Alright, I'm new to this I know when melting down wheel weights the temperature should be about 650 to keep from melting zinc into the alloy. What temperature do you heat the alloy to in order to cast bullets?

Skipper start about 750 deg with your wheel weights. After a few sessions you will figure out what temperature your alloy and mold work best. I like to cast hot and lightly frosted bullets have the best fill out for me, I have a thermometer and hardly ever use it when casting.ymmv

Ideally, with ternary alloys (Pb, Sn, Sb), you should be about 75-150* above full liquidus (the exact temperature at which the last visage of slush is melted), depending on alloy and mould preferences. Most people cast WAY too hot for the alloy, and the "crank up the heat" advice that is often dispensed in response to poor fillout queries is usually inappropriate. I see new casters time and time again complaining of poot fillout when they actually have an oily mould or don't cast fast enough to ever get the mould up to temperature. The key to casting quality boolits with good fillout is to heat the alloy in the pot to the temperature THAT THAT PARTICULAR ALLOY NEEDS TO FLOW WELL, and cast at the correct RHYTHM to keep the MOULD at the temperature the mould likes for good fillout.

Another very important point regarding pot temperature has to do with drossing. Tin in particular drosses out of the alloy very quickly at temperatures much over 700*, and tin becomes ineffective at breaking the surface tension at temps over 750*, so any tin in the mix or tin you have added is wasted if you cast too hot.

A good example of a well-tuned setup: Clip on wheel weight alloy with 1.5% tin added, melt point about 580*, pot temp 680-700*, two cavity Lyman mould running at 400* casts slightly satin, fully filled-out boolits with no frosted edges and razor-sharp base and bands.

Hope this helps,

Gear

I was casting outside last night. Conditions were poor, windy and cold. I started casting about 675 but the wind picked up and my temperature started dropping. I turned up the gas and got the temp to about 725. Then the wind died down and the temp went up to about 800. I did notice the easiest pourig was right around the 700 mark. I can't wait til I get an electric pot so I can move my casting inside, not to mention the pot I have is way too large for casting, I bought it for melting down WW (6-quart cast iron dutch oven) and it just leaves too much surface area so it oxidizes quickly and sheds heat rapidly.

Thanks guys, I'm an engineer so I like to put numbers to things so it's hard to just turn things on with out having a number in mind. The information you have given me plus what I saw last night is narrowing my target number.

ultimately, the individual mould will tell you how hot it likes to be to drop good boolits, but the ideal temp for the alloy is dependent on composition and can be determined in advance.

Gear

What Gear said...........exactly!

quote:

Originally posted by Geargnasher:
Ideally, with ternary alloys (Pb, Sn, Sb), you should be about 75-150* above full liquidus (the exact temperature at which the last visage of slush is melted), depending on alloy and mould preferences. Most people cast WAY too hot for the alloy, and the "crank up the heat" advice that is often dispensed in response to poor fillout queries is usually inappropriate. I see new casters time and time again complaining of poot fillout when they actually have an oily mould or don't cast fast enough to ever get the mould up to temperature. The key to casting quality boolits with good fillout is to heat the alloy in the pot to the temperature THAT THAT PARTICULAR ALLOY NEEDS TO FLOW WELL, and cast at the correct RHYTHM to keep the MOULD at the temperature the mould likes for good fillout.

Another very important point regarding pot temperature has to do with drossing. Tin in particular drosses out of the alloy very quickly at temperatures much over 700*, and tin becomes ineffective at breaking the surface tension at temps over 750*, so any tin in the mix or tin you have added is wasted if you cast too hot.

A good example of a well-tuned setup: Clip on wheel weight alloy with 1.5% tin added, melt point about 580*, pot temp 680-700*, two cavity Lyman mould running at 400* casts slightly satin, fully filled-out boolits with no frosted edges and razor-sharp base and bands.

Hope this helps,

Gear

Skipper check this out...http://castboolits.gunloads.com/showthread.php?t=57105

quote:

Originally posted by Geargnasher:
ultimately, the individual mould will tell you how hot it likes to be to drop good boolits, but the ideal temp for the alloy is dependent on composition and can be determined in advance.

Gear

Probably this is the more important thing mentioned by geargnasher. It has lots to do with the size of the block, the material the blocks are made from, and the size/caliber/style of bullet.

quote:

Originally posted by Skipper488:
I was casting outside last night. Conditions were poor, windy and cold. I started casting about 675 but the wind picked up and my temperature started dropping. I turned up the gas and got the temp to about 725. Then the wind died down and the temp went up to about 800. I did notice the easiest pourig was right around the 700 mark. I can't wait til I get an electric pot so I can move my casting inside, not to mention the pot I have is way too large for casting, I bought it for melting down WW (6-quart cast iron dutch oven) and it just leaves too much surface area so it oxidizes quickly and sheds heat rapidly.

Pour kitty litter or charcoal on the top of the melt and it will prevent it from oxidizing and losing so much heat. If you are outside you can try using a bottom pour ladle if you have trouble keeping the stuff from getting in the ladle and clogging up the sprue.

