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1.1kw motor iffy

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Windy05/06/2019 14:10:36
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768 forum posts
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Am maybe answering my own question but would like it verifying or is it something else.

My Warco 600 lathe motor 1.1kw starts and runs in the low belt speeds.

In the high belt speeds it's slow getting up to speed and find to reduce the belt tension with the belt changing lever first helps starting.

As it has two capacitors am I correct to think the start capacitor is faulty or start windings on the way out.

roy entwistle05/06/2019 14:15:48
1104 forum posts

Start capacitor will be cheapest to try first If there is a centiflugal start switch try cleaning the contacts

Roy

John Haine05/06/2019 14:17:54
2836 forum posts
141 photos

Highly unlikely to be the winding, but could be the cap. Has it always been this way? I find when I start my lathe at a high speed pulley setting it takes a few seconds to get up to speed as the oil warms up.

Ian S C06/06/2019 11:33:55
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7468 forum posts
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In winter time(now) my 1326BH lathe is slow at starting in high gear, and remains slow (bit of belt slip), so I drop the belt ratio down and run it for 10/20 minutes until the headstock bearings warm up. I use SAE 30 oil, I maybe should go to a lighter grade in the winter. I doubt if that's your problem Windy, most likely the capacitor.

As an aside, my milling machine has got a capacitor out, and until I can find a new one (300uf), I'm hand starting it which is a bit of a pain. I'll probably need to put three 100 uf caps together.

Ian S C

Windy06/06/2019 13:15:48
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768 forum posts
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Some years ago the motor would not run very well and replaced the run capacitor it worked ok at highest speed as well.

Lately replaced the same run capacitor but found later the high speeds needed caution to get up to speed as slackening belt helped.

Had also checked centrifugal switch so have ordered a start capacitor from China.

I know some are not keen on quality of some oriental products but I have also had some crap UK products that cost a lot more.

AdrianR06/06/2019 18:26:54
274 forum posts
20 photos

Hi Windy,

I have a BH600 and it is exactly the same in high gears. I only recently got it so don't know what it used to be like, but I assumed it is normal for a capacitor start.

Please let me know if your new start capacitor helps.

Adrian

Windy06/06/2019 21:25:34
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768 forum posts
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Posted by AdrianR on 06/06/2019 18:26:54:

Hi Windy,

I have a BH600 and it is exactly the same in high gears. I only recently got it so don't know what it used to be like, but I assumed it is normal for a capacitor start.

Please let me know if your new start capacitor helps.

Adrian

Will do but might be a few weeks before I get the start capacitor

Edited By Windy on 06/06/2019 21:31:14

Windy29/10/2019 21:22:59
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768 forum posts
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Posted by Windy on 06/06/2019 21:25:34:
Posted by AdrianR on 06/06/2019 18:26:54:

Hi Windy,

I have a BH600 and it is exactly the same in high gears. I only recently got it so don't know what it used to be like, but I assumed it is normal for a capacitor start.

Please let me know if your new start capacitor helps.

Adrian

Will do but might be a few weeks before I get the start capacitor

Edited By Windy on 06/06/2019 21:31:14

Finally got the start capacitor replaced tonight.

It's instant fast starts in the highest speed now.

not done it yet29/10/2019 21:48:47
3944 forum posts
15 photos

My mill (with a newish one horse motor) was often unable to reach top speed in highest gear until the gearbox lube was warm enough - no problem in warm weather.

Changed to a 3 phase motor with VFD and no problem since. Admittedly the motor is 1.2 horses but the difference was very clear - increase in power or not. 3 phase motors are so much better than single phase equivalents!

Clearly you have solved the problem - until next time. Good capacitors do not come cheap these days.

Windy29/10/2019 22:04:11
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768 forum posts
146 photos

I think my problem started when cutting a lot of 20 and 45mm metric threads single phase are not keen on lots of stops and starting

Windy23/11/2019 15:56:33
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768 forum posts
146 photos

A while ago I replaced the start capacitor on my single phase Warco 600 lathe .

The starting was ok but seemed very aggressive I don't seem to remember it was like that when first purchased as a used machine..

Start capacitor has gone again think will have to arrange a clutch to ease things but wonder is there any product that can protect the start capacitor.

Doing metric screw cutting there is a lot of turn, stop and reverse going on.

I have a spare start capacitor to fit the motor it does start in the lower speeds and am reducing belt tension with the pulley speed lever at the moment when starting.

Any suggestions before I replace the start capacitor.

jimmy b23/11/2019 16:26:03
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570 forum posts
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I had endless troubles with my Chester Crusader motor. I changed the run and start capacitors several times, but the motor just kept playing up.

I've now got a VFD on the lathe and easily double the power.

I now suspect that the motor was not to clever!

Jim

Neil Wyatt23/11/2019 17:04:59
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17090 forum posts
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I've been though the"'it could be the capacitor but what it it's something else?" doubt. In the end a swap was easy and instant restoration of performance (my bandsaw).

