Table saw motor problem

[Eddy Ng]

I own a Elektra Beckum table saw model TKHS-315C (2000W,12" blade, 240V). The blade is directly attached to the motor (without belt) but it has a induction motor. I connect with a 3 m extension cord and it work well all the time.
Problem started this morning, when I switched ON, the blade did not spin but I can hear that the motor is activated. I used the push stick to rotate the blade then it spined as normal. After this, I have no chance to rotate the blade anymore as once I switch ON, I can hear the motor activated sound then the fuse in the extension cord broken. I changed the fused 5 times and it repeated breaking the fuse. What is problem? Please advise.

[Tyler Howell]

Hi Eddy,
Welcome to the Creek.
Sounds like the windings of the motor.
Not sure of labor costs or this motor, I would consider replacing the saw, as a new motor or repairs would be excessive.
Good luck!

[Lee DeRaud]

Just to be sure (before you run out and spend a ton of money), try it with a different extension cord: these things tend to take a beating in a shop environment.

[CPeter James]

The problem is probably that the contacts in the starter circuit are dirty. If this motor has a capacitor ( a round tubular thing) that may be defective, but my guess is the points. They can be cleaned. I used a diamond hone to polish them and then clean with alcohol. This is a common problem with woodworking equipment because of all the dust in the air.

CPeter

[martyphee]

If this is an open motor it could be clogged with saw dust. Try blowing out the back of the motor with air.

[Eddy Ng]

I found that the start capasitor was bad (the shape distorted). I replaced it. When I switch ON after replacing the capasitor, the blade start spining for about 3 second (yesterday it did not spin at all) and the fuse blow again.
I change the fuse few times and same thing repeated, spining for about 3 seconds then fuse blow. I start playing around and found that when I removed the blade, the motor spin normally. Once I put the blade on, it spin for 3 seconds then fuse blow. (I confirmed this - with blade removed, the motor spin normally with ON and OFF for few times) Any I dea why it is so interesting? Please advise.
I knew that by having problem I could learn more. Sometimes, it is not fun to learn too many.

[Bryan Cowing]

you need to pull the motor, open it up and check the centrifical switch. It's probably stuck, contacts burnt together. The start winding is staying engaged or some other problem.:D

[Scott Loven]

Could be that the blade is rubbing on something. You could also take it to a motor shop to have it tested.

[Eddy Ng]

I have dismantled and sent the motor to repair. The guy found nothing wrong with the motor. He just clean the braker and did some lubrication. I couldn't believe that and tested on the spot. Everything is fine at that moment. What to do? Paid and went back.

1. The start capasitor was bad.

2. The fuse is malking the problem. The fuse I change is rating at 13A but it is not true. I dismantled the fuse (Bussmann brand, England made) from my planer and put it to the table saw and it run as normal. I repeated with the don't know where it made fuse and it blows again. Repeat again with Bussmann and confirmed.

[Dev Emch]

Eddy....

This is typical of single phase motors having starting issues. I am not sure of all the details here but I can give you some tips.

First of all, take this opportunity to clean your starter (if you have one) and clean out the centrifical cutout switch located often in the back bell of the motor. If this does not cutout on start up, it will smoke your aux or start windings.

Electrolytics contains chemicals that often vent out over time. So your capacitor loses capacitance until it can no longer start you motor. Its possible that a dent in the side of this thing vented some chemicals but I suspect that this capacitor was just old. One should always be on the lookout for these. On startup you will hear a load hummm with no motor rotation or you will need to kick start the motor with a stick or something else. If you detect this, immediately shut down and service the motor.

Fine sawdust has the ability to leach the volatile agents out of bearing grease leaving behind the soaps. This can happen with either regular greasers (i.e. zerk fitting attached) or with sealed for life bearings. You should always keep an eye out on your lube schedule and after so many years, replace those sealed for life bearings.

About once every year (heavy use) or few years (light use), you should pull the end bells and clean out the stator core. Your rotor contains a cast in place aluminum fan that blows air through the stator core. Here is another place where fine sawdust can accumulate and cause you issues.

So far, it sounds like you have fixed your current issues. You should replace the fuses with proper rated, good quality fuses. If your using conventional fuses like a Bussman, make sure that they are rated as SLOW BLOW fuses. There are conventional fuses and slow blow fuses. A slow blow fuse is used in motor applications to delay the trip caused by the high start up current that occurs when you start up the saw. Placing saw blades and other loads onto the motor during start up increases this current and also extends your start up time frame. Both of which are not good if your using a conventional fuse. So make sure your using slow blow motor fuses.

Best of luck here...