keep getting holes in the boolit bases when breaking sprue

[outdoorfan]

I primarily cast with ww's and soft, and usually 2/1. Well, I can't seem to get rid of the cavities/craters (sometimes) in the boolit bases when breaking the sprue. I don't add any tin to the mix. I recently did some casting with lino, and no more craters. Is it the tin? Also, I'm sure there are plenty of people who successfuly cast with the above alloy without getting the holes/craters that I'm getting. What's the secret to success?

Ps. I cast hot, FWIW

[454PB]

Do you ladle cast or use a bottom pour?

Too much pressure from a bottom pour will cause this.

[Springfield]

Cut the sprues sooner so they are softer and don't pull out at the base. I use the same mix, very soft, and I get that sometimes too. It helps if you use Bullplate lube so you can cut sooner without smearing the lead.

[44man]

Just the opposite with me. I let them get harder and use a lot of light taps to cut instead of one smack.
Those holes will not hurt shooting anyway unless you are BR shooting.

[runfiverun]

both above will work for you.
open sooner and avoid the smears with a lube on the mold or wait longer and snap open the sprue cutter, you might end up with a small bump with the second option. easily cured by closing and re-opening the cutter again.

[sqlbullet]

It takes a pretty big tear before I get worried with my pistol bullets. I am looking for plinking rounds, so as long as I can get in the black at 25 yards, that is plenty good for me.

When I do want really pretty bases, I let them cool just a bit longer and use gentle force like 44man.

I have a lee 6 cavity 358 mold that will consistently have an air bubble in the fifth bullet from the handles for the first 4-5 casts. Then it goes away. Doesn't seem to matter how long or thoroughly i pre-heat the mold either, and it is always and only that cavity in the mold by the sixth pour, it is gone and stays gone for the remainder of the session, even when I pause to melt more lead in my 10 lb pot (with the mold on top to keep it warm).

[DLCTEX]

Waiting longer to cut the sprue works for me, but so does the Bullplate lube. I cut the sprue using a heavy glove and pushing with my thumb, I don't like beating on my molds. Try the wet sponge to cool the sprue if it slows you too much. If cutting the sprue leaves a bump, push down on the sprue plate as you cut to prevent it riding up. A quick grab and push does it, if you linger the glove will get hot enough to remind you to go faster.

[nighthunter]

It could be your top plate. If the cutting edge is not sharp enough it could be just tearing a chunk out of the bullet base. I think there was a recent thread about the sharpness of the top plates. I hope this helps.

Nighthunter

[madman]

All the above are good ideas. I have used them all at on time or another. I found that by adding another small angle at bottom of the sprue cutter does the trick. I used a 12 flute carbide cutter designed for small engine valve seats. and cut it by hand. Works for me.

[outdoorfan]

Lots of great responses! Thanks.

I have three LBT molds and one Lyman 4-cavity. They all do this. I also use Bull Plate Lube and do not use a stick to break open the sprue. I cut it early with my gloved hand. I apply some downward pressure when doing this.

It doesn't seem to matter if I cut it early. It still leaves voids. I guess I should also define what early means to me. I cut it pretty much when the sprue changes color. Is that early enough? I don't wait for it to get hard. Maybe I should.
Next casting session I'll try waiting a bit. But, with my .22 mold, waiting for the sprue to really harden means I can't keep the mold hot enough to get good fillout and avoid wrinkles.

If accuracy isn't affected, then I won't worry about it. As long as the cavity is fairly centered and not too deep, I've been shooting them.

[outdoorfan]

Oops. Forgot to add that I'm ladle casting.

[Bass Ackward]

Oops. Forgot to add that I'm ladle casting.

Figured. You are losing the advantage of ventilating through the top of the mold.

So you need a light stoning bevel on each half of your blocks. I said light. If you can see what you have done, that wasn't light.

Then you can cast and break sprue any way you please.

[outdoorfan]

Figured. You are losing the advantage of ventilating through the top of the mold.

