Brass mold help

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Gentlemen'
Tried my hand at casting with a brass mold today with mixed results. Never could get consistant boolits. Do these molds have a narrow heat range to be happy? If so I'm going to purchase a thermometer.
Any/all help is appreciated

David

FYI - Accurate .452 200gr H&G clone - wheel weights alloy

[BSkerj]

I run mine at 700-750 degrees out a my Lyman bottom pour. I have found heating before hand over my turkey cooker is the best way to get them up to temp. I sometimes have to wait for the lead to solidify in the mold for quite awhile when I do it this way and the first couple are always frosty. I found getting a good thermometer was really important when casting with my Miha mould..hope this helps

[white eagle]

I find brass molds a bunch easier to make consistent boolits
compared to aluminum
brass ,at least in my exp.,has a very broad window for casting good boolits
might have not had the mold warm enough

[longbow]

I have 3 brass moulds and really like them.

Like BSkerj says, I pre-heat until they smoke with a little Bullplate on them before casting.

I'd like to say I cast hot but since I cast by eye, I am really not sure.

I heat the lead until I see a golden skin on top then I know the lead is hot enough (I guess I should get a thermometer) then I start casting. If the sprue puddle freezes right away, the mould is too cool. I like to see the sprue puddle molten for as long as it takes to pick up my old hammer handle I use to knock the sprue cutter. The puddle should be mushy by then ~ just a few seconds.

A few more pours and a steady rhythm will get the mould temperature up and keep it there. If the sprue puddle stays molten too long then I turn down the flame under the lead a bit until I can cast in a steady rhythm ~ pour, pick up hammer handle, knock the sprue cutter open, drop the boolits, close the mould, repeat... Don't stop to examine boolits or the mould will lose temperature.

I am guessing you need either higher lead temperature or a faster rate of casting. Try casting steady first then more heat if required.

FWIW

Longbow

[stubshaft]

I agree with white eagle in that they have a wide range. Put some pics of your boolits up. It is hard to determine your problems with the limited description you provided.

[geargnasher]

Here are three cast from one of Tom's fine brass moulds, the one on the left was too hot, the middle one is what I call just right, the one on the right was too cold. The alloy was clip-on WW plus 1.5% tin, came out about 14.4 bhn, pot temperature was kept right around 675*. I cut the sprue while still fairly soft but set enough not to smear, refill the mould right away, and cast about 3.5 to 4 pours a minute to keep the mould up to temp. I preheated it by soaking in my "mould oven" for about 15 minutes. This "oven" is a steel electrical box with a door for the mould and a BBQ themometer fitted through it. It sits on top of a 1/4" steel plate on top of my hot plate that will let the mould get to 380* on full high.

http://castboolits.gunloads.com/attachment.php?attachmentid=28007&d=1293562439

Gear

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Thanks for the comments guys. I tried to take some pics today but my camera won't focus close enough to see the detail. As I looked thru my cast I think I was just having problems with keeping the mold temp up. Have to work on my timing instead of just enjoying the process!!
Thanks again
David

[MtGun44]

Every second the mold is not filled with metal, it is cooling. A lot of beginners spend
a bunch of time sorting, examining and generally admiring their work.

Just keep rolling, you can sort later. Keep the mold temp up. If the sprue puddle
startes taking noticably longer to cool, THEN you can start taking some time and slowing
down the rate of casting, leaving the mold open a bit longer.

Bill

[Bulltipper]

I run all brass molds (well, one iron Lyman) and I get best results around 750-800 degrees. I set the mold on top of the bottom pour and let the whole thing heat up together. I noticed the brass molds can take a while to break in sometimes. Some molds work great right away, some take 50 throws before they start to behave even when I clean the living **** out of them. Sometimes a little stick match smoke helps. One other thing, when I am cranking away and decide to quit for the night, I turn the pot off and keep casting as the temp drops. the boolits drop beautifully on down to 600 degrees... go figure...

[geargnasher]

I run all brass molds (well, one iron Lyman) and I get best results around 750-800 degrees. I set the mold on top of the bottom pour and let the whole thing heat up together. I noticed the brass molds can take a while to break in sometimes. Some molds work great right away, some take 50 throws before they start to behave even when I clean the living **** out of them. Sometimes a little stick match smoke helps. One other thing, when I am cranking away and decide to quit for the night, I turn the pot off and keep casting as the temp drops. the boolits drop beautifully on down to 600 degrees... go figure...

What does that tell you? I'm not going to tell you you're doing it wrong, but if you're running wheel weight or similar ternary alloy (the principle three being Pb, Sb, and Sn), you might be interested to try keeping your pot at around 700 degrees and casting just a little bit faster to keep the mould hotter. The lower pot temp will greatly reduce drossing and allow you to cast faster by imparting less heat to the mould each pour. I find the brass moulds need to be run hot and fast, but that doesn't go for the alloy, the alloys behave according to their composition, and that behaviour is the same for what ever type of mould you're using, regardless of type.

Gear

[SwedeNelson]

That's one of the most important thing I have picked up from Gear.
I was a advocate of running my alloy hot, 780F to 800F was normal.
But once I got a handle on mould temp. I run at 630F to 650F and
don't have near as much garbage (as in tin) come to the top of my pot.
By all means get a thermometer.
And find that sweet spot for your mould.
I have found that our brass moulds like to run about 80F hotter than
our alum. moulds give or take.
Alum. 300F to 330F
Brass 380F to 410F

Swede Nelson