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Thread: How to use a hot plate

  1. #1
    Boolit Buddy
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    How to use a hot plate

    I apologize in advance if the answer to such a question is so simple it shows my inexperience, but here goes.

    Since my last casting event I purchased a hot plate. I never had one before and I wanted to see what would happen to the quality of the boolit. When everything is hot and ready I want to try casting two Lyman molds (44 grain and 55 grain) at the same time.

    In my little brain the process would run like this:
    1. Preheat the molds. Most strings mention 170 degrees for mold temperature but NOE recommends 300? But these are Lyman's.
    2. I would then fill the cavities in the first mold, set it on the hot plate (hot plate running about 170 degrees)
    3. Pour the cavities in the second mold and set it on the hot plate,
    4. Knock the boolits out of the first mold cavities, refill those cavities and set it back on the hot plate,
    5. Knock the boolits out of the second mold, refill those cavities and set it on the hot plate,
    6. Knock the boolits out of the first cavity, refill those cavities and set it on the hot plate,
    7. Repeat,
    8. Repeat,
    9. Repeat…


    I would appreciate comments on the following
    • Is that too much time for the mold to sit on the hot plate?
    • Is that the right temperature for the hot plate to be set at?


    As a reminder, this is being used to cast 22 cal with two cavity Lyman Molds.

    Thanks for all of your support and advice. Bill.

  2. #2
    Boolit Master


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    Most just use a steel plate or saw blade and crank it up to mold temp 300 to 400. Your casting pace should be enough to keep the mold hot, 170 isn't going to help you much. If you are water quenching the boolits you'll need to drop them at about the same time get a count going after the pour, 1,2,3,4,5,6 drop just after you see the spru change color or harden. You'll get good consistent boolits that way. I have more of a time keeping my molds cool enough rather than keeping them hot.

  3. #3
    Boolit Master quail4jake's Avatar
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    Way off...170 degrees F? That's lukewarm enough to make fishing sinkers. NOE aluminum molds run 460 for me to cast spot on with COWW with 2% Sn at 650-680. Lyman iron molds in the 520 range. Heat once on the hotplate using a mold thermometer, start casting with the same mold and control the temp and boolit quality by the speed at which you cast. Don't leave a mold on the hotplate unless you're watching it and monitoring the temperature. Other casters are smarter than me and have more arms that work faster but in my slow, cautious world that's how I do it.

  4. #4
    Boolit Grand Master

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    I'm thinking that 170º is too cool. I run my cheap Walmart hot plate at the half way mark on the dial, probably in the 300º range, and get good bullets on about the second or third cast. I have an 1/8th inch thick piece of steel plate over the coils. Many use an old saw blade.

    I think your casting will be more successful if you use the hot plate to prewarm your molds and then just cast with them. If you are new to casting it may be easier for you to concentrate on using only one mold at the beginning. In a 22 caliber mold you may have to run it fast to keep it up to temp. It seems that if I'm casting anything smaller than 38 caliber bullets that I don't really have the time to juggle 2 molds. Your mold will dictate how fast or slow you need to cast. If you get good bullets your technique is good, if you don't get good bullets you need to change something.

  5. #5
    Boolit Master
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    Whatever allows you to produce good bullets.

    170 isn't very hot. My $5 thrift store plate only has an on/off switch and it runs at 300*F. This works to warm up the mold pretty well. After I start casting the mold never touches the plate again, but I only use one mold at a time. I can't see any benefit to juggling 2 molds.

  6. #6
    Boolit Grand Master

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    Overthinking? I have found that most molds have their own personality and will produce good bullets under slightly different conditions. As I heat my melt, I place a mold on my hot plate set at medium. I cast a few and watch the bullets. If I'm not getting good fillout, I'll turn up the hot plate a bit and try some more. If I get frosting I'll turn the heat down. Often I'll adjust my cadence to get a good working temp. for the mold.

    But I only cast a few thousand boolits per year and my methods, while producing good boolits, may not be scientific or sophisticated enough for some...
    My Anchor is holding fast!

  7. #7
    Boolit Master

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    170 Celsius is 338 Fahrenheit so the units are confusing the OP.
    Liberalism is the triumph of emotion over intellect, but masquerading as the reverse.

    I don't know how we ever shot maximum loads before P/C come along and saved us all. R5R

    "No mosque in the United States flies an American flag."

    "Dueling should have never been made illegal in this country. It settled lots of issues between folks."- Char-Gar

  8. #8
    Boolit Master quail4jake's Avatar
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    Quote Originally Posted by blikseme300 View Post
    170 Celsius is 338 Fahrenheit so the units are confusing the OP.
    which is still cold.

