What Multi cavity molds have taught me

[10x]

I have been using NOE 5 cavity molds for the past 3 years and they have given me a little insight on things that go wrong

These are things I have learned cast 22 and 35 caliber bullets.

1) keep your alloy hot - use a lead thermometer to monitor the temperature of your alloy.
There are inexpensive digital thermometers that give will give extremely acurrate results. I discovered my Lyman pot will only heat to 700F with the internal thermostat set at max ( I have gone to a P.I.D. controller to keep the alloy at the correct temperature - it also gives me a readout on the current temperature of the alloy in the pot)

2) Clean your alloy. And make sure you have enough tin. I run about 5% tin in all alloys I mix. Adding a little tin will result in really nice mold fillout


3) Make sure you mold blocks are clean, break clean takes off oil, so does ammonia. An acetone rince to dry.

4) preheat your molds, I use a hotplate with a PID to ensure the molds are heated to about 400F. usually the first bullets cast are keepers.

5) you can use a ladle or a bottom pour pot. No matter which you use, ensure that you have a large sprue. Large sprues do two things, a) allow a reservoir of metal to fill the cavity as the lead bullet solidifies and b) keeps the sprue plate hot.

6) rate of pour into the mold - if you are using a bottom pour pot or ladle make sure that the lead flows into the mold in an unbroken stream. If you start to see the stream break up into drops you run the risk of wrinkles as the drops sometimes cause layering in the mold

7) Watch the sprue - you can see the transition from molten to solid. Establish a time that the sprue takes to solidify. If it takes much more than a half pound of pressure with your thumb to cut the sprue you are waiting too long, if it takes no pressure at all, that is to fast.

8) Sprue plate and mold maintenance - I will use synthetic 2 stroke motor oil to lubricate the alignment pins, sprue plate screw, mold block retainer pins, and the hinge in the handle. I dilute a couple of drops of 2 stroke oil with a couple drops of mineral spirt and use a q tip to transfer just a little to each of these parts.

9) the bottom of the sprue plate - with a full mold this gets some dilute 2 stroke motor oil rubbed on it from time to time, then wiped off with a paper towel. This reduces the risk of galling. Check to make sure the bullets are filling out and the bases have nice sharp edges, Rounded bases may mean a cool sprue plate, not enough puddle over the sprue hole, or the lube is boiling off the sprue plate.

10) on a multi cavity mold - when you open the mold - about 3 to 10 seconds after you cut the sprue- inspect the bullets if they hang in the mold, or fall onto your catch cloth.

experiment a little if you like. On a multi cavity mold use a large sprue, small sprue, change the difference in distance from the spout to the mold and see how what happens to the bullet.

11) on bottom pour pots, watch the volume of flow when you get to the bottom 1/3 of the pot. it will sometimes slow. Usually the faster the mold files the more risk of getting a good bullet.

Just some observations

I welcome comments and other methods....
It seems even after casting for over 50 years I am still learning
And thank you to all the folks here who have brought me into the world of PID temperature control. Bottom pour pots, home made gas checks, and multi cavity molds
Not to mention all of the information on alloys and gas checks
not

[bangerjim]

Agree on most points. Good listing!

I NEVER clean my molds, even when brand new! In the past 6 months I have purchased four 4-5 cavity brass and 5 six cavity Al molds. All were taken right out of the box, preheated to FULL casting temp (3X on brass molds) (smoked with beeswax candle on the Al molds), and they all dropped perfect boolits from the 1st pour from a bottom pour pot with alloy at correct temp.

the MOST important thing I have found after lots of experimenting, is to pre-heat ALL molds (and ingots to spped up feeding your pot) to full casting temp B4 starting. Perfect drops every time. I cannot understand why so many people refuse to listen to the common sense that so many of us are talking about on here. "Warming" them on the top of the pot is NOT good enough!!!!!!!! A hot plate is just as important to good casting as a lead pot, molds, and the alloy. Never cast without one.

I do not use a thermometer or controller for pot temp. I do check my mold temps on the hotplate with an IR gun shooting at a blackened end to get the correct mold temp. IR does NOT work on shiny surfaces so you have to chemically blacken the aluminum. Sprue plate will be colder and is not a good indicator.

My temp indicator of pour temp is the sharp sizzle I get when I drop the boolits in a pan of water. No sizzle or minimum sizzle-----not hot enough---and they will ALWAYS be wrinkly! Sharp sizzle and things are perfect every time! (Plus 3-4 second sprue puddle hardening!) I only water drop to cool the lead, not to gain any voodoo Sb hardening. I PC everything and that looses all hardness due to the 400F baking.

I use straight (not diluted) 2 cycle "blue" oil dispensed from a hypodermic needle to hinges/pins/surfaces of the mold that need it. Then rub around with my finger. The hypo needle also allows me to add lube during casting if I need it...in tiny drops.

