Lead vs mold over-temp

[wingnut49b]

Hey Guys-

Getting this figured out slowly, and made another trial run this eve.

The first few cycles on the 6 cav HG#68 clone were wrinkled with poor fill. Obviously cool yet.

After a few runs they got really good. Great fill, shiny bullets.

Then I got it too hot, and it took a while to cool the sprue, and the bullets were frosted badly.

Do I need to cool the mold or the pot? Maybe both?

Bruce B's Speed casting can cool the mold, and adding a new PID will hold the temp. Just not sure which to adjust, or if I am missing something.

I searched but didn't see what I was looking for. If I missed it, point me in the right direction...

Thanks!

LEE 20lb bottom pour
Mihac 6 cav aluminum HG#68 PB
New caster operating it all...

[RobS]

Your mold sounds like it wasn't up to temp at first and then the overly hot alloy raised the mold temp where you were casting bullets where everything was in sink, but only for a bit until the mold started to overheat with the too hot alloy.

I've found that a hot plate makes a world of difference in getting mold temp up from the get go and makes it easier on dialing in the right setting for the pot. Mold temp is determined by two factors, alloy temp and casting tempo. Adjust one or the other. I like to cast at a comfortable rate and hate rushing so if my mold shows signs of being too cool then I'll run the alloy at a higer temp. That's just how I do it where as others will pickup their casting temp and run cooler alloy temps.

[AZ-Stew]

The mould temperature controls boolit quality.

If it's too cold, you get wrinkled boolits.

If it's too hot, you get frosty boolits.

The alloy temperature and casting rate control mould temp. If you run a cooler alloy temp., you'll have to cast faster to keep the mould hot enough for good fillout. If you run a hot pot, you'll need to cast slower to prevent overly frosty boolits and slow cooling sprues.

I don't recommend cooling the sprue by artificial means, either by water or by a fan blowing on the sprue plate. The sprue must remain molten until the alloy in the mould cavity cools and shrinks, thereby drawing molten alloy from the sprue puddle to keep the cavity filled as the casting shrinks. If you cool and harden the sprue puddle before this process is complete, you will get base voids, since the shrinking alloy will draw in air.

Regards,

Stew

[theperfessor]

In some ongoing testing I am conducting I run my molds at 400F and run the pot at 100 to 150F above the melting point of the alloy. I have a dual PID controller and have a thermocouple in my mold and one in my pot, the outputs control my hot plate and the pot respectively. I fine tune the pot temperature to get a 4 to 6 second freeze time on the sprue puddle.

[454PB]

I like frosty boolits.

I've found that it's easier to control mould temperature than alloy temperature.

I usually cast with two double cavity moulds, which slows the pace enough to prevent overheating the mould. If it doesn't, I place a folded towel in a cake pan of water and quickly touch the bottom of the FILLED mould on it. After some practice, you'll be able to control mould temperature within 20 to 40 degrees.

[wingnut49b]

Thanks guys. I knew the answer was here. Controlling mold temp makes perfect sense.

I'm going to build a PID to control the alloy temp better. $30-35 for a thermometer, or $100 for a PID... I'm going for the bling!

I like the logic on not artificially cooling the sprue. Makes sense. Not sure I could see the accuracy yet, but hopefully I will by the end of the summer. My 1911 is currently much better than I am.

[lwknight]

Just slow down the pace a little when you realize that the molds are getting too hot.
Like AZ Stew said , keep the alloy temperature down to as low as it will work for you and you will get more production of fine perfect boolits.

[stainless1911]

What is a PID?

[lwknight]

Several posts in the casting equipment section.
Lots of discussion there if you search the threads.
Its an automatic high tech thermostat with a temp probe and relays.

[John Boy]

Wingnut, a thermometer in the melt controls the temperature of both the melt and the mold. When the sprue puddle frost at 5 seconds, the lead and mold are at the temperature to drop nice filled out bullets that are not frosted. Then hold that temperature reading on the thermometer. And make sure to give a mold a good head pressure with the spout fitted tightly in the sprue plate hole and hold the pour for 5 seconds. The edges of the bases will be 'razor' sharp, the sign of an excellent bullet

[mooman76]

It just takes a bit of getting used to. As you see the mould getting up to temp, turn your pot down a little at a time until you get to where it is constant. After awhile it will be second nature to you. I usually start out hot til the mould get to temp and gradually turn it down. I got a new to me mould this weekend. It was a small single cavity steel mould. I had to run it almost wide open to do good boolits.

