembled the switch unfortunately . I'm actually think of doing away with it anyways if it's possible to do this . I'll put a photo of the switch on the side of the lathe and maybe you can give me your opinion on what type of switch it is and do I actually need it , I'm trying to eliminate anything that could be the problem .

Sean

[sean logieParticipant @seanlogie69385]

I've added a photo of the mystery switch ,the cover obviously isn't there but on the cover is the on off push buttons .

Sean

[Martin CargillParticipant @martincargill50290]

The mystery switch is an old style motor starter, the coils and the adjustable dashpots are part of the overload portion of the starter. Its possibly a 3 phase one that has been used for a single phase machine

The burning you have found on the reversing switch is possibly a symptom of the motor being reversed while it has been running.

Assuming that the centrifugal switch on the motor shaft is working ok then the problem is probably either:-

a) The capacitor has given up and needs replaced or

b) the reversing switch is not making proper connections and the start winding is not being properly energised.

Both the capacitor and the reversing switch are connected together as the reversing switch normally reverses the polarity of the start winding (which is connected to the capacitor).

[sean logieParticipant @seanlogie69385]

Thanks Martin ,is it possible to do away with the old motor starter ? and wire straight into the forward and reverse switch ?

Sean

[EmgeeParticipant @emgee]

Sean

If you wire direct to your switch by-passing the starter you will lose the overload protection and the safety provided by switching off if the power fails (NVR) . The screw-on overload pots are oil filled so keep them in a vertical position if removing for service.

Emgee

[EmgeeParticipant @emgee]

removed double posting.

 

Edited By Emgee on 05/11/2016 21:00:21

[sean logieParticipant @seanlogie69385]

Thanks Emgee ,was just thinking on illumination . Regarding the capacitor,im sure I read somewhere that a strip light capacitor can be used on a motor this size ,any truth in that ?

Sean

[EmgeeParticipant @emgee]

Beest to keep with min 400vAC rating for motor starting/running use.

Emgee

[John HaineParticipant @johnhaine32865]

Motor start and run capacitors relatively low cost from Maplin.

[john carruthersParticipant @johncarruthers46255]

Little start/run caps are cheap enough on ebay, 400V 8uF from £2.50.

[sean logieParticipant @seanlogie69385]

I’ve added two photos ,one of the cap and one with the motor details .

Sean

[Martin CargillParticipant @martincargill50290]

Sean.

The motor starter is probably ok but if you want to replace it Toolstation do one. Starter is part number 95364 £20.20 and you will need an overload relay as well, part number 89114 £9.90.

However as I said before the problem is more likely to be the capacitor or the reversing switch. I would try the capacitor first as its the cheapest, as others have said get down to Maplins with the details of your one just make sure the rated voltage on the new one is the same (or higher) than the old one. If that doesn't cure the problem then its down to either the reversing switch or the start winding. The reversing switch must be suspect as you said it was showing signs of burning. This is a more complcated item to try to source and to wire in. Do you use the reverse feature? because it may be possible to remove the switch and do a little bit of re – wiring

Martin

[sean logieParticipant @seanlogie69385]

Evening …. All day sorting out the old Stedal today,made some headway . Lathe is now fixed firmly to the concrete floor nice and level . Stripped the headstock completely ,the grease on the bearing was like marzipan and now they're nice and clean ,just need to see what's best for oiling them with now . I'd ordered new belts one at 728mm and 750mm x 11mmW x 12mmD . I fitted both thinking I could find out which was the right fit (I measured the link belt I'd used previously) . There wasn't room to do this so I had to decide which one to cut (now I know why I don't gamble) I cut the 750mm belt !!!!!! Wrong bloody one the air turned blue needless to say 😀. The headstock wasn't that bad to strip anyways . One good thing happened today ,the motor now starts on its own with clutch engaged so I'm delighted with that I must say . 😊

Sean

[sean logieParticipant @seanlogie69385]

I'm a bit peaved, I took a photo of the frontTimken 14137 bearing but not the rear one ,am I right in assuming they are the same . I also noticed that the brass boss that that normally has the lathes serial No is blank ,is this a bit strange or normal . 

 

Bet your all thinking….. Bloody hell does this man never shut up …😁 

Sean

Edited By sean logie on 06/11/2016 20:15:48

[Ian S CParticipant @iansc]

I don't know your lathe, but DON"T assume(you know the saying), the rear bearing is quite likely different, possibly smaller.

Ian S C

[Howard LewisParticipant @howardlewis46836]

Going off the electrical track, you say that the lathe is bolted down solidly. This may be a mistake, as unless the floor is ABSOLUTELY level, the bed may now be twisted. Now to climb onto one of my hobby horses!

Better to insert rubber pads under the feet and not tighten too much (The idea is only to stop the lathe walking around the shop!)

Once that is done, ideally you need to check that the lathe bed is free of twist.. A lathe with twist in the bed is unlikely to turn parallel, only a taper.

Various ways of doing this:

Use a sensitive level, either across the bed, at Headstock and Tailstock end, or on the Crossslide, and check at each end of its travel along the bed.

OR Follow the method suggested by Myford (Series 7 Manual, pp41 and 42) or The Amateurs Workshop by Ian Bradley (pp 27 and 28). This involves turning a short section at each end of a sturdy bar (with a relieved section between to look like a cotton reel) without changing the Cross Slide setting. Any difference in diameter indicates that the bed is twisted. The instructions then tell you where to put shims to correct the twist.

You keep on checking and shimming until the last turned diameters are the same.

But this will be after you have sorted out the motor and its switchgear.

Then the world will be your oyster

Howard

[sean logieParticipant @seanlogie69385]

I see your reasoning Howard and appreciate your input .I have the electrics sorted ,in the very near future I will be replacing the old cables on all the switches .

Edited By sean logie on 08/11/2016 07:26:12

[Brian HParticipant @brianh50089]

If it's any consolation Sean, and I suppose it isn't, you are not alone. I'm more used to 3 phase electrics but my lathe is now 1 ph and I find wiring up a forward/reverse switch to be a nightmare and only possible because a kind soul on this site has been very helpful and incredibly patient.

[sean logieParticipant @seanlogie69385]

Hi Brian,yes there are a lot of kind people on here .

Sean

[sean logieParticipant @seanlogie69385]

Fortis up and running again… I noticed today when i switch on the the lathe the double strip light above the lathe goes out then turns back on after lathe is up and running . I use a good quality extension lead ,but since i've upgraded to a bigger motor i don't think it's up to the job anymore . I have some 3 core heavy duty cable and a weather proof double socket for outside the kitchen window and i plan boring through the wall and plugging in the weather proof plug so i don't have to bother unplugging the extension every time i'm finished ,would this be a better option ……

Sean

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