And I agree, you should not have to "WHACK" a sprue plate to cut the sprue!!!!! Hence no need for mold whackers. I have a rawhide mallet I nudge the plate open with, but never whack it. If you need to do a whack job, your mold is too cold! And the rawhide mallet is handy for gently tapping (again - not whacking) your mold ON THE HANDLE and NOT THE BLOCK if you have a stubborn boolit that will not drop easily and needs to coaxed out.

Casting is a game of practice. Read all you want. But just get out there and do it. One will learn very fast what works - - - and does not work! Too many new folks read until they are blue in the face and end up messing their casting up by completely overthinking this very simple and enjoyable process. Same with hardness!

Good casting!

bangerjim

[Fishman]

10X, a very good post and one that newbies would do well to read carefully before they cast as well as after they have cast a few times. A lot of information there.


Two things I do a bit different and one thing you didn't really touch on.

I run my alloy a bit hotter most times (710-740 degrees) and don't use as much tin. I think running the alloy a bit hotter helps with fillout and reduces the need for expensive tin. The PID really helps with temperature control.

I don't stop to look at any of the boolits I drop unless they are obvious culls. Once I get the mold casting well I don't want to have to stop. Many times I will cast 40-50 and return them immediately to the pot after each cast until I know the mold is casting well.

I catch my sprues in a gloved hand and return them to the pot as I cast, which extends the time between adding ingots. I preheat my ingots on the hotplate and add them as soon as the alloy level drops enough. I try and keep a (somewhat) uniform amount of alloy in my bottom pour.

[Nicholas]

Fishman makes my bullets and they are all beautiful. Some 340 gr bullet shot incredibly tight groups in my Marlin 1895. I think it is in his genes.

[10x]

10X, a very good post and one that newbies would do well to read carefully before they cast as well as after they have cast a few times. A lot of information there.


Two things I do a bit different and one thing you didn't really touch on.

I run my alloy a bit hotter most times (710-740 degrees) and don't use as much tin. I think running the alloy a bit hotter helps with fillout and reduces the need for expensive tin. The PID really helps with temperature control.

I don't stop to look at any of the boolits I drop unless they are obvious culls. Once I get the mold casting well I don't want to have to stop. Many times I will cast 40-50 and return them immediately to the pot after each cast until I know the mold is casting well.

I catch my sprues in a gloved hand and return them to the pot as I cast, which extends the time between adding ingots. I preheat my ingots on the hotplate and add them as soon as the alloy level drops enough. I try and keep a (somewhat) uniform amount of alloy in my bottom pour.

I run my alloy hotter than I used to now I have PID control
I look at the first dozen or so casts to make sure every thing is working, then it is pour and cast.
of 20 lb of lead cast I will have less than 50 bullets that are rejects - usually caused by me being inattentive or distracted during the pour.
And when all is going well the bullets usually drop from the mold on opening.
I do return the sprue to the pot - i wear a good leather insulated glove and use thumb pressure to cut the sprue, invert the mold, catching the sprue, and returing it to the pot. The PID indicated temperature seldome drops 2C, if that.
I do open the mold with the sprue plate wide open and usually the bullets fall out without any tapping. of the handle hinge

[Fishman]

Fishman makes my bullets and they are all beautiful. Some 340 gr bullet shot incredibly tight groups in my Marlin 1895. I think it is in his genes.

Flattery will get you . . . More boolits! :)

[RogerDat]

Really nice list of things that can make a difference. May print that and put it on the shelf to go through like a check list when things are not going right.

I am far from any sort of expert but a couple of tips that were sent my way have proved useful. Opening the sprue plate like I'm twisting off a jar lid with my palm down over the top. Allows some slight downward pressure where knocking or pushing with a thumb or finger I was sometimes getting a little lift to the sprue plate and leaving a teat on the bullet base.

When ladle casting some molds like the stream poured in differently. Down the middle or along the edge, one likes sort of at an angle to the edge so it swirls in. Then there is tipping the mold up sideways and plugging the spout in then tipping the two together. Pouring under pressure.

[10x]

Really nice list of things that can make a difference. May print that and put it on the shelf to go through like a check list when things are not going right.

I am far from any sort of expert but a couple of tips that were sent my way have proved useful. Opening the sprue plate like I'm twisting off a jar lid with my palm down over the top. Allows some slight downward pressure where knocking or pushing with a thumb or finger I was sometimes getting a little lift to the sprue plate and leaving a teat on the bullet base.

When ladle casting some molds like the stream poured in differently. Down the middle or along the edge, one likes sort of at an angle to the edge so it swirls in. Then there is tipping the mold up sideways and plugging the spout in then tipping the two together. Pouring under pressure.

