This is how accidents happen

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MRDucks2

MRDucks2

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Joined
Jul 17, 2017
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Bristow, IN
Just trimming some pine brick mold for the new 32" door I am putting on the shop. Small wood, soft pine, good and dry so an easy cut with the newish 80 tooth blade on my table saw. Gonna be quick so no need to turn on the dust collector. Almost done and go to trim the piece for the head jamb.

In my shop, I open the garage door for longer cuts & nice days. I noticed this in the late afternoon sun.




Somewhere between the dust housing and the dust collector a fire was starting to smolder. Disconnected from dust collector and it wasn't there. Used the shop vac to suck out the short run of dust collector hose and the run from the blade to the saw discharge. No more smoke. I will leave the shop vac sit outside tonight.

But, this is how accidents happen. It doesn't take much smoldering dust for a shop fire to start.

How many times have I flipped the switch for a quick cut with no dust collection the last few weeks? How much fine dust built up without me thinking about it? How easy would it have been to not notice before going in for dinner? I'm not sure, The Good Lord was watching out for me again. How about you?

The little things can add up and make a big difference.
 
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There are so many ways and things that can go wrong in a shop. Getting complacent is all our problem. Many materials are hazardous that we just do not think about. One thing I am aware of being I do alot of cutting on my tablesaw with aluminum and I make sure to shut the dust collector off. It does make for small filings around the saw more but rather have them cool down before I use dust collector.

Be careful out there.
 
Woodchipper said:
Good story. My Shop Vac is useless for dust collection for my table saw. No budget or room for a DC. BTW, I have a fire extinguisher in the shop.
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I have 3 fire extinguishers in my shop. It was kind of odd standing there watching the smolder and taking time to decide how to deal with it.
 
Man I thought about this as others add thoughts. But find it hard to believe that short of a cut which was probably a crosscut to length created that kind of heat no matter how much dust there is. The super fine blade made for a hotter cut because of the amount of teeth but just can not envision it. Just a silly question, could that just be dust flying in the air because you have the blade throat plate off and you said the garage door was open. Maybe the wind was blowing dust in the air??

Just another thought, without knowing what type saw that is, if it is belt driven could it be the belt is slipping on you and creating extreme heat. Something does not add up in my mind. Just thinking out loud.
 
jttheclockman said:
Man I thought about this as others add thoughts. But find it hard to believe that short of a cut which was probably a crosscut to length created that kind of heat no matter how much dust there is. The super fine blade made for a hotter cut because of the amount of teeth but just can not envision it. Just a silly question, could that just be dust flying in the air because you have the blade throat plate off and you said the garage door was open. Maybe the wind was blowing dust in the air??
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At first glance that's what I wondered, too, John. When I first noticed it, the throat plate was on, the blade guards and anti-kickback pawls were on and, though not running, the dust collect hose was on.

The first cut was a slow and easy rip cut (new door, very old wall, don't ask) with no smoke or burning on the wood. However, there was a superbly thin slice of hard maple between the backside of the blade and dust guard that did show rubbing/heat though it was not smoldering.

There is some sawdust in the cabinet but under harsh light from the Cree bulb flashlight from my truck, the smoke was coming from the hole in the dust guard to the dust collector.

As mentioned, I also watched it, wondering, removing all the safety stuff and opening it up, looking, going to get the light, disconnecting hoses, get the shop vac. Had to have been at least 3-5 minutes.

Saw is a Laguna F2. I will check the drive belt, though the saw is amazingly quiet when running, not sure what belt sheaves are made of these days. They may not squeal.
 
MRDucks2 said:
At first glance that's what I wondered, too, John. When I first noticed it, the throat plate was on, the blade guards and anti-kickback pawls were on and, though not running, the dust collect hose was on.

The first cut was a slow and easy rip cut (new door, very old wall, don't ask) with no smoke or burning on the wood. However, there was a superbly thin slice of hard maple between the backside of the blade and dust guard that did show rubbing/heat though it was not smoldering.

There is some sawdust in the cabinet but under harsh light from the Cree bulb flashlight from my truck, the smoke was coming from the hole in the dust guard to the dust collector.

As mentioned, I also watched it, wondering, removing all the safety stuff and opening it up, looking, going to get the light, disconnecting hoses, get the shop vac. Had to have been at least 3-5 minutes.

