Shopsmith Forums

Does every one hear their centrifugal switch when it actuates and then again when it de-actuates.

It seems to me that in the past I really had to concentrate to be able to hear that switch action. Yesterday, after using the Mark V in the horizontal position all morning, I changed to use the drill press. I drilled a couple holes then, all of a sudden, I could not turn it on. Flip the switch and nothing. Finally, it turned on so I left it switched on until I finished the task at hand.

I have an inline switch that I used during this period of time to turn the Mark V on and off.

This morning, I decided to open it up to see if I had something to fix. After a visual inspection, I saw nothing that appeared abnormal. Since it is open, I might as well clean and lubricate. Lubrication requires a couple on/off cycles and speed changes. All seemed to go well.

She is all buttoned up again after having been completely serviced; even the speed changer. I still can hear the centrifugal switch but but it seems to not be as loud. It has not failed to turn on and off yet today.

My puzzlement is this: How audibly noticeable is the centrifugal switch and is the intermittent operation of the on/off switch action indicative (in your views) of eminent failure?

I have replaced this switch once in its many years and when the original failed it went out in a blaze of sparks and minor smoke.

What do you think I should be prepared for?

Hmmm... I don't think I hear this, but I don't really know what a centrifugal switch is. Under what circumstances would I most likely be able to hear it?

Paul

paul heller wrote:Hmmm... I don't think I hear this, but I don't really know what a centrifugal switch is. Under what circumstances would I most likely be able to hear it?

Paul

The centrifugal switch is sometimes referred to as the "start switch" or the "run switch". Within the Mark V motor there is a start capacitor. This capacitor is connected into the motor circuit only for a short period of time after the motor is first turned on. Once the motor comes up to a certain speed, the centrifugal switch actuates and the start capacitor is no longer connected to the motor circuit. It remains this way until the motor is turned off. As the motor slows down you may again hear the centrifugal switch as it changes to the at rest position (physically prepared to function once again as a start switch).

The sound you hear (if you hear it at all) is just a rather solid clicking noise (one time). Then again about the same sound after you turn the motor off and just before in quits rotating.

I recently replaced the 1 1/8th hp motor on my 520 because it had very little power and would not always start.

After replacing the motor with a "new" one I pulled the cover off the back of the motor and found the centrifugal switch to be mangled. I checked the motor start up, and run winding continuity and it all seemed good(about 2 ohms). I got a new centrifugal switch from a local motor shop and mounted it.

With the new switch in their is a pronounced 'click' when I start the motor, I hadn't noticed it before, but then it was in the headstock and all buttoned up, now it is running as a bare motor on the bench top.

Don't know if that helps or not.

Mike

As sawdust (crud) collects in the motor end, it tends to dampen the noise of the centrifugal switch. I find I have to remove the motor from the motor pan to be able to really blow out all of the sawdust and crud from inside the motor. I find I only get about 20% of the sawdust/crud from the motor if I do not remove the motor from the motor pan. I would recommend cleaning the motor every 5 years or so just to keep it clean and operating. Also a good time to check the insulation on the motor power wires, clean the inside of the headstock and other maintenance.

The very early Greenies had a start relay in place of the centrifugal switch. This relay has a spring that works well in the horizontal position but when placed in the upright (drill press) position, many times this relay spring (as it become weak) would not engage this relay for the start windings. A hard knock on the motor pan normally worked for this problem.

Methinks what you hear is the flyweights and sliding collar flipping back and forth between running and stopped. The switch itself makes no appreciable noise. this mechanism becomes 'looser' with use(wear). I would not be concerned with the 'noise maker'. The condition and reliability of the actual switch is more critical. If your switch is like the one in my 1986 510, the points are essentially sealed. The switch leaves move very little. The flyweight/collar must push on the actuator portion of the switch. I IMHO think the contacts are 'enclosed' to prevent dust from interfering with it 'making'.

You said you 'flipped the switch and nothing'. If nothing means no humming, then the power switch is suspect. If it hummed and did not 'run' then the start switch is suspect.

WHAT did you 'open up'; the headstock or the motor?

[quote="JPG40504"]Methinks what you hear is the flyweights and sliding collar flipping back and forth between running and stopped. The switch itself makes no appreciable noise. this mechanism becomes 'looser' with use(wear). I would not be concerned with the 'noise maker'. The condition and reliability of the actual switch is more critical. If your switch is like the one in my 1986 510, the points are essentially sealed. The switch leaves move very little. The flyweight/collar must push on the actuator portion of the switch. I IMHO think the contacts are 'enclosed' to prevent dust from interfering with it 'making'.

You said you 'flipped the switch and nothing'. If nothing means no humming, then the power switch is suspect. If it hummed and did not 'run' then the start switch is suspect.

WHAT did you 'open up']

All I did was take off the belt cover.

I had the motor out of the pan about a year ago and blew it all out. However, I don't believe I accumulate dust quite like some do because I vacuum and blow out the headstock on a very regular basis. Anytime I have the belt cover off which is no less frequent than every two months I blow it out.

Yes, it seems like a flakey switch. When the motor did not start, there was no indication that the switch had changed except the noise of the switch. If the switch goes bad, I'll put in a new one but I believe I will bypass it in the headstock and switch the Mark V on/off with an external "safety switch".

Like I said earlier, the confusing observation was the clicking noise that I had not noticed before and the intermittancy of the on/off action.

The sure sign that something is about to fail is that it is now working and the centrifugal switch noise is minimal. I no longer hear it at all on start up and must listen closely to hear it as the motor is running down after shut off.

If I order parts, it may work forever. If I do nothing, it will surely fail when I most need it to work.