Another mould/casting problem

[Bub524]

I know this has been beat to death, but here it is:
I have been casting bullets successfully for 30+ years and I have never reached the level of EXTREME FRUSTRATION that I have with casting minies.
I have the following:
-a Gardner mould from Greg Edington that gives me 90% good bullets
-a Lyman 577611 thats results in 98% voids at the apex of the base plug for a 2% yield
-a Lyman 575213OS that gives me 80% good bullets
-a Lyman 578675 that gives me 40% good bullets, most have a hole in the side of the skirt or the skirt doesn't fill out
-Lee trash can mold that puts out 99% good bullets
-Lee Old Style Minie that is 50 %

I use pure lead, the lead temp is between 850 and 950
I have tried a bottom pour Lee and the dipper method. The dipper method gives a higher percentage of good bullets, but I feel anything less than 80% yield is a waste of time. An hour of casting for 12 good bullets is enough to make you want to hang it up.
Round balls are SO much easier.
Did I mention this is EXTREMELY FRUSTRATING??
Any help would be appreciated.

[Southron Sr.]

Put a little pure TIN in your lead pot. A SMALL PERCENTAGE of tin will result in cast bullets that fill out the mould better (hence, less rejects) and produce brighter bullets.

Like I said, just a SMALL AMOUNT OF TIN, too much tin will make the skirts of your Minie's too hard to expand properly.

GOOD LUCK AND HAPPY NEW YEARS!!!!

[Kurt Lacko 7862]

Try canting the mould a few degrees to either side while pouring, obviously as the lead comes up to form the spru you have to level it out. This will give a slight swirl which may/maynot help. It appears your doing everything else correctly.

As a side note, you don't live on the equator do you? Strange things happen there sometimes! Kurt.

[Mike McDaniel]

I think I'l try that mould cant trick myself.

That being said, Minies are a bear to cast. I don't care what you do, the reject rate is going to be pretty high.

[Gary Van Kauwenbergh, 101]

I'm guessing the Edington and Lee molds have aluminum blocks, and the Lyman ones you're having the most problems with are steel. Aluminum blocks warm up to casting temp pretty quick, but will also over-heat if you're casting too quickly.

Steel blocks take longer to warm up than aluminum, but once you get there, you're fine. Either way, you need to get the molds up to the right temp, then find the right rate to cast so the molds don't get too cool or over heat.

Flux well, make sure your spout is clean so you get a good flow into the mold, and leave a healthy sized sprue.

Hang in there. Where are you at in central WI? I'm in Madison, but may be able to connect you with some minie-casters in your area.

[Edwin Flint, 8427]

With the steel moulds, I usually cast the first 15-20 and toss them back in. Takes that long to get the mould up to temp. Then I cast until the pot runs out. No stops. Increases output, decreases rejects. I also cast on the higher end of the temp. scale you mentioned.

Aluminum, same thing except doesn't take as long to get the mould hot. I also preheat the mould on the rim of the pot while the lead is melting. Certain moulds do require the cant.

Stay away from the tin. Pretty bullets, lousy minies.

[tonyb]

While the lead pot heats up heat the steel molds up on a hot plate.

[ken chrestman]

Drill the sprue plate .200-.250 from the back side to allow more volume into the mold. Place mold and dipper horizontal then turn vertical in one motion while holding the dipper in the sprue hole.Let stand a few seconds 3-5.knock open sprue plate and open mold.

I do not add tin.
Heat the mold blocks on a hot plate while the lead furnace gets to molding temp.
Always flux, then cast,I usually get 100 or more before I stop works just fine.

E-mail me and I will mic the exact drill I use if you like, Ken@ShelbySecurity.com

Ken Chrestman, FEC Tennessee

[John Bly]

Casting good minies is largely technique. One must have good lead properly fluxed at the right temp and a good mold at the right temp. Your temps are perhaps a little too high but should work. I use a dipper and pour the bullet over the pot. I get the best results by tilting the mold and pouring the lead down one side of the sprue plate making sure to not block off the air escape by pouring too much, too fast. As the mold fills, bring it to a vertical position while still pouring more lead onto the top plate. On large bullets like minies you must keep a molten column of lead in the sprue while the lead in the mold cools. This will be from 3 to 5 seconds. If you just pour until the mold is full and stop, the sprue hardens and as the bullet cools it will create voids in the bullet because it can't draw more lead into the center of the bullet. These generally show up in the top of the cavity left by the base plug. Voids in round balls are generally not seen, but I would suspect you've got plenty of them in your round balls and never knew it.
I generally enlarge the sprue hole to let more lead in quicker and let the air out. Voids in the skirts are generally caused by the mold or lead not being hot enough or the mold is not vented properly. Voids in the base cavity are almost always the result of poor technique. Keep pouring that lead several seconds after the mold is full and you'll see greatly improved bullets.