If you are getting a small tit of lead when opening the sprue plate there may be two reasons.
You may have to replace the spring washer under your sprue plate retainer screw. Or tighten that screw a wee bit.
Also you are most certainly opening that sprue plate a little late.
I watch the metal turn to solid count to 3 or 4 then open. I get a clean shear. On a multi cavity mold a 4" long sprue sometimes breaks into several pieces when I catch it to put it back into the pot. If that happens I add a second to the count after the sprue goes to "solidus". At that point I will also check the underside of the sprue plate for lead smears and give a quick wipe with a dry paper towel, then a second wipe with a paper towel that has had a drop of synthetic 2 stroke oil diluted with couple of drops of mineral spirit or brake clean on it.

Your advice on ladle casing is well taken. You have far more control over the pour with a ladle for a number of reasons. You can adjust the stream instantly and the amount of alloy in the ladle is always the same. A bottom pour pot I find I have to adjust the stop and keep an eye on the spout and give the spout a quick ream when the stream slows. I certainly understand why some folks prefer a ladle to bottom pour pots.
Not to mention if there is anything in the alloy that shouldn't be there despite all of the cleaning of the alloy a ladle ensures that the alloy is mixed when you fill the ladle, and that there less chance of getting any foreign objects in the ladle when you fill it.

I got both the RCBS and Lyman bottom pour pots at estate sales. Both had sat for years unused and both were a challenge to get the last of the crude and corrosion out. When you are using a ladle crud on the sides of the pot seems to stay on the sides. WIth a bottom pour, the crud seems to accumulate in the pour spout.

[RogerDat]

One of these days I'll buy a pot, for now I'm using cast iron or stainless over electric or propane burner. The propane turkey fryer has a side benefit, warms the garage up a bit in cooler weather. Downside is it uses more propane. Electric pot would be cheaper to operate and could have a PID. See how this works? Always something to look forward to buying one of these days.

I try for some efficiency in that when I make up a dutch oven of alloy to pour into ingots I'll usually cast some bullets out of the pot first, then switch to a large ladle and use the rest of the dutch oven contents to make ingots for later use in the small pot. Seems like the logical time to make some of the heavy cast bullets is when there is a 100# pot-o-lead sitting there.

How does that diluted 2 cycle oil compare to refrigerant oil? I saw a suggestion for using that since it does not discolor from the heat. Wondering if maybe I should be using more on the underside of the sprue plate or possibly some of that 2 cycle mix.

[10x]

One of these days I'll buy a pot, for now I'm using cast iron or stainless over electric or propane burner. The propane turkey fryer has a side benefit, warms the garage up a bit in cooler weather. Downside is it uses more propane. Electric pot would be cheaper to operate and could have a PID. See how this works? Always something to look forward to buying one of these days.

I try for some efficiency in that when I make up a dutch oven of alloy to pour into ingots I'll usually cast some bullets out of the pot first, then switch to a large ladle and use the rest of the dutch oven contents to make ingots for later use in the small pot. Seems like the logical time to make some of the heavy cast bullets is when there is a 100# pot-o-lead sitting there.

How does that diluted 2 cycle oil compare to refrigerant oil? I saw a suggestion for using that since it does not discolor from the heat. Wondering if maybe I should be using more on the underside of the sprue plate or possibly some of that 2 cycle mix.

No idea of how it compares. But 2 stroke synthetic works great on molds if you use it very sparingly.

[DerekP Houston]

wow I guess I really need to speed up my sprue cutting, its usually a good whack to release it with my wooden mallet. Bullets fall right out though.

[10x]

wow I guess I really need to speed up my sprue cutting, its usually a good whack to release it with my wooden mallet. Bullets fall right out though.

If it takes "a good whack" to cut the sprue, you have waited too long. there should be about a pound resistance.
if the sprue changes hue when you cut, you are cutting too soon.
That is my opinion and that is what works for me....
I have Lee aluminum molds that are over 40 years old and have cast several thousand bullets a year with them. They still work well and I really don't understand the problems that folks have with Lee molds. ( I have worn out 2 lee auto prime levers - the handles simply disintegrate after 100,000 or so cycles..)

[Le Loup Solitaire]

Some excellent advice has been given here and it is well appreciated. There is always room to learn something new and worth trying that others are doing. I have used wooden mallets, rawhide leather mallets and recently have successfully tried a plastic mallet. I was surprised to find that it did not melt in long use or get chewed up after many thousands of contacts with the sprue cutters even the larger ones on H&G 4 cavity molds. I bottom pour and ladle cast using Pro-melt, Saeco Models 24 and 34 (both discontinued older pots). For removing an occasional lead smear I use the corner of an ingot which when used to rub the smear, does so. I prefer a slow casting rythm and watch the quality of what I cast rather than the clock. I take good care of my equipment and that is why it has served me well for so long. LLS

[10x]

One thing I didn't mention is that you can fill each cavity of a 5 cavity mold differently and see the results when you cut the sprue and slide the plate away, or open the mold.
Some things don't make any difference, some things will turn a bullet into a remelt.