table saw fire!

[ScottGoddard]

Evening all,

Yup, while cutting the first part of a half-blind joint i heard what i thought was metal being cut, however, there was none in the wood. So i stopped and checked the saw (there was a little smoke) and the bottom of the cabinet was on fire.....Manage to put it all out, although it has caused some damage.

Now i think the motor was sparking and that was the noise, i think this then set alight the dust at the bottom (mixture of MDF and Walnut at the time).

So my question is do you think i can save the motor? Do anyone know of a place near Cardiff?
Would have thought i would need to replace the wiring.

 

[Trevanion]

I've heard good things about Rayles Rewinds in Merthyr, but I believe that kind of service isn't cheap. Might cost the same as a new motor of a similar quality would. On an older, better quality motor I wouldn't hesitate to have it rewound but on those really cheap motors they slap in the new "mid-level" table saws I wouldn't bother. It could be a better option to upgrade the motor to something a little better like an old Brook Crompton motor or similar, Or even the Machinemart motors would be better than the junk they use.

It may not even be the motor and it may be something else that caught fire such as the capacitor or something else on the circuit.

 

[ScottGoddard]

Thanks - worth a shot, the little research i have done suggest that the most come with capacitors but not sure. Do you have a thoughts / links on where to buy one of those motors?

 

[Trevanion]

Thanks - worth a shot, the little research i have done suggest that the most come with capacitors but not sure. Do you have a thoughts / links on where to buy one of those motors?

Having looked at the photos again it looks like it's got a little bit of an interesting mounting, could you get some closer photos of it? It might not take a standard motor if it's a non-standard mounting.

 

[ScottGoddard]

pictures and spec of motor

 

[Ttrees]

I would do a continuity test on the motor first to see if its still ok.
Maybe one of the wires came loose, maybe a capacitor problem?
Here is a guide to see how on three phase motors which is worth watching
I'll try and get the video to appear on screen .....
https://www.youtube.com/watch?v=FUjZwMMoltQ

[youtube]watch?v=FUjZwMMoltQ[/youtube]

It might be a good idea to disassemble the motor also, if its not obvious how it goes back together, make a continuous line
the length of the motor to aid reassembly
Hope this can be somewhat helpful
Tom

Doesn't seem like I can post the video so you'll have to do with the link
Tried selecting the insert URL icon and pasted the link into the pop up, with no joy.
Tried inserting shortened link inbetween the "code display icon" result above...looks like I'm getting closer but no cigar
Attempty no. not counting anymore #-o

[youtube]https://www.youtube.com/watch?v=FUjZwMMoltQ[youtube]

 

[heimlaga]

If the motor has standard mount and standard shaft dimension it isn't worth the effort to rewind a Chineese motor.
If it is a non-standard motor it will almost certainly worth rewinding as converting the mount is rather laborius if you want to get it right.
Good quality European motors are often worth rewinding. The cost of a rewind is roughly the same as the cost of a new inferrior Chineese motor.

However as others have said there is stilla slim chance that it might be something else than the motor that has gone wrong.

 

[Inspector]

I doubt it was the motor itself electrically sparking unless the wiring to the motor arced and that would have tripped a breaker. Even a short in the motor wouldn't mater because there are no openings to the outside, enclosed motor. A cooked capacitor would keep you from starting it and they are sealed under the cover. The fan (maybe the noise) in the end could have been touching the shroud and caused a spark but there is no reason for that to happen unless you banged the shroud or the fan has come loose from the shaft. The mount for that motor is not standard as it is a copy of a Unisaw and their motor had a pair of "ears" (see them in the pictures) it pivoted on to tension. I'd first look at the fan and shroud by hand pulling the belt to see if it makes a noise when it turns. Then I'd try and start the saw and see if it turns on to rule out the capacitor. If it works and there is no noise It could have been an ember from sawing something earlier that created a lot of friction or there was metal or a small stone that made a spark. That ember could have smoked for hours before growing big enough to burn.

Pete

 

[ScottGoddard]

Thanks all logical, electrical is actually my weakest skill in diy (i can rewire stuff but that's about it). I have the motor off and it seems all fine, i did see a fiar glow (while putting the fire out) in the back of the motor (assume this is the fan).

I need to strip the wiring as the outer sheath has melted i can then check the wires to see if they have been damaged.

