Toasty spoilboard

[andre]

I thought this would never happen to me
Cutting mdf at 4.5ips .25 per pass at full rpms on a pc router with a relativly new bit.
Thank god for extinguishers.
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[andre]

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[beacon14]

Yikes - what caused the fire to start? Did you hit some hidden metal in the MDF?

[wberminio]

Boy that was close!
A few weeks ago a my z dropped into my material
with the spindle on.It quickly burned a nice round
circle into the mdf and started smoking!
I sacrificed my cup of coffee just in time.
How quickly things can happen.

Moral:Always keep on eye on your Bot and a cup of coffee in your hand.

Erminio

[myxpykalix]

good thing you were close!

[andre]

two lessons learned
I have been know to leave the shop for a second while the bot ran. Never ever again. Luckily I was right next to it when I smelled something funny comming from one of my feins.
It went from bad to worse in 10 seconds. a glass of water only delayed it before it came back like a white hot blowtorch shooting out from the material.
Second lesson
enough of that mdf @#$%*. Who knows what the heck they put in that stuff. I hardly ever use it, and now I am sure its not worth the money saved over ply core.

[dana_swift]

Andre- thats a reminder to all of us!

Just curious, what bit were you running?

It also makes me think I ought to measure my bit temperatures with a non-contact thermometer and see how hot things are getting when I cut.

If you can figure out the specifics of what caused this, please post. Nobody wants to duplicate that-

D

[andre]

I was running a .25 freud bit that was pretty new, at only 4.5 ips with a .25 depth per pass. Hardly pushing things.

I'm not sure what happened, it was only the second sheet I was cutting. Perhaps this shipment of mdf has a higher level of shmutz.
I am returning this shipment and replacing with plycore.
I will look further today to see if I can determine anyhting more.
My shop reaks of smoke and extinguisher.

[dana_swift]

Is the bit a straight edge? I expect that is the worst case for heat buildup.. how many cutting edges does it have? How well does it clear the chips and dust.. thats where the fire will start because its got the surface-area/mass needed to ignite.

Personally I don't cut MDF that aggressively, I typically use 0.1 or 0.15 per pass and 2.5-3 ips. Usually I use an Onsrud 0.25 down-spiral with a single cutting edge. And sometimes a 0.125 bit.

The performance of the Onsrud bits has been amazing, usually I can touch them and they are hardly even warm right after the router switches off. But I plan to do the measurement with the IR thermometer while it is running.. that should tell me if its just cooling down rapidly, or not heating up much.

D

[dana_swift]

Another question.. is the bit a plunge bit? Do your entry cuts ramp or plunge straight? That is another place where the heat buildup can get intense.

Just "thinking out loud"


D