Casting 2.0

[ebb]

I learned that my first attempt at casting was uninformed and it showed in the boolits I made. They were wrinkled and UGLY, but they came out of the barrel and sometimes actually hit where I was aiming. I want to try and improved version this time. Since last time I have bought a 1000 degree thermometer. What temp do I want to set the Lee melter for? I also have bought a hot plate type single eye to pre heat the mold on, how hot does it want to be? I have heard that I do not want it set for over 350 is this true. I would guess it should be as hot as the lead alloy, but it seems all my choices have been wrong in my previous attempt? Can I use one of the laser thermometers to get it set to the right heat? In my research here I found that adding some Tin to the mix will make the boolits fill out the mold better and make good looking bullets. I talked my daughter out of a postal scale and have weighed out 10 lbs of ingots, and about .66 lbs of pewter to make my alloy. I think this will get me about 18-1, and think this will make decent 9mm bullets if I keep the speed to a sane level. The melter was 1/4 full of some nasty lead mush with a purple film on top so i took it all apart after draining as much as I could and cleaned it up. How should i put the melter away after use to prevent rust? Do i want to drop the new boollits in water or allow them to cool on their own? I totally appreciate all the help and advise you have given so freely!! thanks Mark

[jim147]

You can't just say use this temp for this mix it doesn't work. You need to work your lead mix and pot temp and mold temp to get proper fill out. It just take time you will get there if you stick with it.

If you just want numbers, try 750 for lead temp and hot plate at 400 and see what happens. I don't use a hot plate I dip a corner in and work slow in the first few to raise the mold temp up.

[ryanmattes]

Wrinkles are either because you need a little tin, or your mold isn't hit enough. You want your mold ~400-ish, doesn't have to be exact. Aluminum cools faster than brass cools faster than iron. So you have to find a cadence that gives you good bases, without the bullets getting frosty (too hot) or having wrinkles or bad fillout (too cold).

I probably run my molds a little on the hot side, just by keeping my pace fairly quick. The slowest part is counting after the sprue freezes up, to make sure I'm not tearing holes in the bases. When I see the bases tearing that means it's too hot when I cut the sprue and I need to give it more time. In the pic below they're already coated, but you can clearly see the torn out base. As long as they're within my weight range I'll shoot them anyway, since I'm not doing competition with them, I'm just shooting paper at 10-25 yards.
https://uploads.tapatalk-cdn.com/20210321/e9301fa2542bcd91af49e85d85630b68.jpg

Sent from my Pixel 3a using Tapatalk

[justindad]

You and I are pretty close on the casting learning curve. I’ll share what I’ve found, but verify everything I’m saying ‘cause I’m quite green.


I also have bought a hot plate type single eye to pre heat the mold on, how hot does it want to be?
450F works best for me. My molds have a thermometer port drilled into them, and I heat them in a toaster oven. I will likely buy a hot plate soon, because the oven is slow. When the mold is at 450F, the spruce cuts much easier and you have to wait before cutting so that the lead is both hard & strong.



Can I use one of the laser thermometers to get it set to the right heat?
No. I tried.



The melter was 1/4 full of some nasty lead mush with a purple film on top so i took it all apart after draining as much as I could and cleaned it up. How should i put the melter away after use to prevent rust?
I would throw some wax into that mush and try to melt it into the lead. Might be oxides of your alloy.
Wear a respirator when cleaning your pot, unless you have other necessary precautions. I’m thinking lead dust & flux smoke might be more dangerous than I first thought.



Do i want to drop the new boollits in water or allow them to cool on their own?
The difference between these two processes is aimed at achieving different hardnesses. I think you will have to answer this, after asking yourself “What hardness do I want, and why?” You can heat treat to harden or soften later, so I would just do whatever is easiest until data tells you something needs to change. I am air cooling on a towel, and have no issues with boolits staying hot too long.

[Old Caster]

If you don't have a way to heat up your mold, start by not closing the sprue plate and just put lead into each cavity and also between the cavities on the top making sure you don't go down the sides or on the back edge of the sprue plate because if it does, it will get stuck. Then open the mold and remove all the lead which should be one hunk and put it back in the pot with a pliers. Do this quickly and after 5 or six times the mold will be up to temperature except for the sprue plate. Dip it in the pot for a bit and it will be hot too. Ready to cast Different molds may take more or less times but this method is pretty quick because if you had your mold on the top of the pot while it was warming up it is already fairly hot.

[ebb]

I bought a one eye cook top, but its not the exposed calrod like most I see. It is a cast iron flat surface kinda like a griddle.

[Land Owner]

Some recommendations and observations from "The Learning Curve of Casting":

a.) Get a circular saw blade and a #5 metal coffee or bean can (as wide a mouth as the saw blade if you can find one). Lay the saw blade flat against the hot plate. Cut a "flap" in the open mouth and up the side of the can just big enough for the mold handles to stick through. Put the saw blade on top of the hot plate, the mold on top of the saw blade, and the can on top of "everything" to hold the heat while it all pre-heats. I think 450F is "hot enough" as pre-heat but there are other suggestions further along for what is "hot enough" in the mold and in particular the spru plate. Pre-heat for 20 to 30 minutes before your want to pour...ymmv

b.) Initially, from room temp, set the melt pot temp HOT-HOT-HOT to get the contents liquid, then back it down to a lower temp (maybe 725F) to pour boolits. Temp is itself a "learning curve" and "an equation of multiple variables". Pre-heating the pot might take up to 30 minutes prior to the first pour...ymmv...but 30-minutes gives everything a chance to "warm" to working temp without undue "heat gradients".

