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Dol starter or just a plug is it really worth it?

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Grant Allen 125/04/2019 18:31:37
48 forum posts
5 photos

I'm looking at wiring up my mtype lathe, the original switch hummed like caged angry bees so I've decided to bring it into the future. But I'm trying to work out whether to stick a plug on the end and use a kedu switch or put a dol switch on. Is it really worth the extra ?

clogs25/04/2019 19:22:23
476 forum posts
12 photos

U don’t say if it's 3phase....all my 3phase machine have dol starters....

i have several pillar drills that I have binned the starter buttons and now use an outside type light switch...

not strictly the best idea but it works for me.....it's only me that uses them....

never a prob in 10 years....they are only fractional motors....

Emgee25/04/2019 20:28:48
1189 forum posts
206 photos

Grant, whichever method you use it is best to consider an easily accessable Emergency stop type button to switch the spindle motor off in case of an emergency when you are using the lathe, it could safe you serious injury or even worse,

Emgee

john fletcher 125/04/2019 20:54:11
528 forum posts

Well it come down to how much you value your fingers and life. DOL starter with NO-VOLT release every time and considering the protection they give, they are not so expensive. You might be lucky and pick one second hand. With a bit of luck and care a 415 volt one can be altered to work on 240 volts. If you take some photos and make notes you can carefully dismantle a starter,Take out the operating coil measure its resistance R1 and remove turns of fine copper wire, about 40% need to come off. 240/415 X 415 is the final ratio = R2. then put it all back. together again. John

Ian McVickers25/04/2019 20:56:27
136 forum posts
72 photos

Starter unit with overload protection would be my recommendation. You will have start function, stop function and prevention against auto restart in case of power fail. You can also extend the stop circuit by adding additional estop if required.

Ian P25/04/2019 20:57:39
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2175 forum posts
90 photos

I've no idea what a kedu switch is but DOL are mainly used for three phase motors wired directly to three phase motors. If yours is a single phase then a NVR is ideal if its just on/off, with a reversing switch (if fitted) between it and the motor.

If its at three phase motor running of a VFD then apart from an emergency stop (easily wired into the VFD control) you need an isolating devic e which could be just a 13A plug switched off, or pulled from the wall socket or it could be a more industrial wall mounted isolator which is just feeding that machine. VFDs usually have the NVR facility enabled by default.

Ian P

Peter G. Shaw25/04/2019 21:07:04
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986 forum posts
39 photos

John, you beat me to it! But I would just query one thing with you. The DOL switch on my lathe was re-arranged for both single phase and three phase simply by re-arranging the internal wiring. The contactor coil was connected across one of the three phases and neutral, this being equivalent to a single phase circuit. No need to mess around removing turns of wire.

Otherwise, they can indeed be easily dismantled & reassembled. In my case, the coil failed, so I replaced the coil with a plug-in mains relay and rebuilt the insides to give the same facilities.

An edit: Yes it is worth it for the NVR function alone.

Peter G. Shaw

 

Edited By Peter G. Shaw on 25/04/2019 21:09:22

Mike Poole25/04/2019 21:34:22
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2113 forum posts
51 photos

Any machine where you are going to be intimately involved with the rotating parts such as a lathe, pillar drill or mill etc. are capable of seriously hurting you if they are started unexpectedly. A motor starter will provide you with protection from an unexpected restart after a power interruption (NVR), overload protection for the motor if you fit the overload module and the possibility of remote start and stop buttons and additional emergency stops in useful places. Safety should not rely on you remembering to do something. If you experience a power cut in the workshop while a machine is in auto feed would your first thought be to turn the machine off or find your way out in the dark to find a torch or candle? If your lathe was under auto feed then when power is restored it will carry on cutting until something breaks or the motor burns out, a starter might seem like a bargain then.

Mike

Edited By Mike Poole on 25/04/2019 21:34:55

Edited By Mike Poole on 25/04/2019 21:36:23

Grant Allen 126/04/2019 07:47:54
48 forum posts
5 photos

Thanks all for your advice, should I go for a dol starter or a kedu nvr machine switch.?

I have a separate emergency stop button which I will place somewhere on the bench.

Sam Longley 126/04/2019 08:05:46
722 forum posts
26 photos
Posted by Emgee on 25/04/2019 20:28:48:

Grant, whichever method you use it is best to consider an easily accessable Emergency stop type button to switch the spindle motor off in case of an emergency when you are using the lathe, it could safe you serious injury or even worse,

Emgee

What? worse? you mean as in damage a couple of days work??sad

Edited By Sam Longley 1 on 26/04/2019 08:06:23

Mike Poole26/04/2019 08:21:17
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2113 forum posts
51 photos

The kedu switches do not have overload protection and some at least do not have the facility for extra estops or remote start buttons. Tool station do a DOL starter and overloads to suit and that is what I would use. Additional estops should be wired in the coil circuit and not carry motor current as they are not designed for switching power loads but just control circuit signals.

Mike

Grant Allen 126/04/2019 08:31:38
48 forum posts
5 photos

Cheers Mike. I will get a dol startr and overload but may need a wiring diagram to add the e.stop.

Nicholas Farr26/04/2019 09:34:41
avatar
1976 forum posts
936 photos

Hi Grant, various types available from Axminster Tools **LINK**.

Regards Nick.

Emgee26/04/2019 09:53:48
1189 forum posts
206 photos
Posted by Sam Longley 1 on 26/04/2019 08:05:46:
Posted by Emgee on 25/04/2019 20:28:48:

Grant, whichever method you use it is best to consider an easily accessable Emergency stop type button to switch the spindle motor off in case of an emergency when you are using the lathe, it could safe you serious injury or even worse,

Emgee

What? worse? you mean as in damage a couple of days work??sad

Edited By Sam Longley 1 on 26/04/2019 08:06:23

Sam, worse would be "critical" (just noticed my error, should be save not safe)

Emgee

Grant Allen 126/04/2019 10:04:18
48 forum posts
5 photos

Would this be a practical solution or should it be a dol starter

https://www.axminster.co.uk/axminster-nvr-switch-c-w-box-230v-1ph-340181

Grant Allen 126/04/2019 10:09:34
48 forum posts
5 photos

The motor I'm using has a full load of 2.53 amps, so do I stick to a range ie 2-5 amps overload or would say upto 7 amps be suitable if I decide to change the motor.?

Ian McVickers26/04/2019 10:18:11
136 forum posts
72 photos

2 to 5 amps would be a good range to cover the motor you are using. Overloads are not expensive and would be easy to change if you decide to fit a bigger motor in the future.

Grant Allen 126/04/2019 10:21:09
48 forum posts
5 photos

Hi Ian theres one going on Ebay that 3-5 amps would this be suitable or is it too high. It's a brook crompton one ?

Emgee26/04/2019 10:25:15
1189 forum posts
206 photos

As others have suggested a DOL starter will in addition to NVR will also provide motor protection if you fit an overload unit.
You can also fit remote EMstop/start station's in the DOL starter control circuit.

telemecanique dol 240v coil 4a ol.jpg

telemecanique dol starter 240v coil.jpg

Pic shows a combined DOL starter with overload unit and switch fuse for isolation.

Emgee

Edited By Emgee on 26/04/2019 10:27:14

Ian McVickers26/04/2019 10:37:36
136 forum posts
72 photos

Personally I think it's too high. I wouldn't use it for that motor if it's was me doing the job. If buying one from eBay make sure it comes complete.

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