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Author Topic: 30 cal mold freezing in sprue plate  (Read 1085 times)

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Offline gunther66

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30 cal mold freezing in sprue plate
« on: May 08, 2011, 02:39:18 PM »
I'm not a seasoned hand at casting but have some experience. Here's my problem;Cast a large pile of 379 bullets using 1/4 lb Tin added to 20 lb WW. Bullets look real good.At near the end of the casting session I broke out a new Lee  30 cal 170 gr mold.Mould was prepped by cleaning with  soap & water,Bullplated the sprue plate and sprayed a LITTLE dropout in it. Out of 100+ attempts I only managed to get about 20 good bullets. I don't have a thermometer but temp. was great with the other Lee mold.Also I jacked the Temp up 'till the pot was smoking and still about 80% of the casts solidified before fillout.  Do smaller cal moulds have to be run hotter? Good shootin...G66
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Offline Richard P

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Re: 30 cal mold freezing in sprue plate
« Reply #1 on: May 08, 2011, 04:39:04 PM »
You will find that the aluminum moulds heat quickly and shed heat quickly. You dont want any petroleum lube finding its way into the cavities. Your pace of filling and emptying the mould may have to be increased in order to keep the mould up to temp without running the lead temp so hot. Also, most people advise using more than 2% tin wastes the metal.  2% of 320oz is 6.4oz. If you assume there is a small amount of tin in the WW, your addition of 4oz is pretty close.
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Offline res45

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Re: 30 cal mold freezing in sprue plate
« Reply #2 on: May 08, 2011, 06:17:48 PM »
I run three Lee 30 Cal. moulds in the 150 to 170 gr. range,my pot temps are around 725 degrees with the aluminum moulds.  Bullets are cast from straight WW alloy no tin added.

Molds are cleaned with mineral spirits and lightly smoked with a match.  Sprue plate is lightly lubed with a Q-Tip dipped in Silver anti-seize.  I preheat the mould by dipping the corner in the melt for about ten seconds,melt should not stick to the mould block when removed.  After about two or three pours I'm dropping nice bullet.  Sounds like your mould is not hot enough,I've never had a issue with bad fill out except when the mould was to cold. 
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Offline pourboy

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Re: 30 cal mold freezing in sprue plate
« Reply #3 on: May 21, 2011, 03:55:10 PM »
This isn't very much information. Specifically, what was wrong with the bullets? Knowing this will allow making specific recommendations. Just saying they were "bad" doesn't tell us anything.
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Offline gunther66

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Re: 30 cal mold freezing in sprue plate
« Reply #4 on: May 21, 2011, 04:15:00 PM »
Yes,These were "bad" bullets. The pour froze in the sprue plate before the mold filled resulting in half a bullet or less.It's obvious that the mold was cold, but why? I had cast 500 .379 bullets already and turned the temp way up from that when I encountered this problem with the new mold.G66
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Offline huntducks

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Re: 30 cal mold freezing in sprue plate
« Reply #5 on: May 22, 2011, 09:06:30 AM »
One picture is worth a 1000 words.

Even if you did not pre heat the mold it should have warmed after a 1/2doz bullets.

Are you using a bottom pour or laddle?

loose the mold release....
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Remember it's where the first bullet goes out of a cold barrel that counts most.

Offline bilmac

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Re: 30 cal mold freezing in sprue plate
« Reply #6 on: May 22, 2011, 01:16:00 PM »
I have a Lee 120 gr 30 cal mold that makes nice bullets real easy. Then I have a similar size 32 cal Lee mold that is real cranky. To get any good bullets I have to run the lead hot, and cast as fast as I can. The 30 cal mold is old, but the 32 is new. I hope the 32 will improve with age.
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Offline ratdog

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Re: 30 cal mold freezing in sprue plate
« Reply #7 on: July 05, 2011, 10:52:42 PM »
turn up the heat a little mold is not hot enough if your bullets have in perfections and wrinkles that will tell you that your mold is casting not hot enough.preheat your mold buy putting the corner of mold in the molten lead for a few minits you will get good bullets faster.put just a little lee adlox bullet lube on on spru plate screw do not get any in mold cavity.good luck.
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Offline kbstenberg

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Re: 30 cal mold freezing in sprue plate
« Reply #8 on: July 06, 2011, 04:16:21 AM »
  Just my 2 cents
  Your pot temp is way to hot. You are drossing off a lot of your tin.
  You have to increase the mold temp! Even if the other mold is droppng good bullets you have to change something to increase your mold temp. Not necessarily your pot temperature.
  Things to try
  Dip (THE EDGE) of the 30cal mold into the pot for 15 to 30 seconds. It is best to dip an edge that has both the sprue plate an mold on it. You only have to dip it a 1/4" into the lead. When you immediately start casting your mold an sprueplate will be above the temp to cast good bullets. So you use a slower casting speed to slowly lower the mold to the point that it is casting good bullets. it mite take only a couple of casts to get the molds to the correct temp. Then speed up your tempo to keep the molds at the correct temperature.
  The speed of casting has a lot to do with your mold temperature. Too fast and the mold overheats. Too slow an the mold looses temperature an starts wrinkling your bullets.
  After trying both of the above. If you are not satisfied than you can try increasing the temperature of your lead. But with any increase in pot temperature go back an try the above suggestions.
  Kevin
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Offline anachronism

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Re: 30 cal mold freezing in sprue plate
« Reply #9 on: July 09, 2011, 06:24:15 AM »
Quote from: gunther66 on May 21, 2011, 04:15:00 PM
Yes,These were "bad" bullets. The pour froze in the sprue plate before the mold filled resulting in half a bullet or less.It's obvious that the mold was cold, but why? I had cast 500 .379 bullets already and turned the temp way up from that when I encountered this problem with the new mold.G66

Mould temperature & alloy temperature don't go hand in hand. Your mould is too cold. Most moulds need to maintain an operating temp of around 350 degrees to fill out correctly. Preheating is a must, as is a steady, rather fast casting pace.
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