c.) The "purple" color I have seen and is indicative of a VERY HOT molten alloy of lead and wheel weights, that without flux is disassociating less dense constituents from the lead, and floating those on top of the melt. IDK about the "lead mush" part - perhaps not hot enough? Or if VERY HOT, that could be zinc or other foreign contaminant. I am unfamiliar with contamination.

d.) Put 1/2" thick or more of plain old sawdust on top of the melt in the pot and let it smolder as you pour boolits. The sawdust will flux (stir without stirring) and "take out" contaminants from the alloy while keeping tin and other less dense constituents from disassociating and "floating" to the surface.

e.) Adding 0.66 pounds of pewter (if 100% tin) to 10 pounds of lead will make just greater than 15 to 1 alloy. If the pewter is 90% tin, then 17:1. If the pewter is ~85% tin, then 18:1.

f.) Making 9mm boolits that shoot well has been a struggle for MANY here, so I have read. I don't shoot 9mm, but I do shoot a lot of 380 ACP (9mm Kurz; a short 9mm). Dimensions of the boolits, cases, and rounds are not the same, so similarities stop at the names.

g.) I keep my pot FULL when I turn it off, so no rust on the sides. I use 49-49-2 percent Pb-WW-Sn alloy, about 12-13 BHN I think, not "Pencil Tested" yet, but seems reasonable from what I have read.

h.) Water dropped cooling makes "harder" boolits. Air cooled are "softer". "Hardness" in this regard is a "moving target". As lead cools, it contracts and densifies. The "hardening process", depending on the alloy, takes days to MONTHS to complete and what today is the measured diameter of your boolit may next month be slightly different.

i.) I alluded to the pre-heated mold being "hot enough" earlier and OldCaster and jim147 both recommended putting the mold in the melt. Expounding on that theme - put the mold in the melt! The mold will tell you when it is "hot enough" by sloughing the molten alloy rather than alloy sticking to the sides of the mold. Dip the spru plate into the melt too until it sheds the alloy!

j.) The poured boolit spru should take 5 to 10 seconds to "cool" and "solidify" on top of the spru plate. You can see the change. As ryanmattes shows, if the spru is too hot, it will pull material from the base of the boolit as it cuts. Slow down just a little. Let the mold cool a mite.

k.) Melted alloy that is TOO HOT when cast will "frost". I have cast frosted ingots of alloy that are brittle and no longer malleable - boolits too. Just slow down a little to let "things" cool. Turn down the pot heat too if frosted boolits are encountered.

Casting is an individual Learning Curve. Nothing poured from lead alloy is "set in stone". Put it back into the pot. Melt it again. Pour it again. Or, on the other hand, load it and shoot it. It is ALL fun.

This on line book, a Sticky on this Forum, is a source for beginning the understanding of lead and its alloys in casting and shooting: From Ingot to Target A Cast Bullet Guide for Handgunners (http://castboolits.gunloads.com/showthread.php?110213-From-Ingot-to-Target-A-Cast-Bullet-Guide-for-Handgunners)

[Land Owner]

...My molds...I heat them in a toaster oven.

How do you protect the mold handles while the mold pre-heats in a toaster oven?

[justindad]

How do you protect the mold handles while the mold pre-heats in a toaster oven?
The handles stay outside the oven. That must mean I am using them wrong, and those pins I use as a position stop should go through the metal fingers of the handle. :lol:

[JonB_in_Glencoe]

Alloy temp should be about 100ºF above the alloy's liquidus temp.

I don't use a thermometer on my DIY Hotplate oven, I set it one click above "LOW" and when the alloy is molten in the pot, I start casting, and if the sprue puddle doesn't freeze in 3 to 4 seconds, I take mental note and adjust the hotplate for the next session.

[JonB_in_Glencoe]

How should i put the melter away after use to prevent rust? Do i want to drop the new boollits in water or allow them to cool on their own?

I empty the pot for storage, if I don't have another casting session scheduled in the next few days.
I "air-cool" all my boolits. if I want them harder than the alloy will be air cooled, then I will heat treat them...it's a much more consistent than water dropping from mold.

[Rich/WIS]

Buy a cheap tin of Danish Butter cookies, the tin is about perfect size for a cover on a hotplate. Punch two holes on opposite sides of the tin for a wire bail handle to easily lift off and replace on the hotplate. If buying a hotplate for casting get the solid surface type, about $20 at Walmart. A lead thermometer is not expensive and will let you get an accurate reading on your pot temp, note down the pot settings, and take the guess work out when firing up your pot.

[JoeJames]

I have gotten very good ideas about casting from the book From ingot to target available free as a pdf file on the internet. Two major ideas were 1. heat the mold and spruce plate by turning it upside down over your melter (I do it with the end of the spruce plate almost extended into the melt) and 2. using clean sawdust to flux the melt. However a buddy tried that and it set off his smoke alarm. I don’t have that problem.

[Goofy]

Casting successfully is founded on facts far more than guesswork. There has been some worthy advice passed in this discussion. The Lyman 3D Edition cast bullet book is available online free of charge. Also, a very good website here: http://www.lasc.us/CastBulletNotes.htm

The OP speculated about hardness of his alloy mix and that’s all it is; speculation. One needs to know with reasonable certainty what alloy is made of else the future is bleak. Pure lead, clip on wheel weights and tin are a good start. Buy some tin, a little goes a long way. Pewter w/o assay is guess work. Cheap? No so much.

Apply the science, ditch the guessing.