capacitor question from me

[lubbing5cherubs]

Hi I asked about this yesterday in Twinnie post with the nova 1624 thread but it got overlooked so I will try again.
What been happening with my lathe is not all the time but when I put it in reverse it continues to go forward or vise versa. It is getting more prominent with it. It seems to be not responding to forward and reverse with a little help. So my question is if I just leave it in forward will this help the capacitor to last longer???
Thanks Toni

[echnidna]

the motor must totally stop turning or the direction will stay the same.

[Manuka Jock]

Toni ,
If you put the question to the Nova Owners Forum , http://tinyurl.com/3dxs2d , you may get a response from someone who has experienced the problem.
Tim Geist , from Tecknatool USA pops in from time to time also.
cheers ,
Jock

[malb]

Not totally sure exaxtly what the problem is, but echnidna is correct in saying that the motor must completely stop before reversing.

An electric motor operates by changing magnetic fields in the fixed and rotating parts of the motor. Opposite magnetic fields attract and like magnetic fields repel. For an AC (mains) motor the magnetic fields are provided by feeding mains current through the motor windings.

A three phase motor has three distinct sets of windings, and the direction of rotation is determined by the connections of the 3 phase power supply to the windings. Swapping the connections to two of the three windings while the motor is staationary will reverse the direction of rotation when the motor is restarted.

A simple single phase motor, as fitted to your machine and many other non commercial units does not know which way to run when power is applied. To overcome this situation, some form of additional magnetic field is added (generally temporarily) to 'kick' the motor in one direction or the other to start it spinning. The additional field is normally provided by an auxilliary winding and capacitor, often activated by a switch that opens when the motor has achieved a few RPM.

Once the motor has started to spin, it will maintain that direction of rotation until it comes to rest after being switched off. Interupting the power supply and restoring it again while the motor is freewheeling will restore operation without changing direction.

The reversing switch on a single phase motor;
a. contols the power supply to the motor, and
b. changes the winding connections to determine direction of rotation.

If your motor is not starting or starting in the wrong direction from stationary then there is a problem switching, wiring, or motor and you need to refer the matter to a competant electrical mechanic for diagnosis and rectification.

However if reverse is being selected while the motor is still revolving (even very slowly) you need to allow time for it to come to a complete stop before selecting reverse.

Hope this explains the mechanics of the situation.

[lubbing5cherubs]

Hi Guys, this is after it has been stationery this is happening. I am not doing it before the motor stops. I wait till it has totally stopped before I even change the knob over.
Toni
PS Jim has been in touch with me this is a known problem occasionally with nova and he going to send me out a new one in the morning. How is that for great service. Jim your shop is A1
Toni

[robutacion]

HI lubbing5cherubs,

I read your other post about your problem, when I saw someone post my picture of the damaged capacitor I had on my 1624, and I simply assumed that it you would realise that is not a lot you can do to make the capacitor last any longer, indeed the sooner you replace that small part,(much less expensive) the less the risk to stuff up the reverse switch, and that it will cost a lot more, as the little buggers are damn expensive.

Glad to know that Jim is sending you a new capacitor, is not a complicated job to replace it, you find that you will probably have enough skill to do it yourself, huh? Just make sure, the lathe is unplagued from the wall socket before you touch it...!

If you don't feel confident and or have the proper terminals to do the job, get an electrician to do it, shouldn't take any longer than 15 minutes to do.

Either way, lets us know what did hapen. Good luck.
PS: another pic from my trouble capacitor.

Cheers
RBTCO

NOTE: I forgot, Malb mechanic explanation is pretty spot on, thanks.