 

[ScottGoddard]

I doubt it was the motor itself electrically sparking unless the wiring to the motor arced and that would have tripped a breaker. Even a short in the motor wouldn't mater because there are no openings to the outside, enclosed motor. A cooked capacitor would keep you from starting it and they are sealed under the cover. The fan (maybe the noise) in the end could have been touching the shroud and caused a spark but there is no reason for that to happen unless you banged the shroud or the fan has come loose from the shaft. The mount for that motor is not standard as it is a copy of a Unisaw and their motor had a pair of "ears" (see them in the pictures) it pivoted on to tension. I'd first look at the fan and shroud by hand pulling the belt to see if it makes a noise when it turns. Then I'd try and start the saw and see if it turns on to rule out the capacitor. If it works and there is no noise It could have been an ember from sawing something earlier that created a lot of friction or there was metal or a small stone that made a spark. That ember could have smoked for hours before growing big enough to burn.

Pete

I have just removed the fan covered and there are no marks inside the metal cover possibly suggesting some sort of catching, plus the fan is plastic and now deformed. I will try and rig up the motor outside of the saw to see if it starts up...I have also finished the cut of (that i was doing when this happened) and there is no metal. therefore i am no sure what the spark noise was just before the fire.

 

[Noel]

Hi Scott.

Bit of a long shot, or perhaps the perfect storm.
I notice from your pictures you're using a laminate/ply blade, an 80/90 tooth Freud perhaps. In my experience I'd never use such a blade on solid wood (or at least would not use for any substantial cuts, maybe just minor cross cuts if I'm too lazy to change blades), as too much heat is generated. This is especially worse with some hardwood and more so if the blade is not sharp. Because of this there is a heat build up with the result, as has happened to me in the past, of burnt sawdust dropping into the cabinet. In my case it wasn't so much a fire, although would've likely resulted in one eventually, but just smoking embers. I opened the cabinet and cleaned everything out.
Is it possible this happened without you noticing and the noise from the motor occurred because heat damaged the fan casing? Or perhaps, unluckily, a bit of wood managed to enter the fan housing and the fire was purely coincidence?
Perhaps I'm over thinking but ............

 

[ScottGoddard]

Hi Scott.

Bit of a long shot, or perhaps the perfect storm.
I notice from your pictures you're using a laminate/ply blade, an 80/90 tooth Freud perhaps. In my experience I'd never use such a blade on solid wood (or at least would not use for any substantial cuts, maybe just minor cross cuts if I'm too lazy to change blades), as too much heat is generated. This is especially worse with some hardwood and more so if the blade is not sharp. Because of this there is a heat build up with the result, as has happened to me in the past, of burnt sawdust dropping into the cabinet. In my case it wasn't so much a fire, although would've likely resulted in one eventually, but just smoking embers. I opened the cabinet and cleaned everything out.
Is it possible this happened without you noticing and the noise from the motor occurred because heat damaged the fan casing? Or perhaps, unluckily, a bit of wood managed to enter the fan housing and the fire was purely coincidence?
Perhaps I'm over thinking but ............

Yeah, i did think that but this was only one cut. I used the saw about 30 mins before and no issue. That being said, i do wonder if this was the issue, the noise its what is making me think something else is wrong.

 

[clanger]

I won't get a chance to have a look until the weekend, but I might have a motor from an old SIP compressor that I'm scrapping. The motor is perfectly good (the compressor has thrown a piston and as it is 25+ years old, can't get spares)

If it is a match, we then need to work out how to get it to you - shame really as I have been doing a load of work in Caldicot until last week. Not going to be back there until next March

Chris

 

[Inspector]

Clanger the motor if you look at the pictures again is not a standard motor mount using an attached plate or bolted to the shaft end of the motor. There are two wide ribs flanges welded to the case of the motor on the opposite side of the capacitor covers. One corner has a pin and a clip to pivot on and the other corner a bolt to tighten when tensioning the belt. As kind as you compressor motor offer is it can't be mounted in the saw. The OP has to get this one running or source another special motor with the same kind of mount and they aren't cheap. See the link below for them over here.

https://electricmotorwarehouse.com/delt ... nt-motors/

About the blade causing enough friction to make embers. They can sit in the sawdust for hours smouldering until they burn out or flare up from using the saw again. The blade spinning fans the embers into a flame.

Pete