Saw is a Laguna F2. I will check the drive belt, though the saw is amazingly quiet when running, not sure what belt sheaves are made of these days. They may not squeal.
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The only other thing I could think of that can cause that kind of heat is with the blade and or type of wood you are cutting but I am sure you are well aware of these. Was the blade real hot to touch?? For others a reminder, binding of the blade due to wood having internal stress and closing up on you can make the blade work harder. But a splitter helps there. Dull teeth, dirt on the teeth and blade body from resins in the wood you are cutting. Cleaning a blade is easy enough, just needs to be done. Of course sharpness is self explanatory. Woods being cut such as soft woods that are very resinous can cause burning. As I mentioned before, the use of such a blade with that many teeth will cause the blade to run hot. Not enough gullet space for air to circulate around it. Those are specialty blades and not an everyday use blade. But again I keep going back to the amount of cutting at this time is what is puzzling me. Runout on the arbor can cause rubbing which can cause more heat. But all this will show up in the condition of the cut wood. It would show signs of burning.


Just a side note that is a good saw so whatever is happening can be cured for sure. Hope you do find it and glad you did see this problem if that is what it was and thanks for the reminder about safety in the shop. We all need to be cautious as we work at our play time in our shops. Probably the number one fire hazard is oily rags left in clumps. As pen turners we need to watch the CA on paper towels as well. Work safe.
 
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The brick mold came on the door and I removed it to install the door. One thing I noticed was odd on the door specifications was a fiber glass door, pvc trim, but also showed "wood". I presumed there was wood in the door core (there is). But, while have bought doors with solid pvc trim before, this wood has a white non-paint coating on the exterior surface.

IF that is some type of pvc or other resin/plastic coating, it could have gotten hot quickly on the saw and spat a piece of molten plastic into the fine dust. Maybe hot enough to cause it to smolder?

Regardless, time to put the general purpose blade back on.
 
MRDucks2 said:
The brick mold came on the door and I removed it to install the door. One thing I noticed was odd on the door specifications was a fiber glass door, pvc trim, but also showed "wood". I presumed there was wood in the door core (there is). But, while have bought doors with solid pvc trim before, this wood has a white non-paint coating on the exterior surface.

IF that is some type of pvc or other resin/plastic coating, it could have gotten hot quickly on the saw and spat a piece of molten plastic into the fine dust. Maybe hot enough to cause it to smolder?

Regardless, time to put the general purpose blade back on.
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Agree about the blade. I try to take my 80 off right after the project I need it for. Just too easy to mess up. Whatever did happen hope you do not have to see that again. Maybe that material is something like Trex that is used on decking. I swear at cutting that stuff. It destroys blades and sparks and the junk and adhesives in there is not good to breathe either.
 
By the way, when I put the GP combo blade back on I timed the process. 3.46 minutes. Didn't save a whole lot of time by not changing it in the first place.
 
Good thread... how many people have smoke detectors in the shop? I don't. Have money for everything else, Have every gizmo on the planet but no smoke detector. Do you have a detector in your shop?
I have monoxide detectors in the garage and in few rooms in the house....in case I leave the car running.
 
WriteON said:
Good thread... how many people have smoke detectors in the shop? I don't. Have money for everything else, Have every gizmo on the planet but no smoke detector. Do you have a detector in your shop?
I have monoxide detectors in the garage and in few rooms in the house....in case I leave the car running.
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Not in the shop but next room over in the boiler area and laundry room along with carbon monoxide detectors. Smoke detectors would clog with dust way too fast.
 
Yeah, this kind of thing gets the heart pumping, for sure. I switched entirely to the Fisch wave cutter forstner bits, as all the others I tried early on in my time as a woodworker produced tremendous heat. I found some of the dust smoldering inside of a hole I cut once. I ended up dumping that into a cup of water, as I didn't want to suck it up into the vac and risk the entire vac going up in flames.

I've learned to take back off more often, give things time to cool... I also stop to pull out the shop vac and suck up the dust and shavings scattered about more often too. But it is so easy to let dust pile up.

One thing about table saws that I've learned, as I just purchased one last summer, is they are not very air tight, and there are lots of ways that an attached DC might not do its job well unless all those holes are indeed sealed up. I've also read a few things about table saw dust collection mods, where people put together a port contraption over the top of the blade, and often find another way to create a port inside the compartment below, to ensure that they have adequate dust collection "area" around the blade. I guess there is a formula for how large each port would need to be at most, in order for a DC of a given power to maintain the proper CFM. I forget the site where I found all that... If interested I could try and find a link.
 
Good to revive the thread as a reminder. Have smoke detectors in the shop, laundry area, kitchen and hallway outside the bedrooms.
 
I also have CO detectors but no smoke alarms. Anyone know if the heat sensing type of fire alarms work like the smoke alarms? Maybe they would be a better option for a dusty environment.
 
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