I finally gave in and bought one of those laser-guided infra-red
thermometers for the shop. I've needed one of 'em for a long time (for
solar panel testing) and Hammacher-Schlemmer had one on sale that
covered the range I needed for a price I could almost afford.
Yesterday I was routing MDO and pretty much watching a nice 1/4" solid
carbide 3-flute end mill getting dull. I could see the edges of the dado
getting fuzzier and fuzzier as the bit traveled - and by the end of the
second sheet, they were beginning to look more like "splintery".
Just for grins, I grabbed the new toy and took a temperature reading on
the bit as it was finishing that second sheet (after probably a little
more than 150' of routing)...
I probably should mention that the shop temperature was about 80F and
that the bit was turning at 14,000 rpm and was being fed at a nice even
1.5"/sec (90"/min) with a 1/4" depth of cut - and that, although the bit
was clearly close to the point of being unusable without resharpening, I
couldn't see any burning.
...the bit temperature was a nice cool 93.1F - nowhere near hot enough
for burning to take place, and very much cooler than I'd expected.
It confirmed for me that feed speed has a lot to do with preventing (or
causing) burning during cutting operations.
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