Pot temp for 50/50 alloy

[Marlin Junky]

What are you 50/50 guys setting your thermostats to? I was casting with near 800F 50/50 alloy tonight (for the first time) and was experiencing signs of too cool metal when I occasionally slowed down the casting pace a little. Do I need a dash more tin? I've already added about 9 ounces of tin (18 oz of 50/50 bar solder) to 16 pounds of clip-on WW metal and 15 pounds of lead plates.

Another thing: I've never needed to run my SAECO 352 this hot before and I notice that after the casting session one half of one cavity was bluer than the other three halves. I also had some light frosting on one side of the bullets from one of the cavities. Did I screw up my mold? :(

MJ

[45 2.1]

What are you 50/50 guys setting your thermostats to? I was casting with near 800F 50/50 alloy tonight (for the first time) and was experiencing signs of too cool metal when I occasionally slowed down the casting pace a little. Do I need a dash more tin? I've already added about 9 ounces of tin (18 oz of 50/50 bar solder) to 16 pounds of clip-on WW metal and 15 pounds of lead plates.

Another thing: I've never needed to run my SAECO 352 this hot before and I notice that after the casting session one half of one cavity was bluer than the other three halves. I also had some light frosting on one side of the bullets from one of the cavities. Did I screw up my mold? :(

MJ

We usually cast about 700 to 725 degrees using a big iron pot and ladle. You want the spru puddle to stay liquid three to four seconds and the mold will dictate that temperature. We also don't add tin. Any frosting indicates a mold which is way too hot. These conditions are for iron or aluminum one or two cavity molds. The Lee six bangers need slightly more heat or a larger dipper.

[Ricochet]

I have yet to buy a thermometer. (I know, I know, but I keep buying fun stuff and putting off "essentials.") But if I don't keep my Lee pot turned to about 8 (out of 9, mine doesn't go to 11 like Nigel Tufnel's), the spout is likely to plug.

[454PB]

I cast for 35 years before I bought an RCBS thermometer. I always ran my bottom draw Lee pots (I have three of them) between number 7 and 8 depending on the alloy. Since getting the thermometer, I found this to be about 725 degrees on the 20 pounder, and nearly 800 degrees on the 10 pounders.

I strive for light frosting on my WW alloy boolits, it indicates the perfect temperature for good casting. If the mould starts retaining too much heat, I use a wet towel to cool it down. That's easier and quicker than fiddling with the thermostat.

[Marlin Junky]

Maybe I simply wasn't getting the metal in the mold cavities fast enough (pouring too slowly with the Rowell#2).

I still don't understand why half of one cavity would become hotter than the other 3 halves. Can this happen if one is "burning off" some excess Bullplate lube that may have worked its way into the cavity?

MJ

[runfiverun]

that may be a hot spot from where the metal from your ladle was hitting it
hence the blue spot,same area that was frosted on the boolit.
probably the first hole you poured each time, it is why i alternate holes i pour into first.

[Marlin Junky]

runfiverun,

I always pour the cavity near the hinge pin first as I tilt the mold down toward the melt. In this manner, when the cavity near the hinge pin fills, the runoff heads into the second cavity. In the case I've described above, it is the second cavity that exhibited over heating signs on one half.

I'll make sure the mold is squeaky clean and try it again at about 750F.

MJ

[BABore]

Your flow rate isn't high enough. I've always had dificulty pouring fast enough with a Rowell when trying to shoot the hole. Works ok on some molds, but not always the with the bigger bullets. Switched to a RCBS ladle with 0.161 orifice hole and pour with the ladle tip tight to the sprue plate. Slightly rounded bands with intermittent frosty spots is a dead give away.

Your first cavity is filling out good cause it is venting well with air escape routes on both sides. Not as good as you fill the next one.

I've pressure poured 50/50 down to 675 F with no tin additions. It's very easy to get too much tin in this mix. Exterior inclusions will show up with too much.

[leftiye]

I think BaBore is right about insufficient venting. The second cavity should fill out better because the mold is hotter after the first cavity is poured (or frost if too hot) - unless there is something (like air trapped in the cavity) stopping it. Take a trianguluar file and make a vertical groove clear across the blocks (top to bottom) between the cavities to let air escape.