Anybody ever test lead thermometers?

[fourarmed]

Title pretty much says it. When I cast at my pal's place, we use his thermometer. It will sometimes hit 1000 degrees in the 20 lb. Lee when we come back from breaktime, but the bullets appear to be about the same as what I get at the farm at 800 on my thermometer.

Anybody have a calibration routine?

[bdoyle]

Breaktime?? Who said you get a break? I thought we gave you a break when we hired you...(standard management line...)

Seriously folks, the only easy calibration I know of is, depending on alloy, is to watch the freezing point of your alloy. When I use the lee pot I am constantly turning it down to maintain my alloy temp. I start at full and eventually back it down to around '5'. I am usually casting around 700-750. It will creep up if I don't watch it. I really don't like getting anywhere near lead vapor point. I am using a lyman thermometer. I don't have this issue with my rcbs pot. It stays put pretty good.

HTH

Brian

[7br]

Bring your thermometer back from the farm. Put both in the pot. Watch carefully. When partner isn't looking, swipe the one you think is working correctly.

The only way I can see would be to watch the melt/freeze point of two alloy with different melt temp. MT1 = m * Reading1 +c MT2 = m * Reading2 + c , then do the math.

[fecmech]

IIRC the Antimony Man had something about calibrating thermometers at his site wherein you used linotype and it solidified at 465 degrees. My memory is not the best so please check for yourself. Also you could put your thermometer in the oven at 450-500 degrees and see if it matches the oven thermostat. That would certainly show any gross errors. Nick

[imashooter2]

Water boils at 212 degrees F.

[StarMetal]

only at sea level, it boils at alot lesser temperature up in high mtns.

Joe

[Wayne Smith]

Lyman Cast Bullet Handbook has information on calibrating the thermometer by using solidification of the melt of several different alloys.

[buck1]

Water boils at 212 degrees F.

Thasts how I checked mine. Close enugh for me......Buck

[MTWeatherman]

only at sea level, it boils at alot lesser temperature up in high mtns.

Joe

Yep, it sure does...but while the 15 to 20 degrees makes a huge difference if you're trying to cook those potatoes on the campfire (if you're hungry you might just as well eat them raw rather than boil them at 8000 feet...takes forever to cook), it likely won't effect your temperature calibration on a casting thermometer enough to concern you.

If you need the exact temperature for your calibration...the following link will give you all the information you need:

http://www.biggreenegg.com/boilingPoint.htm

FWIW, I have a 20lb Lee and have noted the temperature begins to rise rapidly as the pot gets down to less than an inch of melt...I've always felt I was partially measuring the heating coil temperature rather than the alloy since the thermometer no longer floats... but could be just the Lee thermostat. Keeping the pot at least 1/4 full helps keep the temperature more stable.

[John Boy]

It will sometimes hit 1000 degrees in the 20 lb. Lee when we come back from breaktime, but the bullets appear to be about the same as what I get at the farm at 800 on my thermometer.
Fourarmed: There is a little piece of paper that came in the box with my Tru-Tel thermometer. It says do not use the thermometer continuously (long term temperature reading) at 800 degrees or more. If done, the thermometer will give false readings or will damage the thermometer. These therm's have a plus or minus 10 degrees calibration.

Your pal may have damaged his thermometer

Also FWIW, there is a metal band on the ones we all use. The band has to be in the melt otherwise ... false readings

[Ken O]

I'm a retired certified welder, and we had crayons called "temp sticks", they were labled for the tempeture they melted at. You could go to your welding supply and pick up a 600º stick, put a piece of flat bar in your melt, pull it out and crayon it.