I finally did get around to a serious casting session and could tell when the temperature was about right. Of course I did this by starting to cast too cool with the gas set to gradually increase the temperature and kept it going right through where the bullets were dropping good right up into the too hot range. It actually seemed to work best between 700 and 750.

OK, you still missed my point. The alloy in you pot is going to be one temperature, whatever it is. The mold blocks will be a different temperature, whatever that is. For all practical purposes the quality of the boolits has NOTHING to do with the alloy temperature, and EVERYTHING to do with the temperature of the blocks themselves. To say that your boolits fill out better at 750 than they do at 700 with an alloy that is at full liquidus at 585 is to misunderstand the properties of molten metals and the process of casting. What's really going on is the hotter alloy is able to transfer more heat to the mould in a given time period, so it's a band-aid to the real problem, which is your casting pace is too slow for what the mould likes.

Alloy temp is regulated by the heating element in the pot working against enviromental conditions. Mould block temp is a function of heat transfer from the hot alloy being poured into it: The more pours in a given time period, the hotter the blocks get. On a colder day you'll have to cast even faster to keep the mould hot.

Run your alloy at a temperature best suited to it's composition (75-150 degrees above full liquidus) and adjust your casting pace to get the mould to the temperature it likes. If the blocks are too cool, don't crank up the pot heat to 750 and burn out all your tin, ramp up your casting pace instead and start casting four pours a minute until the BLOCKS are hot enough for good fillout, then level off to three (or whatever it takes) to maintain that ideal mould temperature.

Understanding the difference and effects of alloy vs. mould temp will go a long way toward casting bliss in the future when you use moulds of vastly different mass, volume, and material.

Gear

Gear,

You method won't work with aluminum blocks that get rid of the heat exceptionally fast. You have to run the alloy temperature higher. There are no SET rules in casting and that is what you are trying to do.

Also you don't set the pace you cast at, the mould and alloy temperature set the pace. How is that? If it's taking your sprue forever to harden the mould or alloy is too hot. If your sprue hardens immediately it will be the reverse of the above. I don't know anyone that cast and sprue hardens and they sit there for God know how long daydreaming or whatever before they finally knock the sprue plate open and drop the bullet.

Actually, Joe, it does work quite well with aluminum moulds of all types from Veral's to NOE to two and six-cavity Lee moulds. The "rules" are the physical properties of the alloy you use and the mould you use, these are not rules I try to make up, I'm just identifying the attributes of the materials to make life easier.

My method works just great, you just have to cast fast enough, which isn't that much of a chore if you use a bottom-pour pot. If I'm using a ladle to get primo boolits from a six-banger, I only use two cavities anyway and keep that part of the mould hot enough. Doing this I can keep even the largest blocks with small cavities (I don't do .22s so I don't know about those!) plenty hot enough to get a light frost, in the 380-400 degree range.

One of the advantages of aluminum moulds is that they cool off fast enough that you don't have to wait more than 5-6 seconds for the sprue to set enough to cut with a gloved thumb, often less. If I'm using a two cavity with huge boolits, sometimes I have to use BruceB's speed casting method where the sprue plate is quenched on a sponge half-submerged in a pan of water. Other times I set a small fan next to me and let the fan blow on the mold for a couple of seconds to speed the cooling. Iron moulds are the worst at overheating and slowing down the process, I use almost no iron moulds anymore, mostly brass and a few aluminum.

I also use a PID temperature controller on my pot and wired around the factory thermostat, that way I control the alloy where it needs to be instead of letting it run my life. WW metal needs about 700 or so, if I add a little tin it works great between 650-675 and I can run through 15lbs without having to skim the dross, since almost none has formed at the lower temps. Of course pure lead needs a lot of heat, I run it at 800+ and get my moulds pretty hot, too, for best fillout.

Gear

quote:

Originally posted by SmokinJ:
Gear,

You method won't work with aluminum blocks that get rid of the heat exceptionally fast. You have to run the alloy temperature higher. There are no SET rules in casting and that is what you are trying to do.

Also you don't set the pace you cast at, the mould and alloy temperature set the pace. How is that? If it's taking your sprue forever to harden the mould or alloy is too hot. If your sprue hardens immediately it will be the reverse of the above. I don't know anyone that cast and sprue hardens and they sit there for God know how long daydreaming or whatever before they finally knock the sprue plate open and drop the bullet.

I'm afraid I've got to agree with Joe on this-OUCH! Bullet casting is as much an art as a science. Not too long ago I read a post by Gear, stating he had finally figured out how to cast good bullets in the Lee cruise missle mold, well I was casting excellent bullets with one 6 or 7 years ago, at that time I never even owned a pot thermometer! ouch again That is the mold I took a fly cutter to and milled it down to cast a shortened cruise missle of about 140 gr, you can find it on CB but in the Aimoo archives. ouch again Theory and science make for good conversation, but cast/casting bullets is as much black magic and voodoo as anything. FWIW .02

I may not be posting for awhile. I suffered a mild heart attack after reading swheeler's last post. Give me time to recooperate.

