My 1st Cast

[cag215]

Been lurking and reading and planing for weeks. Pulled the trigger today on my 1st casting session...over all I'm happy....

MP 277-125 6.8 spl mold....(probably not the easiest to learn on, but way fun)

Started out with wrinkles, but I kept at it and started dropping some 1st pass keepers.

Start of batch left to right, culls at the top of the pic, keepers at the bottom.
http://i176.photobucket.com/albums/w183/CAG215/cast68007.jpg

[Griz44mag]

Looks like your success ratio is way up. Way to go. I love casting almost as much as I enjoy shooting. Can you get some closeups of your boolets? What are you going to do for lube? Do you have a lube sizer or do you plan on panning or Lee-ing?

[runfiverun]

throw a sample of 10 from each pile on the scales that will give you more information as to your casting success.

[geargnasher]

Man, look at that shiny Lee pot! Get yourself a hotplate and make an oven to sit on top of it like this, preheating it to 400F for 30 minutes (while your lead melts and comes up to temp) will take a lot of the drag out of getting those big aluminum blocks up to casting temperature.

http://castboolits.gunloads.com/imagehosting/thum_89094e5ad65ae2e31.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=1966)

BBQ grill replacement thermometer and steel electrical workbox are available at home improvement stores.

This is what your pot may look like in a few years:

http://castboolits.gunloads.com/imagehosting/thum_89094fcea014bfc75.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=5510)

Gear

[cag215]

Get yourself a hotplate and make an oven to sit on top of it like this, preheating it to 400F for 30 minutes (while your lead melts and comes up to temp) will take a lot of the drag out of getting those big aluminum blocks up to casting temperature.
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Gear

Thanks... the oven is already in the works.....The tips and information on this forum are first rate, from safety, mold prep, set up to pour, I would have been lost without all the information here.

I do have a question that has to do with mold temp/pour temp...
When you see craters in the base of the bullet from the sprue cut....is the mold too hot/too cold? or the lead too hot/too cold?
Bullets that dropped out of the mold on their own all had deformed bases. I slowed my casting speed down, letting the mold cool, the base off the bullets cut clean but the bullets were harder to drop out of the mold.

You can see bullets bases in this photo.....

http://i176.photobucket.com/albums/w183/CAG215/cast68005.jpg

[Cherokee]

Congratulations - good first effort !!

[geargnasher]

I do have a question that has to do with mold temp/pour temp...When you see craters in the base of the bullet from the sprue cut....is the mold too hot/too cold? or the lead too hot/too cold?

Bullets that dropped out of the mold on their own all had deformed bases. I slowed my casting speed down, letting the mold cool, the base off the bullets cut clean but the bullets were harder to drop out of the mold.

What I call the "big three" of casting are mould temp, sprue plate temp, and alloy temp. They all have to be right for things to work properly, and they all three will be different for various alloys, moulds, and sprue plates.

First, ALLOY temperature. This should be maintainted at somewhere around 100 degrees hotter than the point where the alloy is "fully molten", meaning no slush or grainy-ness remains. If you check this with a thermometer, you'll notice that the temperature doesn't rise during the mush phase of the alloy, same with all matter during a phase change. This assumes your alloy has a mush phase, as eutectic and some binary alloys do not, they go from solid to liquid all at once and vice-versa. Anyway, note the temperature of the mush phase, and the instant it starts to rise, the metal should me smooth and fully liquid if you stir it, note this temperature and set your pot for 100 degrees hotter than that, and maintain it there. Other than checking and adjusting the pot dial down as your lead level falls in the pot (Lee pots get the metal hotter for the same setting as you drain down the pot), don't mess with the alloy temp any more, the rest is up to mould and sprue plate temp.

Next, MOULD temperature. This is the whole enchilada, right here. How the mould fills out, the size and consistency of your boolits, and the way they drop out of the mould is all controlled by the temperature of the blocks, which is a factor of alloy temp, cavity size, block material, block mass, ambient temp, air drafts, and most importantly casting speed. This assumes a "good" mould that aligns properly when closed and doesn't have any burrs on the edges of the cavities, and the cavities are bored on-center between the blocks. Even when you have everything right, boolits might not all fall out on their own, but may require a light tap on the handle pivot bolt with a rawhide mallet to pop them out. I consider this normal unless it takes excessive force, and the speed/temperature I often cast at tends to make the boolits stick a little more than with a cooler mould, but I get more consistent boolit weights and fillout that way.

