Motor suitability?

[Cornish JackParticipant @cornishjack]

[Cornish JackParticipant @cornishjack]

G'day all.

Yesterday was 'one of those days'!! Amongst other problems, the motor on my ML7 began to make VERY peculiar noises – a bit like rattling nails in a tin can!

The motor is a Crompton Parkinson 1/3 HP single phase 1425 rpm with the plate indicating AC motor. Lurking in the 'it'll come in handy someday' pile, I found a Newman 1/2 HP motor 1425 rpm and labelled Induction motor. Output shafts match on the two and the pulley transfers very easily. Question is – Is the Newman a suitable replacement? The Newman has a standard 3 wire input with a substantial rectangular box on top containing the capacitor. The wiring on the CP is not so obvious as it consists of one thick cable and one thin which both feed into the innards of the motor – no separate external capacitor.

Advice much appreciated.

Rgds

Bill

[Clive FosterParticipant @clivefoster55965]

It will do just fine.

The sounds like Newman is a standard capacitor start single phase induction motor whilst the Crompton Parkinson one appears to have simple start & run windings with no capacitor to improve starting torque. Both types built in numbers beyond convenient counting for light machine duties. No difference in performance once up to speed. Capacitors used to be very expensive (relatively speaking) and less than reliable so simple start windings were often preferred to keep costs down unless the application really needed the extra starting torque given by a capacitor. Often just as economic to use a larger motor to get the starting oompf.

These days capacitors are relatively inexpensive and many low end modern motors use them to boost the performance of an "economy" design of starting winding.

Clive

[Cornish JackParticipant @cornishjack]

Thank you Clive. That is reassuring. Seems the 'come in handy' collection is useful!!

Rgds

Bill

[Cornish JackParticipant @cornishjack]

Apologies for coming back with an 'Oliver Twist ' request, but, having now chopped through the original wiring, rather than the expected two core plus a separate earth, the thicker cable is a full three core and the separate cable has some other function. Could anyone explain, please?

The input feed is via a rotary fwd/off/rev selector and I'm wondering if the separate cable is concerned with the reverse? If not, what does one do with the extra wire, given that the Newman requires only three inputs?

Any advice gratefully received

Rgds

Bill

[Les Jones 1Participant @lesjones1]

Hi Bill,
To run the Newman motor in reverse will require four wires (Plus earth.) between the motor and the switch. Before disconnecting the original wires at the motor or the switch FULLY document which wires go to which terminals both on the motor and the switch. (There will probably be some wires of the same colour in each cable so make a note of which cable as well as the colour connects to each terminal.) Take photographs as well in case you forget to document a connection. The two cables are probably just a way to get the required wires between the switch and the motor. On the Newman motor you will need to identify the start and run windings to enable you to run it in reverse. Again documenting and photographing all the connections inside the box on the Newman motor will enable those trying to help you to identify the way you will need to connect the motor.

Les.

[Sam StonesParticipant @samstones42903]

Hi Bill,

I presume that the Crompton Parkinson motor has been dumped?

On my ML7, (bought second hand from the owner's widow back in the mid 60's), the motor had relatively open cooling vents. Since the motor was positioned where it was designed to sit, swarf could easily find its way inside the motor. The sound would be similar to rattling nails, and a tizzy rasping sound to boot.

There would be occasions when this was accompanied by a loud pop, which I presumed was the swarf arcing across to earth or similar. Since the circuit breakers nor leaky earth ever tripped out, I (lazily) ignored the problem, other than to fit some fine metal gauze over the vent hole.

I must add that when I bought the lathe, the centrifugal switch was stuck in the OPEN position, and I (and presumably the previous owner) would pull the pulley around by hand to get it started.

[Isn't that what pulleys are for?]

I couldn't put up with this and stripped the motor down to apply some grease to the sticking switch. Never had a starting problem after that. I might add that the previous owner had hung the belt guard on the picture rail of his box room workshop. So the problem might have lasted for years.

