chainsaw cylinder temperature?

[Jim Wilkins]

I've been using my late 90's Husqvarna 350 to cut slabs from a large log, to
fit it into my sawmill. It's a high end homeowner saw, not for commercial
use, and I already damaged the plastic housing by running flat out too long
on a 90+ day. I've been idling and then stopping when the cylinder fins
exceed 350F on an IR thermometer. Does that sound reasonable, too much or
too cautious?

[Charlie+]

Post by Jim Wilkins
I've been using my late 90's Husqvarna 350 to cut slabs from a large log, to
fit it into my sawmill. It's a high end homeowner saw, not for commercial
use, and I already damaged the plastic housing by running flat out too long
on a 90+ day. I've been idling and then stopping when the cylinder fins
exceed 350F on an IR thermometer. Does that sound reasonable, too much or
too cautious?

Have you a fin painted (HT) matt black to measure on? Otherwise your
reading with IR maybe low if looking straight at Al? Running rich will
help cool it down a little .. Sorry no experience here on actual running
temps! C+

[Jim Wilkins]

"Charlie+" wrote in message news:***@4ax.com...

On Thu, 11 Jul 2024 21:45:08 -0400, "Jim Wilkins" <***@gmail.com>
wrote as underneath : ...

Have you a fin painted (HT) matt black to measure on? Otherwise your
reading with IR maybe low if looking straight at Al? Running rich will
help cool it down a little .. Sorry no experience here on actual running
temps! C+

---------------------------

I also have thermocouples and a thermal imager. Generally on a heatsink the
imager shows a temperature spread greater than the error from not adjusting
for emissivity, I've left it at the default 0.98 on the IR thermometer and
drill a small hole for a K thermocouple at the indicated hottest spot in the
rare case that I need more accuracy. Typically the place damage will occur
is hidden internally anyway, so comparing IR readings to known values for
similar conditions has to be enough. On power semiconductors a base-emitter
or other diode voltage drop at or corrected to minimal current is a good
indication of actual internal device temperature.

[Jim Wilkins]

Unlike my Stihl the Husqvarna 350 has sufficient torque at part throttle to
cut well, and doesn't heat over 300F. Problem solved.

[Charlie+]

Post by Jim Wilkins
wrote as underneath : ...
Have you a fin painted (HT) matt black to measure on? Otherwise your
reading with IR maybe low if looking straight at Al? Running rich will
help cool it down a little .. Sorry no experience here on actual running
temps! C+
---------------------------
I also have thermocouples and a thermal imager. Generally on a heatsink the
imager shows a temperature spread greater than the error from not adjusting
for emissivity, I've left it at the default 0.98 on the IR thermometer and
drill a small hole for a K thermocouple at the indicated hottest spot in the
rare case that I need more accuracy. Typically the place damage will occur
is hidden internally anyway, so comparing IR readings to known values for
similar conditions has to be enough. On power semiconductors a base-emitter
or other diode voltage drop at or corrected to minimal current is a good
indication of actual internal device temperature.

Thanks for posting Feedback, always useful! Yes I would have used
pyrometer too.. I have my IR at 0.94e as default! Glad you are sorted..
C+

[Jim Wilkins]

"Charlie+" wrote in message news:***@4ax.com...

Thanks for posting Feedback, always useful! Yes I would have used
pyrometer too.. I have my IR at 0.94e as default! Glad you are sorted..
C+

------------------------------------
Here is a take on paint vs the oxide layer:
https://electronics.stackexchange.com/questions/333823/does-the-paint-colour-matter-on-a-heat-sink
"Do not paint heat sinks. The layer of paint will act as an insulator
between the metal and the air, reducing its ability to dissipate heat.

Anodizing a heat sink is less of an issue. The anodization layer is much
thinner than paint (a few micrometers in aluminum, for instance), so it
presents a much lower thermal resistance than paint would."

I use black tape to optically measure the temperature of my walls and window
film, to compare them to interior walls and search for correctable heat
loss. For electronics and motors the IR thermometer and imager show patterns
of temperature rising and stabilizing, relative but not actual values, I
trust only a thermocouple in a well for that. Usually temperature difference
or rate of change are all I need to know, since the temperature that will
cause damage is often uncertain.

If accurate results are important I record the thermocouple data with a
PC-connected TP4000ZC multimeter calibrated to melting ice and boiling
water. The output file can be changed to .csv and imported to a spreadsheet
to correct observed offsets. This is for retired hobby use, to approximate
the professional lab instruments I had used at work.