[theperfessor]

PID stands for proportional-integral-derivative. Its a control mode that looks at the error between your set point and the actual measured value, the duration of the error, and the rate of change of the measured value. I wrote this about my home-made dual PID controller:

http://www.lasc.us/DualPIDTempControl.htm

[44man]

My casting is controlled by my pace which is kind of slow and comfortable. Time changes between pours with no thought needed. The lead temp can vary a little with no change. I don't time or measure a thing.
It all comes from years and years of learning to relax and not trying to make a million boolits at one sitting. It might be why casting is so BORING to me, nothing to fiddle with. I might make 50 or 100 or just dump a 20# pot. That is my limit, you will not see me over a lead pot all day.
Yes, it means more sessions when I run out but casting, lubing, loading really is boring to me. Shooting and hitting is where I have the fun. For instance, I needed .44 loads for deer, had 14 of one boolit left, not sighted for them so sighting and some shooting left me with 5. I shot 2 deer and have 3 shots left.
Then I need to cast for many revolvers and calibers.
I only do it because it is cheaper and cast shoots better then buying anything and not even a store bought boolit will match my own.
Casting is a big adventure to the new guy but it will wear off in time until you are in the comfort zone---then comes BORING! [smilie=l:

[fecmech]

I would respectfully disagree on artificial cooling of the spru. I use the Bruce B method and if done properly there are no base voids. As Bruce said in his explanation you hold the mold and watch till the spru puddle sucks in before you place the damp rag on the spru. Once that action takes place there is no further transfer of metal from the spru puddle to the bullet base.

[RobS]

My casting is controlled by my pace which is kind of slow and comfortable. Time changes between pours with no thought needed. The lead temp can vary a little with no change. I don't time or measure a thing.
It all comes from years and years of learning to relax and not trying to make a million boolits at one sitting. It might be why casting is so BORING to me, nothing to fiddle with. I might make 50 or 100 or just dump a 20# pot. That is my limit, you will not see me over a lead pot all day.
Yes, it means more sessions when I run out but casting, lubing, loading really is boring to me. Shooting and hitting is where I have the fun. For instance, I needed .44 loads for deer, had 14 of one boolit left, not sighted for them so sighting and some shooting left me with 5. I shot 2 deer and have 3 shots left.
Then I need to cast for many revolvers and calibers.
I only do it because it is cheaper and cast shoots better then buying anything and not even a store bought boolit will match my own.
Casting is a big adventure to the new guy but it will wear off in time until you are in the comfort zone---then comes BORING! [smilie=l:

Make another mold and some of the boring wears off for the casting front and more so with load development and shooting....................or..................by another gun in a caliber you don't already cast for so you have to make another mold and it'll begin all over as you learn what the mold likes. :bigsmyl2:

[thx997303]

I wouldn't be concerned about frosty boolits myself.

All the boolits I case and keep are frosty.

Far as I am concerned, so long as you are getting good fill, and the sprue puddle isn't staying liquid for forever, I would just pick shiney or frosty and stick with it.

[AZ-Stew]

I would respectfully disagree on artificial cooling of the spru. I use the Bruce B method and if done properly there are no base voids. As Bruce said in his explanation you hold the mold and watch till the spru puddle sucks in before you place the damp rag on the spru. Once that action takes place there is no further transfer of metal from the spru puddle to the bullet base.

I won't argue with that, but once the dimple forms, the sprue is hard enough to open the plate without further cooling.

Regards,

Stew

[stainless1911]

With all due respect, considering that Im a new-b, what's the difference between cooling the sprue with a small fan, and casting outside on a cool spring or fall day in a breeze?

