forcedconvection
03-01-2013, 01:13 AM
Hi everyone,
I was hoping to get the thoughts of some experienced casters. I just recently got into casting. I really liked the idea of the PID control so I added that within days of getting my Lee Pro 4-20 pot. The lead I am currently using is Lyman #2 purchased from Rotometals and I am fluxing with saw dust.
I then purchased a MP 452-200 HP brass mold and MP Mold Handles. Man, this thing is a work of art. I cleaned the mold with hot water and soap while using a tooth brush. I later cleaned it with a mass air flow sensor cleaner (I would suspect this is very similar to acetone. From what I can tell evaporates almost instantly and seems to leave no residue.) I reassembled the mold with the 5 sided HP pins. I noticed that the pins were very hard to slide in the mold even when lubed. They seemed very much like a friction fit. To make matters worse, it seems that the diameter of the pin is ever so slightly larger than the 2 radii of the mold halves. I figured that maybe at casting temperatures, the different thermal expansion rates of the brass mold and steel pins would solves this issue and may prove that the mold was machined that way on purpose.
Being my first time casting "boolits", I proceeded caustiously and warmed my mold on a griddle (closest thing to a small electric burner I could find at my local walmart). It says it goes up to 400F. I got my pot up to temp (I initally started way to low and of course got wrinkled bullets but I am now around 720F). Ambient temp in my garage is approximately 50F, if that really matters. When casting, I found it still very hard to make the pins slide in the mold. I always had to lightly tap the pins with a small 2x4 block I had lying around to get the boolits out past the lube grove so they could drop. Then the bullets would never drop off the 5 sided pins. I literaly had to pull them off with needle nose pliers every batch. I would also have to push the pins back in place with quite a bit of effort from my gloved hands. Obviously, this is a slow process which is probably letting the mold get too cold. Frustrated, I swapped to the round HP pins. These seemed to slide slightly easier in the mold. When casting with these pins in place, the boolits dropped freely once the pins were slid out past the lube groove with light taps from the 2x4. However, some of these boolits were getting a good amount of the mold split line (I think the proper term is called mold flash/flashing). Also, almost all of the bullets were still lightly wrinkled. I also noticed that there seemed to be a "tit" where the sprue was cut. Do I need to preheat the mold more, do I need hotter lead, do I need to speed up dropping the boolits (I know I need to but am not sure how to with the pin problems), or all of the above.
After finishing up a bad round of boolits, I began to look at my mold (it had a fair amount of time to cool off but still way too hot to hold with a gloved hand for more than a few seconds). I saw significant gaps when holding it to the light (I was holding the mold handles closed tightly). Did I warp my mold? I sure hope not or did I just make a real pretty but very expensive paper weight. Please guys, give this newbie a hand. Looking for constructive criticism, suggestions, anything that would help.
Thanks in advance,
Ryan
627556275662757627586275962760
I was hoping to get the thoughts of some experienced casters. I just recently got into casting. I really liked the idea of the PID control so I added that within days of getting my Lee Pro 4-20 pot. The lead I am currently using is Lyman #2 purchased from Rotometals and I am fluxing with saw dust.
I then purchased a MP 452-200 HP brass mold and MP Mold Handles. Man, this thing is a work of art. I cleaned the mold with hot water and soap while using a tooth brush. I later cleaned it with a mass air flow sensor cleaner (I would suspect this is very similar to acetone. From what I can tell evaporates almost instantly and seems to leave no residue.) I reassembled the mold with the 5 sided HP pins. I noticed that the pins were very hard to slide in the mold even when lubed. They seemed very much like a friction fit. To make matters worse, it seems that the diameter of the pin is ever so slightly larger than the 2 radii of the mold halves. I figured that maybe at casting temperatures, the different thermal expansion rates of the brass mold and steel pins would solves this issue and may prove that the mold was machined that way on purpose.
Being my first time casting "boolits", I proceeded caustiously and warmed my mold on a griddle (closest thing to a small electric burner I could find at my local walmart). It says it goes up to 400F. I got my pot up to temp (I initally started way to low and of course got wrinkled bullets but I am now around 720F). Ambient temp in my garage is approximately 50F, if that really matters. When casting, I found it still very hard to make the pins slide in the mold. I always had to lightly tap the pins with a small 2x4 block I had lying around to get the boolits out past the lube grove so they could drop. Then the bullets would never drop off the 5 sided pins. I literaly had to pull them off with needle nose pliers every batch. I would also have to push the pins back in place with quite a bit of effort from my gloved hands. Obviously, this is a slow process which is probably letting the mold get too cold. Frustrated, I swapped to the round HP pins. These seemed to slide slightly easier in the mold. When casting with these pins in place, the boolits dropped freely once the pins were slid out past the lube groove with light taps from the 2x4. However, some of these boolits were getting a good amount of the mold split line (I think the proper term is called mold flash/flashing). Also, almost all of the bullets were still lightly wrinkled. I also noticed that there seemed to be a "tit" where the sprue was cut. Do I need to preheat the mold more, do I need hotter lead, do I need to speed up dropping the boolits (I know I need to but am not sure how to with the pin problems), or all of the above.
After finishing up a bad round of boolits, I began to look at my mold (it had a fair amount of time to cool off but still way too hot to hold with a gloved hand for more than a few seconds). I saw significant gaps when holding it to the light (I was holding the mold handles closed tightly). Did I warp my mold? I sure hope not or did I just make a real pretty but very expensive paper weight. Please guys, give this newbie a hand. Looking for constructive criticism, suggestions, anything that would help.
Thanks in advance,
Ryan
627556275662757627586275962760