Lastly, SPRUE PLATE TEMPERATURE. This is where your boolit base fillout quality happens, and is most related to your questions about the bases. If the sprue plate is too cool, you will have rounded base edges and the sprue will freeze too quickly, even if the mould blocks are at a good casting temperature. This will make the sprues too hard to cut well, and often leaves bumps on the bases that make it impossible to seat a gas check flat and squarely. If the sprue plate is too hot, usually meaning it takes more than six seconds for the sprue to set enough to cut without smearing molten alloy on top of the blocks, then it slows your casting pace down quite a bit. OK, so how do you control sprue plate temp? It depends on several things, some you can control and some you have to work around. What you can't control is the sprue plate material (and thermal conductivity, some are alum. some are steel, etc.), and thickness of the plate. What you can control is primarily the size of the sprue puddle you pour, and what percentage of time out of the casting cycle that the sprue plate is "open" (and losing heat) and isn't in contact with hot alloy. Another thing, and this is VERY important, is just exactly when you choose to cut the sprue. Cratered bases are universally due to opening the sprue plate before the alloy has fully "set", and is still slightly in the mush phase. The metal is more like packed brown sugar than solid metal, and it sort of tears and crumbles rather than slices cleanly when you cut the sprues. This isn't really an issue as long as you keep the pace consistent and the craters are all the same. Having the craters is a good indicator of casting consistency, but is only part of the equation, the rest of the mould has to be a consistent temp too, so the whole key is a regular rhythm of fill, watch the sprue, cut, dump the sprue, check the bases, open the mould, dumb the boolits, close the mould, close the sprue plate, repeat.

If your bases are rounded, either the sprue plate is too tight and not venting, you're pouring the alloy into the mould too slowly, the sprue plate is too cold, or some combination of the three.


What I try to impress on new casters is to get the alloy temp right for the alloy you're using and forget about it, then quit looking at your boolits on the towel or worrying about them, if you get your temps and pour techniques right the boolits will take care of themselves. Focus on timing, mould/sprue plate temperature, and consistency of rhythm. Once you get "in the habit", it all becomes simple. Glance at the boolits and observe fillout and degree of shine to see how the mould temp is doing, watch the bases and how long it takes the sprues to set just enough to cut (soft but firm), and adjust your pace and sprue puddle size to correct for these. It's just like learning to drive a car, once your brain learns to take over steering and throttle corrections without your constant, concious attention, you can relax and enjoy the trip. Same with casting boolits, once you learn the timing of sprue cooling, (here is the only real "wait" in the process) and do the other operations in a continuous, moving cycle, much of the mystery will be removed. Look at your boolits on the towel while you're waiting those three-five seconds for the sprue to cool so it doesn't interrrupt the rest of the process.

The other things involved with casting that are mould-specific and you really have to determine for yourself have to do with mould venting, pour technique, sprue plate tension, size of the alloy stream going into the cavities, distance you drop the alloy from the spout, angle you hold the mould, how tightly you hold the mould handles (DON'T hold the sprue cam handle together with the mould handles on Lee moulds, it will cam-open the blocks slightly!!), and a myriad of other little details.

So, in review:

Alloy at 100 F over full-liquidus, get a casting thermometer for BEST results, otherwise you're blind.
Preheat mould, cast at 3-4 pours per minute (TIME IT!) until wrinkles go away, boolit edges are clean and sharp and satin frost appears (antimonial alloy only will "frost").
Pour a dime-sized puddle of lead after the sprue plate well is filled.
Cut the sprue while soft, but set enough not to smear melted alloy. Base craters are ok, some prefer to wait another second before cutting and have clean bases.
Observe sprue color/sheen changes, boolit bases before dropping, and surface sheen/sharpness of cooling boolits to determine what changes to make in the timing of sprue set/cut, sprue puddle size, and overall casting speed. Get an analog wall clock with a second hand, mount it over your pot, and watch it. Take notes on ambient temp, alloy temp, and timing of all casting actions for next session once you find the "sweet spot" for that particular mould, alloy, and weather. Yes, weather. Ambient temperature, humidity, and dew point make a noticeable difference to how a casting session goes.

Hope this helps shed a little light on the mystery, you can see why this is considered more of an "art" than a science. Just keep at it, it will come to you gradually, this isn't something that you get really good at overnight, but isn't all that difficult, either once you discover what's going on, how to control it, and what the parameters are.

Gear

[runfiverun]

after looking at your pic i'd double check the sprue plate holes lining up with your cavitys.
many of them seem off center.

[cag215]

I just hit the print key....sharing years of knowledge and insight are most welcome.

