Trying to fix my 30 year old Craftsman table saw - Page 2 - Woodworking Talk - Woodworkers Forum
 6Likes
Reply
 
Thread Tools Display Modes
post #21 of 30 Old 03-15-2019, 07:48 PM
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 25,026
View woodnthings's Photo Album My Photos
Well, that's a problem .....

When a motor hums and won't turn it is typically a starting capacitor that the issue. Your saw is a direct drive model and may not have a capacitor ... I donno?
Here's a parts break down, motors are not available,
https://www.searspartsdirect.com/mod...7/0744000.html
So, now what?
A new motor is probably out of the question, but we need to figure out if your motor is bad. Kinda hard to do over the web. There are ways to measure the resistence in the windings to see if they are bad, but I can't tell you how and you'll need the dreaded multimeter.


You can "bypass" the switch by touching the two connectors together, briefly ..... and see if the motor will turn over BUT that would mean working with LIVE electricity! I can do it, but you shouldn't! There is a 'bypass" to the bypass... where you have the saw unplugged and tape the terminals together to make contact, THEN plug the saw back to a heavy extension cord that's handy to get to in case the "magic smoke" decides to relocate in your work shop. Once the smoke is out of the motor, you can't put it back, a lot like the genie....

Ya'll be careful, this is over your skill set. Not worth burning down the house OR getting hurt over. Take the dang thing somewhere and get it looked at.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
woodnthings is online now  
Sponsored Links
Advertisement
 
post #22 of 30 Old 03-15-2019, 08:30 PM
CharleyL
 
Join Date: Jan 2019
Location: Central North Carolina
Posts: 62
View CharleyL's Photo Album My Photos
Without power, can you spin the motor shaft by hand? Does it spin free or is it hard to turn?

Can you smell any burning smells if you put your nose near the motor? If that motor hums when you power it and it does not run it could be a damaged bearing, my reason for asking if the shaft spins free. Bearings in some motors are easy to replace, but some of this type motor do not lend themselves to easy replacement.

Are there brushes in this motor? If so there should be 2 round plastic caps located at 180 deg opposite to each other on the motor sides. These caps can be removed to access the brushes, but be careful since there is a strong spring beneath the cap. You don't want to loose either the spring or the cap. The brush under each cap and behind the spring will be a black carbon rod with either square or round sides. If the brush is very short (less than 3/8" long) they need replacing. If the brush is broken or missing, especially if the end of the spring is burned, the motor is likely damaged and also history.

If the motor windings have been overloaded and burned, you should be able to smell the strong pungent burn smell when placing your nose near the motor, and if you can smell that, the motor has likely already had the magic smoke let out of it, and it's history. A new motor will be necessary.

If you connected the wires to the two left or the two right terminals on your new switch and there was a flash when you turned the switch on, did the flash come from the motor or the switch? Is there still power at the outlet that the saw was plugged into? Can you plug something else into that outlet to see if it has power?

Accurate answers to these questions is the only way that we can help you without being there to do it for you.

Charley
CharleyL is offline  
post #23 of 30 Old 03-16-2019, 12:24 AM
Senior Member
 
Join Date: Jun 2018
Location: jesup GA
Posts: 367
View Mikhail2400's Photo Album My Photos
When I was reading the post about them trying different wiring hookups to see if any of them worked I had my darn fingers crossed just hunting for a happy ending!

You may want to check the local yellow pages and see if theres anyone close by who specializes in electric motors or check Craigs list for a replacement motor. Who knows you may run across just what you need. Theres also the possibility one of your local schools can help you. Once got a Mercury outboard completely torn down, cleaned and rebuilt for the cost of the parts needed. The small gas engine teacher of the local high school was happy to be able to show his students how a motors rebuilt. Good luck with getting it up and running!!

Mike
Everything i build comes with a redneck warranty. If it breaks you get to keep both pieces.
Mikhail2400 is online now  
Sponsored Links
Advertisement
 
post #24 of 30 Old 03-25-2019, 11:22 PM
Mad
Senior Member
 
Join Date: Dec 2017
Posts: 244
View Mad's Photo Album My Photos
That is a DPST switch (double pole single throw). As Bill said in the beginning, it is useful for table saw switches, especially with dual voltage motors that can be wired 120 or 240.

As to the motor going suddenly quiet after humming... there is likely a somewhat hidden thermal reset switch on the motor itself. The thermal reset probably tripped during the humming event, which is why the humming stopped.

