[Red Stick]

Today I was cutting 5/16 rabbits in 23/32 plywood on my router table. On the 3rd piece I noticed first a lot of smoke, then actual burning wood. Not exactly flames, but fire red. I shut off the router then shut off the dust collector. Was very concerned that the collector bag would suddenly erupt into flames so I as quickly as possible removed it from my dust collector. Emptied the bag and ran the dust collector to clear out any remaining embers. Seeing none I put the bag back into place and assumed the fire was out.

Since this was my third cut with all settings and feed rate the same, I assume there was just something weird in the plywood?

Anyone have any idea what happened?

 

[Stick486]

off shore ply???

dull bit and sulfur content in the plywood or sparked by hitting metal in the ply.....
instead of sulfur there may be some other low flash point chemical present...
what did the smoke smell of???

when you cleared the system did you remove the bag??? sure hope so...
never ever assume the fire is out in saw dust... NEVER!!!
it can set for days and then start up w/o warning...
soak the snot out it and then drown the saw dust again several times...
suggest you treat the ply and saw dust to a strong magnet...
investigate this thoroughly....
you are now on fire watch till this is solved....

 

[gmercer_48083]

I had that happen once routing mdf. Didn't have dust collection connected at the time, and was able to snuff it out with my shoe. A good lesson to have a fire extinguisher handy. When I was a Pup, years ago, where I worked, we had a 55gal drum out back with scraps of wood being burned from shelving being made on pallet racks. After sweeping up all the saw dust, I tossed the saw dust into the burning barrel...and to my surprise, it flashed...like gun powder. Never did that again!

 

[MT Stringer]

I vote for dull bit.

 

[sunnybob]

Ply is very tough on bits. Check the cutting edges, i reckon they will be dark brown or even black. throw it away

 

[Red Stick]

Thanks for replies

Thanks for the replies. Everything seems to be OK now. Maybe a dull bit, but it was the third cut and cut several more afterwards with no problem. Absolutely certain that any remaining embers were gone. This was pretty good birch ply but don't know the origin. Finished project looks very good! Thanks again for the replies.

 

[RDWilson2]

Beware of flames/embers and dust collectors

I had that happen once routing mdf. Didn't have dust collection connected at the time, and was able to snuff it out with my shoe. A good lesson to have a fire extinguisher handy. When I was a Pup, years ago, where I worked, we had a 55gal drum out back with scraps of wood being burned from shelving being made on pallet racks. After sweeping up all the saw dust, I tossed the saw dust into the burning barrel...and to my surprise, it flashed...like gun powder. Never did that again!

Not only saw dust but flour or even just plain dirt-type dust will flash like that and, if it's in a vacuum cleaner/dust collector, it can cause a major explosion.

 

[hawkeye10]

Not only saw dust but flour or even just plain dirt-type dust will flash like that and, if it's in a vacuum cleaner/dust collector, it can cause a major explosion.

never knew dirt dust would flash. I learned something today.

 

[Knothead47]

Fine dust will flash like gasoline. Had it happen. I told the wife about this as we have a burn pile in the back of the lot. FWIW, I went to college with a good ol' boy who worked one summer in a feed mill. That is where he learned to chew tobacco. They were not allowed to smoke in or near the mill as the fine dust would flash. If you lived in the country like I did, you would hear of grain mills exploding due to the fine dust igniting.

 

[JFPNCM]

Watch this video to the end to see how bad it can get when a grain bin goes.

 

[radios]

too much heat causes the fire, either a dull bit, or not feeding the stock in fast enough..

 

[snowysix]

Wood dust as a fuel

In 1987 I was sanding the extensive oak floors of an old house we'd just bought. I was alone, and the job was taking hours! Suddenly I heard a nearby smoke alarm go off. And then I became aware of a roaring sound which was growing louder. It seemed to be coming from the gas-fueled wall-heater (dating back to 1951). I could see the dust being drawn into the heater louvres, and a huge flame roaring up the in-wall chimney. Not quite panicked, I opened all the windows and doors, and a breeze helped disperse the wood dust in the air to the point where the heater flame went out. I then carefully extinguished the pilot light!