Mold cooling plate, retired my fan and wet rags!

[Drew P]

I’d been using a fan to blow on the mold for temp control once up and running hot. I’ve also used a wet rag and set the mold on that, but it required constant water application and was a hassle. But recently I started just sitting the mold on the granite surface of my casting bench and noticed that it kinda sucked some of the heat out of the mold in a way that also left the spruce plate with some of the heat. So that gave me an idea to use a thick 3/4” chunk of steel plate instead and WOW does it work amazing! Way better than the fan or the wet rag technique. Sucks the heat out quicker than I’d expect, and stays consistent. Anyway, not sure why I didn’t think to try this before, I guess I didn’t think it would work this well.
SO, my casting setup got a little better and I thought I’d share my findings.

[Smoke4320]

Great on you to share your discovery

[Conditor22]

Gotta try that, I also am tired of having to keep adding water.

Thanks for sharing.

[John Boy]

No need to keep cooling the mold down if one uses a bimetal thermometer - digital thermometer or a PID.
Objective is to bring the melt & mold temperatures up so a 5 second pour frosts the sprue puddle in 5 -10 seconds, depending on bullet weight ... and hold those temperatures constant within 5 degrees

[rockshooter]

I usually just set the mold on the cement floor beside me. I cast with 2 molds at a time and if the cadence is right overheating isn't an issue very often. If I notice that the bullets seem to be sticking in the mold I just set the mold on the floor between fillings.
Loren

[Drew P]

No need to keep cooling the mold down if one uses a bimetal thermometer - digital thermometer or a PID.
Objective is to bring the melt & mold temperatures up so a 5 second pour frosts the sprue puddle in 5 -10 seconds, depending on bullet weight ... and hold those temperatures constant within 5 degrees

I can easily outrun a 5 sec Frost and benefit from some cooling regardless of lead temp. I’m PID.

[Drew P]

I usually just set the mold on the cement floor beside me. I cast with 2 molds at a time and if the cadence is right overheating isn't an issue very often. If I notice that the bullets seem to be sticking in the mold I just set the mold on the floor between fillings.
Loren

You’re either really short or have a lot stronger back than I do.

[bmortell]

I do that sometimes just on the steel work bench. it would work differently based on the thermal conductivity of the metal, and thickness. in order stainless has garbage conductivity, steel, brass, aluminum, copper, and silver being about best.. incase you have a stash of kilo silver bars handy and need boolits cold immediately.

[kevin c]

...thermal conductivity of the metal...in order...stainless has garbage conductivity, steel, brass, aluminum, copper, and silver being about best.

Would using a copper bottomed frying pan upside down work?

[bmortell]

Would using a copper bottomed frying pan upside down work?

first if you use it id drill holes in it to make sure nobody ever cooks in it after.

copper bottomed can mean many things, some might be aluminum or stainless with copper bottom or clad or many other designs.

to perform a test just have several metal things you could use and set an ice cube on each and measure how long till its melted. melting rate would match mold cool rate, fastest melt would cool mold the fastest

[Drew P]

I wonder how well a nice big lead ingot would work.

[kevin c]

I'd guess more mass would help, so maybe the pan wouldn't be enough of a heat sink. The lead now, plenty of mass, but I don't know about the thermal conductivity. Then there's the need for flatness to get good contact with the mold.

I don't know about yours, but my big storage ingots don't ever have truly flat sides, being cast in sheet steel bread pan molds. The new aluminum Cast Boolits molds, though, may be both rigid enough and big enough to cast ingots that my MP 8 bangers can sit on.

Or next time I hit the scrap metals dealer I can just buy a block of an appropriate metal.

[JimB..]

A few folks have been talking about what to do with copper jackets harvested from range scrap that the scrap yards don’t want. An inch thick slab would suck up some heat in a hurry.

[lightman]

I control my mold temps by my casting speed and managing the pot temps. But I use a 1/2 X 6 X 60" piece of steel for a heat sinc for my ingot molds when smelting scrap. I've tried the wet towel thing, the moving air thing, maybe a few other things and the steel plate works about as well as anything and with the least hassle.

[PJEagle]

Thanks for sharing your experience. I use a PID to control my alloy temp and my mold temp, but sometimes my brass molds go above my set temp. I like your idea better than the fan I am using now.

[Wag]

I wonder how well a nice big lead ingot would work.

That's what I use. I keep one or two on the bench and between pours, I set the mold on a lead block and it works beautifully.

--Wag--

[gunarea]

Hey Guys
Proper and consistent cooling of a receiving mould is imperative when producing match quality projectiles. Removing heat from a mould is best done through the solid bottom, rather than the bi-metal or tri-metal top. While the wet rag is efficient, it is not consistent unless tended to with each use. Water is bad news for ferrous metal moulds. Plate metal heat sinks are also a common option but does not shed at a given rate to match applied rates. Your approach from a heat sink perspective is correct. Let me offer effective options.

Attachment 241103

The common coffee can will draw heat and dissipate very effectively, provided the surfaces match up. Take off any plastic labels as they will make for a mess. Larger size cans will do a much better job than smaller ones. An aluminum heat sink from amplifiers or computer power supplies does exactly what we want to happen.

Attachment 241104 Attachment 241105 Attachment 241106

Add an integral fan and cooling rates increase along with repeatable consistency. My statements are backed with experience and documentation. Careful monitoring of temperatures has shown this method most reliable. The computer supply heat sink was a dollar at my local geek service. Although the cooling fan was rated at 12.5 V/dc, I found a 9v/dc phone charger ran the fan a bit slower and maintained more consistent empty mould temperatures. Consistent receiving mould temperatures produce much more consistent projectile weights. Much more consistent projectile weights, produce higher accuracy and smaller group size. I do not particularly enjoy casting, I do enjoy winning gold medals. Follow my example and reap the benefits.
Roy

[Wag]

Roy, great idea with the CPU heat sinks.

--Wag--

[RED BEAR]

I cast in my garage so if a mold gets to hot i just set it on concrete floor. Cools off pretty quick.

[44magLeo]

As I was reading this it made me think of the aluminum plate thingy I got for quick defrosting of frozen foods.
It lead me to think a thick piece of aluminum would work well. It will draw of the heat and dissipate it into the surrounding air quickly.
I got to gunarea's post and it all came together. A real Duh moment.
I work on old motorcycles. Often the rectifiers go bad for the alternators and stock ones can be hard to find. I build new ones and use computer heat sinks for cooling.
As AC gets rectified to DC the rectifiers get hot, so I use computer heat sinks to cool them.
It just never occurred to me to use them for casting.
Thanks.
Leo