To locate the thermal reset button, consult your manual. If you don't have the manual, google the part number to the saw, and download the manual from vintagemachinery or manualib. The manual will pinpoint the location of the thermal breaker reset switch. Some reset themselves automatically, but not immediately. The component that heated up has to cool down first, and that may not happen between the moment of failure and the moment one throws their hands up in the air in despair... depending on the patience of the hand thrower and circuit blower.

Consider following the advice you came here seeking, which is the advice that Woodnthings offered at the outset, which was to conduct a continuity test on the switch you purchased, to both verify function, and augment your understanding of how it works. That understanding will give you the confidence to properly connect the switch without worry, and to diagnose whether or not the new switch arced internally when connected to power. It isn't too late to follow Woodnthings advice. You will benefit from it for this and future adventures.
woodnthings likes this.
Mad is offline  
post #25 of 30 Old 03-26-2019, 10:53 AM
Junior Member
 
Join Date: Nov 2018
Location: Lancaster, Ohio
Posts: 23
View evilboweivel's Photo Album My Photos
"So I attached the old switch, and when I plugged in the machine it made a humming noise, but but blade didn't spin. Then the humming stopped, and there was no noise."

sounds like a bad capacitor on the motor
evilboweivel is offline  
post #26 of 30 Old 03-26-2019, 12:18 PM
Mad
Senior Member
 
Join Date: Dec 2017
Posts: 244
View Mad's Photo Album My Photos
Quote:
Originally Posted by CharleyL View Post
Without power, can you spin the motor shaft by hand? Does it spin free or is it hard to turn?

Can you smell any burning smells if you put your nose near the motor? If that motor hums when you power it and it does not run it could be a damaged bearing, my reason for asking if the shaft spins free. Bearings in some motors are easy to replace, but some of this type motor do not lend themselves to easy replacement.

Are there brushes in this motor? If so there should be 2 round plastic caps located at 180 deg opposite to each other on the motor sides. These caps can be removed to access the brushes, but be careful since there is a strong spring beneath the cap. You don't want to loose either the spring or the cap. The brush under each cap and behind the spring will be a black carbon rod with either square or round sides. If the brush is very short (less than 3/8" long) they need replacing. If the brush is broken or missing, especially if the end of the spring is burned, the motor is likely damaged and also history.

If the motor windings have been overloaded and burned, you should be able to smell the strong pungent burn smell when placing your nose near the motor, and if you can smell that, the motor has likely already had the magic smoke let out of it, and it's history. A new motor will be necessary.

If you connected the wires to the two left or the two right terminals on your new switch and there was a flash when you turned the switch on, did the flash come from the motor or the switch? Is there still power at the outlet that the saw was plugged into? Can you plug something else into that outlet to see if it has power?

Accurate answers to these questions is the only way that we can help you without being there to do it for you.

Charley

In reviewing your predicament ... your table saw was working, then it died in the middle of use, and then a friend of yours suggested buying a new switch. After your struggles in figuring out how to connect the new switch, you reconnected the old switch again, and after doing so, a change in state of the saw occurred. The saw hummed. The fact that the saw hummed means that the old switch functioned well enough to pass power through it, which indicates that the root cause of your problem wasn't likely the switch after all.

The thing is, with a continuity tester, as Woodnthings suggested, you can not only test the new switch to verify for yourself which terminals make or break when the switch is on or off, you can also test the old switch too (without it being connected to wall power). Having that capability to test can help you demonstrate to your friend that the problem isn't the switch.

Is there a lot of sawdust under the table of your saw? An excess accumulation under the saw is often accompanied by an excess accumulation of sawdust inside the motor. An electrical motor packed with sawdust can overheat quickly, become finicky, or even catch fire. If you haven't done so already, consider vacuuming out the cabinet of the saw, and then, simultaneously with the vacuum in operation, directing a nozzle of compressed air through the openings in the motor to expel the dust accumulated inside. Be sure and use a different outlet, feed by a different circuit in the home or shop, to segregate where the vacuum cleaner and the air compressor are plugged in, to avoid running two high current loads on the same circuit simultaneously for prolonged periods of time. It might take time too. It took me as long as a full hour to clean all the dust out of one table saw and motor that I acquired used.

With your switch function confirmed and better understood by you, and with your saw motor completely clear of dust, and your saw underpinnings now clean enough for you to locate and access the components on the motor, such as the thermal reset switch on the motor itself, the capacitor cover if the motor is so configured, and the shaft, to test for restriction in rotation by hand (when disconnected to power)... you are now ready to try all of Charley's suggestions quoted above, which are all excellent questions for you to answer, and a recommended path toward diagnosis.

