Bullet size and mold temp.

[MrXrings]

New to casting and picked up a couple lee six cavity 357 molds, was casting some last night and noticed they were oversize and out of round and the bullets were very frosty, I pre-heated the molds on a single burner stove(electric). Was wondering if getting the aluminum molds too hot caused them to expand and drop larger, out of round bullets. Is this a known issue with aluminum molds?

[44man]

Actually expansion is different with half a cavity at the side of a block. Unlike a hole that expands, the cavity will shrink and make a smaller boolit if too hot.
Out of round is possible because of the way the block expands towards the half cavity.
With a hole in a solid block, metal expands away from the hole sides but a mold is not a solid block and metal expands outward in all directions.
Be aware I will get some discussion from this! :mrgreen:

[HangFireW8]

Consider that mold handle holding technique is far more likely to produce noticable diameter variations within normal temp ranges. If your temps are not within the normal range, then fillout issues will predominate anyway.

[John Boy]

New to casting Excellent casting reference for new and experienced casters ... http://www.grafs.com/retail/catalog/product/productId/20465

[williamwaco]

New to casting and picked up a couple lee six cavity 357 molds, was casting some last night and noticed they were oversize and out of round and the bullets were very frosty, I pre-heated the molds on a single burner stove(electric). Was wondering if getting the aluminum molds too hot caused them to expand and drop larger, out of round bullets. Is this a known issue with aluminum molds?

See this chart:

http://reloadingtips.com/pages/exp_Bullet-diameter-vs-temp.htm



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[MrXrings]

Thanks for the link, not what I expected to see. Are bullets cast from iron/steel molds less out of round than the aluminum molds? I did some more casting today and checked the temps of the molds before I started casting and turned the burner down some to where the molds were 350-400deg before I started and the casts looked much better. I let them sit a while on the burner to let them stabilize temps before starting.

[44man]

Not really, different expansion, shrinkage rates.
Casting is more "feel" and fixing a problem fast before the next pour that comes with experience. Hands on help is better then writing about it.
It will come to you until you get bored silly while casting! :mrgreen: Soon you will see no difference in block material.
When I was a kid I wanted heavier pellets for my air gun so I drilled holes in hardwood, poured pellets and was hitting pigeons at 100 yards. Is a wood mold crazy or what? [smilie=w:

[Alan in Vermont]

When I was a kid I wanted heavier pellets for my air gun so I drilled holes in hardwood, poured pellets and was hitting pigeons at 100 yards. Is a wood mold crazy or what? [smilie=w:

Maybe, just a little.

Some of your comments are getting way hard to believe so a wood mold isn't all that much of a stretch.

[MrXrings]

Thanks for all the comments, I heated the molds to a lower temp on my next cast and the bullets came out looking much better. Out of round was about .004 and I ran them trough my lee 358 sizer and loaded them up. weighed them also about 2g variation, range tomorrow!

[williamwaco]

I think I am about to get myself in trouble here but I truly believe that casting bullets is more art than science.

Obviously science is involved in every step. The problem is that there are so many variables it is not possible to accurately predict what any give change will do.


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[MrXrings]

I think I am about to get myself in trouble here but I truly believe that casting bullets is more art than science.

Obviously science is involved in every step. The problem is that there are so many variables it is not possible to accurately predict what any give change will do.


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But it seems so simple, just heat the lead up and pour it into the mold and out comes boolits. LOL!

[geargnasher]

I think I am about to get myself in trouble here but I truly believe that casting bullets is more art than science.

Obviously science is involved in every step. The problem is that there are so many variables it is not possible to accurately predict what any give change will do.


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I agree it's more art than science in practice. Just like playing a complex musical instrument, you don't "do it by rote", you learn to feel the music. Even sightreading, the notations are merely a technicality, the phrasing and timing only suggestions. If it speaks to you, you "feel" the right way to play a piece. There's WAY too much going on to think about all the details, you just know when things are right after a while, and learn to automatically correct when things slide out of balance when casting.