[Bullshop]

I have to agree with AZ-Stew. I dont understand why there would be a need for further cooling after the flash or pull down or what ever you will call it.
I find that I get a smoother base if I cut the sprue at the flash/pull down point and not allow further cooling. Cooling beyond that point makes the sprue harder to cut. I try to avoid having to tap the mold or the sprue plate with anything and in this way I can cut the sprue very easily simple by pushing the plate with a finger. I do hold slight downward pressure on the plate while cutting the sprue and that also aids in having a smooth flat base on the boolit.
Tapping on a sprue plate to cut a sprue cooled beyond the flash/pull down can allow the sprue plate to climb the sprue when it is being cut and result in a small bump where the cut takes place. If fairly centered the bump has little effect on accuracy but does make applying a gas check more difficult. I think the bump is fairly common and is why all my early ejector pins from my sizing dies have a flat end and a concave end. The concave end would allow for the bump but still seat the check square all the way around the edge. That is speculation on my part but I could never figure any other reason for the concave end. Apparently they no longer make the ejector pins this way and I am not surprised with that because it takes more time to do so and that means less profit at the same price.

[45r]

I think opening the sprue plate as soon as possible is better also,better to have a little tear than a bump from the sprue hole.The plate needs to stay hot enough for square bases,If I need to cool the mold with fan or damp towell I do it after plate is opened and then cooling the bottom of mold.I keep boolits that have sharp square bases with perfect fillout and heavy consistant weight for hunting and testing loads and only use others for offhand plinking.Sometimes it takes a little time to get a mold where it likes to cast perfect boolits.I look my boolits over and keep the pace where the mold wants to be.I water quench my boolits all at once later.The nice thing about casting your own is you can throw them back in the pot later if they don't come out right.The next time you cast everything might come out perfect.I've found that the bases have to be right and the GC's on right to get the best groups.The heaviest ones I use for hunting.

[firefly1957]

I always used to have the same problem so now I just get out at least two molds and alternate that way neither mold overheats. I do cut the sprue after I pour the lead in other mold it works well for me.

[Jech]

That's quite the project there Perfessor! Your product looks downright scientific, makes feel like I'm back in the stone age gauging temps by eyeballing everything. I'm hoping that SWMBO buys me a lead thermometer for Christmas, gotta start saving up to have one of your PID units custom crafted ;)

~ Jech

[AZ-Stew]

With all due respect, considering that Im a new-b, what's the difference between cooling the sprue with a small fan, and casting outside on a cool spring or fall day in a breeze?

One or two seconds, at most, in the hardening of the sprue. The wind speed from the fan has more effect than the air temperature. And the cooling time will depend on the "system" temperature.

Regardless, depending on alloy and mould temperature, it may or may not result in base voids. It all depends on whether the sprue cools before the alloy in the mould cavity has cooled and shrunk to it's final volume. The cavity cooling time will also be affected by the cavity volume. A .45 caliber 500 gr boolit will take longer to cool and shrink than will a .38 caliber 158 gr SWC or a .22 caliber 55 gr boolit. You can "speed cool" the sprue with less risk on the smaller boolits.

Regards,

Stew

[fecmech]

I won't argue with that, but once the dimple forms, the sprue is hard enough to open the plate without further cooling.

Regards,

Stew

Actually AZ if you cut right after the dimple forms, particularly with WW metal, it is still very soft and will gall and smear on your spru plate and the top of your blocks. The wet rag solidifies the metal and prevents the smearing.

[theperfessor]

Bullplate! I can cut my sprues by hand as soon as they freeze w/o smearing by using it.

[geargnasher]

OK, here's the best explanation I can give:

RULE #1: Mould temperature determines boolit quality, not pot temperature. Each mould is somewhat unique with regard to its "ideal" casting temperature, or the point at which it casts the boolits you think are best. This temperature is controlled by casting rhythm (# of pours-per-minute). Factors such as ambient temperature, humidity, quenching the sprue plate, alloy temperature, method of pour (ladle or bottom pour), etc affect the ideal casting pace for each mould in each casting session.