Scot ask Larry about some certain 6.5 bullets. See what he says.

Joe

quote:

Originally posted by SmokinJ:
Gear,

You method won't work with aluminum blocks that get rid of the heat exceptionally fast. You have to run the alloy temperature higher. There are no SET rules in casting and that is what you are trying to do.

Also you don't set the pace you cast at, the mould and alloy temperature set the pace. How is that? If it's taking your sprue forever to harden the mould or alloy is too hot. If your sprue hardens immediately it will be the reverse of the above. I don't know anyone that cast and sprue hardens and they sit there for God know how long daydreaming or whatever before they finally knock the sprue plate open and drop the bullet.

I cast pretty much the same alloy temp regardless of mold type. I will run two molds & when one starts getting too hot, then I set it aside open to cool a bit, then go to the other mold. The pot pretty much runs in the 700-750deg range w/ WW alloy, a bit hotter for 25-1 lead/tin. It's been working fine like that for decades now.

I usually cast an iron or brass mould at 700 degrees, alloy temp (about 775 on the thermostat) and with 6cav aluminum moulds , I go up about 10-15 degrees alloy temp. I also use kitty litter on top of the pot.

I usually cast at 80 degrees or less--any hotter than that it's getting time to find a cool shade tree.

I think the casting pace may have a lot to do with it. I din't realize I should be trying to cast 3 pours a minute? I was just going along at an apparent snails pace of maybe 1 drop a minute. At that pace my melter will be empty in just a few minutes.

quote:

Originally posted by Skipper488:
I think the casting pace may have a lot to do with it. I din't realize I should be trying to cast 3 pours a minute? I was just going along at an apparent snails pace of maybe 1 drop a minute. At that pace my melter will be empty in just a few minutes.

Ya need a bigger pot! I use a Lee 20#, runs great upto 6cav molds. My old Lee 10# only gets used for HP molds w/ 25-1 alloy.

Also, lead vaporized around 750 degree's.
It's alot healthier for you to keep your temperature below that.

quote:

Originally posted by Antelope Sniper:
Also, lead vaporized around 750 degree's.
It's alot healthier for you to keep your temperature below that.

You're off by about 300*F

Heya Skipper

Yea, I remember when I first started casting back in 1969 making .38 Special bullets with my first Lyman mold. Had a heck of a time figuring that out..
There is science involved, but there is an art to it as well

I may have missed it, but you didn't say if you are using iron or aluminum molds..

First, your concern over zinc.. If, you have properly identified the wheel weights as lead/antimony as opposed to the other ones, you shouldn't have much worry over this. But your mix should never get hot enough for this to be a worry anyway.

The thing with wheel weights, at least the ones I am familiar with, are a lead/antimony alloy, without the presence of tin.
Tin is rather important in what we are trying to do here.

If you have ever been around soldering copper pipe joints, you know that the solder nowadays is 97% tin. It used to be, in the old days, 50/50 lead/tin. Why so much tin?
Well tin in it's molten state has the ability to creep into the smallest of voids (tight copper joint) and completely fill that void, with very little heat applied to it. Lead, cannot do this as well.

So, by adding some tin in our bullet alloys helps the alloy 'fill the void' more completely and, do it with a lower temperature.

My experience with using 100% wheel weights in iron molds is I had to cast a little hotter to get the metal to completely fill the mold to where the edges are nice and sharp. This also meant that the bullets would be frosty. Now there is nothing wrong with this, as we know to keep the velocity down under 900fps with this alloy.

Now if you add some tin to this, you not only get a harder alloy, but you don't have to heat the alloy so hot.. Probably around 600° to get nice crisp shiny bullets.
Oh, if you don't have a casting thermometer, ya need to get one..

Of course now you need to understand a little about ‘fluxing’ the metal.. More on that later I guess..

When you discover linotype, a whole new world will open up for you..

Now with iron molds, timing is very important. Experience will teach you just what pace is right with the alloy you are working with.
If you have good normal mold, where the bullets drop out without much trouble..(sometimes you can get a mold that you have to beat the hell out of it..on the handles.. to get the bullets to drop out.) you will be goin along pouring, dropping, and you suddenly see 'smearing' across your spru plate.. Now you have to decide whether your alloy is too hot, or you are going to fast, or both.

Once you get mold and alloy at the optimal temperature, you should be able to pour and drop in a nice pace until you use up all the alloy in the furnace. The only time you should have to stop the process, is to lift up on the nice soft towel, that you are dropping to bullets onto the keep them from deforming. You will run out of landing spots eventually..

With aluminum molds timing is also important, the only difference here is you just dip a corner of the mold into the molten alloy for a few seconds and you're off and runnin in no time.

Anyway, There is quite a bit too this..just my 2¢.. Hope it helps some.