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.

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[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. :p

[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.

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.

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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

[NyFirefighter357]

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

I was going to suggest the same. Pour 1/2"-1" of lead into an old baking pan as a mold.

[bmortell]

if you were gonna make a lead heat sink you would just have to keep re melting the surface with propane torch as it solidifies so it don't suck down or get rough crystal surface. that's what I do to my pot ingots so I can write on them after it makes them nice and flat

[Drew P]

Only problem with lead might be that we would eventually cannibalize it for other purposes!

[kevin c]

So. gunarea, to make sure I understand, you're saying a solid plate of metal, even one with good thermal conductivity, will take the heat out of the mold, but may not dissipate that heat very well itself, and will therefore start heating up and will pull heat out of the mold more slowly with each subsequent attempt? That means cooling the mold the same amount takes longer and longer, and disrupts the casting cadence? A designed heat sink (+\- a fan) is better because it's made to radiate heat out through the fins as quickly as it takes it in from the object to be cooled?

BTW, I found out the wet rag technique is hard on aluminum molds too, or at least the steel hardware on them; heat, drying and surface oiling did not prevent a nasty rust problem from developing from the steam and water, especially inside the threaded parts.

[robg]

I use 2 molds if they're getting to hot I add another mold so I don't have to slow down and I get more boolits cast .

[gunarea]

Hey kevin c

You are correct. Continued heating of the plate heat sink will eventually result in raised temperature. Just as cooling with water, the water will increase in temperature and give a different cooling coefficient. Surface area is key for heat dissipation. The air cooled heat sink will dissipate heat quickly enough for the temperature of the heat sink to be at a consistent receiving temperature. Without the spaced fins, it is a plate heat sink. Heat sink cooling fins come in different lengths for different applications and desired heat levels. They are called "cooling fins" and the lengths are based upon surface area desired. A "finned" heat sink is designed specifically to remove heat from a source and then shed the heat efficiently in the air flow.


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My particular set up has a digital quick change thermometer attached directly to the middle of finned section. With a Lyman four cavity 38 caliber mould, the sink will rise to 278* before moving the mould off to empty it. By the time I fill the four cavities and return the mould to the sink, the temperature of the sink is at 72* again to receive the hot mould.

I understand the vast majority of shooter and casters do not need, nor are interested in, hyper accurate cast projectiles. This thread invasion is primarily for those who wish to participate at high level competition. Even above average skill shooters will not notice significant advantages. My shooting coach told me, "you ain't that good, so everything else better be perfect". 600 X 47x does not happen with "good enough" ammunition! Take what you want from the information offered, I'll see you at the match.
Roy

[Sig556r]

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

Will still take time if you cast with multi-cav steel mold with large block like RCBS...

[Clouds]

I have been using a old 12" Steel Challenge (Bennox) plate to do this for a while now.
I think that for an extended casting session, one would need more than one plate or one per mould.

[Kraschenbirn]

For several years I've been using a 6"x12" piece of 1 1/4" aluminum tool plate for a heatsink. By the time it becomes noticeably 'warm' my carpal tunnel has begun to kick in and I know it's time to take a break, anyway.

Bill

[Hardcast416taylor]

Back when I was still casting I was doing it to feed my hobby, shooting. I went the route of trying for some sort of a heat sink to draw off excess mold heat, but was always looking for a better way. I finally hit on a truth that should have been evident from the start, slow down my molding cadence and actually enjoy the process of casting.Robert

[ackleyman]

I use a 3/4" thick piece of 6061 aluminum as a heat sink, works great

CPU heat sink is a great idea!

[redhawk0]

I kinda do the same thing. I setup my casting equipment on the cast iron table top of my table saw. I set the molds on the cast iron table top between castings.

redhawk

[glaciers]

I like the idea of K.I.S.S. keep it simple stupid.
If you go to a welding shop you can pick up a steel plate from their scrap pile for peanuts. 6 x 10 x 1/2 inch or 3/4 inch whatever is available. Plop it down on your bench and it will not move accidentally because of a handle sticking out or wires getting snagged.
Now gunarea has a little different need than most going for the most consistent boolit for competition. I don't fall in that category of shooter/caster, but, as someone said, your millage may vary.

[15meter]

I have a 5"x18"x1/2" steel plate mortised into my workbench, it is drilled and tapped for every kind of reloading equipment I have used over the last 30 years. When casting, the reloading press/lubrisizer/primer/ comes off the bench and the casting pot goes up on the bench to the left of the plate under the powered fume hood.

Fill mold, swing to the right, set mold flat on steel plate for a couple of seconds, open sprue plate and dump the boolits on a cookie pan with a cardboard liner in the bottom, cookie pan on a slight angle so the boolits run down hill to the end of the pan. Do it again.

That 2-3 seconds is enough to keep the mold from overheating on all but the largest molds. Those get 3-4 seconds. I find it faster and easier than trying to use two molds and the back gives out before the plate gets too hot to be an efficient heat sink.

[hawkeye1]

I’ve been using the same idea for some time. I run two molds. One on the left I set on my drill press table (steel), and a large drill press vise with a nice flat service on my right. Both make nice heat sinks. Plus a fan to one side to keep air moving.

[catmandu]

I use a heat sink from a motor drive controller. It’s aluminum and 6 x 12 with 4 inch fins. Made to cool the SCRs in the drive controller. Find a electech and offer to buy him a beer or two.

[beagle]

Piece of aluminum metal plate withh work better than steel. Dissipates heat faster. We tried fastening aluminum heat sinks off electronics to mould bottoms on large capacity .457 moulds to eliminate frosting and rounded corners. Worked great but increased the mould overall size to where it was hard to cast with./beagle

[country gent]

Maybe a block of aluminum 1"x 4" x 4"2 1/4" holes drilled thru it 1" in from each edge and a hole connecting them on 1 end plugged on ends leaving the path open. An aquarium pump circulating water from a 5 gallon bucket. This would keep the plate a constant temp. With a end mill a simple scroll could be cut and a plate bolted down for even more even cooling. Ice water in the bucket might even be an option.

The aquarium pump would provide a flow of water to carry the heat to the bucket dissipating it. Keeping the block cool for longer periods of time

[kevin c]

I see that I was on this thread when it started 4 years ago.

Actually I find I have the opposite problem nowadays, casting with aluminum 8 cavity gang molds: they cool too easily so that I have to push the cadence or pause to put them on a hot plate. I’ve started using two molds in a session, one warming while the other is casting, switching off as needed.