[Bub524]

Thanks everybody! I tried the horizontal to vertical pour technique and had 100% return with the 575611 mould!
This was the one I was getting about 2% good bullets from. The 578675 still has skirt problems, or rather I with it.
The other moulds are putting out 95% now.
Thanks again.
Bob

[paul w/McGregor's 385V]

Bub,
Tilting will improve your casting as you have found. Another reason for the voids is the flow pattern at the base plug. Several years back I put my base plugs in a drill and ground the tips on the plugs to a flat, just enough to remove that point. Voids stopped, bullet weights became consistent. Use pure lead for minies.

Take care and be safe
pfb

[William H. Shuey]

I have noticed the small grooves in the top surface of the blocks which is under the sprue cutter. I assume they let escaping air get out under the plate. Is it a good idea to use a small wire brush to clean these out regularly??

Bill Shuey

[R. McAuley 3014V]

Firstly, I am somewhat surprised that you would be casting minies at between 850 and 950°F considering that the melting point of lead is merely 621°F. So, what does the other 200-300 degrees do for your minies besides tempering them to make them harder? I don’t suppose it ever occurred to you that such a high temperature, although having very little effect on steel blocks, actually begins to anneal aluminum, reducing its strength and causing deformation. Although the melting point of aluminum occurs at 1218°F, foundaries who forge aluminum use gas-fired industrial ovens as well as infrared ovens into which blanks are placed and raised the temperature to 800°F before they are ready to be forged. This is called “pre-heating” and the aluminum (depending on alloy) begins to anneal at about 200 to 300°F below its melting point such that at the temperature you are using is actually above its recrystallization point (800°F). Just about 900°F is when aluminum begins to deform, which once its yield point is reached, elastic deformation becomes permanent. So if you continue to use such high temperatures with your aluminum moulds, you'll soon be having problems with them as well.

[paul w/McGregor's 385V]

RM,
The melting point and clear flow temperatures are not the same. Lead will indeed melt at 621°F, but it is not yet free flowing. Ice melts at 32.6°F, but water is not yet flowing.

To correctly cast, the metal must reach a temperature where it is fluid. That temperature is approximately 750°F. As most electric pots are not exact, setting the temperature at 800 on the dial ensures you have the lead at a fluid state.

Also unless you have the lead at a fluid state, it is more difficult to clear the dross and flux other impurities from the pot.

Take care and be safe
pfb

[J Weber 4114V]

I also cast minnes at 850+ deg. So my .02 worth
Pure PB does not work harden,can not be tempered I seem to recall
Alloys be a whole diffrent game though.
Casting just the other day with steel block mould @ my 850+ pot temp I checked the temp of my blocks with a laser temp therometer thingy and the hottest temp was the spru plate at about 580-600 The outside of the blocks were around 220-250.The core pin was @ 400 or so. This was after casting 70 or so 500 gn traditional minnes. I will take temp readings on a Al mold next time I use one.
Remember if the mold is over the melting point of the lead it will not solidify.
So with a steel mold the temps will not be high enough to hurt anything.
One thing with Al moldsI have noticed is Lee blocks are made of a soft alloy They are very prone to being damaged by any miss use that does not seem to effect more expensive blocks ie Rapine.

[Scott Kurki, 12475]

I have developed a skill at casting minies using an RCBS bottom pour furnace and a Rapine 580510 mould. I experimented to find the best pour rate that resulted in the best minie consistency. I have found that if I tilt the mould a little at the beginning of the pour and straighten it during the pour works to eliminate bubbles in the cavity of the base. This technique along with the best pouring speed has greatly reduced my bad pours. Pouring a good minie consistently takes some experimentation and practice.

