LumberJocks

Smoke coming from table saw motor

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by gtg601 posted 04-25-2015 12:05 AM 2622 views 0 times favorited 7 replies Add to Favorites Watch
View gtg601's profile

gtg601

4 posts in 595 days


04-25-2015 12:05 AM

Hi,

I was using my table saw the other day, and then all of the sudden the motor started acting like it was having trouble. I thought the electricity in the house might have gone off and come back on quickly or something with how the motor speed was going up and down all of the sudden. I turned the saw off and noticed the blade came to a quicker stop than the normal spin-down time, and that smoke was coming from it. I checked the motor brushes, which were somewhat stuck and a little dirty, but not too bad. Looking in through the vents, the motor looks surprisingly clean, despite the housing for the brushes being dirty. What could make a motor start fine, and then struggle and smoke after about 10 seconds?

Thanks


7 replies so far

View MrUnix's profile

MrUnix

4244 posts in 1666 days


#1 posted 04-25-2015 12:21 AM

What saw (and/or what type of motor)... since it has brushes, I’m guessing it’s a universal screamer. Most have plastic housings that hold the rear motor bearing, and those are prone to doing the warping/melting thing with any kind of sustained use. If so, you might get lucky and just need to replace the bearings… if not so lucky, the housing is beyond hope and you will need to replace the motor.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

View gtg601's profile

gtg601

4 posts in 595 days


#2 posted 04-25-2015 03:00 AM

This is a small Craftsman model 137.248830, with motor number rm871. I’m not sure of the type, but the motor is 3 HP/5000 RPM, and is located directly under the table (as opposed to our older saw in which the motor is off to the side and uses a belt).

View MrUnix's profile

MrUnix

4244 posts in 1666 days


#3 posted 04-25-2015 03:33 AM

This is a small Craftsman model 137.248830, with motor number rm871. I m not sure of the type, but the motor is 3 HP/5000 RPM, and is located directly under the table (as opposed to our older saw in which the motor is off to the side and uses a belt).

Yup, it’s got a universal motor. I had almost the same saw (137.248880) that I used for years until it finally just melted. The plastic motor housing holds the rear bearing, and when it gets heated up, it allows the plastic housing to warp and melt… eventually, if you don’t catch it in time, it will allow enough movement of the armature to contact the field coil and then it will start shooting sparks (don’t ask how I know!). Sounds like you might be lucky since you are just seeing smoke and not sparks.

I’m not sure if those motors are still available from the usual places as it’s listed as obsolete, but they do turn up on e-bay now and then. If you want to try and fix it, take it off the stand and flip it over so you can pull the motor. The housing is only held on with 4 screws IIRC. Once you get the housing off, you can see what that rear bearing and housing looks like. Most likely, the bearing is toast. If the housing still looks good, you can replace the bearing and you should be good to go. If the housing is all melted and warped, you are probably SOL.

Cheers,
Brad

PS: Actually, looking at the parts diagram for your saw, it might be a bushing instead of a bearing (kind of hard to tell as it’s barely legible)... mine was a bearing, which seems more appropriate. Once you open yours up, you can figure out what is there and if it can be salvaged.

PSS: I just looked at the parts diagram for the saw I had and it shows a bushing as well (as does the parts diagram in the owners manual I have!)... but there was in fact a bearing there, so the diagram might not be entirely accurate :) More than likely yours has a bearing also… as it makes no sense to use a bushing for that application.

-- Brad in FL - To be old and wise, you must first be young and stupid

View gtg601's profile

gtg601

4 posts in 595 days


#4 posted 04-25-2015 06:36 AM

Thanks. I believe you’re right about the bearing. I found a Youtube video of a guy with what looks like the exact same saw, describing similar problems, and it turned out to be the bearing and a melted housing. It seems the diagram is calling the melted housing the bushing, but does not show the bearing (the guy in the video was talking about this too), and the bearing fits into the plastic “bushing”. He had to epoxy the bushing onto the end, but he got it to work. So it seems like maybe it can be saved even if the housing/bushing has melted, but I don’t remember him talking about how he got the old one out, or if he had to somehow cut it out.

There were three videos, and here is the link to his account with the three videos at the top:
https://www.youtube.com/user/bctruck/search?query=craftsman

View MrUnix's profile

MrUnix

4244 posts in 1666 days


#5 posted 04-25-2015 06:59 AM

LOL – I Don’t need to watch the videos… I’ve lived it :)

IIRC, the bearing was in a metal cup (don’t remember it being plastic) that was held in the plastic housing. I didn’t have any problem getting it out, and I messed with that bearing a bunch trying to keep that saw going. Probably took it apart 4 or 5 times in total to replace/fix the bearing. One time, I was able to just re-pack the bearing to keep it going – I was in the middle of a project and didn’t have time to get a replacement. In the end, the thing just became too melted and warped and my last ‘fix’ lasted about an hour before it started shooting sparks.

Open it up and see what you got. It may or may not be salvageable.

Cheers,
Brad

PS: They do still have the housing available for sale, but it’s like $50 or so.. I just got tired of fighting it though, and now I just use it as a router table :)

-- Brad in FL - To be old and wise, you must first be young and stupid

View gtg601's profile

gtg601

4 posts in 595 days


#6 posted 04-26-2015 07:44 AM

It was the bearing on the end. It looks like it just barely started to melt by the smallest amount. The cup almost looks like plastic or rubber on the outside, and metal on the inside. Hopefully the inside is not too worn to hold a new bearing. I didn’t mention this before, but I also found some very thin washers (each one broken in half) lying underneath the table saw when I turned it over. I’m not sure where they came from, or if they are really washers considering how thin they are, and they are not in the diagram.

I thought you threw yours out when it melted, so that’s why I posted the link. The guy in the video had is melt on him too, but he was able to fix it. However, I guess there was nothing he showed in the video about this, but only talked about using epoxy to seat a new cup for the bearing. I’m not sure how much trouble this thing is worth, but probably not $50 (about 1/3 of the price of the whole saw brand new).

View toolie's profile

toolie

2025 posts in 2095 days


#7 posted 04-26-2015 11:36 AM

Dump it and look for a used 113 c-man. They had true 1 or11/2 ho motors. Those direct drive saws like yours are light weight and appear to be relatively disposable.

-- there's a solution to every problem.......you just have to be willing to find it.

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com