I have a couple of questions, though, about your chart. I notice your Lee impressions all measured the same, but there's a variation in the BHN you recorded, not that it matters, but the impression size should be a little different, no? Also, did you happen to record the "full liquidus" temperature of the alloy? It must have been pretty low if you were able to pour boolits at 500F.

Gear

[btroj]

I agree entirely that casting, and shooting cast, is an art.
It requires a certain ability to feel the changes and sense what is happening.

Other will disagree and say it is all science, do this and it will work. I don't but that.

I don't worry too much aout my mould getting hotter and expanding. I try my best to keep a reasonably consistant mould temp so that factor is not an issue. Wild variations in mould temp is going to cause I consistant bullets in many ways, not just diameter.

Poor mould temp control is just plain poor casting technique. Understanding this is part of the art of casting. It is a learned thing.

[44man]

I have never understood the extreme temperature variations some cast at.
I use a thermometer when alloying a batch to stay at 600* for adding antimony. Never needed it when casting. One temperature is good for any mold and I suppose I have over 100 molds. I get along with the dial and set the Lee at 750 for all alloys except pure or pure with tin, I go to 800 for them.
Low temps means casting so fast and cutting wet sprues to keep heat up. I will never use glove cutting molten lead sprues.
Casting is not a speed process, it is a laid back relaxed thing. Too much time and work is spent culling rejects when you want a ton of boolits too fast.
It is akin to swinging a progressive press handle at warp speed.
Loading is a slow, relaxed process too. Load ten rounds right and hit ten targets or kill ten deer. Fill a huge ammo can fast and you might hit ten targets out of the thousand.
Quantity is like velocity, neither needed.
I do all I can to eliminate the "FRANTIC" stuff. Ease off guys and relax.

[williamwaco]

I agree it's more art than science in practice. Just like playing a complex musical instrument, you don't "do it by rote", you learn to feel the music. Even sightreading, the notations are merely a technicality, the phrasing and timing only suggestions. If it speaks to you, you "feel" the right way to play a piece. There's WAY too much going on to think about all the details, you just know when things are right after a while, and learn to automatically correct when things slide out of balance when casting.

I have a couple of questions, though, about your chart. I notice your Lee impressions all measured the same, but there's a variation in the BHN you recorded, not that it matters, but the impression size should be a little different, no? Also, did you happen to record the "full liquidus" temperature of the alloy? It must have been pretty low if you were able to pour boolits at 500F.

Gear


The Lee impression numbers are clearly incorrect. Looks like I got “paste” happy.
I will pull out the notes and update that chart.


I did not record full liquidus. It would be a little below 500. Note that the alloy was 50% Linotye.


I started with a clean, cold pot and added 10 pounds of alloy.
I turned on the pot and waited. When the alloy was thin enough to stir like liquid instead of a thin sludge, I used a butane candle lighter to heat up the down spout enough to allow me to cast. Then I cast several, 8 to 10 fillings, to heat up the mold. I then picked up all the bullets and sprue and plopped them back into the pot. At this point the NOE thermometer read about 490. I waited for 500 and began the experiment. I would not attempt to cast normally at this temperature. I had to unfreeze the downspout several times. I was determined to get as wide a temperature range as possible. 500 and 550 were both problematical. I usually cast around 600-700. I prefer 6he 600 range but my lee pot cannot maintain a temperature range less than about 150 degrees without some manual intervention ( adding new ingots )


At each temperature level I cast enough to heat up the mold to whatever temperature would result in a sprue puddle that took five to six seconds to solidify ( solid, not hard ). I cast enough to get 12 perfect bullets at each temperature and then return all imperfects and sprue to the pot and wait for the next temperature to stabilize.


The BNH readings were taken about 4 hours after the final castings.

I would say that I was not able to "pour bullets at 500". I was able to, with determination, manage to get a few good ones.

