Electric motor problems.

[wannabe]

Help. My toy is broken!!
I'm hoping someone on here knows more about electric motors than I do. I'm having trouble with the motor on my mill. It's a 1.5KW single phase motor on a Hafco VM1 Mill (around 1987 vintage).
I went to fire up my mill today but when I turned it on all it did was hum. I've since found that by manually rotating the spindle to different position it will sometimes start. My initial thought was the capacitor but since it's either humming or starting I don't think that's the problem.
After taking the fan cowling off and looking inside I can see a contact switch and sliding centrifugal weights. From what I can determine the switch is normally closed when the motor is stationary. When the motor starts rotating the centrifugal weights slide down the shaft and allow the switch to open. I assume that with the switch in the closed position this allows the motor to start under reduced power and once the switch opens the motor then receives full power.
I think that due to wear the switch is not making full contact sometimes. I notice at the bottom of the centrifugal weights is a clamp that looks like it allows the weights to be moved up or down the shaft. What I'm thinking is that the switch needs a little more tension on it and was planning to slide the weights up a little to put a bit more tension on the switch. Does this sound feasible?
Looking at the size of the capacitor in this thing I'm very wary of sticking my finger in there. It would have one major bite to it.

Sorry this is so wordy. I was going to take a picture but it was 8 degrees out in the shed and got too cold. The joys of Canberra.

[tanii51]

not too sure but i think its the opposite when the contacts are closed it uses full power directed to the start windings then when it reaches full speed it shuts off but im sure a qualified leccy will tell you more

[Penpal]

Hi,
Before you suffer a mischief take the motor to Delta Electrics in Woden and seek professional advice, you may be correct but if you inadvertantly put yourself at risk it would in my opinion unneccesary and dangerous.

With the motor belts removed and you switch it on and by spinning manually the in the right direction and it then runs up slowly to full speed it could be the capacitor.

The function of the centrifical switch is the opposite of your explanation the capacitor applies an additional starting boost to overcome the running from inertia.

As a sparkie I want you to know with due respect the advice given me when I bought my mill drill from a similar country of origen, get rid of the original motor and replace it with a 2hp unit in my mills case a three phase that suited me since I have 3 phase in my workshop. No more centrifical switch. All very well for you I hear you say I only have single phase.

So back to my original suggestion take the motor and get an opinion, my understanding is centrifical switches are both fickle and appropriate switches like hens teeth.

Take care and have success. Peter in Canberra.

[Timmo]

Hi,
Before you suffer a mischief take the motor to Delta Electrics in Woden and seek professional advice, you may be correct but if you inadvertantly put yourself at risk it would in my opinion unneccesary and dangerous.

With the motor belts removed and you switch it on and by spinning manually the in the right direction and it then runs up slowly to full speed it could be the capacitor.

The function of the centrifical switch is the opposite of your explanation the capacitor applies an additional starting boost to overcome the running from inertia.

As a sparkie I want you to know with due respect the advice given me when I bought my mill drill from a similar country of origen, get rid of the original motor and replace it with a 2hp unit in my mills case a three phase that suited me since I have 3 phase in my workshop. No more centrifical switch. All very well for you I hear you say I only have single phase.

So back to my original suggestion take the motor and get an opinion, my understanding is centrifical switches are both fickle and appropriate switches like hens teeth.

Take care and have success. Peter in Canberra.

Another one for Delta. We use delta all the time for our motor repairs. You'll find them in Dundas Court, Phillip.

[wannabe]

Thanks guys. Despite your wise warnings I had to have a go at fixing it. Wouldn't be me if I didn't have a go.
I marked the spindle so I could put things back to where they were if it didn't work and very carefully loosened the two screws holding the centrifugal switch to the shaft. They weren't very tight either. Loose would probably be a better description. I then levered the centrifugal setup up about .75mm and tightened things up. Works like a bought one again.

Thanks for the tip on Delta for repairs. Good to know that and that's where it will be going if this fix doesn't hold. I hadn't heard of them.
My main worry was having to buy a new motor which meant the mountings would be different, the shaft would be different, etc, etc ... as it's definitely of eastern origin and parts would be impossible to find. I once asked Hare and Forbes about spare parts for the mill and he just smiled at me.

PenPal: Point taken on the 3 phase motor unfortunately I don't have it connected to the shed so I'm stuck with single phase.