Alloy temperature

[Wm Cook]

Today I found that my new Mag 25 digital scale was reading 760 degrees, while my old Lyman dipstick thermometer said it was only 700. Which one is right? And can I recalibrate the old Lyman dipstick? (Just kidding)

Kind of ironic that I’ve been pulling my hair out chasing quality boolit’s out of a brass MP hollow point mold for over a month now.

And I can hear the responses now. “Dang it, you don’t need to check temperature, just let the looks and smell of the boolit’s tell you how hot to run it”. And as much as I hate to admit it, they would be right in this case.

But if I had done that I wouldn’t have learned (for the umteenth time) that ya just gotta double check everything. Bill.

[Stewbaby]

You could buy a cheap thermocouple and compare the millivolt output to its corresponding temp chart.

$8 type K thermocouple
T-PRO K-Type Thermocouple Temperature Sensors 2M/6.6Ft Wire，Stainless Steel Probe (Probe Length 100mm) https://www.amazon.com/dp/B0748DFJFN/ref=cm_sw_r_cp_api_glc_fabc_wXpaGbGAR3F45?_encodin g=UTF8&psc=1

Type K millivolt temp chart (add 32 degree to T measured, 32=the reference temp)

T actual = T measured + T reference
(Temp = temp from chart + 32)

https://www.pyromation.com/Downloads/Data/emfk_f.pdf

[USSR]

Let your mold tell your Lyman Mag 25 what temperature it likes. That's what I do with mine.

Don

[Mal Paso]

Once you get a rhythm going you can adjust the temperature down to keep the sprue freeze time down.

I have a piece of 1/4 steel plate on my hotplate to get the mold and pins up to temperature.

The Lyman could be off. They don't have the thermocouple In The Melt. They have it outside the pot and if it wasn't placed correctly it could be wrong. Might want to get a thermocouple and check like Stewbaby said. You can also get dedicated meters for thermocouples that read in degrees.

[Conditor22]

You can boil some water and see if the temp reads Water/Boiling point 212°F 100°C when the water starts boiling.

Unfortunately, Lyman dipstick thermometers were notorious for being off. some could be adjusted by holding the top and twisting the stem.

[Winger Ed.]

I don't own a thermometer.

I start off with the old Pro-Melt turned almost all the way up with the mold sitting on top.

I start casting, as the mold finishes heating up and the boolits have a little frost on them,
I turn the pot down a couple of numbers on it.
Then go on, and the frost will stop pretty soon, and the boolits fill perfectly, and look Chrome plated..

Then I'll rock along until I need to add to the pot.
I'll do that, come here & hang out awhile, and get back to it.

This system works great for me.
Boolits come out great, and I'm not over thinking or splitting hairs over anything.

[ABJ]

I have three mag 25's, and have checked them against a buddy's high$ HVAC digital handheld and been within 10 degrees every time. I have owned several sticks and the closest one was 50 degrees off and the worst was 100 degrees. I now have the Lyman digital handheld and it seems to read the same as the mag 25. The Lyman digital cost me $30 a few years ago, no telling now?
Tony

[Wm Cook]

Good reply. I think a third party should weight in and it'll have to be another digital measurement. I already have a two channel Digital 2 Channels K-Type Thermometer rated for 2372 degrees but the needle point probes are only rated for 752 degrees. Measuring anything over 600 and it goes crazy.

I use its needle probe to measure internal cavity temperature (thanks Jsizemore) and with the right temp I can be dropping good boolits after the first few discards. The temperature of the aluminum mold I was using yesterday was saved for the next time I used it. And I have a piece of 1/4 by 6 inch steel in my Amazon cart along a 4" x 4" x 6' steel junction conduit box so's I can build a mini furnace on the steel plate. All good ideas that I found on some great threads on the forum. There's a wealth of information available to us if we look for it.

And now the standard disclaimer. Many on the site will scoff and say "Ya just don't need all that cra_, just get the melt and mold as hot as you need to make good boolits". Please be patient. There are some of us who like to futz around. Doing those little "useless", "not necessary" things makes casting boolits fun. We're geeks, OCD or what ever the politically correct word is. Just be kind understanding you are dealing with someone less gifted than you. And to those that are blessed with that rare commodity of uncommon sense who just watch and listen for the bullet to fall to make perfect boolits, I envy you. Kind of.

A question for Stewbaby. Can you just stick a stainless steel thermocouple in 770 degrees alloy and have it read properly and come out clean?? I thought about doing that yesterday but was scared a demon could come out of the pot and eat me alive. I'm kink of glad I chickened out because like I said, I found out later that the reading went ---.- when it over 600 degrees. But like you said, a probe rated for 1000 would be a cheap check.

[JonB_in_Glencoe]

When calibrating (or even comparing) thermometers (or electronic devices that read temperature), it is best to have a "standard" that is near the range where your devices need to work.

If you have some pure Lead, must be PURE. Pure Lead melts at precisely 621º F.
Clean your pot, put some pure lead in there and monitor when it melts and when it freezes. That may take a couple cycles to get the best reading. I assume your Lyman thermometer is off. IMHO, being 50ºF off, for that type of Thermometer could be expected, one drop to the floor could do that.

[Wm Cook]

I’ll be darn. I’d of guessed it was the digital on the Mag furnace. I have pure lead that I could put into my ladle or in an ingot mold, bring it to melt temp and see what the dipstick reads. I know that’s backward but it could find the dipstick inaccurate and that would give me confidence with the digital reading on the bottom pour. Thanks a lot. Bill.

[centershot]

The use of a P.I.D. would solve this problem in short order. Dial in your temp and let 'er rip! No guesswork, no fussing with thermometers, just turn it on, set the temp and go!

[William Yanda]

Is accuracy being confused with repeatability? Use the digital, find out the temperature that works, repeat. Or, alternatively, use the other thermometer in the same manner. Or continue to futz as desired.