By the way, for me the best pour speed is not the fastest, I slow it down quite a bit. The bullets are weighing out consistently most of the time.

[William H. Shuey]

"Another reason for the voids is the flow pattern at the base plug. Several years back I put my base plugs in a drill and ground the tips on the plugs to a flat, just enough to remove that point. Voids stopped, bullet weights became consistent."

I was having void problems with my Lyman 575602 and tried your fix, worked marvelously. I wonder why?? Probably some bearded Albert Einstein type with a PHd in high temperature mechanics could explain, but I'm just as happy in my ignorance! :-)

Bill Shuey

[Tom Magno, 9269V]

Solution - Use a Wilkinson design and be rid of hollow-based minnies! More accurate, more tolerant to base defects, can be gang moulded, no worries of blown skirts! :D

[Bub524]

Where would I get a Wilkinson mold?

[Tom Magno, 9269V]

Check with Greg Edington (bridesburgh AT hotmail DOT com) or with Bill Osborne at Lodgewood Mfg (http://www.lodgewood.com).

[Southron Sr.]

Time to drive a WOODEN STAKE through the HEART of this CASTING MYTH.

Lyman moulds ARE NOT MADE FROM STEEL-they are made from SOFT IRON!!!

If you have ever drilled into a Lyman mould (as I have) you know that the iron they are made from is "soft as butter." Among other things, soft iron moulds means that Lyman's mould production tooling will last a lot longer before it has to be re-sharpened.

Matter of fact, I don't know of ANY MOULD MANUFACTURER that uses STEEL to make mould blocks.

Some rather exotic materials have been used to make mould blocks in the past. Frontier gunsmiths on the Eastern Frontier in the 1700's sometimes made their round ball moulds out of sandstone! More recently (in the 20th Century) mould blocks have been made from NICKEL.

The BEST "all around" metal from which to make moulds is probably BRASS. But, brass is very expensive when compared to either soft iron or aluminum-so that is why the majority of moulds on the market are made from either aluminum or soft iron. It is a "cost" thing and nothing more.

[paul w/McGregor's 385V]

Bub,
North East Trader, John DeWald had a few Wilkerson moulds last time I spoke with him.

Take care and be safe
pfb

[jerry ashley]

To Southron Sr.
The Iron used in Lyman molds was 32510 Mallable Iron. When poured it is like glass and will break as such. But after a 36 hour 3 phase annealing cycle it comes out soft as steel. This is why its called semi-steel sometimes. I think I read some where that some civil war musket barrels were made of semi-steel. But during that time period the material was 35018 Mallable Iron. The foundry I worked for made 3 different sizes of blocks for Lyman. I took the patterns back in 1993 give or take.
Jerry Ashley

[Southron Sr.]

Contrary to popular opinion, "STEEL MULLET MOULDS" ARE NOT MADE BY LYMAN!

Their moulds are made from a SOFT IRON! There are several reasons for that and among those reasons is that Lyman's tooling will last a lot longer when it comes to cutting soft iron as compared to cutting steel.

If you have ever milled or drilled into a Lyman mould (and I have done so many times) you will find that a Lyman mould is literally "as soft as butter."

[DAVE FRANCE]

Bub,I know how you feel. It took me years to be able to cast over 95% good Minies or any other bullets.
er
I wrote an article about casting the larger bullets skirmishers use. You can find it doing an internet search. Look for CASTING GOOD BULLETS BY DAVE FRANCE.

YOU GOT SOME GOOD ADVICE. YOU USUALLY NEED TO CAST SOFT LEAD AT ABOUT 850 FOR MINIES. I USUALLY GOT BETTER MINIES USING A DIPPER AND WITH AN ENLARGED HOLE AND A SPRUE CUTTER WITH AN ENLARGED HOLE.

KEEPING THE MOLD CLEAN, AND WARMING BEFORE CASTING ARE A BIG HELP.

i USED ALUMINUM MOLDS FOR YEARS BUT THE CAN BE WARPED BY HOT TEMPERATURE. aLUMINUM IS STRONG WHEN COLD, BUT ITS STRENGTH IS REDUCED AT HIGHT TEMPS.
There are some good suggestion on some web sites. If what you have is not all you need, send me a message, and I will send you some more information.