Too many cavities for heavy boolits?

[rongaudier]

The saga continues...
First I had my own mold made. Iron block, single cavity 374 gr .452 cal. Boolits came out great, but the ogive did not work in the throat of my rifle so had to reject that.
Went ahead and ordered a 3 cavity, .452 400 grain aluminum block mold from Accurate Molds.
Let the mold warm up...tried casting at temps ranging from 770 all the way up to 900. Getting plenty good flow out the pot. Boolits came out wrinkly and looking like dog ****.
I'm thinking a 3 cavity mold may be to hard to keep up to operating temp with these heavy boolits. What else may be going on?

[rongaudier]

I think I've answered my own question. Another mold for the scrap heap I guess. I don't think I'll be able to keep this one warm enough to NOT get wrinkled boolits. I have run a 6 cavity Lee mold before with no problems, but that was with 158 gr boolits, not 400 gr. I guess the bigger they get the more of a challenge it is to keep everything up to temp.

[ascast]

you have really de-greased them, right? I have found larger boolits heat things up faster. Ladle or bottom spout? You might try pouring lead over the side of the block to warm it up. You might try that for 10-15 casts. Pour over one side, then the other.

[rongaudier]

So you think a 3 cavity of this size isn't too large? You know, I didn't really degrease the mold hate to say. Looked pretty clean when I got it.

[Kitika]

Clean the mold thoroughly and make sure the lead itself is hot enough for a good fill. I cast 500gns .45s in a five cavity yesterday and the only trouble I had was keeping the mold cool enough to solidify the bullets. I was running the pot slightly hotter than normal to stop the wrinkles and after every pour rested the mold on a wet rag to cool it down. Hope that helps you get some good bullets!

[rongaudier]

How hot is too hot? I poured at 900 degrees and no wiping on the sprue plate also no frosty appearance. Still wrinkly. Had to take a break. Thanks.

[waksupi]

Try adding more tin.

[Kitika]

I don't run a temp gauge I just go and start casting and get it working. Degrease the mold preheat the mold in/on the pot and start casting quick until you get full fillout and try and maintain that heat in the mold which should be easy because of the large amount of hot molten lead going into it.
With the bigger molds like my new 500gn I did all of the above but couldn't get rid of the wrinkles until I turned up the lead heat a little.

[OS OK]

So you think a 3 cavity of this size isn't too large? You know, I didn't really degrease the mold hate to say. Looked pretty clean when I got it.

There is part of the problem...you'll have to solve this one before you can worry about the mould temp.

[Harter66]

I have a NOE 454424 aluminum 5 C . It takes about 17-20 pours with a 750° pot on the preheated mould to have it over heated . Even the 6C Lee 452-255 isn't all that hard to get too hot .
I think that a bath in Dawn and hot water will set the mould straight .

[Dan Cash]

I am casting with an Accurate 3 cavity 46-510P mould using a ladle. Afte degreasing the mould, I bring it up to temp by pouring copious quantities of melt in the sprue holes. Once hot, the trick is to keep from over heating. I pour, give 1 minute cooling with the mould sitting on a heat sink, dab the sprue plate on a wet cloth then cut the sprues. This gives me mearly perfect bases and an acceptable rate of production.

Clean your mould and get a ladle.

[JonB_in_Glencoe]

there must be some grease in the mold.

I have a couple large cavity molds, both 3 cavity. One is a Iron Ballisticast 501 385gr RF (for 500 S&W) and the other is a alum NOE 501 550gr RN. Both of these heat up quick and want to easily overheat. I run a small fan to blow over the area where I dump the boolits, and will hold the mold open in that area, so the fan can cool it off some, when the mold is getting too hot. It takes a while, but you will develop a rhythm for how long you need to 'hesitate' holding the mold in the fan breeze.

btw, when I ordered the Ballisticast, it was strongly suggested I go with 4 cavity blocks, but with 3 cavities, for a mold with large cavities...more mass makes for more consistent heat, meaning that minimizes the fast temp swings.

[country gent]

I would clean the mould good. first with acetone brake cleaner or thinner and a tooth brush. scrub it really good. Then hot water and dish soap with the tooth brush and really work up a lather. rinse under running hot water. If there are vent lines with a awl, scribe, or bamboo skewers point make sure vent lines are clear and open. Warm mould on top of pot or in a mould oven while pot comes up to temp. I would start out with a lead temp of 750* and work from there.

[John Boy]

First a clean mold, then
* heat the melt & mold to a temperature so the sprue puddle frosts in 5 to 8 seconds
* Then, pour each mold cavity with a full ladle with a 5 second pour

[runfiverun]

put your alloy temp back down.
more like 700 is all you need 725 maybe if your loafing along.
all that lead your putting in the cavity's is heat, keeping the mold up to temp should be no problem.

you just need to get all the cutting oil out of the mold.
then run a couple of short sessions and allow the mold to cool back down in between.
you can do this by pouring about 20 pours into the mold then setting it off to the side to cool then warming it up again and doing another short run.

you'll see the boolits start getting good during one of the short runs.
that's when you just go ahead and make a pile of them.

[longbow]

I'll go with more heat. Pre-heat the mould until the sprue plate lube just starts to smoke and you will have the mould just a bit hotter than it should be but it will settle in after a few pours. At first the sprue puddle will stay molten a bit long so just wait a few seconds.

Most clean the heck out of new moulds to get them to cast but I don't bother much. I think pre-heating the mould to just under the melting point of the lead is the secret... works for me anyway. Nothing wrong with cleaning the mould though. Use brake cleaner, mineral spirits or scrub with Dawn dishwashing soap and a toothbrush. All will work.

I have not used an Accurate aluminum mould but have cast with two Accurate brass moulds and both behaved the same... they like to be run hot and fast to keep the mould up to temperature. Start casting and keep going at a steady and fast pace. Don't stop to look at each boolit. I suspect the Accurate aluminum mould acts much like the NOE's ~ pre-heat and cast fast and steady.

Even the thought of scrapping an Accurate mould makes me cringe! Tom wouldn't make it if it wouldn't work. That and the large boolits certainly will keep that mould hot enough. If you think it is a bad mould then I am sure there are many here who will pay the shipping to take it off your hands.

As for temperature, well, I can't be very precise there as I do not use a thermometer. I learned to cast "by eye" looking at the surface and colour of the alloy to judge when it is the right temperature. What I do know is that I have to turn up the heat and make sure I keep up a quick steady cadence with brass moulds and NOE aluminum moulds. If I am not casting fast enough that I wind up waiting for the sprue puddle to harden then the alloy and/or mould is not hot enough.

I find more heat usually helps fill out. Also, fluxing and drossing regularly helps bunches.

Waksupi's suggestion of more tin is a good one too. Adding some 50/50 bar solder certainly won't hurt and will make the alloy more fluid giving better fill out.

Try again with more heat, maybe some added tin and cast fast and steady. I am confident the mould, boolit size or number of cavities is not the problem.

Longbow

[mold maker]

Pour melt generously into a cleaned HOT mold until you get frosting. That means pouring and dumping fast without inspecting the product. Then reduce the frosting by, 1. cooler melt, 2. slower pace, 3. using a damp rag. You likely created your problem by skipping the mould cleaning.
The larger the boolit the more heat your introducing into the mold, not the other way around. As others have said, think of it as pouring heat, not lead.
Aluminum molds absorb and transfer heat faster than the other mold materials, so the pace will need to be somewhat altered. Use mold lube VERY SPARINGLY as in a slightly damp Qtip, and wipe any wet spots off with a dry Qtip. The correct amount can barely be seen.
Just keep at it and success will be the reward.

[rongaudier]

I just finished my session after giving a good clean. I ended up with about half rejects, but enough that are good enough to go ahead and powder coat. It does seem like they did better once the mold got up to temp. I might try the ladle method. Gotta get a ladle first. Thanks for the input and I'll post pics later.

[reddog81]

I always thought larger grain molds were much easier to heat up. If anything I have to use a slower casting pace to keep them from over heating. Little 32 ACP molds have the opposite problem. They take much longer to heat up and you must keep the casting pace fast otherwise the mold cools off.

[Oklahoma Rebel]

the larger cavities mean it will heat up faster, because there is less mass in the mold blocks to heat up, but it also means it will not hold heat as long. so as long as you have a good rhythm going it should stay hot, even get too hot like some said