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.
7301

[andre]

7302

[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

[bleeth]

Andre: For the first time ever in a pinch a few months ago I put a 1/4" Freud in the spindle (brand new) and the carbide was toasted in no time running the same files the same way that I normally will run with a Whiteside, Onsrud, or Centurian with no problems. I suggest throwing away your Freuds. We cut MDF all day long around here and it is also generally pre-laminated with veneer or p-lam. It's not just feed and speed. You can't use a bit made for a handrouter and get the same results as a cnc bit.

[andre]

Dave thanks for info. I have been using Amanas up to now and never had any heat problems. This is the first freud bit I have used in the shopbot and what do you know- It starts a fire.

[yobot]

Hi, folks.

I keep an A,B,C 15lb fire extinguisher right by the bot. I also keep a pumped up 2 gallon sprayer, filled with water.

If something wooden starts burning, kill the power and grab the sprayer. If you don't know what is burning, kill the power and grab the extinguisher.

That's my $0.02 for the day.

David

[bleeth]

It has been said many time before on this forum but worth repeating on a regular basis, particularly now that the archives are so big and searching for info can be such a challenge:
"FREUD BITS ARE (Insert word not allowed on the forum here)" For CNC use they are in the same category as Grizzly. Frankly I never liked them for a hand router either. I had burning problems using them in a table mounted 3.25 PC as well. If someone thinks they are not making enough off their work or squeezing their costs too much to buy a decent bit they should rethink their business strategy. At least I can rest assured that the reason I'm broke is from plowing it all back into the plant. Hopefully it will pay off by the time I'm sixty!! Oh wait-I damned near am!!

[harryball]

Another reminder, spoil board fires are a real concern, if I smell smoke while I'm working I immediately start searching for the source. Read this as "Stay in the shop while equipment is running". Exhausting your DC and vac outside acutally calls for more caution as you are putting the smoke and smell outside as well.

<opinion> Freud bits are an over rated low quality tool, best avoided. </opinion>

/RB

[andre]

Dave I had know Idea you felt that way

I feel the same about cheap things. I always try to buy quality because it reflects in my work. How ever I have had great luck with bits less than $30.00. I never dreamed something like this would happen because of an inferior bit.
To tell you the truth if you would have told me it could happen I may not have believed you.

I have a freud rail and stile set in my table routers and have had great results with them.
I think I will try white side next.

[myxpykalix]

Consider www.centuriontools.com (http://www.centuriontools.com) high quality, decent prices, decent people to deal with.

[gpari]

Does your cutting strategy include straight plunges?

[gene]

i Agree with mr Ball on the Frued bit issue . I also caught a spoilboard on fire with one that wasnt that old. The next time you get your hands on a new frued bit , scrape it on your fingernail LIGHTLY and you will see the difference between that bit and a new bit centurion sells . I use the bits from centurion and have had excellent results , I would rather have a used resharpened centurion in stead of a box of new frued bits.. (My Opinion)
I definately think that the only reason frued sells what they do is because of the packaging and extensive marketing ... not to me anymore.....

[elcruisr]

In 7 years I've had three spoil board fires. Thankfully all caught very quickly since we keep the machine manned when it's running. Two fires in MDF one in plywood. Two caused by metallic trash (and that included the plywood) and one from a stalled computer. They happen fast so you keep your eyes (and nose) on the job. They are not uncommon on big iron either. It's just one of those things that can go with the shop environment.

Cutting strategy can contribute and you don't want me to get started on cheap tooling. Ramped entries are a big help (and will keep your tool sharp longer) and proper chip loading is a must. You can underload a tool and cause overheating/fires. Learn your chiploads folks! We cut 3/4" mdf at 8"/sec in one pass with a 3/8" single flute tool or 6"/sec with a single flute 1/4" tool. Too many flutes can contribute to overheating because of too small a chip load to carry away the heat.

Safety, safety, safety!

Dave, you ever find some good help? Things are picking up around here and I'm dreading it if I have to look for more myself.......