Cooling the mold blocks

[4296]

While casting large 45/70 bullets I have a problem with rough(almost porous) surfaces on the bullets multiple bands- while the nose and forward driving band look good. From info I have received on this forum the consensus seems to be the mold is running too hot. I have not encountered this problem before and need to know what I can do to cool the mold between casts. I also understand that a slow(er) casting rate may be required- though I feel my cadence is not at all rushed now. Thanks for the (continuing) advice!!

[montana_charlie]

If your sprue doesn't take at least five seconds to solidify, something is too cool...mould or alloy, or both.

If your alloy is 'soft' (like 20-1 or 30-1) and about 750 degrees, you should get good bullets by emulating this guy...
http://www.youtube.com/watch?v=OiJikigdIow

CM

[prs]

Your local hardware store will have aluminum angle in about 1 1/2" X 1 /2". A piece long enough to act as a tool rest for your mold ( a foot would be plenty) while you fill a second mold (or whistle one course of Dixie) will soak away the excess heat. If you whistle the Battle Hym of the Republic, your boolits will be lousy. ;-)

prs

[btroj]

I just keep a damp rag handy. Touch the mould to it for a second and it will cool enough to help.
This is part of the learning curve.

Brad

[Walter Laich]

+1 on the damp rag. After the spur plate lead hardens I lightly and quickly touch each side and bottom on the rag and then go from there.

[Le Loup Solitaire]

When running metal that is too hot, casting too fast, or especially when casting bullets of larger caliber and weight, like 45/70's.....mold blocks can and will overheat. All sorts of signs appear like sprues that take too long to solidify, metal smeared across the tops of the blocks, and frosted bullets. The last one isn't especially bad, but there are ways to cool things down. Lowering the pot temperature is one way, casting slower is another; some folks use a piece of damp sponge or a damp pad of folded rag pressed to the top of the sprue or the bottom of the blocks. I'm not a fan of "steaming" my molds as it produces a thin film of rust which is a nuisance to remove especially in tight places. Flushing that rust with oil does nothing to chase it in screw holes. What I have found to work very well is a small electric fan such as those sold in Walmart, Target or Sears for under $10. Bigger works too. It also keeps you and the casting bench a lot cooler and the fumes away from your face. An aluminum "heat sink" to rest the blocks on will work as well as already noted. With all of the above in sync with your adjusted cadence you should have no further trouble, It may take some fishing, practice and patience to get it right, but you will. LLS

[XWrench3]

i use either the damp rag trick, or a spray bottle with water in it. sometimes one is more conveinient than the other. both work well. just be sure that ALL of the water is evaporated from the inside of the mold before you add some more lead to it, or the tinsel fairy will come, and hose you down with hot, molten lead!

[BABore]

Quick cooling the sprue plate or mold blocks is a guaranteed way to run up your boolit weight variation. Cast at a steady tempo and use a small cooling fan to cool the sprue plate after the sprue solidifies, then the open mold after dumping the boolits. Time your cooling times for repeatability. 3-5 seconds of fan time at each point is about right.

[Tazman1602]

+1

What I do when casting the big boys (45-70's, over 400 grains) is to keep another mold handy ---- usually a .444 Marlin mold that doesn't heat up so quick.

I make two pours on the .444 mold then one pour on the big 45-70 and it appears to keep the big 45 mold cool enough to cast nice shiny bullets every time.

I have also found (I know I know.............) that for some reason, even if I am extremely careful in controlling temp of the mix, that ladle pouring the big bullets results (for me at least) in a more consistent, round bullet than using my hated drip-o-matic bottom pour pot.

It's just something that works for me, the OP may find a different way, Bruce's suggestion of the small high speed fan is an excellent suggestion also.

Art


Quick cooling the sprue plate or mold blocks is a guaranteed way to run up your boolit weight variation. Cast at a steady tempo and use a small cooling fan to cool the sprue plate after the sprue solidifies, then the open mold after dumping the boolits. Time your cooling times for repeatability. 3-5 seconds of fan time at each point is about right.

[dverna]

Damp towel worked for me when casting with a 10 cavity H&G. Flip mold over and let sprue and plate cool for a few seconds. That mold gave me a work out too! After three hours my forearm had enough; but I had oodles of bullets.

Don Verna

[Dale53]

I am a BIG fan (pun intended) of a manicurists fan (I got mine at Target, but Walmart also has a similar one). I fill the mould, then slide it over under the fan and the sprue solidifies in 2-3 seconds. It actually speeds up the casting process and it cools the mould at the same time, maintaining excellent casting temperature:

http://i269.photobucket.com/albums/jj80/Dale53/Castingfan-3723.jpg

Dale53

[Bullshop]

I use two of these type fans. I have a fairly heavy aluminum plate on my bench top to set the mold on and there is a fan on each side. Both fans blow in the same direction so one is pushing hot air away from the mold and the other is pulling.
This does increase the air velocity over the mold that only one fan can provide.
I believe this because if I turn off one fan I can hear the other fan slow down.
Turn it back on and the speed picks up again.
Works great for me and allows between 3 and 4 casts per minute even with large caliber multi cavity molds.

[John Boy]

Gentlemen: Explain to me why I can cast using a 6 gang mold with the melt temperature @ a constant 710 degrees - the bullets are not frosted - over 95% of the time, the bullets gravity drop out of the mold - and for 20# batch of 45190's using the Lee 6 gang, the bell curve weight variance is no greater than 1 grain and with a 3 second pour in each cavity & a 5 second sprue puddle frost .... I never had the mold over heat and had to cool it with a fan - wet sponge/towel or a shallow pan of water?
In fact, I casted another 20# batch the same way and the mold never over heated where at 5 seconds waiting for the puddle to frost, when I cut the sprue ... there was lead smeared across the tops of all 6 cavities!

