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Lead Pot temp

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Melnic

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OK, I have a new Lyman Lead thermometer. Up until now, I have been flying blind.
So far, I have found that 750-800 and a warmed up mold seems to be a good temp range to heat up the lead to mold. I was surprised that the setting I had it on heated it up to almost 900F. I got the thermometer so I can try to keep the temp consistent from both within the batch and from batch to batch.
Right now, I have been working on some .578" minie balls using a Lyman Mold which is aluminum.
I'm concerned about both fill and shrinkage, but I have some sizing dies on the way so I can size the bullets to my guns (.580", .578" and .576" dies on the way)

How does mold as well as lead temp affect shrinkage and fill?

I'm using pure lead with Brinell harness of approx 5.0 (using Lee hardness tester)
 
Imho, nothing wrong with seat of the pants casting. Know people who are excellent casters. One keeps himself supplied with fine whiskey and cigars by providing cast to friends.

Had a lyman and RCBS thermometer that never agreed; 25 degrees apart. So I never knew exactly what temp I was casting at. Don't even trust exactly the readout on my lyman mag 25. So I don't sweat my melt temp except to be consistent on my equipment.

I try to cast with the melt at the same level, almost to the top, and don't change the setting on my lee 20# furnaces. Won't be chasing temp that way. Just let the melt stabilize and verify using a thermometer.

Soft lead, I cast at 850-ish. Need the high temp to get a good fill out on my lyman minie molds. I've never seen a lyman aluminum mold. Where did you get yours?

Just my .02 cents....
 
Last edited:
Melnic,
Once your mould gets up to proper temperature, you will get maximum fill-out if your pouring technique allows for a fast fill and a large sprue. Keeping the base-plug at the same temperature as the blocks is a challenge as it cools quickly while your are getting the casting out of the mould. I put mine Lyman plugs on an electric hotplate to keep them hot between pours. Your casting cadence should be fast enough so that the mould stays up to temperature. Variations in temperature of mould, base plug, or molten lead will result in variations in fill-out which result in differences in weight and diameter. I have had more consistent minie bullets casting from a 20 pound bottom pour lead pot and Lee aluminum minie ball moulds over Lyman Iron moulds. Some folks get better results by ladle pouring. YMMV. I also add a little less than 1/2% tin to the melt for better fill-out and cast at 800 degrees maintained with a PID temperature controller. Both of which has resulted in much more consistent minie ball casting and eliminating accuracy destroying voids in their hollow bases.
 
My bad, Lee Aluminum mold

I have a Lee bottom pour pot, but it free flowed on me the other day (It may have been my temp being too low and adding more lead locked up the top of the lead).

Was using the Lyman Big dipper today.
 
Bend a hacksaw blade into a "C" shape and use it to clamp over the spout. I install it from the top of the pot to the spout and leave a straight section on the bottom to cover the spout. It will stop the free flows. I have a 10# Lee pot. Don't know if the blade will fit the 20#. Just the pressure from the blade keeps the spout hole cool and plugged until you are up to temp.
I also keep a Lyman ingot mold under the spout to catch the drips. A pie pan works about as well. I already had the mold.
 
I do use a thermometer. .36 and .40 balls are ok running around 800* F. Bigger balls 900-950. My 550 gr minies I use a Hot Pot as the bottom pour 20 lb doesn’t flow as fast as I would like.
 
I found a thermometer designed for BBQ grills that registers up to 1200f. It's now a fixture on my Lee 20# pot. I cast minies at 850-900 using pure lead. A couple of my molds are steel, a couple aluminum.

What I've observed in casting minies, it doesn't matter what the mold material is made from, the temp of the bottom plug and angle of pour control quality. If the plug is cold relative to the mold, cavities and voids are common. If the plug is at the temp of the mold, and the mold held at an angle so the pour isn't directly into the mold, then reject rate drops to under 1%. Also, have a generous amount on top of the sprue plate. My guess is it helps to keep the mold at the optimum temp between the sprue and the point of the bottom plug and that is where most voids occur. I knock the sprue off directly back into the pot. Temps on the pot stay pretty much stable at 850-900f this way.
 
Not Shure on my temp but I have a small Lee pot that I set at 4-5 on the gauge. Then after the lead is melted I let it set for about 5 minutes. Then I put a corner of the mold into the melted lead and let it set in it for 20 seconds. What that dose is it heats the mold up. Then I do the same thing with the spue plate. Helps when I'm casting Minnie's r.e.a.l.s or round balls. All my molds r Lee molds. Took alot of trial and error to figure out but that's what I do. And everything seems to work good for me. I been using Lee molds for 18 years.
 
I use the big dipper as well, but no thermometer. If the round balls I'm casting have no wrinkles.....I just keep going.

Same here for me. It is results that count. Hang the temps. I don't mess much with numbers. I do use a Lee bottom pour but dip from it. In use I just set the dial to where it was last time I did casting. I only use soft lead in this and keep the pot full. I'm a proponent of the KISS principal for doing things. Seriously, consistency is what is important for getting good results in this game and casting is just one step in that process.
 
Ok. Did some experiments today.
Known factors:
lead is 5.
Molds, lee double, 495 and 457.
Lee bottom pour pot.
Molds preheated on top of pot while lead got to temp.
Poured at 500, 550, 600, 650, 700 and 750. 750 tops for my pot.
Minimum 3/8 diameter build up on cutter.
Ambient temp 65-68.

Made no difference in measurements.
Could make rounds faster at 500-600. Less cooling time.
 
My information also says pure lead melts at 621°F.

Many lead alloys melt at lower temperatures so if bang was pouring bullets at 500°F he must be using some lead alloy.
Tin is one of the things that will lower the melting temperature so he might have had some solder in the pot?
 
Lead purchased at robometals.
Could be thermometer. Nothing to compare it with. The point is at melt and above to max of pot there was no difference in measurements.
 
Lead purchased at robometals.
Could be thermometer. Nothing to compare it with. The point is at melt and above to max of pot there was no difference in measurements.

We have seen a number of people post temps here that only prove most of the lead thermometers available are unreliable. Personally, I don't sweat the numbers. When my lead is hot enough to cast nice balls that is the temp I want. FWIW, the dial on my Lee is set at a little over '9'. Works for me.
 
Just got good temp probe. Lee bottom pour, at least mine, runs 775-800 on 4 3/4.
 
I hate bottom pour and pure needs 800° to cast. Alloys need less heat. I ladle cast and the secret is to hold the ladle tight in place until cooling balls take more metal from the ladle. A sprue will NOT feed as it cools faster then the ball. Keep molten lead at the mold with a ladle. Bottom pour has never made anything worth shooting for me.
I have Lyman pots and my friend has RCBS, all bottom pour but thermostats fail fast and I have watched lead harden between cycles.
I use a Lee 20# and took the bottom pour junk off and plugged the hole. I can cast the full 20# without a reject, balls or bullets of any weight. A Lee 20# production pot and a Lyman ladle is top dog.
 
I bottom pour pistol, rifle and RB. Started with Lyman, Lee and Saeco 10# and now use a Lee 20#. What you are melting makes big difference in temp required. Run alloyed rifle and pistol at 750+/- and RB at 800. Same is true of molds, aluminum seems to like a hotter alloy than steel to fill correctly. A lot of the dripping is due to dirty lead, that is lead not thoroughly cleaned when smelted, and my experience over 40+ years of casting is all pots will drip if not cleaned once in a while. A trick with some pots is to hang a fishing sinker/several washers/etc on the handle to add a bit of weight, keeps the rod tighter in its seat in the valve.
 

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