Electric motor help needed

Electric motor help needed · 09-10-2009, 12:46 PM

Hi,

I am looking for advice on starting up a reluctant motor.
I have inherited a very old Delta jointer that came with a very old 1hp 3450 rpm Montgomery Wards motor. It runs but it does that thing where it will buzz when you turn it on initially and the shaft looks like it is trying to decide which way it is going to turn. I give it a helpful push and it slowly gets up to speed. I had a similiar problem on a very, very old Delta Radial Arm Saw motor and I am thinking that the solution with that was to clean out the motor as best I could and get a new capacitor. I do not see a capacitor, that hump I see on all other motors, on this. I can live with having to nudge the belt when I run it but I'd rather fix it if I can.

I would also like to get any information that I can on this motor. It clearly says "Montgomery Wards" on it and it is huge compared to the size of all my other motors. On the tag it says:
Amps 14.2/7.1
Does that give me any information on the actual power of the motor? I am thinking of using it for my table saw if I can mount it and if it is substantially more power. Can I just compare AMP ratings to determine the actual ooomph of the motor? It also has this on the tag as a model numbers:

YWL-4669 - Model
311P199-A MFG number

Any info would be most appreciated.

Thanks very much,
Jim Lee

Joe Scharle · 09-10-2009, 01:29 PM

Many of those old motors used a centrifugal switch. You'll find it mounted in one end bell housing. At rest, power is applied to the start and run windings. After spinning up to some speed, the switch is thrown open leaving the run windings only. Usually the contacts get dirty and need to be blown out and all is fine for awhile.
The Amps 14.2/7.1, states the operating current draw for 120V/240V respectively. Not exactly accurate based on amperage, but the hp could be 1.5.
Is your tablesaw designed for 3450RPM?

Don Sorensen · 09-10-2009, 01:35 PM

Are you sure it's only 1 hp? I brushed off some old brain cells and did some quick pencil figurin' and it seemed closer to 1-1/2 or 2.

It's a dual voltage motor we can tell from the two ampere ratings.

ah hah...Joe answers while I'm scribblin..

CarvedTones · 09-10-2009, 02:12 PM

Jim,

I have dealt with a few old motors. The first thing I do is blow out dust. The next is to take off the start capacitor, assuming it is external in a little outer housing, and take it to the motor place off Atlantic just inside the beltline (name escapes me).

EDIT - This is the place I was referring to:

Originally Posted by DIYGUY

If you can't get it working yourself, then a good place to take it is Motors and Controls on Hodges St in Raleigh ...

They will test it and sell you another if you need one. Hopefully you do, because they are cheap and that is about the easiest fix there is. Past that, you are into opening it up and carefully cleaning contacts in that centrifugal switch mess.

Mike Davis · 09-10-2009, 02:37 PM

I usually deal with really old motors by throwing them in the corner and getting a more efficient modern motor. Sealed and air cooled so I don't have dust problems.

Ozzie-x · 09-10-2009, 10:39 PM

There are a lot of different type single phase motor starting methods other than capcitor start. Without looking at it, it's hard to say. Joe offered some good advice, open it up, clean everything well and lubricate the non-electrical moving parts. Based on those ampere numbers, it is a 1 HP motor.

algustaf · 09-11-2009, 08:41 AM

Here is some great information for electric motor basics.

http://www.sawdustmaking.com/ELECTRI...ricmotors.html

Hope this helps

ALG

CarvedTones · 09-11-2009, 08:49 AM

Originally Posted by Ozzie-x

There are a lot of different type single phase motor starting methods other than capcitor start. Without looking at it, it's hard to say. Joe offered some good advice, open it up, clean everything well and lubricate the non-electrical moving parts. Based on those ampere numbers, it is a 1 HP motor.

That's true, but every single motor I have ever looked at on an old belt driven tool has been cap start. Not a huge sample, but it's probably at least 2 dozen. If it has a little external bump out for a cap, I would check it before opening the "main can" I have dealt with a couple that were nightmares to get closed up again; wires that needed to be worked around something as it closed, but only after it was closed too far to reach in with any standard tool and other similar issues.

DIYGUY · 09-11-2009, 09:21 AM

If you can't get it working yourself, then a good place to take it is Motors and Controls on Hodges St in Raleigh ...

Charles Lent · 09-11-2009, 01:16 PM

There are 2 common problems with these motors that can cause this type of starting problem:

1. The centrifugal start switch contacts are corroded
2. The centrifugal weight/cam assembly is sticking

They are both relatively easy to correct, although you will need to remove the end cover of the motor to access them - the end cover opposite the shaft end is usually the one that needs to be removed. It is also most likely to be the one that has the power cable entrance. Double shaft motors may have this switch at either end.

Unplug or disconnect the motor from the power source.

Remove the 4 long bolts/nuts that hold the end covers on the motors.
Using a flat blade screwdriver and a hammer drive the end cover free of the motor center section. You may have to hit the edge of the cover at several points around it's circumference to free it.
You will find a switch contact assembly mounted inside the end cover and the contacts of this switch will need to be cleaned - folded sand paper slid between the contacts a few times should do it. The switch is spring loaded and the contacts should want to stay together. You will have to spread them open to insert the sand paper, but they should go tightly back together when you remove the sand paper.

On the exposed end of the motor shaft you will find a plastic ring with spring loaded weights behind it. This ring needs to slide freely on the shaft and dirt/corrosion of the shaft is usually the cause of it malfunctioning - clean and polish the shaft between this plastic ring the end of the motor shaft until it is smooth and shiny, but don't disturb the spring/weight components on the other side of the plastic ring. Apply a very light film of oil to the shaft surface where you have cleaned/polished it, and to where the shaft goes through the plastic ring. The weights apply force to the plastic ring when the motor spins, causing the plastic ring to slide toward the end of the motor, opening the contacts of the switch and turning off the start winding of the motor, as the motor reaches about 70% of it's run speed. If the plastic ring cannot slide on the shaft it will hold the switch contacts open and the motor's start winding will not operate.

Inspect the wiring to be sure that none of them are damaged and repair if necessary. Also inspect the motor bearings and replace them if they do not turn freely.
Re-assemble the motor making sure that you have oriented the end cover correctly. Install and tighten the 4 long bolts/nuts.

Test run the motor - start and stop it several times to be sure that it's working properly before re-installing it in the tool.

Charley

Don Sorensen · 09-11-2009, 02:32 PM

I had a problem with my centrifugal switch on my washing machine here a while back - at first I thought they were sticking - come to find out that the shaft bearings were so dry and dirty that the motor would never get up enough speed to fling the weights out - which the machine treated as a problem and would shut off, briefly. And it never happened during the first or second load of wash - usually the third load would fill up with water and then just sit there. I figured it took that long for the motor to heat up enough for the shaft to drag in the bearings. A little 3 in 1 oil here and there, and that machine has been running fine since.

So, yeah, give the motor a good cleaning, and a little lube.