iGeocacher
09-13-2016, 10:28 PM
I've enjoyed reading the posts here and first found the site when seeking subsonic load data. Back in the "good old days" when men were men and we all used film in our cameras, I had my own darkroom. One thing doing my own color printing taught me was that the key to success with many processes is mainly consistency. In particular, controlling the process temperature and timing the same way every time was key. That seems to hold true in boolit casting as much as in that other hobby. I've read about all of the trouble folks seem to have when starting out with casting and I almost feel guilty (NOT!) because I've had so very little. So I thought I'd pass along a couple of tips that have seemed to really contribute to my early success as nearly as I can tell.
1. I use Lee molds, mainly because of the economics but as an engineer, once I had them, I could really appreciate the design as well. They do good stuff, IMO.
2. I followed the instructions to the letter, especially the part about cleaning and prepping a new mold. I clean and brush (soft bristle) the new mold all over the metal parts with Acetone to remove any oils. Then I "smoke" the mold faces and cavities with a butane lighter. I used kitchen matches before trying the lighter as the better option and found it was much easier using the lighter. But both work. On the first heating of the mold resting on top of the pot (see below) I use a bit of Permatex aluminum anti-seize compound (any auto parts store should have it) on the hinge and alignment pins as directed. Per their recommendation I do NOT use ANY mold release spray or agent besides the "smoke" film.
Again, these are LEE molds. I followed THEIR instructions. Your molds may differ but carefully follow the manufacturers instructions for first time use.
3. I use a Lee 10 pound pot set on about #7. I set the mold on top of the pot while it is heating.
4. My secret weapon for consistency is an infrared thermometer from Harbor Frieght tools. I believe it is made by CENTECH and typically runs around $25-$29 though I've seen it on sale for $19 from time to time. I point the laser aiming dot at the top side of black sprue plate of the mold (shiny surfaces don't read IR well) and don't even try to cast the first boolit until it reads about 275 degrees. I arrived at this by my early trials and reading of casting in the Lee loading manual and instructions. I found that when my boolits started nicely filling out and with nice shine, the sprue plate of the mold typically reads near 300 degrees F. As you continue to cast and drop boolits, the mold gets hotter and you'll start to get that frosty surface as well as some smearing of the lead on the top of the mold as you shear the sprue off the boolits. Typically the sprue plate shoots about 350-375 degrees at this point. I usually either slow down, grab a cool drink, or just let the mold cool a bit on the top of the pot while fetching boolits out of the quench bucket to put on a towel to dry. When the mold gets back down to around 300 degrees (just takes a few minutes of rest) I start another round of casting. Keeping the mold between 300-350 degrees (as measured shooting the sprue plate top) seems to be the sweet spot for me with the lead I'm using.
One additional note: Those temps sound low to me given the melting point of lead. But then again, IR thermometers are a bit tricky in that they have a "field of view" that isn't always that precise so you are picking up other temps in the cone of the IR sensor that can skew the reading. The key is to do it consistently. I do note that if you point the IR thermometer a the top of the lead in the pot it reads 700-odd degrees but the pot is a much larger target than the sprue plate which is only about an inch wide. I lift the mold OFF the pot typically to "shoot" the sprue plate with the IR thermometer. Otherwise, if you just "shoot" the mold with the molten pot of led in the background you will get a much HIGHER temperature. So just bear in mind that the IR thermometer is reading the temp in it's view cone which may be 10 or so degrees wide. The laser aiming dot is merely at the center of this cone and when holding the thermometer about 8-10 inches away the sprue plate will not fill the view of the cone in all likelihood. But if you hold it the same way and shoot the same way you can achieve CONSISTENCY, even if your numbers with your equipment differ somewhat from mine.
Now your temps may vary depending on your mold and thermometer but the main point to take away from this (IMHO) is that when you find the temp range that works, stick with it. I took a brand new mold that hadn't been broken-in, prepped it, and used this technique and cast about 110 boolits to get 100 nearly perfect. Really, another five of the 10 "rejects" would have been fine but I'm having such good luck that I'm getting picky ;-)
Now I haven't added Brinell testing of my alloy into the process control mix yet but I plan to.
My lead is reclaimed shot I purchased from Rotometals. They sell 50 pounds (two 25 pound bags) for about $69 and if you order two sets of two to get your order over $100 the shipping is free. So for $138 I got a 100 pounds of scrap shot. After melting it down, de-slagging, fluxing with candle wax and sawdust I ended up with about 88-90 pounds (digital bathroom scale) in 1 pound ingots. So that ballparks at about $1.50/pound which isn't bad for not having to scrounge and delivered to your door. I didn't add any tin, antimony or anything to the alloy and it seems to be medium hard. It's definitely not soft lead because I tried to slug my barrel with a piece and couldn't. I was able to do it easily with some sinker lead out of my fishing box which is much softer so I'm assuming whatever the alloy is that is use for the reclaimed shot is significantly harder than pure lead.
All of which is to say that I might have been "lucky" to get some lead in an alloy that gives me good mold fill but I also think a BIG part of that is temperature control and initial mold prep when they come out of the box for the first time. When I pay attention to temperature, especially on starting from the warm-up, I get wonderful results. I've done several different sets of Lee molds now in both two and six boolit varieties and the same technique works with either type.