[220swiftfn]

Gentlemen: Explain to me why I can cast using a 6 gang mold with the melt temperature @ a constant 710 degrees - the bullets are not frosted - over 95% of the time, the bullets gravity drop out of the mold - and for 20# batch of 45190's using the Lee 6 gang, the bell curve weight variance is no greater than 1 grain and with a 3 second pour in each cavity & a 5 second sprue puddle frost .... I never had the mold over heat and had to cool it with a fan - wet sponge/towel or a shallow pan of water?
In fact, I casted another 20# batch the same way and the mold never over heated where at 5 seconds waiting for the puddle to frost, when I cut the sprue ... there was lead smeared across the tops of all 6 cavities!

Because an aluminum mold sheds heat faster than a steel/iron one does.........
Same reason for the smear......Your sprue plate was too hot, but the mold was fine.


Dan

[Reload3006]

+1 on the aluminum shedding the heat faster .. Aluminum is the most efficient metal commonly available at transferring heat. It is the metal of choice for heat sinks on all electronic gear. It has a second advantage in that Lead Solder etc will not stick to it.

[williamwaco]

+ 1 On the fan.

Another option is an old worn out hair dryer - one with the heater burned out but the blower still working.

[snuffy]

Since no one else mentioned it, I will. A wet sponge. Really wet, but not sitting in water, just soaked. I ONLY use it for big boolits like 452-300's in a 2 cav lee, and the bigger .501-440 also in a lee 2 cav. AND that's while casting with 2 molds at the same time. Pour, set on sponge for 5 seconds, set the mold down on the drop towel. Shear the sprue on the other mold, drop those boolits, pour that mold, set on sponge, then pick up the last one.


This keeps the molds cool enough to cast shiny boolits, completely filled out, no frosting.

[John Boy]

Snuffy, having to cool a mold has only one cause - the melt is too hot. So why not just reduce the pot temperature so the sprue puddle frosts in 5 seconds?
PS: Today's sponges are made from synthetic materials ... that can melt. Use a wet folded wash rag and if you need to cool the mold for 5 seconds - your casting WAY TO HOT ... 1 second is sufficient

[snuffy]

Snuffy, cooling a mold has only one cause - the melt is too hot. So why not just reduce the pot temperature so the sprue puddle frosts in 5 seconds?
PS: Today's sponges are made from synthetic materials ... that can melt. Use a wet folded wash rag and if you need to cool the mold for 5 seconds - you're casting WAY TOO HOT

I should have said the alloy was at 675 degrees, measured and controlled by my PID. If the mold gets too hot, the boolits get frosty AND undersized. Hence the need to cool the molds. If I didn't use some sort of cooling, I would be making only about 50 boolits a hour, waiting for the mold to cool. I may try the method listed above, with the personal cooling fan idea. Or the aluminum angle to use as a heat sinc.

Yes, the material the sponges are made of did melt and adhere to the bottom of the mold, IF the water content was too low on the surface. Minor inconvenience.

The point is; if you're using a lee two cavity mold that has two BEEEEG boolits in it, the whole mold gets too hot real quick. No need for the same blocks with tiny 115 9mm boolits. Just the opposite, you'll be needing to find a way to keep it hot.

[Dale53]

Some time ago, Mike Venturino mentioned using a Manicurists fan (small 6-7" fan the ladies use to dry their nails) mounted where it blows directly on the top of the mould when waiting for the sprue to cool.

I bought one at Target Stores for $6-7.00 (Walmart has a similar one at a similar price). The fan blows softly but does the trick equally well on iron, brass, and aluminum moulds. I cast rather quickly (used to cast commercially) and ALL moulds tend to overheat for me. The fan allows me to cool the sprue in TWO SECONDS without smearing lead over the top of the mould. It also helps to maintain mould temperature. I would not willingly cast without it.

Thank you, Mike!

Dale53

[cbrick]

I also use a fan while casting but a note of caution, it should be set up similiar to what Dale has in post #11. Mine is set up a bit further from the mold but maybe my fan is stronger. The caution is to NOT have it blow onto the alloy in the pot, that will tremendously increase the rate of oxidation on top of the pot if it does.

Rick

[gandydancer]

Cast with at least 2 molds. fill one set it down fill the next one set it down pick up the 1st one remove bullets. refill it set it down pick up the 2nd mold remove bullets refill mold set in down. so on & so on if your working with single cavity molds use three. been doing it that way for over 40 years. GD

[Andrew Quigley]

I learned the wet rag trick on the site from Goatlips. I use a Lee 6 cavity mold for my 9mm, 38's and 45acp & 45 colts. Try to use 2 molds at a time and switch everyother pour but sometimes I only need a bunch of the one so I use a soaked rag and cool the sprue plate and keep right on running. Did a bunch of 9mm and 45 acp this weekend the same way.

[Carolina Cast Bullets]

I like the two mold method. Works really well if you have two molds of about the same size boolit. Works even with 6 gang molds.

Jerry
Carolina Cast Bullets

[MikeS]

I use a small fan, and I've never had a mould overheat on me from casting. I have had a mould overheat on more than one occasion from putting it on the hot plate with it set too high while I took a short break (like when adding more lead to the pot), but that was purely my mistake while I was learning the settings on a new hot plate. In the other direction, I have a 30 cal rifle mould that's hard to keep hot enough, but I suspect that part of it's problem is that it doesn't release it's boolits as easily as it should, so the time taken trying to get them out is letting the aluminum blocks cool off too much. I'm going to try leementing the mould, and see if that helps.

[TCFAN]

Like Dale53 I too picked up on what Mike Venturino said about using a small fan to cool his molds. I bought one at Wal-Mart and mounted it on a piece of steel for a heat sink and it works great..............Terry