So you need a light stoning bevel on each half of your blocks. I said light. If you can see what you have done, that wasn't light.

Then you can cast and break sprue any way you please.


Do you mean to add a vent line running from one side of each mold block to the other? And how am I losing some advantage? Obviously, I don't get it.

[anachronism]

LBT moulds already have the parting line beveled. Don't add any more! I have this problem with some Lyman moulds & blame a dull sprueplate for it. My LBTs haven't done this to me yet. I too break sprues by hand, at least on the 2 cavity moulds. I can't make it happen on the 4 cavitys. What sort of alloy are you using?

[montana_charlie]

Do you mean to add a vent line running from one side of each mold block to the other? And how am I losing some advantage? Obviously, I don't get it.
Yes. Breaking the top corner of the mould halves adds a ventline under the sprue plate which improves the escape of air from the top of the mould.
But, if your bases are flat, and their corners sharp, you have sufficient venting.

I am (also) a ladel caster, and I use soft alloy...although mine does contain tin, and no antimony.

My casting sequence takes forty seconds to complete one cycle.
Timing from the moment I begin the pour to fill the (single) cavity, it will be a full thirty seconds before I cut the sprue. It will have been solid for at least twenty seconds when I cut it.

I only have tear-out of the sprue when I try to hurry the cut.

CM

[outdoorfan]

I am primarily using 2/1 ww/soft. My casting sequence usually falls into 20 seconds for the .22 mold. The .30 and .45 will take around 30 seconds. They are all 2-cavity LBT's.

Yes, I thought they (LBT's) already had a vent line in them. The bases of the boolits sometimes fill out nice and sharp, but sometimes are a little rounded too. I haven't been able to tell any difference, as far as the holes in the bases go, when they are filled out (sharp) or not.

Sounds like slowing down might be the ticket. But I can't do that with the .22 mold.

[theperfessor]

I have had problems with base tear out using certain batches with WWs as the base material. I believe I caused my own problem by getting batch too hot and not sorting out zinc. Not enough contamination to cause too many problems but tear out was definitely worse with some batches than with others. I've learned better refining practices since joining this site.

Have you tried different batches using same mold? How sure are you of your materials? You said that you get better fillout with lino (presumably relatively uncontaminated with zinc and formulated for casting ease) than you do with WWs (designed to be tough enough to hang on a wheel rim) + soft (are you sure about composition of everything?). I believe that zinc increases surface tension and tin reduces it, so you have to cast hotter for good fillout.

I have some batches that will cast good bullets as long as they have mostly rounded surfaces with shallow grooves (such as a Lee 429-200-RF) but won't fill out a SWC with square grease grooves/corners/shoulders. I use it up making the bullets it will make and use the "better" stuff for SWCs and HPs.

Not questioning your smelting practices or anything, just suggesting that sometimes dumping out the pot and using materials from different sources is sometimes helpful.

[DLCTEX]

For 22 casting I use the damp sponge to cool the sprue, wait for it to flash, then flip the mold over and press it against the sponge for a count of 3. Vary the count to find the time needed to harden the sprue enough without cooling the mold.

[Blammer]

I'd suggest letting the sprue cool more then hit with several taps to cut sprue.

[outdoorfan]

I have had problems with base tear out using certain batches with WWs as the base material. I believe I caused my own problem by getting batch too hot and not sorting out zinc. Not enough contamination to cause too many problems but tear out was definitely worse with some batches than with others. I've learned better refining practices since joining this site.

Have you tried different batches using same mold? How sure are you of your materials? You said that you get better fillout with lino (presumably relatively uncontaminated with zinc and formulated for casting ease) than you do with WWs (designed to be tough enough to hang on a wheel rim) + soft (are you sure about composition of everything?). I believe that zinc increases surface tension and tin reduces it, so you have to cast hotter for good fillout.

