Casting Thermometer Accuracy

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  • Last Post 25 August 2018
OU812 posted this 23 August 2018

Discovered that both of my RCBS casting thermometers read about 50 degrees cooler than actual. I purchased another cheap casting thermometer through Roto Metals and it reads better, but about 10 degrees cooler than actuall. I wonder if RCBS will test and recalibrate?

Adding a rotating dial face would work to calibrate.

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David Reiss posted this 23 August 2018

I bought a Lyman electronic thermometer a while back and found my RCBS was off by about 30 degrees. However I am real happy with the Lyman, it has been real accurate so far. 

David Reiss - NRA Life Member & PSC Range Member Retired Police Firearms Instructor/Armorer
-Services: Wars Fought, Uprisings Quelled, Bars Emptied, Revolutions Started, Tigers Tamed, Assassinations Plotted, Women Seduced, Governments Run, Gun Appraisals, Lost Treasure Found.
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John Carlson posted this 23 August 2018

What are each of you using to establish "actual" temperature?

John Carlson. CBA Director of Military Competition.

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OU812 posted this 23 August 2018

I pointed a infrared thermometer at melt and compared this reading to the digital reading on my new RCBS Easymelt thermometer. Temps were within 2 degree using the infrared. The old RCBS thermometers read 50 and 40 degrees cooler.

The Easymelt furnace reads actual pot temperature and is usually spot on with outside air temeratures when first turned on and not set to casting temps.

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rmrix posted this 23 August 2018

I somehow got the idea that the point and shoot infrared thermometers did not work with shinny hot metal like lead. Sounds like at least yours does. Is there a type that works better and some that don't ?

I have often wondered about my four decades old Lyman. A few drops on the concrete over the years does not give confidence either.  Maybe it works consistently enough to work for me but offering a working range to someone else might be like inches and centimeters.

You wrote:

I pointed a infrared thermometer at melt and compared this reading to the digital reading on my new RCBS Easymelt thermometer. Temps were within 2 degree using the infrared. The old RCBS thermometers read 50 and 40 degrees cooler.

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RicinYakima posted this 23 August 2018

I put water in the a pot and boil it. I know that at my elevation with 29.5 inches of atmospheric pressure it will be 209 degrees F.

 

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OU812 posted this 23 August 2018

Melt is not shinny when not fluxed. Very easy to get infrared reading on rough surface. 

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pat i. posted this 23 August 2018

Its funny since I leave a thermometer in my pot all the time and am addicted to it but if I'm throwing good bullets does it really matter how accurate it is? I usually set the dial on the pots I have around 750 and it seems to work most of the time. Knowing the actual temp of the lead down to + or - a couple of degrees might he going overboard. I'm NOT disparaging anyone who wants to know to the exact temp of their melt because I'm an equipment junkie and have tons of reloading and shooting products around here I've spent a bundle of money on but I just wonder if in this case it matters.

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R. Dupraz posted this 24 August 2018

I have dip poured from a 20 lb Waage pot for years and the thermometer never gets taken out of the pot either. Unless it goes south and is replaced. Frankly, I only use the numbers as a frame of reference for repeatability for another casting session because I set the temp just hot enough to cast good bullets  in the mold that I'm using at the time. Usually between 700-750 degrees. Except for a couple of nose pour molds that require a little increase in temp. Otherwise, I don't really care what the numbers say. No doubt they wouldn't be accurate anyway.

At our monthly military match last Sat. at the Hawkeye, the old Israelie 7.62x51 98 Mauser won it with a 399/400. Works for me, I don't sweat it.

Working on more important things. Such as consistent bench technique, marksmanship and reading conditions.

R.  

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Ken T posted this 24 August 2018

I have two of the Lyman electronic thermometers and a dial thermometer from Brownells.My lead pot is a Lyman Mag25.The readings on all three are within a degree or two of each other.I expect that may be unusual.

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rmrix posted this 24 August 2018

OU812, Thanks for the info.

I really get along fine without. If things aren't fine, I know how to change temp. or pour rate or what ever to make it cast well.  Just experience.

However, after starting casting in the seventies until present, I am just now trying to keep a log book on my most used molds. Better late than never. Recording accurate temperatures and settings for summer vs winter may be a help to me. I cast in my unheated building and get swings that need seasonal adjustment.  An accurate point and shoot meter might be good for this. Okay, I admit it.  ...I also have six LEE 20 pounders for most of my alloys smile   I should join a twelve step program for those that can't stop.

Anyway, maybe you can recommend a price range for a reliable meter? I may give one a try.

Thanks for reading my ramblings.

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Larry Gibson posted this 25 August 2018

I also use 2 thermometers in my Mag20.  I have found over the years with different pots that the heating coils are not located so that an even alloy temp is not maintained as the alloy level drops in the pot.  I've found when the alloy level reaches a certain low point the remaining alloy temp increases.  Thermometers measure the temp at their tip end.  Thus for the last several years I've been using a short thermometer that measures the top half temp and a longer thermometer that measures the temp at the bottom of the pot. 

 

These type thermometers can also be easily "calibrated".  I use a pan of boiling water and measure the temp.  If not 212 degrees the dial can be moved so the hand reads 212 degrees by using a wrench on the nut on the back and turning the dial.  I "calibrated both to read 212 degrees and in a full pot of #2 alloy they both will read the same temp.  I usually cast with the alloy at 715 - 725 degrees and they both read the same.  When the shorter one's reading starts dropping and the longer one doesn't it is time to add alloy to the pot to keep the alloy temp even during casting. 

This is working out very well for me as I am casting excellent and very uniform cast bullets as evidenced by weight selection.  It is one of the details that is allowing me to shoot a #2 alloyed cast NOE 30 XCB bullet and 2900 fps and hold moa accuracy to 600 yards.  This method also allows casting very uniform (also proven through weight selection) 314299s  with which I've won numerous CBA matches with ....... hard to argue with success.

LMG

Concealment is not cover.........

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