First Bullets Cast, Now the Questions....

[August]

I cast my first bullets yesterday. Using dipper method and Lyman 457677 (490 grain), I started getting some good looking bullets after about a dozen, or so, failed to fill out the mold. After a time, it seemed that things got a bit overheated, as the booolets started to show a crystalized surface. I slowed down, things got better.

Last night, I weighed the results. Got about 160 booolets that "looked" good. They weighed between 490.8 and 494.3 grains. Most of them were within .5 grains of 192.0. I thought that distribution was pretty good for the first attempt at this high art. BTW, alloy is 30/1 (ish).

Here's my question: It seems that most of the weight variation (not all, but most) is associated with the the way the sprue cutter finished off the base of the boolet. If the cutter took a hunk of lead -- leaving a crytalized hole -- the bullets went to the light end of the spectrum. If, OTOH, the cutter made a smooth cut without pulling any boolet up with it, they weighed to the high end. Makes sense, donut?

How do I get the cutting part of this process more consistent???? Also, are there any tips for adjusting the sprue cutter????

Thanks!!!!!!!!

[klausg]

August- I don't own any really big moulds, so I may be off-base a little. My casting is mainly handgun. That being said, what you're describing is not so much an adjustment of the sprue plate, but when you decide to cut it. I like to give a six-Mississpi count once the puddle solidifies before cutting; with your bigger boolits you may have to give more time. I'm sure someone else will chime in here with more experience with the bigger boolits. Hope this helps.

-Klaus

[HEAD0001]

I try to do things in a cadence. I think this makes my bullets more consistent. I use a wooden mallet and tap my "sprue cutter" with the same amount of pressure every time(give or take). I use a three tap cadence. I overpour with a slight tilt of the mold away from sprue cutter.The first light tap takes cutter over to lead. The second(the hard tap) cuts the sprue, The third cleans all the lead off the top. I do not know how many guys tilt their mold slightly so lead pours away from the sprue cutter side, but I think it gives a more consistent cut.
I have never had to adjust a sprue cutter, only replace them. Tom.

[Leftoverdj]

I'll agree that it's mostly timing. I don't really cut sprues, it's more of a fracture, not elevated, not recessed, just a little rough spot where the sprue was attached. I dunno it that's the right way or the wrong way, but it's my way. When I do cut sprues, it's while the mould is coming to temperature and I get a little raised spot which interferes with getting GCs seated flat and square.

[montana_charlie]

Sprue plate adjustment (in my mind) is mainly to protect the the mould from damage. Too tight means wear on the blocks, and too loose lets the plate flop around uncontrollably.

Snug enough so it will try to swing when you give the (cold and empty) mould a medium-firm shake seems about right. It's just a bit looser when the mould is hot.
Of course, the plate must also be ground flat on it's bottom.

As for timing the cut, I wait about three seconds after the sprue solidifies. This is on .45 cal bullets in the heavy weights. Then I swing the plate by hand, like opening a jar of pickles, with one smooth turn. The mark left on the bullet is slightly teardrop-shaped, and absolutely flat to the base.

I have a 'knocker' on the bench, but I rarely pick it up.
CM

[Bret4207]

Read the sticky on "The Bruce B Speedcasting Method" It's located here someplace. Basicly you cool the sprue with a wet cloth. I use this method with some of my moulds and NEVER get a bad sprue cut. Worth a try fer sure!

[wills]

Read the sticky on "The Bruce B Speedcasting Method" It's located here someplace. Basicly you cool the sprue with a wet cloth. I use this method with some of my moulds and NEVER get a bad sprue cut. Worth a try fer sure!



http://ktsammo.250x.com/castboolits/cst1.html

[mooman76]

Sounds to me like the lead was a tad too hot. That's where the bullets come out with a crystalized look. Doesn't hurt a thing but some people don't like it and want the shiny boolits. Just turn the temp down a bit. That should help with your spew also because I think your lead in the mould is still a little soft when you cut it and it is pulling some of the lead out!

[44man]

I have been poked fun at but I wait until the sprue just sets and swing my arm 4 times, then cut it. If the mould gets too hot, just make 5 swings.

[Bass Ackward]

I have been poked fun at but I wait until the sprue just sets and swing my arm 4 times, then cut it. If the mould gets too hot, just make 5 swings.


44man,

Boy you really have to watch with that technique and make sure that you have solidified before you start the swing. Otherwise, that circular swing takes it over some fairly critical body parts. :grin:

[HORNET]

August,
What you might try is sharpening the sprue hole in the plate. Most of the stamped ones have an unsharpened straight section between the chamfer and the bottom of the plate. Use a countersink and deepen the chamfer to get a sharp edge that will give a clean cut. You'll need to stone the bottom of the plate to deburr after you get it sharp.
If you have lots of trouble getting good fillout on the mold, you might want to increase the diameter of the sprus while you're at it . Drill bits can be used to gauge the size. About 3/16 dia. (stock is about .150) should show improvement, some go even bigger. try smaller first ( its easy to remove more metal but real tough to add it back).
Since you're dipper casting, leave the sprue plate a little loose and hold it down with the side of the spout on the dipper while pouring. This keeps the plate flat on the top of the blocks to help keep the base of the boolit square to the universe. If you tilt the blocks a little and keep pouring slowly AFTER the cavity fills, you will be able to see the puddle suck in as the alloy in the cavity shrinks when it goes solid. By keeping the lead pouring, you help keep the sprue open to minimize any shrinkage voids ( this is what the aftermarket super-thick plates achieve). When it sucks in, stop pouring, wait a few seconds for the puddle to color change as it sets up, then cut the sprue. A sharp plate will cut a fairly good sized sprue very easily.[smilie=1:
Let the flames begin.:killingpc