I have some batches that will cast good bullets as long as they have mostly rounded surfaces with shallow grooves (such as a Lee 429-200-RF) but won't fill out a SWC with square grease grooves/corners/shoulders. I use it up making the bullets it will make and use the "better" stuff for SWCs and HPs.

Not questioning your smelting practices or anything, just suggesting that sometimes dumping out the pot and using materials from different sources is sometimes helpful.


I haven't been casting for very long, that's for sure. But, I have been fairly careful about not letting any zinc ww's melt in the mix. As far as the soft lead that I have, it's mainly lead piping. I did have a big block of soft lead that could have had some contaminate in it, but I doubt it because my casting results have pretty much been the same with whatever batch I was using.

[outdoorfan]

I'd suggest letting the sprue cool more then hit with several taps to cut sprue.


I'll try that next time, but I like the convenience of using my gloved hand (rather than holding the wooden dowel).

[outdoorfan]

For 22 casting I use the damp sponge to cool the sprue, wait for it to flash, then flip the mold over and press it against the sponge for a count of 3. Vary the count to find the time needed to harden the sprue enough without cooling the mold.


I haven't found that your technique will work with my 2-cavity aluminum .22 mold. I say that because even with casting as fast as I reasonably want to go, the sprue is hardening on it's own within 5 seconds or so after I'm done pouring the lead.

[snaggdit]

Then you are casting about right. I still flip the mold over onto a wet rag just as the sprue goes hard. Then I cut it and drop the boolits and do it again. I think that cooling the top plate helps me maintain temp on the mold. Also allows me to drop a lot of boolits per hour. Since reading about Bruce B's Speed casting technique that has been my new best friend.

[Bass Ackward]

Jon,

LBT molds, while they have a great reputation for venting, the fit is generally so good, that air can still be trapped as a mold breaks in. His sprue plates are very thin over the cavities while arched on the sides. So what you get is bow down expansion over the cavities as the steel plate heats and expands that increases the seal tension. Problem is that they cool so fast that this can't be recognized. Bull Plate completes the seal.

Third is the hold down finger an plate can be a little tight as the blocks heat as well. But if you are breaking sprue by hand, then you aught to be able feel that. If the plate is adjusted right, you won't need bull plate lube. I have 30 year old LBTs that are still like new after thousands of slugs.

You don't need to go clear across. Just break the edges from the cavities out. It's a shorter distance to the central vent. And keep the blocks clean. He uses and recommends his wax for the pins and boasts at how long it lasts. This can be a disadvantage as this stuff is like sealant in a stick if it gets up on the blocks limiting the generous venting that the eye sees.

Or you can just cast hotter to give the air more time to leave out before solidifying. This is what he counts on as he likes frosty bullets. But this has drawbacks as well. And I am not sure that ladling as a .... young caster that you can maintain the pace well enough in smaller calibers. I don't want to try. I just improve the venting.

[armyrat1970]

Good info. Been wondering if I have been cutting my sprue a little to quickly. Here is what I do. When I cast I fill the cavity, and sometimes overfill but always try to fill the sprue hole. When I see a dimple form and the texture of the alloy change I wait about five seconds and then cut the sprue.
Having some other problems with some of my Lee molds and will post in the mold maintenance section about those.

[outdoorfan]

Jon,

LBT molds, while they have a great reputation for venting, the fit is generally so good, that air can still be trapped as a mold breaks in. His sprue plates are very thin over the cavities while arched on the sides. So what you get is bow down expansion over the cavities as the steel plate heats and expands that increases the seal tension. Problem is that they cool so fast that this can't be recognized. Bull Plate completes the seal. I do use Bull Plate, FWIW.

Third is the hold down finger an plate can be a little tight as the blocks heat as well. But if you are breaking sprue by hand, then you aught to be able feel that. I figured it should be fairly tight, but I'll try loosening it to the point that it's not really holding the plate down at all. If the plate is adjusted right, you won't need bull plate lube. I have 30 year old LBTs that are still like new after thousands of slugs.