Last edited by Mad; 03-26-2019 at 12:21 PM.
Mad is offline  
post #27 of 30 Old 05-07-2019, 10:28 PM
Senior Member
 
Join Date: May 2018
Posts: 145
View Mycrossover's Photo Album My Photos
Quote:
Originally Posted by woodnthings View Post
I just ordered the multimeter and the powered test light because my cheap HF meters are crap. I think they were free or in the $2.00 bin but I'll throw them out when I get the new ones.
The cheap freebie HF meter is more than enough to see which contacts are paired together. Put it on an ohms range and if it reads anything close to zero when you put the leads together you can check out the switch. It is almost certain that the contacts across the switch are the pairs, not the two that are right next to each other. The problem with the HF freebie meters is the leads are trash and break internally or just fall apart. I bought some very decent leads on ebay for a buck a pair which was all I was willing to invest for free meters.

Sent from my SM-G900V using Tapatalk
Mycrossover is online now  
post #28 of 30 Old 05-08-2019, 07:56 AM
Senior Member
 
Join Date: Jul 2008
Location: Florida Panhandle
Posts: 11,479
View GeorgeC's Photo Album My Photos
This thread is about 6 weeks old. I wonder what the original poster was able to accomplish.


As far as Harbor Freight meters go, I have found one completely adequate for most household needs. I do have a much better one, but for a quick look the HF model is easy to grab and use.


George
GeorgeC is offline  
post #29 of 30 Old 05-08-2019, 08:14 AM
Moderator
 
Steve Neul's Avatar
 
Join Date: Sep 2011
Posts: 25,365
View Steve Neul's Photo Album My Photos
I have had good luck with the Harbor Freight meters. Occasionally they malfunction but if you change the battery in it once in a while the unit will work fine. I wonder how many know they contain a 9v battery.
Steve Neul is offline  
post #30 of 30 Old 05-08-2019, 04:25 PM
Ancient Termite
 
Join Date: Mar 2018
Location: Huntington Beach, California
Posts: 329
View NoThankyou's Photo Album My Photos
Let me put it this way.
It doesn't make no never mind which way the switch is used in the saw.

Connect the black of the power cord to any terminal on the switch. Connect the black wire of the motor to any terminal. Plug in the power cord and see if you can turn on the saw. If yes you are done and reassemble.

If the saw doesn't turn on, unplug and move the black motor wire to any other terminal on the switch. (Diagonal would be my choice but irrelevant) Repeat the power on test. If it fails, repeat this step using the other terminal.

In North America, our electrical terms are intended to confuse. For 120 volts we switch the hot (black) to neutral (White). The neutral is really a ground because it is tied to the green wire inside the circuit breaker box. With 240 volts we use two hot wires, black and usually red. The black can be considered plus 120 volts and the red can be considered minus 120 volts. (Not really, but don't beat me up on this because it makes it easier to understand.) When you measure across the red and black you get 240 volts. Why? Because you are measuring from 120 volts above ground to 120 volts below ground, thus giving 240 volts between them. In Europe and elsewhere where normal electricity is delivered as 240 volts, one wire 240 volts and neutral or ground.

The voltages basically make no never mind. The 110, 115 and 120 are all taken to mean the hot leg. Nominal is hopefully 115 volts. However you can measure anywhere from 110 to 120. Your appliances specified at nominal will work anywhere from 110 to 120. Here I am about 5 miles from the power generating plant and I've seen voltages from 114 to 118.

If you understand transformer terminology, the explanation is that our household electricity is from a center tapped transformer. Or 120 up and 120 down. Voltage is always measured to a reference point.

Rich
In furniture 1/32" is a Grand Canyon
NoThankyou is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Craftsman Pro Series 10" Contractors Table Saw w/30" Fence (TJZ10/3 ) CLS89 Power Tools & Machinery 16 09-30-2018 09:46 PM
craftsman table saw motor mount clips Samshappywood Power Tools & Machinery 1 08-20-2018 03:01 PM
Craftsman Table Saw 315 228390 NHS Power Tools & Machinery 1 06-11-2018 10:23 AM
Wolfcraft 6157 router table. dbhost Tool Reviews 2 10-02-2015 07:22 PM
Craftsman Table saw Attachment tchara Power Tools & Machinery 4 08-03-2015 12:05 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome