Switch for Myford ML7

Me again,

At the moment I have a straight connection from the motor to the plug, but would obviously prefer to have an on/off switch. Can I buy any type or what should I look out for? There is one going on ebay at the moment.

Thanks

Charlene

Hi Charlene,
A switch similar to THIS ONE will provide basic switchin an a no volt release function. (This means the motor will not start up when the lathe is plugged in or after a mains failure.) This type will not provide any overload protection for the motor. For that you need a direct online starter. This must be rated to match the current drawn by the motor. Here is an example of a direct online starter.

Les.

Thanks Les, I suppose it would be better to get the direct online starter - I guess the overload protection would be there to protect the motor? My motor states 3.7 Amps.

Charlene

Hi Charlene .Most workshop tools are switched using a device with a "panic " button,I think most people would advize using one ,much safer.

maurice

Hi guys,

This is the switch I got. My motor states 0.5hp and 3.7A, so I reckoned this one should be capable of doing the job. I can go and exchange it if I need to.

Charlene

Hi Charlene,
You were quick going out to buy a starter. From the picture it looks like the one you bought is rated at 12 amps. This will not protect your motor. One with 4 or 5 amp rating would be better. It should be possible to fit an external emergency stop button by connecting it in series with the internal stop button. Interlocks on the chuck guard and belt cover can be added in the same way.

Note added. While looking for information on the starter in your picture I found that it does not have any thermal overload protection. The company do make thermal overload relays to go with this starter but I do not know if these fit inside the starter or inside a separate box.

Les.

Edited By Les Jones 1 on 07/10/2012 15:44:39

Thanks for that Les. Yes, I had to go and buy some extractors, so I thought while I was at it I might buy one, but unfortunately the wrong one. Maybe I should just order the one in your link from Machine Mart. I think I will do the external emergency stop button as you suggest as well.

Charlene

Hi Charlene

What Les says is quite right but the most important part of the starter is that it is NVR i.e. when the mains go off for any reason the switch trips out and the machine will not start again when the mains are restored. That way you get to keep all your fingers etc. when the power suddenly comes back and you have chosen that time to do the annual clean-up on your lathe. Protection for motor - nice- but penalty for not having it is the price of a new motor should the overload happen. Stop switch ( or to give it a more suitable name - Panic Button.) Big and easily accessible so you can't miss it when all goes pear shaped - yes good idea but you may be very careful of course! It is likely that the starter switch you have can be wired for a remote Stop button- if so just providing a big red "STOP" button in a suitable position and wiring it in might be the cheapest option unless you can change the one you have bought.

Cheers

Norman

Edited By NJH on 07/10/2012 17:55:30

Hi Norman,

Yes I made sure I could return that starter before I bought it. I have 30 days, so it will go back ASAP. I would take the meaning of NVR to be that it opens the contacts until you physically pull it out again to close it so that power is restored only when you decide it to be?

Thanks

hi Charlene,

The starter you have purchased should be suitable for your motor, the overload unit is an optional item and will fit inside the enclosure. Toolstation sell these starters and the overload units, their part number for the overload is 44178 to suit your motor. They also sell mushroom head buttons for remote stops. The stop button on the starter is raised and the start button is flush so a panic fumble for the stop should find it even with out looking. The siteing of the starter should be considered for ease of use and so you will not be in line with the chuck on start up , if the work should leave the chuck for any reason it could hit you. The figures quoted on your starter are the ratings of the contactor and as it is rated up to 4hp is quite ok for a smaller load. The overload is the important item for motor protection and they should be adjusted to suit your motor the unit mentioned has a range from 2.8A to 4.2A and usually they are set to the lower value when you get it out of the box. If not set to 3.7A you may have nuisance tripping. if the overload ever trips do not be tempted to turn up the overload, you either are oveloading the motor or you have a fault, turning up the setting will eventually result in smoke and be expensive.

Mike

Hi again Charlene

I think NVR means " No Volt Release

This type of switch is essentially a relay. The "Start" button operates the relay which then holds in via the current flowing through its coil. Another pair of contacts connect the mains supply through to the motor. The supply to the motor is disconnected by disconnecting the supply to the relay coil either by pressing the "Stop" button ( the normal way) or because the mains supply has failed. In either case the relay releases and the circuit path to the motor is broken until the mains is restored AND the "Start" button is again pressed.

You could exchange the starter for one of the correct rating as advised by Les. It is also worth seeing if they can supply a switch with a big "STOP" button built in. They are available - I have one on my mill.

You can just see it on the right in this picture - conveniently placed next to my knee when I am working on the machine!  ( Click on photo to enlarge)

Cheers

Norman

Edited By NJH on 07/10/2012 21:13:08

PS. Or go with Mike's suggestion and see if they do a remote "Stop" but this will require wiring etc.

Edited By NJH on 07/10/2012 21:18:38

Edited By NJH on 07/10/2012 21:21:34

Hi Charlene/Norman

The remote stop for knee or foot operation is a good idea, Colchester had a foot stop/brake on some lathes, very nice to use. A foot stop on a pillar drill I would consider essential especially if like me you don't always bolt the vice down, a jam up can be very difficult to let go of to hit the stop with your hand.

Mike

Hi Michael,

I was going to take that one back, but if you say it will do then I'm glad. I could just go and buy the Thermal Overload Relay extra. I realised the stop button is raised on the box, not sure whether i will still need a remote one then. I will need someone to assist me in the wiring, because the insides don't look like anything I've seen before, lol.

Hi Charlene,
Now that Mike has confirmed that the thermal overload unit fits inside the starter I think buying one from Toolstation is the best option. (I had originally assumed that you live in France from your name and the fact that you do not have a profile.) The Toolstation stop button (17283) looks ideal. Don't forget to buy cable glands for where the cable enters the starter and stop button. (Item 25329 on page 390 if you get them from toolstation.) The advantage of this unit over the Machine Mart one is that if you ever need to use it with a different size motor you just need to replace the thermal overload relay. You could just wire it up as it is for now and add the thermal overload and stop button at a later date. (I do not have thermal overloads on my lathe or drill.) It could be argued that as you will always be by the lathe that you would probably notice if the motor slowed down or stopped due to an overload.

Les.

NJH -

Norman, totally OT, but where exactly do you do your workshop activities??? Obviously not in that demonstration hall in your photo - or is that your dining room ( eating off the floor, of course!!!) I was teetering on the edge of taking an (out of focus) piccy of my shambles for another current thread but I'm not sure that I shall ever venture into it again. Such exquisite squeaky cleanliness is very disheartening to we mortals!

Rgds

Bill

It is a Palace of Engineering, not for working in!

Best place for on Estop on a milling or drilling machine is forehead hight.

That way when you get dragged in you belt the E stop with your forhead and both hands are free to hold onto whatever is most valuable.

Very good idea John, but unfortunately I don't have that option.