[geargnasher]

Thanks for the info, WW, I hope you realize I'm not trying to be a nitpicking jerk, just thought I'd point out something that didn't quite make sense. I like your reloadingtips pages, just the sort of interesting stuff we need but don't often see in print.

I did notice the alloy, I was thinking it's melt point should be right around 500F, so I wasn't far off in that.

The thing I like the most about your test was that you made sure the mould was about the same temperature for each alloy temp test, so the mould itself didn't introduce another variable.

What I'd love to see done is a "boolit size vs. MOULD temp" with constant alloy temp test. Just from reading on this site it seems this is where most casters go wrong and get variances in size and weight. You've shown that there really isn't a significant difference in alloy temp/boolit size, but that there's definitely a "zone" where things work the best. I find a similar "zone" with moulds, right around the light, satin frost temperature, but it varies with mould material. I don't remember for sure, but The Perfesser and Swede Nelson may have already done some testing to this effect, but I took a break to look for it and can't seem to find it if they've posted about that here.

Gear

[williamwaco]

Thanks for the info, WW, I hope you realize I'm not trying to be a nitpicking jerk, just thought I'd point out something that didn't quite make sense. I like your reloadingtips pages, just the sort of interesting stuff we need but don't often see in print.

I did notice the alloy, I was thinking it's melt point should be right around 500F, so I wasn't far off in that.

The thing I like the most about your test was that you made sure the mould was about the same temperature for each alloy temp test, so the mould itself didn't introduce another variable.

What I'd love to see done is a "boolit size vs. MOULD temp" with constant alloy temp test. Just from reading on this site it seems this is where most casters go wrong and get variances in size and weight. You've shown that there really isn't a significant difference in alloy temp/boolit size, but that there's definitely a "zone" where things work the best. I find a similar "zone" with moulds, right around the light, satin frost temperature, but it varies with mould material. I don't remember for sure, but The Perfesser and Swede Nelson may have already done some testing to this effect, but I took a break to look for it and can't seem to find it if they've posted about that here.

Gear


Not to worry. I didn't think you were picking nits. I thought you were helping me proofread.


I would love to see this done too but I don't have the equipment for it and am not "handy" enough to build it.

I find exactly the same.

PS: The Lee impression diameters have been updated.

PPS:

I found these related posts. That I found really interesting:


http://castboolits.gunloads.com/showthread.php?t=104800

http://castboolits.gunloads.com/showthread.php?t=108257

http://castboolits.gunloads.com/showthread.php?t=60129




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[44man]

Have to remember all pots vary in cycle times. I feel the Lee holds the closest temps.
I have seen Lyman and RCBS pots start to freeze lead before the thermostat closed again. Seems as if when they get old, things start to swing too far.
My best luck with the old pots was a voltage adjustment but they cost too much to build and fail from heat too soon.
I have been looking for a schematic for something that will work, no luck. I had to retire my older pots.
Lee is the best for the money and the remote thermostat really does best.

[williamwaco]

Have to remember all pots vary in cycle times. I feel the Lee holds the closest temps.
I have seen Lyman and RCBS pots start to freeze lead before the thermostat closed again. Seems as if when they get old, things start to swing too far.
My best luck with the old pots was a voltage adjustment but they cost too much to build and fail from heat too soon.
I have been looking for a schematic for something that will work, no luck. I had to retire my older pots.
Lee is the best for the money and the remote thermostat really does best.

Absolutely agree. I can buy 7 Lee 20 pound pots for the price of one RCBS.

I have owned Saeco - (2), Lyman (2), both 10 pounders.
One of the Lee "toy" 10 pound pots. And one lee 20 Pounder.

None of them have ever been able to hold temperature within +/- 100 degrees - DURING A CASTING SESSION with ingots going in and bullets coming out. I control the temperature by setting it too hot and adding metal to cool it down when it gets too hot.



YIKES! I just got a flyer via email and those Lee post are $71.00 on the summer flyer.
I expect I exaggerated how many of them I could buy for the price of an RCBS.

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