  9. #9
    Boolit Master

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    Quote Originally Posted by quail4jake View Post
    which is still cold.
    Yes, it probably is. I use a solid top single hot plate I got from *mart a few years ago and I just run it at full power to pre-heat my molds, never actually measured the temps. I just experimented until I found it works at full power and that it gets the molds up to casting temp in about 15 minutes.

    Something I have not come across on this and other forums on this subject is that until the mold and handles are up to casting temps things won't run smoothly.

    Most of my molds use the Lee handles and they have quite a bit of mass in the metal. These handles act as a heat sink so unless these are heated up as well they will draw heat away from the molds. By heat soaking the mold and handles on the hot plate before starting to cast better and quicker good results are achieved.
    Liberalism is the triumph of emotion over intellect, but masquerading as the reverse.

    I don't know how we ever shot maximum loads before P/C come along and saved us all. R5R

    "No mosque in the United States flies an American flag."

    "Dueling should have never been made illegal in this country. It settled lots of issues between folks."- Char-Gar

  10. #10
    Boolit Master

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    Interesting thought. Most of us use hotplates to get a mold up to temperature so we don't have to waste time pouring lead into them, making reject bullets, until they finally decide they are hot enough to perform adequately. Once it's there, I only use the hotplate to keep the mold warm while I stand up to stretch, take a potty break, etc...

    If a mold still shows signs of being too cold, I'll dip a corner of the mold in the lead pot in such a way that I'm heating up both the blocks and the sprue plate. This usually only takes about 10 seconds or so to get it to behave. Once rolling, heat of the alloy going in is usually enough to maintain temperature. Hotplate not required from then on.

    My own thinking is that small-caliber molds take too much focus to run properly that I wouldn't want to try running two at once. Your descriptions sounds like a hellish amount of juggling. YMMV.
    WWJMBD?

    In the Land of Oz, we cast with wheel weight and 2% Tin, Man.

  11. #11
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    Wm Cook,
    You don't mention your experience level in regards to casting, but casting 22 boolits isn't necessarily for the beginner

    everythins lightman mentions here is excellent advice, IHMO.
    Quote Originally Posted by lightman View Post
    I'm thinking that 170º is too cool. I run my cheap Walmart hot plate at the half way mark on the dial, probably in the 300º range, and get good bullets on about the second or third cast. I have an 1/8th inch thick piece of steel plate over the coils. Many use an old saw blade.

    I think your casting will be more successful if you use the hot plate to prewarm your molds and then just cast with them. If you are new to casting it may be easier for you to concentrate on using only one mold at the beginning. In a 22 caliber mold you may have to run it fast to keep it up to temp. It seems that if I'm casting anything smaller than 38 caliber bullets that I don't really have the time to juggle 2 molds. Your mold will dictate how fast or slow you need to cast. If you get good bullets your technique is good, if you don't get good bullets you need to change something.
    When I started casting 22 boolits, I found I couldn't cast fast enough to keep the mold hot enough, Maybe that is why you are thinking of casting with 2 molds and using a Hotplate during casting?

    Anyway, what I did back then, was preheat the mold on the Hotplate, then cast with one mold, maybe 4 or 5 pours, til the mold wasn't seemingly hot enough anymore, then place the Mold on the Hotplate for a few minutes to come back up to temperature, then cast another 4 or 5 pours.

    Once you develop a good technique and have a mold that is functioning well, there will be no need to use a Hotplate during the casting session, I only use it to preheat the mold now.
    good luck
    ~~~~~~~~~~~~~~
    “If someone has a gun and is trying to kill you, it would be reasonable to shoot back with your own gun.”
    ― The Dalai Lama, Seattle Times, May 2001

  12. #12
    Boolit Master

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    As mentioned casting good small boolits can be a serious challenge for beginners, never mind reloading for good shooting in an auto loader rifle.

    Getting the mold up to good temperature and keeping it there is not trivial but not too hard to master. The environmental temperature and airflow can make things difficult even when everything else is lined up. Don't have a large volume of fast moving cold air when casting small & light boolits, it won't turn out well.

    What does not help things at all is that the volume of the sprues of the small/light boolits are typically the same as for large/heavy. The amount of heat added to the mold during casting matters a lot in keeping it up to casting temperature. Consider this: the heat added during the pour needs to be equal or greater than the heat lost during the cooling or the mold gets too cold. There is an alloy temperature ceiling so just running the alloy hotter is not the answer. Think of a pour as adding heat back into the mold to match the heat lost during cooling.

    There are a number of ways to get this balance of heating & cooling right and there is no single correct way, experiment and see what works for you. Some folks use ladles and pour a stream of alloy over the sprue to add more heat. Others add resting of the mold on a hot plate or melting pot to reheat. Some use a gas flame or torch. There are pros and cons to every method.

    What I have done on some of my molds is to mill a trough into the sprue plate that allows a larger volume of alloy in the sprue that enables me to add more heat to the mold during pours.

