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View Full Version : Smokin ShopVacs - Fire in the Hole!



Mayo
09-06-2003, 12:58 AM
I was cutting some boards made out of wheat stalks (made by Dow and coated white for use as shelving). About 1/3 through the file, some pieces began to shift because I didn't put enough screws as hold downs.

As the material shifted, I hit the keyboard to stop the cutting. This of course didn't stop my router from spinning and I had to shut that off next. Then I shut off the shop vac which I use as my dust pick-up.

Next, I straightened the material and then edited the file to only cut the remaining uncut pieces. I made a new file to place screw holes on the remaining material.

I ran the file to drill the screw holes and while it was running, I thought I smelled something like charred wood, but I just figured it was because the bit had got jammed previously and the aroma was in the air.

I placed the screws in the holes to secure the material to the table. I was ready to run the edited file and I made sure the shopbot was zeroed on all x,y, and z positions.

I went over to the shopvac to turn it on and I saw little puffs of smoke seeping out from the rim. I thought, "is this just dust... or... UHH OHH!" I quickly realized there was either smoke or fire inside the shopvac.

Unbeknownst to me, when I stopped the motion of the Bot, and the bit was still spinning and the shopvac was still vacuuming the dust, it must have sucked up some red hot particles of this shelf material.

I went and got a container of water (just in case) and when I opened the vac, it was full of thick smoke. At the bottom of the container there was a very red glow of embers!

I poured about a half gallon of water into the container and it basically seeped underneath the smouldering red glow and didn't put it out.

At that point I removed the container from the basement and brought it outside where I thoroughly hosed it with water from a garden hose.

After this was all over I thought just how lucky I was that I didn't get disgusted when the material shifted because I had considered leaving the work for another day. Those glowing embers would have probably caused a major fire.

So, the moral of this story is check your dust collection container if you ever have to stop your shopbot in the middle of a job and the bit continues to spin for even a short time. And empty dust collectors at the end of every day. And if you smell something like smoke, don't always assume it's "just in the air".

kerrazy
09-06-2003, 02:41 AM
Mayo I am glad to here all is safe now!
This is a very good lesson to be learned. I was speaking with a local crafter of just something similar today regarding dust collection.

Ensure all your stuff is grounded well, as one spark can cause a serious explosion of the fine particled generated in a wood working environemnt.

I too, had similar thing occur were a spinning bit left unattended for just a minute in MDF caused a .5 inch glowing ember very quickly and could have resulted in a similar situation or even worse.

rgbrown@itexas.net
09-06-2003, 07:57 AM
I know of several shops that have burned to the ground as a result of "dust collector fires". I put my dust collector outside for that reason. And, there is a fire-resistant wall between the dust collector and the shop.

On the next shop I will have even further separation between the dust collection and the stuff I would hate to loose. I also believe I might build a few alarms for fire/smoke.

Ron