RULE #2: Alloy temperature should be maintained at the temperature that is chemically best for the particular alloy blend you're using. Generally, boolit metals should be maintained at a temperature 75 to 150 degrees F above FULL liquidus, the point at which the alloy is totally molten and has no frozen antimony crystals floating around in it. Tin, which is generally used in small amounts to aid fillout, drosses out at an astronomical rate above 750 degrees F, so all alloys containing any significant amount of tin (.5% or above) should be maintained well below that. Most clip-on wheel weight metal melts around 575* or so, and often 650 degrees is all that is needed for casting. Pure lead, which melts at about 621 degrees, requires a much higher pot temperature, usually near 800 degrees, for good fillout. Pure lead boolits such as Minie balls or thin-skirted shotgun slugs need a very hot mould, too. Straight linotype will make excellent boolits at a pot temperature of only 550 degrees or so, but if the pot is run up to 750 degrees the surface drosses over so quickly that it is impossible to skim it shiny.

The bottom line is most people cast too slow (mould stays too cool), and run their alloy too hot in an attempt to compensate for that, hence the common misadvice to "crank up the heat" to get good fillout.

If you maintain your alloy at the best temperature for the alloy and adjust your casting pace once your mould comes up to temperature, you can maintain a long run of consistent boolits.

Gear

[lwknight]

Gear , you must be reading my posts. LOL!
Thats exactly what I've been preaching since I joined up here.

[geargnasher]

Gear , you must be reading my posts. LOL!
Thats exactly what I've been preaching since I joined up here.

Yours and many others, combined with information gleaned from the RCBS bullet casting manual, the Lyman Cast Bullet Handbook #3, the more complete version of the metallurgical data listed in those in the Metals Handbook, as well as a very dim recollection of some engineering classes from college. All verified with a good casting thermometer, PID controller/thermocouple, IR thermometer, and a little experience.

Gear

[Dale53]

I pre-heat my moulds on a hot plate. I heat to just under casting temperature. One or two casts and I am up to heat. I am one that uses a small manicurists fan
to cool the sprue. That way, I have the sprue ready to cut in 2-3 seconds. I often use six cavity aluminum moulds but also run iron and brass moulds (brass is my favorite). They ALL benefit from the fan cooling the sprue. It also helps to regulate the over all temperature of the mould. I get into a steady pace and run the 22# pot nearly dry. Six cavity moulds take me 45-60 minutes to empty the pot. A four cavity is slightly longer. I can empty a pot with the MiHec two cavity Cramer style hollow point moulds in 1½ hours. I am talking match quality bullets. All of this with a steady pace.

I listen to a talk show normally when I cast. I am fresher in the morning and that's when I cast. It has been bitterly cold around here (at least bitter by Ohio standards - gonna get down to 5 degrees tonight). I'll wait until it warms up a bit (Friday) and plan to cast Friday and Saturday to keep my stock of bullets up. After next week we are supposed to get into a warming spell and I look to cast nearly every day.

FWIW
Dale53

[amosp1]

I would like to ask a few questions. I made a bunch of boolits and have some problems. I am using a .458 300gr fp mold in 45/70 2 cavity. The mold makes 325 gr boolit w/gas check. My boolits are coming out at finish size or undersize. when i size them at .458 they are out of round.
Am I heating the pot too hot? They are mostly frosted. Are the boolits I already made re-useable. Did lose tin or antimony? I have been mixing 18lb w/w to 2lb lino, with 3oz of tin.in a 20lb pot. If I reuse them should I put anything back in the mix or just lower the temp?
I am thinking my temp guage is off. I will get it checked. Any help would be appreciated.
Thank You

[454PB]

Your alloy is fine, and if you decide to recast with it, that will be fine as well.

It sounds like you have a mould problem. Out-of-round is not good, depending on how much.

I'm guessing it's an aluminum mould, they tend to increase the likelihood of "frosted" boolits.

As I said in my original reply, there's nothing wrong with a light frosting, but when it goes too far, you need to drop the speed of casting, alloy temperature, and mould temperature. See all the previous posts to accomplish that.

[geargnasher]

Sounds like a mould manufacturing problem to me, especially the out-of-round part combined with undersize. Usually out-of-round combined with oversize is trash between the block faces causing incomplete closure.

Gear

[Dale53]

amosp1;
If your bullets are "almost" frosted that can lead to an undersize bullet where the frosting is. On the other hand, if the bullets are uniformly frosted over their entire surface will not really be a problem.

