mozeppa
08-24-2015, 09:52 PM
First....I'll admit when I'm wnorg! .... err... wrong!....and wrong I was!
I observed that many would cast around 700 degrees to get good boolits...and thought I had to as well.
Not so... from what I did today.
I use a 90 pound capacity 240v. magma bottom pour pot on a "PID".
A "oster" brand hot plated set at 475 degrees (using a thermometer known to me as accurate)
3 different caliber molds ...45 acp 230 gn ...45 colt 230gn 44 mangum 225 gn.
all three hardline iron molds w/ 4 cavities each.
my shop which is at a cool 100 degrees, no humidity.
Heres the alloy...mixed by me using nearly exact proportions.
Pure lead plus "lino" to bring it up to Brinell # 12/13 using cabin tree hardness tester.
This mix was a 10 pound ingot....tested several areas, its 12/13 on the scale.
Then the main mix netted me almost 400 pounds of 12/13 brinell alloy.
Then i melted the test ingot and started casting ....
I noted that the mold wasn't filling out fully so I tossed all the test pieces back in the pot,
and added 5% pewter to the pot ...about 1/2 a pound.
Then the mold was filling out good ......but was getting a lot of frost at the temperature i was at, which was 700 degrees.
with the "PID" I'm using, setting at "700" really means that the lowest i'll get IS 700 gegrees.
The temperature yoyo's from 700 to about 713 / 715 then goes into a cooling cycle back to 700.
Moving on ...
I pre-heat my molds on the hot plate to about 475 degrees.
My flow rate from the pot is a moderate steady flow not too fast and not too slow...about like the stream of water you'd leave on in the kitchen to keep your pipes from freezing in the winter.
So it begins...I cast away.
filled a mold...waited a while...broke sprue and dump.
Got good boolits from the get go....except for the frost around the bases....around the boolit noses they were mirror shiney!
and it seems that they don't want to release from the molds, I either had to poke at them with a stick or tap the mold with the sprue mallet.
The sprue puddle frosted but only a little bit ...enough you could tell it was solid...yet when swinging the sprue plate out of the way to open the mold I was getting smears of lead in arches across the top of the molds.
Either way it was annoying.
so... i wondered if i lowered the temperature in 10 degree increments if things would improve.
They did! .....later.
at 690 degrees...not much change
at 680 degrees...not much change
at 670 degrees...not much change
at 660 degrees...there was change!...the base frost was all but gone.
they would let go of the mold upon opening...some times all 4 would release...if one or two would hang on a very light tap on the mold easily dis-lodged them.
Then I, as a limbo master, wondered "how low could i go"?
I was getting great fills and releases all the way down to a "PID" setting of 590 degrees ....meaning the bottom threshold was 590 but yoyo's up to 605 then cools , then back up.
i also noted that when the sprue puddle "frosted over" that in the beginning there was a light frost....just like when set on 700 degrees, BUT about 7 seconds later it turns to a full on WHITE frost over almost the whole puddle!
AND no more smearing of lead.
AND for molds that haven't been polished with jewlers rouge ...dang!...these are shiney!
thats just me rattling on about what i observed....i did note that there semms to be a "window" of temperatures that work well...
590 is too low...works but its slower.
650 to 670 for me seems to work well.
again ....my observances ....point out where i'm further wrong...PLEASE i'm new to casting!
I observed that many would cast around 700 degrees to get good boolits...and thought I had to as well.
Not so... from what I did today.
I use a 90 pound capacity 240v. magma bottom pour pot on a "PID".
A "oster" brand hot plated set at 475 degrees (using a thermometer known to me as accurate)
3 different caliber molds ...45 acp 230 gn ...45 colt 230gn 44 mangum 225 gn.
all three hardline iron molds w/ 4 cavities each.
my shop which is at a cool 100 degrees, no humidity.
Heres the alloy...mixed by me using nearly exact proportions.
Pure lead plus "lino" to bring it up to Brinell # 12/13 using cabin tree hardness tester.
This mix was a 10 pound ingot....tested several areas, its 12/13 on the scale.
Then the main mix netted me almost 400 pounds of 12/13 brinell alloy.
Then i melted the test ingot and started casting ....
I noted that the mold wasn't filling out fully so I tossed all the test pieces back in the pot,
and added 5% pewter to the pot ...about 1/2 a pound.
Then the mold was filling out good ......but was getting a lot of frost at the temperature i was at, which was 700 degrees.
with the "PID" I'm using, setting at "700" really means that the lowest i'll get IS 700 gegrees.
The temperature yoyo's from 700 to about 713 / 715 then goes into a cooling cycle back to 700.
Moving on ...
I pre-heat my molds on the hot plate to about 475 degrees.
My flow rate from the pot is a moderate steady flow not too fast and not too slow...about like the stream of water you'd leave on in the kitchen to keep your pipes from freezing in the winter.
So it begins...I cast away.
filled a mold...waited a while...broke sprue and dump.
Got good boolits from the get go....except for the frost around the bases....around the boolit noses they were mirror shiney!
and it seems that they don't want to release from the molds, I either had to poke at them with a stick or tap the mold with the sprue mallet.
The sprue puddle frosted but only a little bit ...enough you could tell it was solid...yet when swinging the sprue plate out of the way to open the mold I was getting smears of lead in arches across the top of the molds.
Either way it was annoying.
so... i wondered if i lowered the temperature in 10 degree increments if things would improve.
They did! .....later.
at 690 degrees...not much change
at 680 degrees...not much change
at 670 degrees...not much change
at 660 degrees...there was change!...the base frost was all but gone.
they would let go of the mold upon opening...some times all 4 would release...if one or two would hang on a very light tap on the mold easily dis-lodged them.
Then I, as a limbo master, wondered "how low could i go"?
I was getting great fills and releases all the way down to a "PID" setting of 590 degrees ....meaning the bottom threshold was 590 but yoyo's up to 605 then cools , then back up.
i also noted that when the sprue puddle "frosted over" that in the beginning there was a light frost....just like when set on 700 degrees, BUT about 7 seconds later it turns to a full on WHITE frost over almost the whole puddle!
AND no more smearing of lead.
AND for molds that haven't been polished with jewlers rouge ...dang!...these are shiney!
thats just me rattling on about what i observed....i did note that there semms to be a "window" of temperatures that work well...
590 is too low...works but its slower.
650 to 670 for me seems to work well.
again ....my observances ....point out where i'm further wrong...PLEASE i'm new to casting!