You don't need to go clear across. Just break the edges from the cavities out. It's a shorter distance to the central vent. I'll give that a try.And keep the blocks clean. He uses and recommends his wax for the pins and boasts at how long it lasts. This can be a disadvantage as this stuff is like sealant in a stick if it gets up on the blocks limiting the generous venting that the eye sees. I haven't been using that wax, as BP has been doing the job just fine.

Or you can just cast hotter to give the air more time to leave out before solidifying. This is what he counts on as he likes frosty bullets. But this has drawbacks as well. And I am not sure that ladling as a .... young caster that you can maintain the pace well enough in smaller calibers. I don't want to try. I just improve the venting.

One more thing. Would it be fair to say that if lino casts wonderfully for me, then I don't have a problem with the molds (venting)? Of course, lino hardens hard quite fast, and it takes a lot more effort to break the sprue.

My next casting session will be in a week or two.

[Bass Ackward]

One more thing. Would it be fair to say that if lino casts wonderfully for me, then I don't have a problem with the molds (venting)? Of course, lino hardens hard quite fast, and it takes a lot more effort to break the sprue.

My next casting session will be in a week or two.


Jon,

Lino is the gold standard for casting. Smooth seas do not a good mariner make.

You will have the most trouble with smaller diameter bullets, narrow drive band designs, designs with sharp shoulders / edges, and closer to pure lead mixes. The closer to pure lead is not only because of the melt / hardening temp, but the higher temp of the blocks may cause moe expansion and change how the venting works.

Any one of these or combinations thereof, could be venting issues.

And perfectly ventilated molds can get worse as they age. So just because they start out fine, doesn't mean that they too won't become a victim as burs wear off and blocks close a little better. That is if it doesn't get dirty either. You may notice your sprue plates tension change for many reasons either stiffer or loser. Loser is good, tight isn't right.

Holes in bases is a darned good excuse to try something else. Air is NOT getting enough time to get out of the bullet and be replaced by lead. So, what are your choices? You can increase temp of your mix to stay liquid longer, add tin to lower the hardening stage (increase liquid time), mold faster to keep the blocks hotter, or improve the venting.

Pick your poison.

[outdoorfan]

Jon,


Holes in bases is a darned good excuse to try something else. Air is NOT getting enough time to get out of the bullet and be replaced by lead. So, what are your choices? You can increase temp of your mix to stay liquid longer, add tin to lower the hardening stage (increase liquid time), mold faster to keep the blocks hotter, or improve the venting.

Pick your poison.

I'd rather not add any tin except as a last resort, so I'll work on making sure the blocks are clean AND improving the venting like you described.

Thanks, John (and the others, as well).

[Nora]

All but one of my molds are Lee. About half of them would tear the sprue to one degree or another. I was able to cure it with mine by sharpening the sprue plate and haven't had any problem sense. Now that is part of my new mold Lee-menting proses. Just remove the sprue plate, and hone the bottom of the plate till smooth with a good extra hard stone. It's got to be perfectly flat, a concave surface on the stone won't do it properly. I also use Bull Plate lube after honing.

[Dollar Bill]

I've found the most effective way to produce good bases is to let the sprue cool enought that the base doesn't smear, and then (this is the key) do not smack the sprue handle. With a gloved hand, push it open. Haven't had a bad base since. If it's a hard alloy, the sprue handle can be extended 4 inches by drilling 2 #10 holes and bolting a steel plate extension on it for better leverage.

[GSSP]

Outdoorfan,

Some questions and some helpful, hopefully, hints for you.

1. How many 22 cal bullets would you say you've cast with the new LBT mold?

2. You say you want to not use Tin; is that correct?

I too use LBT molds. I've been using two 45 cal molds, 230 LFN for my 45 ACP and a 280 WFN for my 45LC. I recently added a 160 gr FN for a 38 Special. Each mold took about 100 cast bullets before it started throwing good bullets and about 400-500 bullets before each started throwing beautiful bullets. Thus my question on how many 22 cal bullets you've thrown.