I cannot emphasize too strongly how important I consider pre-heating a mould. If you have an aluminum mould, you can put the base corner into the melt for thirty seconds and that will pre-heat your mould - I prefer a solid top (not a Calrod unit) on a hot plate to preheat my moulds.

At any rate, if the mould is pre-heated, and the metal is up to temp, then you should NOT have frosted spots on your bullets (typically in one, undersized place).

Maintain a candence when casting. I have found that a small manicurists fan ($7.00 or so at a WalMart or Target Store in the fan department) helps me to not only cool the sprue quickly but to help maintain proper mould temperatures when that cadence is working for you.

FWIW
Dale53

[Crawdaddy]

PID stands for proportional-integral-derivative. Its a control mode that looks at the error between your set point and the actual measured value, the duration of the error, and the rate of change of the measured value. I wrote this about my home-made dual PID controller:

http://www.lasc.us/DualPIDTempControl.htm

Now I know how you got the name perfessor! Great explanation.

[MikeS]

You don't mention what temp you're casting at. If it's too high, that can cause the boolits to come out smaller. Try casting right around 650F and see if the boolits are any larger. If they're still too small, you could try beagling the mould (do a search here on 'Beagling', basically it's putting strips of metal tape on the faces of the mould to hold it open .002 or so) and see if that helps. Once the boolits are large enough sizing them should take care of any out of roundness they have.

You can remelt any boolits you consider to be rejects at any time. I recently found some boolits I cast when I first started, and was amazed that I considered them keepers back then! I just tossed them back into the pot, the boolit lube on them acts as a flux, so there's no reason to try and remove it.

Read Gear's post above a few times, it's all good info that will help you cast good boolits!

[Boolseye]

I like frosty boolits.
+1. Once the mold's hot enough, I just keep going 'til I'm done. They tend to self-regulate and get shiny again.

[FirstBrit]

I would like to ask a few questions. I made a bunch of boolits and have some problems. I am using a .458 300gr fp mold in 45/70 2 cavity. The mold makes 325 gr boolit w/gas check. My boolits are coming out at finish size or undersize. when i size them at .458 they are out of round.
Am I heating the pot too hot? They are mostly frosted. Are the boolits I already made re-useable. Did lose tin or antimony? I have been mixing 18lb w/w to 2lb lino, with 3oz of tin.in a 20lb pot. If I reuse them should I put anything back in the mix or just lower the temp?
I am thinking my temp guage is off. I will get it checked. Any help would be appreciated.
Thank You

It is not necessarily your mould which is out of round, it may well be that your mould is too hot! From your alloy recipe it sounds that your alloy has about 4% Antimony and about 2% Tin with a hardness of air cooled bullets of about 15-16BHN I observe this with some of my moulds with a similar alloy composition. And the problem doesn't occur immediately. but after a certain time and goes hand-in-hand with the frosted areas. I suggest you check some of your bullets for diameter and out of roundness before they develop the frosted appearance. If diameters are okay - even thoough you might have some slight wrinkles on the nose section then I bet it is a mould temperature issue. If your bullets are only partly frosted, check the bullet diameter on the driving bands and compare them. If non-frosted diameter is larger than frosted then again probably mould temperature issue. The moulds where this occurs most often are 2-cavity, with large bullet diameters and heavy bullets like 45 Colt or 45-70 Gov. The problem is partly due to the very thin metal dividing wall between the two cavities. IMHO this is too thin and the metal in this area cannot dissipate the heat as well as in other areas and/or the vent lines don't work as they should. Hence bullet fill-out in this area is poor and we see it in the undersize and/or out-of-round bullets. Short term remedy is to cool the mould with a damp cloth while bullets are still in the mould. But medium term also reduce the melt temperature by 20-30°F.

Best regards & merry Xmas,

Adrian, Germany.

[tuckerdog]

alloy temp 750 iron or whatever they call'em molds get a 5 count aluminum or brass get a 3 count after sprue frosts unless I'm running 2 molds at a time (which is most of the time) then I dont worry about it just cast and smile at a big ole pile