Need help regarding the correct temp range of lead for casting?

[azshtr]

I probably missed it but have searched various articles trying to find what the correct range of temp for the lead when casting and failed to find info.

I am finally getting around to casting some boolits and am at a loss as to what the lead temp should be. I am using clip on wheel weight lead, Lee 6 Cavity Molds, Lee Magnum Melter and Lee Production Pot IV with bottom pour and will be water dropping the boolits. I have a lead thermometer and would prefer to trust that rather than the heat control guides on the Lee pots, if I can receive info on the proper temp range from some of the very knowledgeable members on this site.

Any and all info will be greatly appreciated.

[trying2learn]

Well I am not sure what the correct temp is. But I have a mold that likes it as cold as I can get the lead and a lee one that has to be feed lead that is about 720. If my memory serves. Not sire why but they do. My understanding is the mold sort of determines the proper lead temp. I am sure others will come and give much more wisdom then I could.

[RobsTV]

Around 75 to 100 degrees hotter than liquid melt works best here.

Note that if you don't calibrate your thermometer to the exact same as others, then the number others cast at probably won't be true for your gear. My Tel-Tru face rotated somehow and was about 80 degrees off. Use the 75 to 100 hotter and you will be fine.

[geargnasher]

The best anwer will always be near 100 F hotter than the full-liquidus point of the alloy, meaning after the grainy, slushy, lumpy stuff all melts in and the phase change is complete from solid to liquid.

Most clippy WW alloy likes around 700F, give or take.

Keep it under 750 no matter what if you're using anything containing tin.

Mould temperature is where your fillout and boolit quality come from. If you have wrinkles, rounded edges, or incomplete fill, it's because your mould is too cold, no that your alloy is too cold. Cast fast to keep the mold hot.

Gear

Edit: I see Rob beat me to it!

[williamwaco]

I use a lot of wheel weights. I get best results at a melt temperature of 650 to 700 degrees.

If you are getting symptoms of the melt being too cool, do not increase the temperature. You can eliminate those problems by raising the temperature of the mold. Do that by pouring a large puddle of sprue on the top of the sprue plate. As large as a quarter dollar or larger, and casting faster.

This will raise the temperature of the mold. When everything is up to temperature, it will take three to five seconds for the sprue to harden. When you begin to get severe frosting, slow down the casting cadence. ( light frosting is not a problem. Many casters prefer lightly frosted bullets.)

.

[HATCH]

i run my pure lead pot at 800 but run my master caster at 750

i use a PID.

[azshtr]

From the response it looks like a good starting point is to melt to liquid and then increase another 100 or so degrees and adjust from there. Thanks to all responders.

[40Super]

I run 675F almost entirely, it comes out to roughly 100 over melt temp. All changes for casting issues is handled by mold temp and such or adding tin . I found out when my pot temp gets hotter, the bullets start frosting too easy and it takes longer for the sprue to harden and have to cool the molds longer.

[captaint]

Anytime I get over 725, I like to sneak my pot temp down as long as boolits come out good. When we get too cool, it will show up. Then I know where I need to be. With a 6 cav aluminum mold, it's around 700 for all to go well. Take a 2 cav iron mold, you can run that a little cooler and still be OK. As others have said - do avoid going over 750. We tend to "burn up" the good stuff above that. Mike

[Shuz]

For those using bottom pour pots, a layer of new kitty litter, about 1/4" to 1/2" inch thick laid, on top of the melt, allows the pot to run hotter without oxidizing the melt. I run my pots from 725 to 800 deg.F

[geargnasher]

For those using bottom pour pots, a layer of new kitty litter, about 1/4" to 1/2" inch thick laid, on top of the melt, allows the pot to run hotter without oxidizing the melt. I run my pots from 725 to 800 deg.F

This is true in a certain context, but not in all. Insulating and running hot helps particularly when bottom-pouring pure lead, which needs a LOT more heat than 100 over full liquidus to cast well. I run pure lead at 800-850 with a thick layer of either kitty litter or ash from a LOT of sawdust to help insulate and prevent dross formation.

HOWEVER, if you run a tin-containing alloy at temperatures above 750F, you still ruin any beneficial effect of tin because it loses it's oxide-barrier characteristics and the metal literally won't flow as well. Tin flash-oxidizes on the surface of the molten lead stream and provides a soft skin that breaks, stretches, and flexes better than the lead's natural 'skin'. This tin oxide barrier, in effect, reduces the surface tension of the lead and makes the alloy cast better. If you get the metal too hot, you lose the effect because the tin oxide can't handle the heat, so you might as well not have any tin in the melt other than for the effect it has on the alloy after it's cooled.

Gear

[azshtr]

Thanks to all, looks like I now have a place to start getting the lead to a correct temp.

[geargnasher]

If you have a casting thermometer, observe the temperature of the "mush" or "slush" phase of the alloy, when it first starts getting soft enough you can poke the thermometer down in there and get a reading if starting from a cold, full pot. If you're melting ingots in the pot, let them all melt and then turn it off until the alloy starts getting grainy and mushy. During the "phase change" from solid to liquid, the temperature of the metal will be constant, same as water when freezing, thawing, boiling, or condensing. Once the phase change is complete, the temperature will begin to change. So note the mush phase temperature and add heat until it's fully melted. You'll notice the last grains disappear right about the time the temperature of the mix begins to climb. Once you establish the phase-change temperature, you might add 100 to it and mark it on your thermometer face as a target casting temperature. This is a 'quick and dirty' way of determining a good starting pot temperature for a new or unknown alloy. If it won't cast well at 100 over the full-liquidus point, you have other problems like mould temperature, venting, cavities contaminated, or bad alloy.

If you're casting in a drafty or cold area, you might need to run the alloy a bit hotter. If you're using a mould like a two-cavity iron mould with huge cavities and little mould material that tends to overheat easily, you can run your pot cooler than 100 over full-liquidus. Some alloys that are light on tin and antimony need a little more heat to promote good fillout, so the 100 degree recommendation is only a guideline. What you DON'T want to do is run a pot of Lyman #2 at 800 F during a session, because by the end of a pot your boolits won't have much tin in them.

Gear

[lead4me]

For those using bottom pour pots, a layer of new kitty litter, about 1/4" to 1/2" inch thick laid, on top of the melt, allows the pot to run hotter without oxidizing the melt. I run my pots from 725 to 800 deg.F

As Shuz say's new kitty litter!! I wonder how he came to that?? I can't even imagine using used litter...wow talk about needing a respirator :-}

[Mk42gunner]

As Shuz say's new kitty litter!! I wonder how he came to that?? I can't even imagine using used litter...wow talk about needing a respirator :-}

I just knew someone was going to go there as soon as I read Shuz' post about using new kitty litter.

Robert