alloy temp?

[Fernando]

How important is it to keep alloy temp static?
I want to run a 1000 lot but will have to add metal as the pot
goes down.
Do you pour in full pots or add a little as you go?
How much temp variance is OK?

[Larry Gibson]

I run at an average 725 degrees (thermometer) with most alloys in my Lyman Mag20. Sometimes hotter with smaller bullets and/or a "harder" alloy I will run at 750 degrees. I also generally put the cut off sprue back into the pot while waiting for the next pour to cool/harden. Tis makes the alloy temp very from 710 - 725 degrees. Also the thermostat causes variation of +/- 25 degrees. Thus I usually cast with an alloy between 710 and 735 degrees.

Letting the alloy get below 1/3 full also will add more +/- to that so I don't let the alloy get below 1/2 before adding more alloy. This is especially the case when I'm casting rifle bullets for hunting, HV and other "precision" shooting. However, when cranking out handgun bullets for general shooting with 4 or 6 cavity moulds I let the pot get down to 1/3 full before adding more alloy.

Larry Gibson

[41 mag fan]

I'll run my pots, depending on temp and humidity between 675*-710* . I'll let it get like Larry about 1/2 empty and refill. But I've got 2 different pots going, my Lyman mag and my Lee. One gets low, I'll switch to the other one.
One thing I have done that seems to work good, is I'll use a pot, melt lead in it, let it sit hot and as my pot gets low, I'll add to it, and within a couple minutes, be able to keep right on casting. This was before i bought my Lyman furnace

[runfiverun]

if you use a larger pot the alloy doesn't vary much in temp at all.

using a lee 20 lb pot adding a 1 lb ingot of room temp lead will drop the pot's temp about 50-f for over a minute.
i done a write-up on the lee 20 lber about 3-4 years ago and different amounts of lead added to it to re-fill it.
[my solution was to buy a 40 lb magma pot and heat up the ingots]
for the 20 lb pot i use a top i made from some heavy guage sheet metal to set the ingot that i am gonna add on top of to warm up before adding it.
i also make the ingots smaller for this pot [like 4-oz's]

[357shooter]

I take a different approach. Bascially I don't add lead while casting, just the sprues. I monitor and adjust the to keep the temp where I want it, and cast the first pot. If I want to cast more, I fill it, let it come back to temp while taking a break or doing something else. It keeps the spout from freezing, and fits with my casting needs so it works for me.

[geargnasher]

HERE: http://castboolits.gunloads.com/showthread.php?181092-Need-help-regarding-the-correct-temp-range-of-lead-for-casting

Also buy a Lyman Cast Bullet Handbook, 3rd edition or 4th if that's all you can find.

Gear

[blikseme300]

How important is it to keep alloy temp static?
I want to run a 1000 lot but will have to add metal as the pot
goes down.
Do you pour in full pots or add a little as you go?
How much temp variance is OK?

Consistency is key to good casting. Keeping the temperature in a narrow band really helps achieving this. You don't mention what boolit you are casting but casting 300+ grain boolits will require a larger pot than lighter boolits. I asked the same questions you did a few years ago and the answer was to build a large capacity pot (70lb) and control it with a PID. This allows me not to need to top up the pot during a volume run of heavy boolits and keeps the temperature stable within 10 degrees. I return the spruces to the pot immediately after cutting and the top of the pot is covered in a layer of ash from wood shavings used for fluxing.

Some folks use 2 pots in a cascade and others use a hot plate to preheat the ingots to minimize the drop in temperature when adding more alloy. I preferred not to go this route as it is risky, think burning, and the alloy won't be fluxed uniformly. Both of these factors are eliminated by going with a large pot. This is my experience and opinion, YMMV.

[Charlie Two Tracks]

These guys have it covered for you. I want to add about the safety. You will be using lead at 700 deg (more or less) and that is TWICE as hot as the casserole that comes out of the oven. It burns fast and deep. Welders gloves, eye protection and common sense will help you getting started. geargnasher pretty well nailed it. Oh ya. Make sure the pot is fastened down. You don't want to spill 20 lbs of melted lead in your lap or on your legs. I would kind of mess this summer up at the very minimum. Welcome to the site.