I noticed it was a bit harder to keep the 38 mold hot until I changed my technique.

I took Veral's advice and snip off about 2" of Tin solder to throw into each 10 lb pot of WW in my Lee Production Pot. It seemed to help the mix flow better into the molds. I picked up a 1lb roll of Oakley "lead free" solder down at our local Home Base hardware store. I called Oakley and they said it was 98% pure tin. I think I paid $8-9 IIRC which I'm probably not.

I also took Veral's advice and run my pot "hot". I mean I think nothing of cranking the thermometer to max and letting it hit 825 deg F though it usually runs around 775 to 800. I also throw back 1-2 sprues at a time to keep the pot fuller and yet not let the max temp get away from me though I doubt that's a problem. Veral says he'll let it glow red without a problem. It keeps my molds plenty hot and the bullets just kept getting better and better. It did slow down my production as I had to keep each cycle to about 40 seconds which felt agonizingly slow. So, I went and bought a second RCBS mold handle and started casting two molds at a time. The natural rythym I discovered between switching back and forth actually caused me to produce more bullets overall in each 10 lb pot.

If you do buy a new RCBS handle beware, the new production handles have a new thicker portion back from the holds which needs to be filed flat for LBT molds to fit. It took me a few minutes with a flat bastard file.

Just sharing my experience.[smilie=s:

Alan

[outdoorfan]

Outdoorfan,

Some questions and some helpful, hopefully, hints for you.

1. How many 22 cal bullets would you say you've cast with the new LBT mold?

2. You say you want to not use Tin; is that correct?

I too use LBT molds. I've been using two 45 cal molds, 230 LFN for my 45 ACP and a 280 WFN for my 45LC. I recently added a 160 gr FN for a 38 Special. Each mold took about 100 cast bullets before it started throwing good bullets and about 400-500 bullets before each started throwing beautiful bullets. Thus my question on how many 22 cal bullets you've thrown.

I noticed it was a bit harder to keep the 38 mold hot until I changed my technique.

I took Veral's advice and snip off about 2" of Tin solder to throw into each 10 lb pot of WW in my Lee Production Pot. It seemed to help the mix flow better into the molds. I picked up a 1lb roll of Oakley "lead free" solder down at our local Home Base hardware store. I called Oakley and they said it was 98% pure tin. I think I paid $8-9 IIRC which I'm probably not.

I also took Veral's advice and run my pot "hot". I mean I think nothing of cranking the thermometer to max and letting it hit 825 deg F though it usually runs around 775 to 800. I also throw back 1-2 sprues at a time to keep the pot fuller and yet not let the max temp get away from me though I doubt that's a problem. Veral says he'll let it glow red without a problem. It keeps my molds plenty hot and the bullets just kept getting better and better. It did slow down my production as I had to keep each cycle to about 40 seconds which felt agonizingly slow. So, I went and bought a second RCBS mold handle and started casting two molds at a time. The natural rythym I discovered between switching back and forth actually caused me to produce more bullets overall in each 10 lb pot.

If you do buy a new RCBS handle beware, the new production handles have a new thicker portion back from the holds which needs to be filed flat for LBT molds to fit. It took me a few minutes with a flat bastard file.

Just sharing my experience.[smilie=s:

Alan


Thanks.

I probably have around 1000 casts with that .22 mold by now. My last casting session went the best so far. I had maybe 3-5% rejects. I do have some lead-free tin solder, which I got to mix with soft lead in a special project that I had going on, but I've been holding back on adding it into my 2/1 mix of ww/soft because I heat treat that and don't want to mess that up. However, one little sliver like you are talking about can't do much harm. I'll try it next time.

I'm casting as hot as my Coleman propane stove will allow. My infrared temp gun says maybe 750-800 or so.

I also recently got a new pair of RCBS handles, and I had to file that same spot down.