How to use a hot plate

[Wm Cook]

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:

Preheat the molds. Most strings mention 170 degrees for mold temperature but NOE recommends 300? But these are Lyman's.
I would then fill the cavities in the first mold, set it on the hot plate (hot plate running about 170 degrees)
Pour the cavities in the second mold and set it on the hot plate,
Knock the boolits out of the first mold cavities, refill those cavities and set it back on the hot plate,
Knock the boolits out of the second mold, refill those cavities and set it on the hot plate,
Knock the boolits out of the first cavity, refill those cavities and set it on the hot plate,
Repeat,
Repeat,
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.

[kungfustyle]

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.

[quail4jake]

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.

[lightman]

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.

[reddog81]

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.

[mdi]

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...

[blikseme300]

170 Celsius is 338 Fahrenheit so the units are confusing the OP.

[quail4jake]

170 Celsius is 338 Fahrenheit so the units are confusing the OP.
which is still cold.

[blikseme300]

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.

[Bigslug]

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.

[JonB_in_Glencoe]

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.

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

[blikseme300]

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.

[blikseme300]

<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.

[Leadmelter]

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

[Biggin]

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

[bangerjim]

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

[runfiverun]

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.

[Handloader109]

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.

[44Blam]

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.

[trapper9260]

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.

[Jack Stanley]

While I have run two molds with larger calibers I don't with the .22 stuff . A two cavity mold can lose a lot of heat but having to run a hot plate seems like you are working against at least one of the molds .

.22 molds like an alloy that fills well some say linotype or a 50/50 mix of that and pure lead . When using my old four cavity Lyman mold I can get away with using softer alloys because I can pour a huge sprue on top and keep it hot . A two cavity at times can't get enough heat using the same alloy . After casting four different styles of .22 bullets I don't think the hot plate and two molds in tandem would work . If you're going to try though heat is your friend and keep the desk fan away from the molds resting place .

Jack

[Wm Cook]

This is Bill again, the one that started this string and thanks for the help.

Well, reading the above was certainly an eye opener. I was targeting 170F for the mold because I thought that’s what was mentioned in some of my previous searches. So that’ll be ratcheted up to 500 – 550F for steel and 450 – 480F for aluminum molds. Pot temperature will probably be about 780F. Anyone disagree with that?

And you were right in guessing that I wanted to use the hot plate and two molds to keep the molds hot enough to cast sharp 22’s.

So this is where I’m headed: I’ll start with clean molds (another story for another time, stay tuned for that one) the Lyman molds heated on a hot plate to say about 550F and I’ll run the pot in the 780F range, and shuck them out of the mold as fast as the sprue set ups.

Then adjust the speed of casting to the quality coming out of the mold. The wild card for me is the small 22 and loosing mold temperature after a few casts. Do you guys use an IR gun or what to read mold temperature?

Someone very politely asked about my experience with casting. I think I'm in about 3rd grade. I'm starting to chart success with various pot temperatures and I am about to just start using a hot plate. I think I think I am about to finalize on an alloy and a lube. So far I’m casting for the 35 Remington, 7.62 x 54 Mosin, 30-30, 357, 9mm and the 22’s. Success has been very good on all but the 22. That’s the reason I was leaning toward the two mold and a hot plate theory. Of the four 22 molds I have the 37 grain NOE pours beautiful boolits that literally jump out of the mold. The 44grain Lyman was casting plum ugly boolits (more on that later with another thread), the 55 grain’s front cavity of the two cavity mold would not readily release the cast boolit (more on that later as well). The fourth 22 is another NOE that should drop boolits in the 60 grain range. That's fresh out of the oven after the initial 4 temperature heat up and cool downs.

Now to answer why am I messing with 22’s. Real simple here. Casting for the 35, 30, 9mm was so simple I had to give it a try. I am very fond of shooting 800fps to 1600 fps loads in about everything. Its like eating candy. I just can get enough trigger time to satisfy the fun I have shooting small groups with rifles like the Marlin 35 Rem or the old Finish Mosin. I know this sounds crazy but a pinch of pistol powder and cast loads can give you hours of fun. But while a 3” group offhand at 50 yards is a terrific group with one rifle, one shooting position I'm a small group shooter at heart.

I shoot short range 6PPC benchrest and I’m always trying to put them all through the same hole. But I’m blessed with just enough common sense that I can enjoy a low velocity 3” off-hand group @ 50 yards with my 35 Remington as I am shooting .099 groups @ 100 yards with my 6PPC. So I guess you could say I’m always in pursuit of shooting small groups.

My goal is to shoot sub MOA groups with the .22 K Hornet, .222 Sako Vixen and my 223 Remington.

Heck, it’s all for the fun of it anyway. Again, thanks for the help, Bill.

[lightman]

I'm thinking that 780º is a little warm. Most of my molds work ok at a little less than that, like 720-740º or so. You can try it and adjust as needed. The small 22 cal mold is going to be a challenge for you but if you are already getting good bullets with other molds you will get the hang of the smaller bullet pretty easy. You are correct about adjusting the speed of your casting, and also the temp of your pot. Since you are a Benchrest shooter I expect that you will pick this casting stuff up pretty quick. Please feel free to ask any questions.

[Jack Stanley]

Bill when I run range scrap through my four cavity Lyman 225462 I set the pot at eight hundred . The sprue gets cut just so the bases don't get torn open and I don't really look close at each bullet while casting . That mold is for my gallery loads , no gas check , one groove of lube , loaded in a .223 case , 700-X powder and great accuracy for short range .

Yes I do run them fast and hot , sometimes need a fan to help cool sprues .

Jack

[quail4jake]

Mostly good, I would get a mold thermometer from NOE and keep alloy temp under 750 as this is the point that tin begins to form dross excessively and reduction is more difficult at higher temp.

[trixter]

My 2 cavity Lee C 225 RFN likes very hot lead, so I set my melter at 780° to 800° and my hot plate set to the end of the MED setting (towards the MAX side). And then I cast as fast as I can with lots of sprue. This was learned after many sessions of trial and error.

[nh7792]

Not sure about the rest of the folks, but the hotplate was only used to heat up the mold while I got the pot filled and ready, then to keep the mold ready if I needed to walk away for a sec or to refill pot. Once you get casting, you can maintain temp on 2 molds without the use of the hot plate just by rotating them as you go.