New Thermometer Off !

[MKN]

I think my brand new Thermometer is off, first time I had a thermometer. I wanted to start looking at the differences with temperature changes in the pot. I set my pot at the usual number, for range scrap I use. It read 1000 F. Dnag, had to cool that down, got the 725 degree, and no fill out, snail tracks, wood grub trails. Brought it back to my normal pot temp #7, had 1000 degrees again, and casting is fine?
Boiled water and it was 220 - 222 degrees, that is the low end of the scale so inherently its not accurate.

Tell me that on my Lee 20# bottom pour, set on #7 is not 1000 degrees.

I want my $35 back !
Matt

[Bzcraig]

Water boils at 220 so it sounds right to me. Are you sure your mold is up to temp? Yes, #7 could be 1000, it's just a number with no value attached to it temp wise.

[shoot-n-lead]

Water boils at 220 so it sounds right to me. Are you sure your mold is up to temp? Yes, #7 could be 1000, it's just a number with no value attached to it temp wise.

I believe water boils at 212...

[CastingFool]

Yes, water boils at 212 deg F, at sea level.

[MKN]

BZ,
I'd say the mold (s) is up to temp, some casting sessions are 15 - 20 # of 9 mm on a 6 cavity, with just enough time for the sprue pools to create the small divots as it cools and hardens - 3 - 4 seconds , No frosting of boolits.
It is the first time I have had a thermometer, so I'm not saying definitively it is wrong, but how could I have been casting at 1000 degrees and have seen no frosting with aluminum molds 2 and 6 cavity, 9 mm, lee 170 g 30 cal. , 300 blk, cutting the sprue just after it hardens, drop and refill quickly, Casting 10 - 20# per session good fill out and no tin added.
Drop it to the 725 degree on the themo and I loose fill out? I know there are many variables , and we are only taking 300 +/- over temp. I just don't see how it's possible I cast normally at 1000 with range scrap? The boiling water test is 212 degrees, so it reads 8 - 10 degrees high on the low end of the scale, not sure how that would correlate on the upper end of the scale.

[Bzcraig]

I believe water boils at 212...

Dang it, I'm too old to remember 6th grade stuff......

[Bzcraig]

BZ,
I'd say the mold (s) is up to temp, some casting sessions are 15 - 20 # of 9 mm on a 6 cavity, with just enough time for the sprue pools to create the small divots as it cools and hardens - 3 - 4 seconds , No frosting of boolits.
It is the first time I have had a thermometer, so I'm not saying definitively it is wrong, but how could I have been casting at 1000 degrees and have seen no frosting with aluminum molds 2 and 6 cavity, 9 mm, lee 170 g 30 cal. , 300 blk, cutting the sprue just after it hardens, drop and refill quickly, Casting 10 - 20# per session good fill out and no tin added.
Drop it to the 725 degree on the themo and I loose fill out? I know there are many variables , and we are only taking 300 +/- over temp. I just don't see how it's possible I cast normally at 1000 with range scrap? The boiling water test is 212 degrees, so it reads 8 - 10 degrees high on the low end of the scale, not sure how that would correlate on the upper end of the scale.

All good questions. The BBQ thermometer I have (0-1000) is adjustable and like you used the boiling water to valid accuracy.

[MKN]

I guess I should stick to what has worked, and " if it fits, it ships" out the pipe and down range !

[jim147]

Is it a bimetal thermostat? There are almost always off and will be worse at one extreme of the range then the other.

[MKN]

Good question, it's the Lyman casting thermo, not sure how the probe is made.

[RickinTN]

Frosting comes from the mold being too hot, not the mix, so no frosting is not an indication of a cool alloy. I've been through 3 thermometers and they usually all need calibrating. A sure sign that your melt is over 750 degrees is that the tin will oxidize out (gold hue on top of the melt) or the antimony will begin to oxidize out (sludgy lumps on the top). After calibrating the thermometers are usually pretty close.
Good Luck,
Rick

[MKN]

Thanks Rick, Yes my melt looks good, not too hot with the gold hue, although I don't see it often, I keep a fairly heavy layer of sawdust flux on it. I am now trying to see if I can calibrate this Lyman Casting Dial Thermo. I mentioned the no frosting because if my melt was 1000 and casting at the cadence am, I would certainly have frosting, small divot in sprue puddle, glazes over, cut dump, fill again, aluminum mold.

At this point, I wish I had just bought primers with the $35........and kept doing what I've been doing ! Maybe Lyman will take it back and credit me towards a mold or something. It does not look easy to calibrate.
Matt

[Pawpaw757]

So how does one go about calibrating a thermometer?

[Boolseye]

FWIW, my 4-20 would probably hit 1000º if I left it at 7...I start at 7, then down to 2.5 or 3 once its up to temp. It hovers around 750-800 til I add sprues or ingots again.

Hey Johnson, I'm down in Westminster.

[Ateam]

I just returned a lyman analog because of the same problem. I bought mine through ebay and they have purchase protection, which I find a necessity in this day and age of cheap-chineese-sometimes-junk. I an going to build a pid next, but am hesitant.

[hpdrifter]

....... Maybe Lyman will take it back and credit me towards a mold or something. It does not look easy to calibrate.
Matt

I have bought two Lyman thermometers. Neither of them worked. I emailed Lyman and got no reply.. Good luck!

[alamogunr]

I also have 2 thermometers. Both are Tel-Tru and I would hazard a guess that the Lyman's are also made by Tel-Tru. Each of mine has a different probe. One is about .125" dia and the other is approx .25" maybe slightly less. One I got several years ago from Bill Ferguson and the other from GAR when they went out of business.(first time?)

I also can't see any way to calibrate but Tel-Tru(http://www.teltru.com/c-113-bullet-casting.aspx) might shed some light. Mine aren't that far off so I don't worry about it.

[Boolseye]

I bought my thermometer from rotometals when I started casting in 2010. As I recall it was the same brand that rcbs uses, but unmarked and cheaper. It has always worked well.

[sutherpride59]

I would suggest you use the same method I have adopted with my PID. My PID is way off and says room temp is 200ish degrees. But when using my hollow point molds I set the temp to 1200 and have great results. Is this actually 1200 degrees? Heck no but is it a consistent setting that I can reproduce every time? Absolutely! The thermometer may not give you the precise correct reading you want but it will give you a repeatable reading and tell you when you are going over and ideal temp or under it. Just use it like you would a busted speedometer. If it reads 78mph and your in a 45 mph area and you are moving with the flow of traffic then every time you drive there you should try to drive what your speedometer says is 78mph. It's not perfect but I am more worried about repeatability than a true reading of my temp.

[sutherpride59]

Also if you go the PID route I think I spent $40 total on eBay and my weight variance has gone way down since. Search PID and you should find the build thread if you're interested or you can PM me and I'll point you in the right direction.