DoN's got it right, as usual. I've used them to study energy balances around a rotary kiln. Lower means way lower, like 0.2 instead of
0.95. Rusty steel would read o.k., painted surfaces probably will read way low. Basically, I don't trust 'em except for the most qualitative measurements, even with an emissivity adjustment. With the emissivity adjustment, you can pretty much dial the temperature you want to believe.Pete Keillor
Many digital multimeters will accept a thermocouple temperature probe, the common ones being made of thin wire. If one tapes the tip to the mill head, it ought to give a pretty accurate temperature reading.
Joe Gwinn
After a Computer crash and the demise of civilization, it was learned Gunner wrote on Wed, 27 Jun 2007 17:57:43 GMT in rec.crafts.metalworking :
And lubrication. Unless there is a reason for metal to metal contact, some lubrication is in order. I was futzing around the other day, trying to look like I was working while waiting for a part inspection, decided to oil the pencil grinders at the downdraft table. (I know it doesn't get done every shift). One I figured wasn't long for this world, it was getting warm at the business end even without a load. Of course, I could also feel the "rocks" in the bearings when spinning it by hand with no air. OTOH, improved the one by replacing the air hose. Something about having the air hose about half cut through at the unit base doesn't help. (I snagged a bunch of dead pencil grinders, earlier in the year, and had an extra hose. Bwahahahaha! Gave the cut off hose to a co-worker "Don't say I never give you nutin'".)
pyotr
-- pyotr filipivich "Quemadmoeum gladuis neminem occidit, occidentis telum est. " Lucius Annaeus Seneca, circa 45 AD (A sword is never a killer, it is a tool in the killer's hands.)
Agreed. I'd trust it to about 1 deg. if new. Iron-constantan (Type J) thermocouples drift on heat cycling over time. When I really want to know, I use a three or four wire rtd, which is mostly what I use for process r&d applications.
Pete Keillor
I have a couple of the cheap HF units. They've proven to be extremely handy. If you want to measure something shiny, try sticking a piece of black tape on it.
Jerry
Have something to add? Share your thoughts — no account required.
Ask the community — no account required