have to start motor by hand

[trojan62]

hi
i have an old lathe from 1980 that i bought about 2 months ago, recently i noticed that there was an auful clanging noise from the motor and presumed that the fan had come loose. when i opened up the motor this was the case.
anyhow, i fixed the fan back and it was running ok, but since i put the motor all back together again i can only start it by giving the belt wheel a quick helping hand spin. when i turn the lathe on it sounds as though is wnats to run with a humm noise, but then i have to spin it to get it going.
im not sure if im right, but is this trouble with the capacitor, if my motor has one.
the only thing is, is if it is the capacitor its not the type on the outside of the motor and must be inside somewhere.
if this is the case, im a bit loath to open up the motor again.

any ideas......

thanks......

 

[Chrispy]

Have another look, it may not be attached to the motor may be to the control gear, unless it's running on three phase it will I'm sure have one.
Or has it got a speed controller?

 

[procell]

It sounds like the Capacitor needs changing. I had a similar problem on an Elu 180DB lathe.
They are inexpensive to buy but make sure you get one with the same rating as the current one.

 

[CHJ]

Can you post a picture of the motor specification plate.

If it is an older machine it may have a centrifugal switch mechanism inside the motor housing to control the start winding supply.
If this is not making contact then the start circuit will not be functioning.

Have a browse of this PDF by R C Minchin for a better understanding of associated circuits.

http://homepage.ntlworld.com/bob.minchi ... Issue2.pdf

 

[bogmonster]

I know this thread is a couple of days old but I don't visit much. I would think Chas is almost certainly right given the fan issue you had. The centrifugal switch is often just under the fan. If it isn't contacting when powered up the starting coil wont energize. Whilst you will get an unloaded motor running just on the main winding by giving it a helping hand - (it needs to be spinning to know which direction to turn), it will not have any real starting torque and you will just fry it if you ahve a large block of wood attached. Hopefully you have just dislodged the switch or a connecting wire. The CF switch in my lathe motor is on its way out and this is one reason I am looking for a new lathe.

If the switch is damaged then you may be able to get a replacement if it is a common motor - if not you are into a whole world of pain. There are special voltage sensing relays that can replace the switch. In fact I bought one for my lathe but never bothered fitting it.

Let me know if you need more pointers.

BM

 

[bogmonster]

If the switch is damaged and you can't get a replacement you can use one of these:

http://www.supco.com/images/pdfs/Manuals-Instructions/apr5 - supr.pdf

You need to mount it in an external box and run the wires to it - a real phaf so fingers crossed the fan incident has not trashed the switch.

 

[DonJohnson]

If you can put up with spinning by hand to get the lathe going, it will run fine and come to no harm.

One advantage of this is that you can start it spinning it in the reverse direction when sanding - which can improve the finish.

 

[Shrubby]

A motor rewinding company can repair failed centrifugal switches
I've used Hmelectricmotor in London to do a unique startrite saw motor
Matt

 

[finneyb]

If you can put up with spinning by hand to get the lathe going, it will run fine and come to no harm.

One advantage of this is that you can start it spinning it in the reverse direction when sanding - which can improve the finish.

Until the chuck comes off, unless you have a chuck with grub screws fastening it to the shaft :roll: :roll: