trouble with iron molds

[mongoosesnipe]

i just picked up a lyman 9mm 147gr mold and am having a lot of trouble with it compared to my aluminum lee molds it seems to go from not hot enough to too hot in about 3 boolits and the boolits stop dropping out and get pretty frosty and i end up with a 75% reject rate water dropping the boolits

is there a trick to getting good boolits from iron molds or am i doing something dramatically wrong i have the lee dipper casting pot and it is set on 2 trying to get the alloy cool enough i run at about 6 with the aluminum molds without issue but the iron molds are just giving me a fit

[runfiverun]

i run my iron molds at 675-700.
i slow down my casting pace from 4 to 3 pours a minute.
and watch the sprue go grey before opening,you can still open them with the push of a thumb at this point.
the boolits go from shiney to grey coming out of the mold i run no hotter and no cooler than this color.
not shiney and not white...grey.

[nhrifle]

I started with Lee moulds and had the same problem when I got my first Lyman. Aluminum moulds need to be run screaming hot compared to iron or steel blocks, since the aluminum cools off so much quicker than iron. I use a Lee 20 lb bottom pour pot. What I do is start the melt as high as it will go. When molten, flux and stir and turn the temp down to around 7. Give it a couple minutes to stabilize and start casting. Once the sprue takes 5 to 6 seconds to harden, back the temp off to 3. Let the mould cool for a few minutes. Start casting again, watching sprue freeze time, and repeat the temp lowering/cooling cycle until the sprue consistently has a 3 to 4 second freeze time.

[longbow]

In all honesty, I prefer iron moulds to all others. I have several iron Lyman, Ohaus and RCBS moulds ~ mostly old Lymans and a few newer Lyman round ball moulds. I also have Lee, NOE, Mihec and Accurate moulds. If I had to choose one material it would be iron.

I love my brass moulds as they are so nice to look at, cast perfect boolits and work well but... I do like iron.

Now as to heating up too much, well, I don't worry about a bit of frosting as it doesn't hurt anything as far as I can tell. I have several large round ball moulds and yes, they do heat up but you can also cool them by setting them on a wet towel, wet sponge, spritzing with fine water mist or believe it or not when I cast in winter... outside... in the snow... I often set the bottom of the mould in the snow to cool it some. I let it steam for a bit with a boolit/ball in the cavity then drop the boolit onto my wet towel and carry on for a few more pours then repeat. It allows me to keep up a fast pace with iron moulds. As nhrifle says, I watch my sprue puddle freezing time and adjust pot heat but once I am down to "sustainable" pot heat and sprue puddle cooling time stretches out, I cool the mould.

I have never damaged or warped a mould in about 40 years of doing this.

YMMV but it works for me.

Longbow

[mongoosesnipe]

i figured it was to high of a mold temp i will try cooling the molds in between casts tomorrow

thanks

[winelover]

Try casting with 2 iron molds, alternating, so they can cool accordingly. You can also put a small fan on your bench for extra cooling.

Winelover

[mongoosesnipe]

Got it running good today had the pot turned all the way down and keeper the mold cool enough that I could touch it bare handed for about half a send seemed about he perfect temp