    I used to do the dip-in-the-alloy method to help things along but stopped doing that after once getting molten alloy into the alignment pin cavities - it took a while to clean that out right.

    USE THE FOLLOWING AT OWN RISK. What I now do is to have a trigger actuated MAP torch which I use with care to bump the temperature up if needed. This method of mine is sometimes used to soften the alloy of the sprue when too cold to prevent the damaging or breakage of the sprue plate and camming lever. By applying the torch flame to the frozen sprue it is easy to soften it up so it is easy to cut.
    Liberalism is the triumph of emotion over intellect, but masquerading as the reverse.

    I don't know how we ever shot maximum loads before P/C come along and saved us all. R5R

    "No mosque in the United States flies an American flag."

    "Dueling should have never been made illegal in this country. It settled lots of issues between folks."- Char-Gar

  13. #13
    Boolit Master

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    Quote Originally Posted by Bigslug View Post
    <snip>

    My own thinking is that small-caliber molds take too much focus to run properly that I wouldn't want to try running two at once. Your descriptions sounds like a hellish amount of juggling. YMMV.
    I agree, the only time I have had luck using 2 molds is when casting 2-cavity 450gn boolits. 900gn of molten alloy sure keeps the mold hot so the cooling time allows me to use 2 molds.
    Liberalism is the triumph of emotion over intellect, but masquerading as the reverse.

    I don't know how we ever shot maximum loads before P/C come along and saved us all. R5R

    "No mosque in the United States flies an American flag."

    "Dueling should have never been made illegal in this country. It settled lots of issues between folks."- Char-Gar

  14. #14
    Boolit Master
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    My Method:

    I have a GE single burner from Wally World. When I get ready to cast:
    1. I put the mold on the burner to about the six oclock position. I find this a good spot for me.
    2. I put the mold on the burner. I made a cover from a four gang box. I cut a slot to fit over the mold.
    3. Turn on the pot.
    4. Thirty minutes later I am ready to go.
    5. Usually, I am getting good bullets
    5. Usually, by the fifth cast I am getting good bullets.
    Leadmelter
    MI

  15. #15
    Boolit Buddy
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    I'm still new at this but I've started using a hot plate to preheat my moulds. I've got a 1/4" steel plate on it and any time I stop casting the mold goes on the plate. I get less rejects that way. Ymmv

  16. #16
    Boolit Grand Master
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    I NEVER put a mold back on a hotplate after I start casting and it gets to FULL CASTING TEMP.....the temp YOU determine from experience at which the mold drops perfect boolits. Not 150F. Not 320F. Way toooool cold. Get them HOT HOT HOT!!!! And once you get started casting, the molds will actually get too hot and you will have to slow down or pause to let them cool off a bit. It all takes a lot of practice. Not just thinking! Don't overthink......just do it.

    And don't forget about those feed ingots of alloy! I preheat them on the same hotplate to save time when feeding my casting pot.

    This whole casting thing takes a lot of actual hands-on experience. You can read until your are cross-eyed and ponder what will and may not work. But until you get out there and do a lot of it, you will not works for you and your molds. Every mold has it's own personality! Get to know them.

    BTW.......doing it my way, I get 99.7% good boolits (many thousands of them over the years) from the 1st drop. A HOT mold is a good thing.
    Banger

  17. #17
    Banned

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    This whole casting thing takes a lot of actual hands-on experience. You can read until your are cross-eyed and ponder what will and may not work. But until you get out there and do a lot of it, you will not works for you and your molds. Every mold has it's own personality! Get to know them.

    I just copy and pasted this from the post above.

  18. #18
    Boolit Master Handloader109's Avatar
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    I've a Lee bator 2 cavity and a 6cav noe 37gr and have no issues making good booklist with either with no hot plate. Takes a Few pours, but quick work is the key. Never tried both at same time.

  19. #19
    Boolit Master 44Blam's Avatar
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    I find that I get the mould hot on a hot plate while melting my alloy. Then when I start pouring, I knock the sprew off on a towel and drop the boolits into water. I set my temp on my pot to fairly low... About 600 degrees f.
    Then when I have a lot of sprew lead, I dump it all in. This cools the pot and lets my mould cool a little.
    Then when my pot is back up, I go again.

  20. #20
    Boolit Master trapper9260's Avatar
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    I do almost like 44Blam what i do different is I do not drop the boolits in water I let them air cool. I drop also the sprews in the pot when they start to take up too much space or the pot get too low for me.After the mold is up to temp I just run them and like was stated that if i stop for some reason. I do not take the boolits out of the mold I just place it on the hot plate and then take it off when I cast again. Each mold has it own temp to cast it. it will tell you by the boolits. Some will need to run hotter then others. I try to run two molds but I see i do better with one.This is what works for me.
    Life Member of NRA,NTA,DAV ,ITA. Also member of FTA,CBA

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