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Fire on the table

8/30/17       
Phill

Website: http://www.dreamclosets.org

We have recently experienced our second fire in the past two weeks created while cutting furniture frame parts. I have been running these programs for about three years and, although we have had hot spots before, I have never had the kind of flame up issues I am suddenly experiencing. I have checked with various bit suppliers regarding feed, speed, and proper style bit, and those issues do not appear to be the problem. The only thing different that I can think of is we switched material to a soft basswood plywood, primarily for the pricing issue. I am suspecting this "soft" material is creating a greater opportunity for the bit to ignite the shavings while moving slowly in tight turns. Is this theory viable? Has anyone else experienced these sort of problems?
Thanks for any insights.

8/30/17       #3: Fire on the table ...
rich c.

Get better dust collection, or better dust boot, to get the dust out of the cut. What kind of bit? Downcut? Go to a compression bit.

8/31/17       #4: Fire on the table ...
Bill

Are you leading in and out of every cut? Every cut not most of them? Is it enough of a lead in?

8/31/17       #5: Fire on the table ...
Dropout Member

What bit are you using?

9/1/17       #6: Fire on the table ...
Phill

We are cutting the material in two passes. We're using a 3/8" compression 2 flute roughing bit removing 17.5mm of material, then the final pass all the way through with a 1/4" compression, 2 flute. We are not ramping in but plunge cutting. the problem isn't in the entry but in some of the small routs in the corners, and always with the final rout, never the first pass. That's why I was thinking that the fine, soft material is more susceptible to flame up.

9/1/17       #7: Fire on the table ...
Bill

Most bits are not meant to plunge. It also hammers the bearings in the router. You may want to revisit your thinking. We never ever plunge.

9/1/17       #8: Fire on the table ...
Phill

I will Bill. Thank you.

9/1/17       #9: Fire on the table ...
rich c.

How clean is the kerf after the first cut?

9/3/17       #10: Fire on the table ...
B.H. Davis Member

Why are you using a compression bit on the first pass? The whole point of using compression bits is to get a clean cut on the top and bottom of the material. If you aren't cutting all the way through on the first pass then all you are doing is using a more expensive bit unnecessarily.

So step one is to go to either an upcut or downcut bit on the first pass. Probably you'll need the downcut bit for a better top edge result so you'll still get material compressed in the cut slots. Then second is to ramp in as suggest above instead of plunge cutting.

BH Davis

9/3/17       #11: Fire on the table ...
Dropout Member

I prefer a roughing bit for the first pass. A low helix upcut cuts cool and shouldn't damage the top edge. I use one for maple and walnut show wood chair arms.

Ditto on the ramp in.


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