Thank You

[bowfin]

Welcome and congratulations!

Are you planning on hunting with these, or are they for practice/paper punching?

As a personal favor, if you could guesstimate your keepers and add them here:

http://castboolits.gunloads.com/showthread.php?t=153432

I would appreciate it.

[geargnasher]

after looking at your pic i'd double check the sprue plate holes lining up with your cavitys.
many of them seem off center.

Yup, I noticed that too, really the only imperfections I noticed in most of the boolits other than a tiny trace of a nose wrinkle on one or two. Really not a bad job at all, CAG215. I'll bet there's some galling on the sprue plate where it engages the latch bolt, and sometimes it's not swinging shut all the way. A light polish with some fine sandpaper and frequent treatment with some synthetic two-cycle premix oil applied sparingly with a Q-tip to that area will reduce the problem.

Those small boolits will really make a person hustle the casting sequence to keep the mould hot compared to some of the larger, heavier boolit designs. My sequence with the smaller ones goes something like this: Mould under spout, farthest cavity first, angle mould slightly down on handle end, lift the valve handle to dump straight into the sprue hole, fill until about a dime-sized puddle forms and "blip" to the next one quickly, so it goes blip, blip, blip, blip, blip, blip, (watch the sprue sheen change......) and slip the mould off the support shelf, cut and dump the sprue off in one smooth motion, glance at the bases for one second, then open and dump the boolits, immediately close the mould, swing the sprue plate closed and poke it under the spout again to start the filling right away. This sequence takes 15-20 seconds to complete most of the time with 675-700 degree wheel weight alloy + a pinch of tin in a 75 degree room using a Lee six-cavity mould 30 caliber or smaller.

Gear

[Moonie]

That there is a Miha mold, I'd bet the spru plate isn't getting closed all the way before I thought something was up with the alignment of one of his molds.

[cag215]

Welcome and congratulations!

Are you planning on hunting with these, or are they for practice/paper punching?

As a personal favor, if you could guesstimate your keepers and add them here:

http://castboolits.gunloads.com/showthread.php?t=153432

I would appreciate it.

Mostly I want to shoot paper with the cast, and add to my hobby of reloading. As I have been going through the keepers piles, I keep finding more culls. I will post the SWAG number of keepers as soon as I sort everything.

[cag215]

Yup, I noticed that too, really the only imperfections I noticed in most of the boolits other than a tiny trace of a nose wrinkle on one or two. Really not a bad job at all, CAG215. I'll bet there's some galling on the sprue plate where it engages the latch bolt, and sometimes it's not swinging shut all the way. A light polish with some fine sandpaper and frequent treatment with some synthetic two-cycle premix oil applied sparingly with a Q-tip to that area will reduce the problem.

Those small boolits will really make a person hustle the casting sequence to keep the mould hot compared to some of the larger, heavier boolit designs. My sequence with the smaller ones goes something like this: Mould under spout, farthest cavity first, angle mould slightly down on handle end, lift the valve handle to dump straight into the sprue hole, fill until about a dime-sized puddle forms and "blip" to the next one quickly, so it goes blip, blip, blip, blip, blip, blip, (watch the sprue sheen change......) and slip the mould off the support shelf, cut and dump the sprue off in one smooth motion, glance at the bases for one second, then open and dump the boolits, immediately close the mould, swing the sprue plate closed and poke it under the spout again to start the filling right away. This sequence takes 15-20 seconds to complete most of the time with 675-700 degree wheel weight alloy + a pinch of tin in a 75 degree room using a Lee six-cavity mould 30 caliber or smaller.

Gear

I was thinking of doing a very light polish with 0000 steel wool and gun oil on the sprue plate. Then make any adjustments and give the mold a good cleaning and hard look at to see if it all aligns..... most likely there was operator error involved.

As far the casting process goes, I had a bit of beginners luck, I was casting very much like you describe.... except for that 75°F room temp.
I was outside and concerned about sweating in the pot. I was getting four to five casts, then I had to stop to dry off. I was setting the mold on top of the pot every time I stopped.

The best part of having a cull bullet....you get the chance to turn it into a perfect bullet next time....

[geargnasher]

Lead doesn't wear out no matter how many times you recast it as long as you chemically "reduce" back the oxides rather than skimming them off the top each time you remelt. Reduction being the opposite of the oxidation reaction, which is done with grease/wax/oil/sawdust to revert the oxide scum on top of the melt back to pure metals. Keep the pot temperature low will drastically decrease oxide formation.

Keep up the good work there, you're doing great!

Gear