Casting Question

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  • Last Post 01 September 2023
cove posted this 15 August 2023

I get the best fillout when casting with Pb/Sn alloys at a temperature of around 800 degrees F. Problem is, when using an open pot and dipper, the high temperature causes lots of oxide/slush which sticks to the dipper and probably effects the quality of the bullet.  Kitty litter works with bottom pour pots, so my question is: has anyone out there tried kitty litter with a dipper?

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Wm Cook posted this 15 August 2023

Maybe you’re trying to prevent wrinkles and a high melt temperature helps remove them?

Usually 680 to 700 is kind of the norm and I never saw alloy hotter than that help prevent wrinkles.  But I do see what looks like separation of the alloy mix causing a mud like scum if I accidentally run it too hot.  At 720 it progressively gets worse.

Even at 690 I flux every 50 drops (single cavity, Linotype, 220g) in my little my little 10lb pot.  I ladle cast is in small batches of 150pcs and I’m not in a hurry. 

If wrinkles are the reason you’re running the alloy so hot you might want to monitor your mold temperature.  

Different mold material will require different cadence to keep the mold temperature where you want it.  Iron, brass and aluminum are all different animals.   All this is just an opinion.   Bill C.

A “Measured Response” is as effective as tongue lashing a stuck door.

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Aaron posted this 15 August 2023

Are you mating the dipper spout to the mold and then rotating to fill or are you pouring into the mold from the dipper? I have never had much success pouring from a dipper into the mold.

With rifle in hand, I confidently go forth into the darkness.

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cove posted this 16 August 2023

Thanks for the comments guys.  I am a pressure caster, meaning that I cast with dipper or bottom pour spout in contact with sprue plate.  I am working on an article about casting at high temp, so will not go into more details here.  I was just curious as to whether one could use a dipper with kitty litter floating on top.

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linoww posted this 16 August 2023

I have successful casting with no ladle contact with the sprue plate. I may be the only one because none of my other casting friends get decent bullets this way

"if it was easy we'd let women do it" don't tell my wife I said that!

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RicinYakima posted this 16 August 2023

I am successful doing it without contact because I pour the complete ladle full over the mould and let the rest run back into the pot. Mould stays hot and plenty of material on top of the cavity. When the mould is hot enough, there is little material left on the top of the plate. 

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linoww posted this 16 August 2023

That is the same exact process that I use Ric.

"if it was easy we'd let women do it" don't tell my wife I said that!

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Tom Acheson posted this 16 August 2023

Everyone’s experience on the task will vary.

For a large single cavity mold, 420-grains, making a bullet for use in my BPC rifle, the spout is inserted into the opening on the sprue plate and both rotated together 90 degrees to glet the alloy to flow. When the cavity is full I pull the ladle up and ket excess alloy flow onto the sprue plate. 

For multiple cavity smokeless powder loads, I have a Rowell 1-pound capacity ladle. I fill it by dipping into the pot and then pour alloy, starting with the front cavity moving to the rear cavity (currently an aluminum 4-cavity) and let excess lead accumulate across the length of the sprue plate. This has worked for me for quite a few years.

Tom

 

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Eutectic posted this 16 August 2023

Rick is right 650 to 700 F is plenty, you are burning the tin out of your alloy at 800.

The problem with ladle casting is it is SLOOOOW. The mold never gets up to the temperature needed. The solution is to put in extra heat. You can do this by pouring alloy over the sprue plate or a method I use, pouring alloy on the base of the mold. Lee molds recommend dipping a corner of the mold in the pot for a few seconds. I have done this with two cavity Lee molds, but I hesitate to recommend it as the large temperature gradient may warp some blocks.

Even with a bottom pour pot and multiple cavity molds, small bullets, less than 150 grains, may require added heat to cast good bullets.

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TRKakaCatWhisperer posted this 16 August 2023

Not getting fillout at alloy temp of 800 dF suggests that the mold may be too cold.

For larger bullets to increase speed of filling I reamed the ladle spigot to a larger diameter.

 

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cove posted this 17 August 2023

 Well guys, I can now see why nobody described his experience casting with a dipper and cat litter.  I tried it and it was a waste of time.  I thought one could dip through the litter but that was a mistake and the litter coated the dipper so I could see no way to pour into the mold without including litter.  Oh well, nothing ventured, nothing gained. I suspect my oxide sludge may be due to tired lead or contamination and need to try swith a fresh batch of alloy.  Anyway, thanks for your input.

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RicinYakima posted this 17 August 2023

Heat it to 750* and wait an hour and scrape everything floating into the junk container. Then flux and start over with lead at < 3% tin and antimony. 

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OU812 posted this 17 August 2023

Skip the kitty litter, saw dust etc and just Flux more often using wax.

I have lots of moulds and some can be more difficult to cast with than others, requiring different methods until you find the sweat spot.

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smokyboom posted this 17 August 2023

Been casting using a dipper, tried pouring it in and over, and tried mating the spout to the mold. Best thing I've done is lower the melt to ~710 and preheat the mold on a hotplate set to a middling temperature. Set on hotplate while waiting for the melt then Cast,cast,cast set mold on hot plate, wash rinse repeat.

 

My last batch came out all shiny and wrinkle free. Lowering the melt temp help keep the tin from rising out even with fluxing.

 

 

-------- Andrew BPCR in 45-70, and 38-55

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delmarskid posted this 18 August 2023

Today I cast about 10 pounds of .58 mini (burton) bullets of pure lead at 700 degrees with about a 10% rejection using a dipper. I doubt that you need to cast as hot as you are. Strangely I had more dross than when I run an alloy at a similar temperature.

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Eutectic posted this 18 August 2023

Cove,

The answer is yes maybe. What I tried was ground up charcoal briquettes. It slowed down oxidation and dross production but did not eliminate it. I did not try to exclude the charcoal from the dipper, it floated on top. There were still dross inclusions, some of them might have been charcoal.Too much trouble no discernible advantage.

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Bill*B posted this 29 August 2023

I don't use a thermometer, but get the lead pot hot enough that the mix literally pours like water, runs off the mold like water, and then I'm happiest when the bullets are dropping out lightly frosted.  Scrape off the scum whenever it starts to interfere with the pour. Amen to preheating the mold on a hot plate!

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Glaciers posted this 01 September 2023

I’m a dipper and one day may try bottom pouring. But I run my pot at 725* and preheat molds on a hot plate. I’m considering dropping pot temperature down a bit to say 710.
I stay away from higher temperatures for one main reason, zinc. Zinc is in newer wheel weights and will melt starting at about 775. I just won’t risk contamination. But secondly I haven’t seen the need for more heat in the mix, but preheating the mold or simply mold temp. Of course this varies a 40 grain mold will be considerably different than a 400 grain mold.

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