Thermometer was enlighting

[Gripit]

So I started casting about a month ago and I didn't have a casting thermometer...yet. I read what other guys were setting their LEE pots at, 7 or so on the dial, was a common theme. My early results were okay and after some advice from guys on this forum things got better. Then my thermometer arrived and I had to see what I was actually casting at. Well it turns out that 7 and a half was pushing 900 degrees. I was seeing the rainbow on top of the melt. I played with the pot temperature settings until I was able to get the melt at 750, which turned out to be just under 5 on the dial.
What a difference!!! I was able to maintain a rhythm, cast some great boolits and make small temp adjustments when needed.

I bought my thermometer from Rotometals, they say it's the same as the RCBS unit. Does anyone know if that's true? How does one know if their thermometer is accurate/calibrated ? I was just wondering if the temps displayed can be trusted. It seemed to be a very useful tool.
Is there anything else I should know regarding thermometer use?

Thanks

[Conditor22]

You can't trust the thermostat settings on pots, there are too many variables that can affect them. I have several Lee production pots and they range from 4 to 8 to get 700° in the pot.

Put the thermometer in a pot of water and bring it to a boil. the thermometer should read close to 212°F IF it's accurate.

The hotter the pot when you cast, the more the boolits will shrink when they cool.

I normally don't cast at 750° unless I'm casting pure lead (which has a higher melting point than other alloys)

Dlon't let the thermometer touch the bottom or sides of the pot.

[Gripit]

I was reading the LEE instructions and they stated 750 was a good temp for Lyman #1. I'm using "Hardball" from Rotometals. I thought pure lead melted at a lower temp than alloys. So you figure 700 is a better temp for what I'm casting ?

[jdfoxinc]

Just the opposite is true. Alloys melt at lower temps.

[reddog81]

I’m on my second Lee 20 pound pot. While heating up the pot I turn it to 7 or 8. When I start casting I turn it down to 5. Once the pot gets below half full it seems to run hotter and I turn it down again or drop some more lead in. This has worked on both pots.

Keeping the pot at 7 or more would result in long wait times between pours or the having to run 2 molds in order to wait for molds to cool down. In my experience it seems like prolonged use above 7 would potentially warp molds

[Dieselhorses]

Was in the same boat as many trying to "guess" and use thermometers to get right temp. Wasn't until I recently purchased a PID from Hatch that I realized I should have bought sooner! Amazing little machine that keeps your lead +/-5 degrees of temperature you want. Just keep the Lee pot dial way up there and the PID does all the work. Not saying thermometers don't work but considering a good lead casting thermometer cost over 40.00 I resorted to the PID.

[Conditor22]

jdfoxinc is correct the softer the lead/alloy the higher the melting point

I do most of my casting around 680 - 700° [controlled by a PID connected to my casting pot] and pre-heat my molds on a hotplate with a 3/8" slab of steel on it

IF I don't get good fill - I toss in .5 oz of tin.

You can make a PID for $40, maybe not to the quality of Hatches but my PID's work for me.

One for casting and one for baking /powder coating boolits

https://i.imgur.com/tT3lfSk.jpg

[Gripit]

It sounds like the PID is the way to go. How do I buy one from Hatch ?

[Oyeboten]

What is a "PID"?

[Gripit]

https://en.wikipedia.org/wiki/PID_controller

[Dusty Bannister]

It sounds like the PID is the way to go. How do I buy one from Hatch ?

See the vendor sponsor section in the Swap and Sell area. He is also a list member so you can PM direct if you can not find him as a Vendor.

[Minerat]

It sounds like the PID is the way to go. How do I buy one from Hatch ?

Here, this will get you to his listing.

http://castboolits.gunloads.com/showthread.php?344578-VS-120v-220V-PID-setup-May-2020-update

[Mitch]

I did the same as many here when i started.then wnet with a thermometer for a few years then on to the PID.Just one thing less to worrie about.as often here the casting mep peole use is differnt by say 50 to 75 deg.several reasons for this.Mold they have ,alloyspeed they ar casting at and some others.One thung i found was the beeter and faster i got the lower my temps got.Many of the same molds i use to cast at 750 i now cast at about 720.I am faster so the mold gets hot and stys there now.
How accurate your themometer really will not matter unless it is way off.at this point it is just a number you set the pot at and it works as long as it repetes every casting session you are gold.the next persons tem they cast at likely will not work for you.I do not worrie if my PID is accurate just that i can set the same number and it works.

[Bookworm]

What is a "PID"?

Quick answer, it's an electronic device that uses a predictive algorithm to get (and keep) a device at a specific temperature.

It's a very intelligent thermostat.

[fcvan]

Is there anything else I should know regarding thermometer use?

Thanks

I cast without a thermometer for 40+ years. I only bought one because the local mom and pop gun store I've visited for 3 decades had one sitting there the whole time, and it was reasonable. I had always cast by sight and how long the sprue took to cool. Buying the thermometer confirmed what I had seen, casting temp, mold temp was spot on for my alloy.

Hot boolits start getting frosty. Cold melt or mold gives wrinkles. A sprue takes time to cool and harden. All of these signs indicate a certain temp, something I learned on advice of older casters, and reinforced from comments here. These things are observable without a thermometer. Sometimes I cast with 2 molds, sometimes I speed cast with one. It varies from the caliber and weight, mold being steel or aluminium, and the QC of the inspected boolits.

If I am speed casting a 3 cav NOE 225-62 RN, I know I need to run the mold fast to keep the al. mold up to temps. I pour, blow on the sprue until solid, and drop purty boolits. It is a 3 cavity mold and I can crank out 100+ PDQ. Casting the Lyman C225-415 steel mold throws purtey boolits and the still holds it's temp.

I read an article 3 decades ago, about a caster in Idaho who loaded 30-06 and how he did it. His targets at 100 yards were 1 ragged hole. His methodology was consistency. Lots of details, but repeatable success through observation.

[Gripit]

Thanks again for all of your help. I'm still trying to get my method perfected.
My boolits are getting more consistent with every session.
I really need to pay attention to the cues from the mold, melt and cadence.
I'll holler

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