Best regards,

Sam

 

Edited By Sam Stones on 26/05/2012 07:54:43

[MikeParticipant @mike89748]

Sam, this is exactly the same problem I had with a similar motor on a Myford in the early 70s. A good clean worked wonders! I was amazed at how much muck had got inside the motor.

[Cornish JackParticipant @cornishjack]

Thank you Les – My requirement for reversing the motor is just about negligible so am considering doing without it, in which case, presumably, a straightforward live, neutral, earth connection will suffice?

Sam – Thank you and Mike also. No, the motor hasn't been dumped – much to SWMBO's chagrin, I have long been infected with the 'Magpie Complex' – hoarder of monumental proportions!! Your comments will lead (eventually) to a strip down and clean – your description of operating noises fit my situation exactly. If that is, indeed, the problem, the C-P can go back in the MCIHS corner!!

Rgds

Bill

[Cornish JackParticipant @cornishjack]

Returns quickly , highly embarrassed!! Should have checked that the Newman would fit … it doesn't! It would require a great deal of modification to do so. Soooooo .. Plan B. Also lurking in the shed is a brand new 3 phase 1/2 HP motor plus the bits and pieces in the photo's. Not having ventured into this sort of area before, is it a reasonably straightforward operation or should I get a wiggly amp guru to do it for me? It appears to be pretty obvious but are there hidden snags and what are the pros and cons?

Again any help much appreciated

Rgds

Bill

[Cornish JackParticipant @cornishjack]

Apologies for returning to this, but with no responses to my last, I've put the 3 phase to one side and 'invested' in a new C-P motor. I would still like at some time to go 3 phase but without a simple guide to connections, I foresee an outpouring of 'magic smoke'.

MEW 180 contained an article by Alan Hearsum with good info on the code inputs and indicating that he would include the motor wiring details in a subsequent article. Haven't seen anything since. The reluctance to go ahead with the 3 phase is compounded by the need to modify the drive pulley – different shaft sizes, so a further pulley required.

Google search shows that this has been done by forum members but none of the threads I've found contain the basics of wie connections to the motor. Would greatly appreciate 'A goes to B' type guidance if antbody could oblige.

TIA

Rgds

Bill

[John ThorneParticipant @johnthorne49048]

Hi Bill

You can download a users manual for your inverter from

**LINK**

Regards

John

[Cornish JackParticipant @cornishjack]

Thank you John.

Yes, I have that already. The problem is, as can be seen in photo's 1 and 4 the output from the Omron consists of FOUR wires into a 'chocolate strip' connector. My motor, in common with all the others I've seen has only THREE input connectors. While tracing the individual wires will indicate which is which, there is nothing that I can find in some three days of searching which shows how 4 into 3 should be connected. The Omron manual is very clear about the way to wire it to the supply but absolutely nothing for the downstream connections – presumably thought to be too obvious!! Well it isn't to me! Thr motor manual is similarly unhelpful. Is 3 phase technology really so complex that it can't be offered as connect wire a to terminal b – at least in this instance? Aaaaaargh! wiggly amps – I hate 'em

Rgds

Bill

[joegibParticipant @joegib]

Post in error

Edited By joegib on 29/05/2012 16:04:26

[Cornish JackParticipant @cornishjack]

Back again and hopefully with the problem resolved.

Not quite sure how, but have found a source of appropriate info which covers what is needed – at least it does for me! The source is "Use of induction motors in the home workshop" by RC Minchin. (Free download from the Web) It presents the details in an understandable form and has provided all the answers I was after. I can recommend it to anyone in a similar situation (and similarly flummoxed!)

Thanks to all who have offered help and I shall now retire to the shed with a sporting chance of avoiding the 'magic smoke'

Rgds

Bill

[John ThorneParticipant @johnthorne49048]

Hi Bill

Looking at your photos again one of the four wires is the earth wire,yellow and green,this is conected to the motor frame, the other 3 wires will be conected to the 3 motor terminals. I fitted a Imo inverter and 3 phase motor to my WMT300 lathe last year and I am very pleased with the results.There are some photos in my album. I must admit I thought it would be more difficult to do than it was. No magic smoke. Would not go back to single phase motor.Good Luck.

Regards

John

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