Who knows, my next batch of lead might not be so good but I'm about a third of the way through this batch and the results have been stellar for a newbie to the casting game. I hope this help someone. If it does, pay it forward for the next newbie ;-)
1. I use Lee molds, mainly because of the economics but as an engineer, once I had them, I could really appreciate the design as well. They do good stuff, IMO.
2. I followed the instructions to the letter, especially the part about cleaning and prepping a new mold. I clean and brush (soft bristle) the new mold all over the metal parts with Acetone to remove any oils. Then I "smoke" the mold faces and cavities with a butane lighter. I used kitchen matches before trying the lighter as the better option and found it was much easier using the lighter. But both work. On the first heating of the mold resting on top of the pot (see below) I use a bit of Permatex aluminum anti-seize compound (any auto parts store should have it) on the hinge and alignment pins as directed. Per their recommendation I do NOT use ANY mold release spray or agent besides the "smoke" film.
Again, these are LEE molds. I followed THEIR instructions. Your molds may differ but carefully follow the manufacturers instructions for first time use.
3. I use a Lee 10 pound pot set on about #7. I set the mold on top of the pot while it is heating.
4. My secret weapon for consistency is an infrared thermometer from Harbor Frieght tools. I believe it is made by CENTECH and typically runs around $25-$29 though I've seen it on sale for $19 from time to time. I point the laser aiming dot at the top side of black sprue plate of the mold (shiny surfaces don't read IR well) and don't even try to cast the first boolit until it reads about 275 degrees. I arrived at this by my early trials and reading of casting in the Lee loading manual and instructions. I found that when my boolits started nicely filling out and with nice shine, the sprue plate of the mold typically reads near 300 degrees F. As you continue to cast and drop boolits, the mold gets hotter and you'll start to get that frosty surface as well as some smearing of the lead on the top of the mold as you shear the sprue off the boolits. Typically the sprue plate shoots about 350-375 degrees at this point. I usually either slow down, grab a cool drink, or just let the mold cool a bit on the top of the pot while fetching boolits out of the quench bucket to put on a towel to dry. When the mold gets back down to around 300 degrees (just takes a few minutes of rest) I start another round of casting. Keeping the mold between 300-350 degrees (as measured shooting the sprue plate top) seems to be the sweet spot for me with the lead I'm using.
One additional note: Those temps sound low to me given the melting point of lead. But then again, IR thermometers are a bit tricky in that they have a "field of view" that isn't always that precise so you are picking up other temps in the cone of the IR sensor that can skew the reading. The key is to do it consistently. I do note that if you point the IR thermometer a the top of the lead in the pot it reads 700-odd degrees but the pot is a much larger target than the sprue plate which is only about an inch wide. I lift the mold OFF the pot typically to "shoot" the sprue plate with the IR thermometer. Otherwise, if you just "shoot" the mold with the molten pot of led in the background you will get a much HIGHER temperature. So just bear in mind that the IR thermometer is reading the temp in it's view cone which may be 10 or so degrees wide. The laser aiming dot is merely at the center of this cone and when holding the thermometer about 8-10 inches away the sprue plate will not fill the view of the cone in all likelihood. But if you hold it the same way and shoot the same way you can achieve CONSISTENCY, even if your numbers with your equipment differ somewhat from mine.
Now your temps may vary depending on your mold and thermometer but the main point to take away from this (IMHO) is that when you find the temp range that works, stick with it. I took a brand new mold that hadn't been broken-in, prepped it, and used this technique and cast about 110 boolits to get 100 nearly perfect. Really, another five of the 10 "rejects" would have been fine but I'm having such good luck that I'm getting picky ;-)
Now I haven't added Brinell testing of my alloy into the process control mix yet but I plan to.
My lead is reclaimed shot I purchased from Rotometals. They sell 50 pounds (two 25 pound bags) for about $69 and if you order two sets of two to get your order over $100 the shipping is free. So for $138 I got a 100 pounds of scrap shot. After melting it down, de-slagging, fluxing with candle wax and sawdust I ended up with about 88-90 pounds (digital bathroom scale) in 1 pound ingots. So that ballparks at about $1.50/pound which isn't bad for not having to scrounge and delivered to your door. I didn't add any tin, antimony or anything to the alloy and it seems to be medium hard. It's definitely not soft lead because I tried to slug my barrel with a piece and couldn't. I was able to do it easily with some sinker lead out of my fishing box which is much softer so I'm assuming whatever the alloy is that is use for the reclaimed shot is significantly harder than pure lead.
All of which is to say that I might have been "lucky" to get some lead in an alloy that gives me good mold fill but I also think a BIG part of that is temperature control and initial mold prep when they come out of the box for the first time. When I pay attention to temperature, especially on starting from the warm-up, I get wonderful results. I've done several different sets of Lee molds now in both two and six boolit varieties and the same technique works with either type.
Who knows, my next batch of lead might not be so good but I'm about a third of the way through this batch and the results have been stellar for a newbie to the casting game. I hope this help someone. If it does, pay it forward for the next newbie ;-)