Router bit temperature

[Morris Dovey]

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.

[Puckdropper]

"Upscale" wrote in news:15bc7$48dce19d$cef88bc5 $ [e-mail]:

Especially with a laser light on it. I've used mine about a dozen times for actual temperature measurement, and a dozen times a dozen times as a cat toy!

Puckdropper

[Morris Dovey]

I bought a laser pointer (still in my briefcase) back about '84 - and have to admit that it's logged a lot more hours in "cat mode" that in "presentation mode". BTW, a drifting red spot on a wall/ceiling works fairly well for settling down sleepy tots. :-)

I did spend a good part of the evening of this gizmo's arrival taking the temperature of (almost) everything at home. ;-)

All of the end mills/router bits I've managed to break were destroyed by overheating, and I was expecting this one to be near/at the breaking point - and was surprised (a) that it /didn't/ break and (b) that it had stayed that cool.

[Morris Dovey]

Well, the red dot was dead on - but the bit was turning (cutting edges going past at the rate of 42,000/sec). I would guess that when a bit overheats, the entire thing gets hot.

By the time I pulled the bit two or three minutes afterward (after unclamping the parts and cleaning up some of the mess) I don't recall that it felt particularly warm.

More "play" is definitely called for. :-)

[Upscale]

Admit it. You walked around all day testing the heat of anything and everything you could see didn't you?

There's few things more engrossing than a new toy.

[dpb]

Certainly...but while running it's only the bulk temperature that's going to get sensed for sure.

It's not likely there's sufficient focus in the sensor to precisely measure the tip temperature, anyway, even if "spot on" w/ the guiding laser.

[Upscale]

I've got the cat toy only version, but don't use it as often as I might anymore. 10 minutes with the cat and the two mini batteries are dead. At $5 a pop each, playing with the cat started getting too expensive.

[Chris Friesen]

Now you've done it...now Morris will have to buy a thermal imaging camera.

Chris

[Morris Dovey]

Ooooooh... I hadn't even thought of that - and it's deductable! :-D

[Upscale]

Are you sure you had it properly centred on the cutting edge? Even with small short easy cuts, the few times I've touched the carbide after the bit spun down, it always seemed a lot hotter than 100 F.

[Morris Dovey]

Absolutely. And better still - if I get a DoE grant I can buy it with Tim's taxes!

[spaco]

I suspect you were actaully reading an average temp for the area around and including the bit. The (what you said) thermometer that I have has an 8:1 field ratio. I think this means that for every 8 inches you are away from the target, the reading is taking the average of a 1" diameter circle. I also bought one of the HF pocket sized IR thermometers. It's pretty neat, too, but it has a 1:1 field ratio, so if I was 8" from a target, I'd be reading the average temp within an 8" diameter circle. I use carbide tooling in my metal shop and its easy to get the tool up to 800 or 900 degrees. In the wood shop, (I'm a poor router guy) I have easily gotten HSS router bits hot enough to turn them Blue. That's about 570° F and the lowest temperature where "temper colors" show up is about 450° F, (straw").

Pete Stanaitis

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Morris Dovey wrote:

[Morris Dovey]

Hmm - I hadn't thought about that. I took the reading with the nose about 3" from the router bit, so might have (by luck only) gotten a more or less decent reading of the average bit temperature. Even so, it was still a lot cooler than I would have expected with an ambient temperature only 11F cooler.

Double "Hmm". The HF thermometer might actually have been better for what I wanted at the time (checking heat re-radiated back thru the glazing of a solar panel). I'll stick with the one I've got because it's probably better suited for the fluidyne R&D, but I'll keep the HF pocket version in mind...

(Thanks!)

[Upscale]

An ultra, high speed, thermal imaging camera. Entirely necessary to catch those spinning router bits right at the proper moment.

[Upscale]

Damn you Morris. Now I've got Pepsi all over my monitor, keyboard and half my desk. :)

[PDQ]

It's nice to know you appreciate a really fine libation.

P D Q

[Morris Dovey]

It's also a good way to economize on Post-It pads. [DAMHIKT]

[Robatoy]

Pepsi?? I din not know you vere Vrench?

[Morris Dovey]

Eh? I don't understand (and my Larousse is not helpful). What am I missing?

[Puckdropper]

"Upscale" wrote in news:e9b98$48dd0346$cef88bc5$ [e-mail]:

If you drank Coke, you wouldn't have that problem... You'd have Coke all over your monitor, keyboard, and half your desk. :-)

Puckdropper