Neil

Dave Halford23/11/2019 17:40:37
562 forum posts
5 photos

Hi Windy,

There are various qualities of capacitor out there, it might be better to buy one based on the specs from somewhere like RS. Does the spec printed on the cap body match the old one?

The start Cap takes a beating, higher volts and life hours are better, that said I would expect a new cap to last longer than a month.

Windy23/11/2019 19:24:11
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768 forum posts
146 photos
Posted by Dave Halford on 23/11/2019 17:40:37:

Hi Windy,

There are various qualities of capacitor out there, it might be better to buy one based on the specs from somewhere like RS. Does the spec printed on the cap body match the old one?

The start Cap takes a beating, higher volts and life hours are better, that said I would expect a new cap to last longer than a month.

All the numbers are the same as the original duff one if this replacement blows in a short time will try a better quality capacitor

Windy24/11/2019 00:17:39
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768 forum posts
146 photos

Apart from installing a simple clutch probably related to a belt tensioner to reduce starts the problem will be with the metric screw cutting.

Have checked with a single phase motor supplier

N.B.: it is recommended that single phase motors are not stop/started more than 15 times within a 1 hour .

It's also in Tuba Cain model engineer handbook.

Afraid have exceeded that at times my early Warco 600 is certainly my workhorse for much of my machining.

Have a Myford for more delicate work but is rarely used now as on a larger project.

Edited By Windy on 24/11/2019 00:18:43

Edited By Windy on 24/11/2019 00:19:19

jimmy b24/11/2019 05:47:07
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570 forum posts
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That could explain a lot!

Jim

Peter Bell24/11/2019 07:38:52
280 forum posts
137 photos

Ive had similar experiences over the years with start capacitors not lasting when used to start frequently. As they are often back to back electrolytic capacitors which tend to overheat and dry out,t I replaced them with motor run capacitors which eliminated the problem for me. Some ended up being larger than the originals but normally managed to fit them somewhere. Peter

SillyOldDuffer24/11/2019 10:44:39
5138 forum posts
1074 photos
Posted by Windy on 24/11/2019 00:17:39:

...

Have checked with a single phase motor supplier

N.B.: it is recommended that single phase motors are not stop/started more than 15 times within a 1 hour .

...

Afraid have exceeded that at times my early Warco 600 is certainly my workhorse for much of my machining.

Have a Myford for more delicate work but is rarely used now as on a larger project.

...

Physics mean it's much easier to make electric motors spin when presented with DC or 3-phase AC than it is to make a motor able to run on single phase AC.

As producing the magnetic fields needed to turn the armature from a single phase supply is tricky, single-phase motors are a complicated compromise. The complexity consists of separate Start and Run Windings, one or two high-voltage high-value capacitors, and maybe a centrifugal switch. There is a lot to go wrong!

Unfortunately, all this complexity doesn't result in a high-performance motor. Compared with 3-phase, single-phase motors vibrate, have less torque, are inefficient, and dislike starting and stopping because it stresses the components and overheats the windings. Maximum power output from the type is limited - it's unusual to find a single-phase motor above 4kW.

Single-phase motors meet an important need. They can be plugged straight into the ordinary domestic supply and do useful work. And for most domestic purposes the long list of single-phase disadvantages don't matter much in practice. Workshops are more challenging. Single-phase is fine for small machine tools like my bandsaw. Anything given time to cool down that isn't frequently restarted in bursts should be OK. But single phase is a poor choice for anything worked hard and especially unwise for anything that's also turned on/off in rapid bursts.

The motor on Windy's lathe isn't a good match to his work profile. A clutch would help, but I think it would be easier to fit a 3-phase motor and VFD. They really do make a difference!

Myford fitted single-phase motors in 1947 because they were the best choice for hobbyists and small workshops at the time. DC motors were out because AC/DC convertors were hideously expensive back then, and 3-phase ruled out because it was (and still can be) hard to get installed. Modern electronics walk all over both problems: converting single phase to either DC or 3-phase isn't difficult or unaffordium.

Difficult to advise Windy: I wouldn't replace a working single-phase motor on a lathe just for the sake of 3-phase smoothness. But faced with an unreliable single-phase motor, I think I'd bite the bullet and replace it with a VFD/3-hase combo.

Dave

Nigel McBurney 124/11/2019 11:11:07
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641 forum posts
3 photos

I had an oil fired central heating boiler ,the fuel pump was driven by a single phase motor, the start capacitor was clamped to the motor within the dust cover and close to the burner housing. Occasionally the boiler failed to fire,internet boiler problem searches suggested capacitor failure,a new capacitor cured the problem,a friend with the right test meter confirmed the capicitance was just less than half the rating, some time later the capacitor failed again ,so I put the problem to the the capacitor was working in a confined hot location so I added longer wires and secured the capacitor in a remote cooler location within the boiler casing ,problem solved. I have single phase cap start motors on my myford and Fobco drill both over 40 years old ,good English built motors ,are modern motors being built with capacitors which are only just up to the job and fail when overloaded by multiple starts per hour.?

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