When outside temp goes down does your pot temp go up?

[Strtspdlx]

I've been casting about 2 years now and I've noticed on hot summer days I ran my pot alot cooler. Maybe between 680-750 depending on the mold. This is the third time for me that I've noticed when outside temp gets below 45ish degrees I need to run my pot about 50*f hotter and really pick up the pace to make it run. What say you?

[OS OK]

I imagine that extra heat is being used to keep the mould at the right temperature.

[6bg6ga]

I've been casting about 2 years now and I've noticed on hot summer days I ran my pot alot cooler. Maybe between 680-750 depending on the mold. This is the third time for me that I've noticed when outside temp gets below 45ish degrees I need to run my pot about 50*f hotter and really pick up the pace to make it run. What say you?

Its simple physics. When your ambient temp is higher in the area you are casting in the temp setting will be a little lower because it requires a little less heat to achieve your temp set point. When the ambient temp is lower the amount of heat from your heating element will have to be higher in order to hit your set temp point.

[gwpercle]

Notice how you have to put on a coat so your body heat doesn't get sucked away by the cold air, well the pot has to heat some of that surrounding cold air (no pot coat) so you have to jack up the heat.
Wind will also cool a pot.

[6bg6ga]

Notice how you have to put on a coat so your body heat doesn't get sucked away by the cold air, well the pot has to heat some of that surrounding cold air (no pot coat) so you have to jack up the heat.
Wind will also cool a pot.

Good points.

I fabricated a cover to put on the top of my 50Lb pot which helps with temp loss.

[centershot]

I leave the pot temp alone and light the propane heater in the casting shed. It might only be 15 degrees outside but it's roasty-toasty inside!

[country gent]

While ambient temp dosnt actually affect the lead temps it does the cooling of the stream of lead and the moulds rate of cooling. Used to be with the older powders ambient temp wouldalso greatly affect velocity and pressures. Your upping the pot temps and pace to offset the faster cooling of the stream and blocks. I would think that this will be more pronounced with aluminum moulds than brass or steel

[6bg6ga]

Actually the ambient temp does effect how long the heating element has to run. The hotter the day the quicker the lead will reach its set temp point. It is not changing the set point you have your thermostat set at but will require the heating element to run longer. In the case of a fired setup it will require more time for the lead to melt and get to your desired temperature. Yes, it will affect the mold cooling rate and the stream of lead as its being released.

[Strtspdlx]

I was just curious as to everyone's experiences. I had the pot spout freezing up on me at 640* which is usually where I run my lee 457-450 mold. I had to bring the pot to about 720 to get the pot to run. Then the mold wouldn't run. But I've never had any luck with this mold. I've been trying to make it work considering it casts under .457. But I may give up and just buy an noe 405gn mold for my 45-70

[mdi]

Jes wonderin'; how many degrees does the alloy drop in the 1" of travel from spout to mold, open to ambient air? I'm no expert on thermodynamics, but some of the posts above may be OK as to theory, but in real life???

[adam_mac84]

I find my pot wants to run hot when ambient temp is down in the garage. I have to turn from about 5.5/6 on the Lee to about 3.5. My theory was that the cooler air was cooling the electronics in the back portion of the pot and making it think it was not up to temp and running the heating element. Use Lyman Thermometer for 700-725 (nozzle freezes below 700)

[BattleRife]

My theory was that the cooler air was cooling the electronics in the back portion of the pot and making it think it was not up to temp and running the heating element.

The OP doesn't say what brand of pot he is running, but for those of us with Lee pots, adam_mac84's description of the mechanism is the best so far. The Lee pots use an electromechanical (not electronic) switch that is located in the back control housing. It appears that it relies on heat being tranferred via conduction and radiation from the pot housing to the control housing. When the ambient air is cooler, or when there is air movement, some of the heat is lost to the surroundings on the journey. Thus the pot gets hotter before enough heat can make it to the control housing to trip the switch.

[blikseme300]

I was just curious as to everyone's experiences. I had the pot spout freezing up on me at 640* which is usually where I run my lee 457-450 mold. I had to bring the pot to about 720 to get the pot to run. Then the mold wouldn't run. But I've never had any luck with this mold. I've been trying to make it work considering it casts under .457. But I may give up and just buy an noe 405gn mold for my 45-70

I have the same 457-450 mold and I opened it up to drop at .459" by lapping with 600 grit Comet. I use the CB's from this mold in my 458WM and of all of my molds this one produces the best shooting CB's.

The mold easily overheats as 900gn of alloy per cast, plus the sprues, puts a lot of heat into the mold alloy. To get it to run right I cast at 685* and use 1 cavity only. When the mold gets too hot CB's will be frosty and drop small. Contrary to popular thought cavities shrink when heated and not expand.

What I have learned about casting these large and heavy CB's is that the alloy stream with bottom pours, such as the Lee, is on the small side for large casts. My early solution was to open up the spout on a Lee to have a larger alloy stream. I have never used a ladle to cast but this is what others have recommended so when I built my own casting pots the one I use for the large CB's has an opening of 1/8".

[Drew P]

I know my hot tub temp goes up when the ambient temp goes down. With my body completely under water it shouldn’t make a difference what ambient temp is, yet, it does. 102° summer, 104° spring and fall, 106° winter. Seems to be a similar situation.

[beagle]

I once tried to melt down some oily WWs at the range to avoid the fumes. Pot sitting on a concrete bench and a gentle wind blowing. Temps in the 40s. I was unable to melt those down until I fabricated a wind shield to protect the pot. The temp and breeze does have an affect but I have no idea how much. I'd have thought that the thermostat would have compensated for the breeze but apparently it didn't./beagle

[Retumbo]

My shed was at 35°c this afternoon. So answer is no

[Strtspdlx]

I have the same 457-450 mold and I opened it up to drop at .459" by lapping with 600 grit Comet. I use the CB's from this mold in my 458WM and of all of my molds this one produces the best shooting CB's.

The mold easily overheats as 900gn of alloy per cast, plus the sprues, puts a lot of heat into the mold alloy. To get it to run right I cast at 685* and use 1 cavity only. When the mold gets too hot CB's will be frosty and drop small. Contrary to popular thought cavities shrink when heated and not expand.

What I have learned about casting these large and heavy CB's is that the alloy stream with bottom pours, such as the Lee, is on the small side for large casts. My early solution was to open up the spout on a Lee to have a larger alloy stream. I have never used a ladle to cast but this is what others have recommended so when I built my own casting pots the one I use for the large CB's has an opening of 1/8".

I run a lee 20lb with a my pin pid controller, the tc is connected directly to the pour spout.