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View Full Version : Strange this past Monday.



armyrat1970
11-05-2009, 08:40 AM
I was casting some 8mm boolits with my single cavity Lee C324-175-R mold with HardBall alloy. Have cast with this mold before with straight Linotype. I have always run my temps very hot and kept my mold very hot. Read some past post about running alloy temps around 600 to 700. I decided to run my temps around 725 instead of my usual 880 to 900. Heated my mold over my gas stove. I always heat until I can't touch it quickly without burning my hand. The mold was hot. I poured a boolit and it came out completly frosted with excellent fill out. I poured another and it dropped with a little frosting but good fillout. I dropped another and it was shiny but good fillout. The next one I dropped had some wrinkles around the nose. The next one I drooped had many more wrinkles. Mold was to cold. Reheated my mold and tried again. Same results. Now I know it was a little cool around here that night. Don't laugh but 70 degree weather in SouthEast Louisiana is cool.:smile: But I decided to crank up the temps on my alloy. Went up to 850 and had no more problems. I am a firm believer that you have to run your Lee molds and alloy temps very hot. This is the first time I tried with a lower alloy temp and it seemed it would not keep the mold hot enough. Even with a single cavity. Run my temps around 880 to 900 with double cavities and have never had this problem.

HORNET
11-05-2009, 10:04 AM
Not so strange. You've got to match the rate of heat input to the rate of heat loss. You can crank the melt temp up or you can speed up your casting rate. I've got a couple of 2 cavity .22 molds that I've run with only one cavity and run real fast...
As to melt temp, Bass Ackwards once claimed that he got good results running melt temp 100 degrees above the melting point for steel/iron molds and 200 degrees for aluminum blocks. YMMV Sometimes you just gotta play with it.

felix
11-05-2009, 10:25 AM
The lower the melt temp of the lead mix in the pot, the more heat you need in the pot to keep the mold hot enough. Using a fast cooling mold makes the situation worse. ... felix

Jbar4Ranch
11-05-2009, 10:43 AM
Aluminum transmits and dissipates heat much faster than iron, so the melt has to be at a higher temperature. It's just that simple. Nine hundred degrees is a bit much though, I think. At around 930, steel begins crossing from the infrared spectrum to the visible light spectrum, aka "red hot". Lead melts at about 620, and starts fuming off at around 800. Lead oxides will actually start vaporizing at around 800.
I spent 23 years working at a lead smelter, and we would pump our finish lead at ~700 into ten 10 ton moulds twice a day; two hundred tons every 24 hours. Very much hotter, and there would be a significant amount of lead fume coming off the kettles.

Calamity Jake
11-05-2009, 10:55 AM
All of my alum. molds which include lee 6 cavs NEI and NOE require high melt temp(750 +) and a fast casting pace to get good boolits and only allow me to use one mild at a time, I like to
cast with two at a time.

NoZombies
11-05-2009, 01:00 PM
The fact that you were taking the time between each cast to examine the results might have also effected the mold temp when running the melt at a lower temp than you're used to.

mpmarty
11-05-2009, 01:29 PM
I used to cast at 700-725 with my six cav aluminum molds. Last week there was an article on smoking the mold with acetylene from an oxy acetylene welding rig. I have never bothered smoking molds as the boolits drop out OK without it. However, the discussion involved the smoke keeping the boolit insulated from the mold to keep it molten a bit longer and improve fillout. I tried it and the first cast in the mold had no wrinkles and I backed the pot down to 625 and still no wrinkles and fill out was great with sharp edges and there was no frosting. Best looking boolits I've cast in this particular 230gr LEE TL truncated cone mold. YMMV but I'm firing up the welder before I start casting from now on.

armyrat1970
11-06-2009, 03:48 AM
The fact that you were taking the time between each cast to examine the results might have also effected the mold temp when running the melt at a lower temp than you're used to.

Zombie you may have hit the nail on the head. Never gave it a thought. Next time when my mold is hot and dropping good I will just run with it. And check my results later. I'll go back to a lower temp and give it a go.;-)

1Shirt
11-06-2009, 10:11 AM
It has always been my practice to run the hotter the better, and if over frosted to slow down the casting rate to adjust for it. I do like some frosting.
1Shirt!:coffee: