Reloading EverythingLoad DataLee PrecisionMidSouth Shooters Supply
WidenersTitan ReloadingRotoMetals2Inline Fabrication
Repackbox
Page 1 of 3 123 LastLast
Results 1 to 20 of 54

Thread: Alloy Temperature for Casting, and Keeping Molds Hot

  1. #1
    Boolit Man
    Join Date
    Apr 2018
    Location
    SATX
    Posts
    87

    Alloy Temperature for Casting, and Keeping Molds Hot

    Sorry for the length of this post, but here goes...

    Today I cast my first bullets. I cast a LOT. And almost all of them were bad. I made over 350 bullets, and I got 22 that were not totally awful.

    Most were wrinkled and layered-looking, primarily at the nose, but some looked like I'd poured alloy in two different tries. I've seen the term "sharpei" bullets, and many of mine looked that wrinkled, but to varying degrees, especially the ones that looked like I'd poured twice.

    I have a Lee 4-20 bottom pour casting pot connected to a PID controller, and I was running at 750F.

    It was really obvious when my molds weren't hot - the alloy would start cooling on contact and only a little went into the mold. But after a while, I got good filling and nice, sharp bases. The bases were the only things that were nice though. I got a few instances of "sprue smearing" so I waited a little longer before cutting sprues and dumping the bullets. The only thing I didn't have happen was bullets deforming for being dropped too soon.

    So I dug into Lyman's Cast Bullet Handbook 4th Edition and a couple other sources, and it looks like what I had going on was that the alloy and/or the molds were too cool.

    Is there a rule of thumb for how hot the alloy (wheel weight in this case) should be for a given size and weight of bullet? I was using two Lee molds; their 452-200-RF flat point and their 452-228-1R RN mold; the flat point is a 6-cavity mold, and the RN is a two cavity mold. Is the amount of alloy in the pot

    Second, I have read a lot about "cadence," but nowhere has anyone quantified cadence. How quickly should I pour into a 2-cavity or 6-cavity mold, how long should I give the sprue to harden, and how quickly should I work to cut the sprue and dump the bullets? Obviously it should be pretty quick, and the soft landing zone for those new bullets should be very close to where I'm pouring, but just how quickly is "pretty quick"? I'm sure it's no hard-and-fast time that fits every mold, but there's got to be some sort of starting point. Some numbers would be very helpful.

    Lastly, I've read that it's useful to rest molds on the edge of the casting pot to keep them hot, and some people use a hot plate for this purpose. The idea seems to be related to using two molds in the same casting session, and/or keeping the mold(s) hot while adding alloy and bringing the pot back up to temperature - please correct me if I am not properly understanding. Well I had a very tough time getting either the 6- or 2- cavity mold to balance on the top of the pot at all because the handles seemed to be heavier than the molds and the mold blocks kept tipping off the pot. That makes me wonder how they'll sit on a hot plate... Do folks use a support for the handles?

    Any guidance on this would be greatly appreciated.

  2. #2
    Boolit Buddy Valornor's Avatar
    Join Date
    Mar 2016
    Location
    Somewhere, Utah
    Posts
    339

    Alloy Temperature for Casting, and Keeping Molds Hot

    Cadence is hard to quantify. It’s kind of like a blacksmith banging on his anvil. Every blacksmith is going to be a little bit different, and if they all get the same results is any of their cadences really wrong?

    When I cast I like to cast with two molds. Typically I’ll try and cast two different bullets molds. Really doesn’t make if they are the same caliber or not. I find that keeps me constantly moving.

    I fill one mold set it aside on a brick, pick up the second mold, cut the sprues, drop the bullets and fill the mold. Set it aside on a brick. Pick up the first mold. My cycle time is probably 30-45 seconds...it’s not something I have timed...

    I find this cadence prevents me from over heating the mold. But giving things time to cool. I’m never in a rush, I do every action deliberately, and try and be consistent with my motions.

    The real trick can be when I need to refill the pot. If let the level drop too far then I am waiting for awhile before the pot gets back up to temperature, and I have to try and keep my molds hot. Either way I end up throwing away the first few bullets cast. I’ll either drop them aside or sort them out when I QC them later on.

    The wrinkled bullets don’t bother me if I’m just casting range fodder.

    700-750 is what I like to run my pot at but I’m not fancy enough to have a PID. Yeah it can be a bit tricky to get the molds to set on a pot to heat them. I’ll dip the front of the mold in the lead to heat it up until the lead won’t stick to it. Then I start casting with it. Pouring the lead into the mold and using it is the best way that I have found to get it up to temp and start casting good bullets.


    If I have to add more lead and it will be a minute before I can use the mold, I’ll leave the bullets in the mold to try and keep the heat in the mold. How fast a mold warms up and cools is dependent on the material it is made of. Aluminum molds will heat up and cool much faster then a Brass or Iron Mold.



    Check out my website www.theballisticassistant.com
    Last edited by Valornor; 10-06-2019 at 05:17 PM.

  3. #3
    Boolit Man
    Join Date
    Apr 2018
    Location
    SATX
    Posts
    87
    Quote Originally Posted by Valornor View Post
    I’ll dip the front of the mold in the lead to heat it up until the lead won’t stick to it.
    That's something I've never heard of. I'll have to try it next time I can get out and cast.

    I understand what you're saying about cadence being hard to quantify, but you've provided more detail than I've ever found in other posts. Does the brick you rest the molds on help them cool, or keep them hot? And I assume you go directly from the first mold to the second, without a pause; am I right?

  4. #4
    Boolit Buddy Valornor's Avatar
    Join Date
    Mar 2016
    Location
    Somewhere, Utah
    Posts
    339
    Usually I am just trying not to burn anything.

    A brick doesn’t draw away heat as quickly as metal. Ideally a refractory brick will help insulate the bottom of the mold and keep a little heat in the mold, but I just use any brick that is clean, and readily available.

    I don’t pause, but I’m not in a rush either.

    A good indicator that the mold had cooled is the condition of the sprue. It should be solid, and it is dimpled. Lead shrinks as it cools and this manifests itself as a dimple over each of the holes.

    If I am moving too fast and the molds start to get too hot, I have had instances where the sprue hasn’t hardened all the way. When this happens it won’t cut cleanly, instead smearing on the top of the mold. This is the mold saying “Hey you, slow down!”

    I’ll set the mold on a nearby cool lead ingot. Let the ingot absorb some of the heat. Slowly work the other mold, and then reintroduce the cooled mold into the cycle.

    No ones process is the same, you’ll sit down and develop your own unique rhythm. It’ll take a few casting sessions but it’ll come to you.




    Check out my website www.theballisticassistant.com

  5. #5
    Boolit Master
    Join Date
    Feb 2015
    Location
    Central Iowa
    Posts
    1,427
    Until my mold gets warmed up and making perfect bullets i just go as fast as possible. The cadence is dependent upon how fast the bullets fall out of the mold. The temperature of the sprue plate has an effect on fill out of the base and I try to get it warmed up with a couple large pours covering as much of the sprue plate as possible right away.

    The first casting session generally seems to be as much of a learning experience as it is about making bullets. Run the pot a little hotter and go a little faster next time and things will start to click.

    I’ve cast 10,000+ bullets and have tried to run 2 molds at a time and for me it’s more of a pain switching back and forth than any benefit I can see. You’ve got to walk before you can run. If your mold gets too hot take a 30 second break and inspect some of your bullets.

  6. #6
    Boolit Master 44Blam's Avatar
    Join Date
    Sep 2017
    Location
    Nashville, Indiana
    Posts
    1,603
    It sounds like you might have some machine oil still on the mold. Might take a brush and some dish soap and really clean it under warm water.

    I do this for each new mold. Then I put my mold on a hot plate right at or just under medium. I like to cast at around 675 or so.

    The cadence is going to change based on the mold temp/alloy temp and boolit size. I find that I have to cast larger boolits slower as they tend to heat up the mold a bit more. Then with small boolits you have to cast faster just to keep the mold warm enough.

    What I do is heat my mold and alloy at the same time. Then my first 2-3 casts I plan on just throwing them back in the pot and I start out quickly to get everything warm. Then I slow down a little and try to keep the mold at the same temp. Also, I pour each cavity and hold the mold tightly closed. Then when the lead on the sprue plate frosts over, I give it another second or so before opening the sprue plate and mold and drop out the boolits on a towel. Then I inspect them and throw the bad ones back. I find that once a mold is working, you will get very few bad boolits and they tend to be where I've messed up the pour...

    A mold from cool to hot will do the following:
    Too cool and you'll get wrinkly boolits and poor fill out. A mold that is warmer will start to fill out properly but will have very shiny boolits. When your mold is warm the boolits will start to get frosty in places. I tend to try to stay just under frosty because frosty boolits tend to be just ever so slightly bigger and in some shapes I find that I can get chambering issues. When your mold is too hot - it will start to stick together and not want to open. Also, the warmer the mold is, the longer it will take for the lead on the sprue to frost over.

    Hope this is helpful.
    WWG1WGA

  7. #7
    Boolit Buddy Valornor's Avatar
    Join Date
    Mar 2016
    Location
    Somewhere, Utah
    Posts
    339

    Alloy Temperature for Casting, and Keeping Molds Hot

    I should clarify. If I am running two molds, it is typically two, two cavity molds, or two six cavity molds. I don’t usually run one two cavity mold and one six cavity mold at once.

    Intermixing molds with different numbers of cavities Getz kind of messy. You always end up over heating a mold, and you never get into a steady rhythm. At least I don’t.


    Check out my website www.theballisticassistant.com

  8. #8
    Boolit Grand Master Outpost75's Avatar
    Join Date
    May 2013
    Location
    over the hill, out in the woods and far away
    Posts
    10,158
    ANother method which works well is to use an electric hot plate, placing a piece of ceramic tile over the coil to spread the heat uniformly. Start with the "medium" setting on the hot plate and pre-heat your mold on it. Experiment with the setting until you get good bullets almost immediately. I cast outdoors in a screened porch to be assured of good ventilation, so the hotplate setting needs to be adjusted seasonally, as you need more in winter when wearing the snowmobile suit than in summer in a T-shirt. I use a 450-degree F. Tempilstik crayon to mark the mold blocks and calibrate the hotplate setting.
    The ENEMY is listening.
    HE wants to know what YOU know.
    Keep it to yourself.

  9. #9
    Boolit Buddy
    Slugster's Avatar
    Join Date
    Jul 2019
    Location
    Kentucky, USA
    Posts
    370
    OTShooter:
    A short list of things to consider:

    Add a little tin to your alloy for better fill out.

    Smoke the molds with a butane lighter or wooden kitchen match.

    Have a stand to hold the handles of your molds when placing the mold on the edge of the lead pot. I use a coffee can filled with
    sand setting on a piece of 2x8 board to get the proper height. You may have to adjust for your setup.

    Check the calibration on your PID controller.

    Always clean molds before using. I use an old toothbrush, hot water, and Dawn dish soap.

    If none of the above suggestions works for you, thoroughly reclean the mold and swab the cavities with Kano Kroil on a Q-tip.
    Read about the Kroil tip on this forum and it definantly works.

    Don't let small setbacks discourage you, keep casting and you will begin making quality boolits.

    Hope this helps, Richard.
    NRA Life 1992
    My avatar is almost a dead ringer for my little buddy Chico. Six pounds of mean that thought he was a Pit Bull. Miss that little guy.

  10. #10
    Boolit Master
    Join Date
    Sep 2016
    Posts
    2,659
    I use 8 cavity aluminum molds with a bottom pour (old RCBS ProMelt) at around 720 degrees. Usually it's one mold only, with a pour every 20 to 25 seconds (out door casting in the evening in a wind sheltered area, ambient temps 60's to 70's). At that pace, I can inspect and cull the last pour as the next cools in the mold. If I use two molds, it's the same cadence for each mold as for one, only I'm producing twice the boolits in the same time by interpolating the actions needed for one mold with the same actions for the other. I like my bullets with a very light matte frost; they're the most consistent that way with my alloy and casting technique. Heavy frost means I'm going too fast, which mainly happens with one mold (too many things to juggle with two molds for me to outrun them). No time to inspect and cull while casting with two molds, though.

    I pre warm and keep the molds hot while reloading the pot using a 1100 watt coil hot plate. I was a bit leery at first but I ended up using close to the max setting with the blocks set directly on the red hot element. Done just for a few minutes (hot plate turned on and mold in place just during the final fluxing of the fully melted alloy, and while refilling the casting pot from the feeder pot directly over it) I haven't had any mold damage. Maybe not suprising since I put a temp probe on the coil at maximum and couldn't get a reading over 800 degrees). Preheated, I usually only have to discard a couple pours, most commonly for heavy frosting, before I get keepers.

    Yup, Miha's eight bangers with the three handles won't balance just on the blocks. I use a piece of 2x4 on edge to prop the end of the handles; just right for my hot plate.

    ETA: to second a suggestion made above - if the molds are new, they may not have been cleaned enough prior to use. Gotta get any and all lubricating/cutting/rust preventive oils completely removed from the cavities.
    Last edited by kevin c; 10-06-2019 at 06:48 PM. Reason: More to say

  11. #11
    Boolit Master kmw1954's Avatar
    Join Date
    Mar 2016
    Location
    SE Wisconsin
    Posts
    1,448
    I too have just started and am proceeding a bit more difficult than you. I am using a hot plate and a SS sauce pan as my alloy melting/working pot that doesn't have a lot of temperature control to it other than giving it time to reach full temp and watching the fill level. Then the mold I am using is a Lee Aluminum 2 cavity casting .356" X 102gr RN. From what I have learned so far is that these small bullets need to be run faster in order to heat the mold properly.

    My second session I was getting wrinkled bullets and finally gave up for the day. My last session I increases the tempo so that I wasn't waiting as long to cut the sprue and empty the mold. Before long I actually started to get frosted bullets so I slowed the timing between cutting the sprue and dropping the bullets but not slowing too much between dropping and pouring and the frosting faded.

    I too used the method of placing the mold into the melted alloy and with my pot if it was too cold the lead would start to freeze around the mold so I would leave it until it would come out clean, then it would be about the right temp. So once I got to the point that I was seeing frosted bullets I know the temp was good and I needed a longer interval between pours so as to not over heat the mold.

    Now with this mold an alloy I was waiting for the sprue puddle to freeze over to the point that I could knock the sprue plate open with my gloved hand. The session before I was waiting what I believe was too long and had to really hit the sprue with the mallet to get it to open. Last thought I am also pouring with a Lyman ladle.

  12. #12
    Boolit Grand Master popper's Avatar
    Join Date
    Jun 2011
    Posts
    10,572
    Cold mould, cold Sprue plate. Try smoking with bic, may be venting problem. Happened to me on last mould.
    Whatever!

  13. #13
    Boolit Man
    Join Date
    Apr 2018
    Location
    SATX
    Posts
    87
    I did clean my molds, but I didn't scrub them with a toothbrush; I'll take care of that before the next session.

    I'll also "smoke" them. It's a cheap strategy, and it can't hurt.

    As to adding tin to my wheel weight alloy, are we talking about adding an ounce per pound, or what?

    I'm shopping for a hot plate right now. Depending on which one I get, I'll buy a ceramic tile of the appropriate size so I won't have to worry about exactly where I place the mold(s). I have a couple of ideas for rests to support mold handles - Lee 6-cavity mold handles will need a different support than their 2-cavity handles.

    Almost all of the bullets I cast today are pretty darn shiny, which is enough to tell me that the molds were just too cool. I obviously need to speed up my movements, and that means rethinking how I have everything organized. My back yard work space is kind of limited, but that just helps push me toward getting everything closer together, which should speed up each mold cycle.

    Thanks for the inputs so far! I'm learning a lot about technique that no YouTube video or (even very well written) book can teach.

  14. #14
    Boolit Man
    Join Date
    Feb 2016
    Location
    Bakersfield, CA
    Posts
    82
    My experience, (which in no way compares the expertise of others posting on this thread), is the aluminum molds like the Lees are more difficult to get up to and maintain a good working temperature. Often times, I will sit there and cast a big pile of rejects before I start getting acceptable results with the aluminum molds. About then, I have to watch it because that's about the point the mold is getting too hot. Personally, I like the steel molds like RCBS or Lyman better. With those, I'm getting great results within the second or third pour and the temperature stays much more consistent throughout the process. They cost more but in my opinion, they are worth it.

  15. #15
    Boolit Master
    Join Date
    Jan 2011
    Location
    NE Kansas
    Posts
    2,421
    I believe you have already found a few suggestions that might improve your product. First, make sure that the temperature probe for the PID is located at least 1/2 inch from the side and from the bottom of the casting pot. Otherwise you are reading the pot temperature and not the alloy temp. Next, open the valve to allow free flowing stream to enter the center of the sprue hole. Slow flow gives off too much heat. If you are casting in a breeze or strong cross ventilation, be sure that this does not draw heat from the lead stream before it enters the sprue hole. Have about 1/4 or 3/8 inch of drop from the nozzle to the sprue plate. Cold weather casting will exacerbate this type of heat loss. Use only one mold. The first problem with the 6 cavity mold is allowing the sprue to cool too long, it will get hard, and you will break the sprue cutting handle. Watch the sprue puddle as it cools. It should be fluid right after pouring, then haze over and then become solid. Usually 3 to 5 seconds. Cut the sprue a few seconds after it becomes solid and see if that leaves a wet looking bullet base. If so, let it cool just a bit longer. You should be casting quite rapidly to keep the mold temp up. If you have sticking bullets that slow you down, you will need to fix that before you will enjoy success. Do a site search with the search feature in the upper right corner of the page for your topic words. Be sure to lubricate the sprue plate hold down screw and the alignment pins. Just a light touch, not so much that it migrates into the cavities. I find no need to smoke a mold and once you get things figured out, you will probably abandon that as well.

    I would suggest you work with the two cav mold as that will go a lot faster and with the 6 hole you might tend to let it get too hard by the time you fill the cavities and put yourself out of production while waiting for a broken part.

    If the mold is too hot, the castings will be showing a "galvanized" appearance. It is just excessive frosting of the surface. Minor frosting is harmless and many prefer that to a shiny and undersized casting. If you have not run that mold for 20-30 minutes, you are not getting any kind of a consistent tempo going. You can speed up or slow down depending upon how the castings look as they drop from the mold. If it is a new mold it might just take some heat cycling to form a patina and start working really well. Stay with it. You will get it figured out.

  16. #16
    Boolit Master


    kungfustyle's Avatar
    Join Date
    Feb 2013
    Location
    Knoxville, TN
    Posts
    1,227
    Just cast with one mold. Get it up to temp (your alloy temp is great) aka no wrinkles and start casting. Pour out the lead, watch it frost over, count 1, 2, 3, cut the sprue. (that's cadence). Once you get a few pots emptied then try with two molds. Sometimes less is more. Once you are up to speed and its the middle of July you can run two molds. However, aluminum molds cool down very quickly, so for now try just one mold and enjoy what you are doing.

  17. #17
    Moderator Emeritus
    garandsrus's Avatar
    Join Date
    Jan 2006
    Location
    Warren, MI
    Posts
    2,935
    A couple suggestions:

    I normally cast WW about 675. The 75 degree difference (from your 750) makes a lot of difference with mold temp.

    Always preheat your mold! This is one of the biggest lessons I have learned. I use a cheap hot plate. The first few casts may not be perfect, but they will be within just a few mold cycles. If the spruce plate isn’t hot enough to cut the bullets easily, use a propane torch to heat the spruce more before the next cast.

    Return the sprue to the pot as they are cut. They are still plenty hot and don’t affect the alloy temp when added back right after they are cut. That will give you 10 lbs of bullets from 10 lbs of alloy instead of 5 lbs of each. If you start with a full pot, you will probably be ready to quit casting for the day before you need to add lead.

    Cut the sprue as soon as it solidifies and changes color. You will see the sprue puddle go from bright silver to a more dull color. At that point, you can cut it with your gloved hand. I drop it from the mold back into the pot. No big deal. I hate beating on molds to open the sprue plate. It’s just not necessary.

    The speed of casting is pretty much determined by how easily bullets drop from the mold. If they drop really easily, a 2 cavity mold cycle is probably 10 seconds from filling to filling again. A 6 cavity is only 5 or so seconds longer, which is the time to fill the other 4 cavities. The lower alloy temp helps keep the mold from overheating. Once I open the spout on the bottom pout pot, I don’t close it until the mold is full. Just slide the mold to the next cavity.

    Casting 500 bullets per hour with a 2 cavity mold is only 250 cycles in 3600 seconds, so an average of 14-15 seconds per cycle will get you there. That’s a comfortable pace after you have some experience under your belt.

    If the mold gets too hot, cool it by putting it on a wet sponge for 4 or 5 seconds. Search for “speed casting” for more detail.

    Good luck...
    Last edited by garandsrus; 10-06-2019 at 10:41 PM.

  18. #18
    Moderator


    Winger Ed.'s Avatar
    Join Date
    May 2007
    Location
    Just outside Gun Barrel City, Texas
    Posts
    9,484
    Quote Originally Posted by kungfustyle View Post
    Just cast with one mold. Get it up to temp (your alloy temp is great) aka no wrinkles and start casting. Pour out the lead, watch it frost over, count 1, 2, 3, cut the sprue. (that's cadence).
    That is how I do it, and have great results.
    I've used a few Lee molds, but keep coming back to my Lyman and RCBS one or 2 cavity ones

    Also-
    I wear heavy welding gloves.
    I cut the sprue by hand, catch it, set it back in the pot, then open the mold & water drop.
    I never timed it, but I think doing 2-3 mold drops a minute is fairly realistic for my production rate.
    In school: We learn lessons, and are given tests.
    In life: We are given tests, and learn lessons.


    OK People. Enough of this idle chit-chat.
    This ain't your Grandma's sewing circle.
    EVERYONE!
    Back to your oars. The Captain wants to waterski.

  19. #19
    Boolit Master Shopdog's Avatar
    Join Date
    Oct 2017
    Location
    Va. mnts
    Posts
    562
    Coming from,not as far out in left field as it's gonna sound.....

    When you aren't casting,and you're hungry..... start using old cast iron skillets in the kitchen. It should bolster,or reinforce your understanding of how heat,patience,and practice all go together to making perfect fired eggs that when you jiggle the pan,they slide from side to side in as perfect of non stick as it gets.

    It's not that big of a stretch to understand the time period of days gone by.... cast iron skillets for meals,provided by bullets cast over a fire. They sort of go together. I'd have to rank patience right up near the top of priorities on both,casting and cooking. "Time and temperature" is one of the foundational basics in chef school...... about the same for casting. Good luck with your project.

  20. #20
    Boolit Man
    Join Date
    Apr 2018
    Location
    SATX
    Posts
    87
    I was indeed letting the molds cool too long before cutting the sprue. It struck me that my first couple of casts "smeared" the sprue plate, so I slowed down. Maybe that wasn't smearing, just "marking."

    Knowing I should count "1, 2, 3" or so before cutting the sprue, rather than sort of admiring the sprues makes a big difference.

    I'm running around today, and I'll be looking at hot plates, among other things. Thanks for all the advice!

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check