Hot Plate Question ?

[kevin c]

I use an 1100 watt single coil that I got at Ace Hardware ("Broil-King" I think).

Every saw blade I tried has warped so that heat transfer to the mold was slowed. There's also the fact that I can be clumsy and once scratched the block of one mold on the teeth (just cosmetic, but still). I'm now experimenting with thick strips of aluminum and a mold "garage" made from an old bread pan.

[jsizemore]

$5 open coil I found at the flea market. I fix appliances for a living. I set my mold directly on the coil at the medium setting. I stick the probe of a digital meat thermometer through the sprue hole against the bottom of one of the mold cavities. I set the alarm for 400 but will start casting when it hits 375 if everything else is ready. I do the same with aluminum, brass or iron molds.

[kevin c]

Jsizemore: I've read claims here that putting an (aluminum) mold directly on the coils can warp the blocks. Have you had that problem? Do you see the coils turn red at the setting you use? I can't get my molds up to casting temp (~400°) unless the coil is definitely a dull red color.

[Walks]

I've a 1100 hot plate I found when My Mom passed. And a cast iron heat diffuser plate too.
It does get hot enough to melt ingots if turned up too high. And yeah, it's coils will glow red if turned all the way up. My little HF therm gun reads 550degrees for that.

[jsizemore]

Jsizemore: I've read claims here that putting an (aluminum) mold directly on the coils can warp the blocks. Have you had that problem? Do you see the coils turn red at the setting you use? I can't get my molds up to casting temp (~400°) unless the coil is definitely a dull red color.

NEI,Noe and Accurate 3,4 and 5 cavity aluminum molds. Digital meat thermometer probe placed through the sprue plate hole set on the nose portion of the cavity. I see the coil get a red glow and then cycles off. My setting is just below "M" on the scale. I don't blast anything with wide open heat. I'm not trying to race. 375-400degF takes about 10-12 minutes. Big 8-10 cavity iron mold takes 15. Real easy to set the alarm on the digital meat thermometer. No warp, no melted mold, no loose alignment pins. We pour 700-800degF lead in the cavity and the mold doesn't warp or melt. A much thinner aluminum pan sits on a burner coil or flame at very high heat. I don't walk away and leave a mold unattended on a burner or a pot of liquid lead. Do whatever you think is right. I don't use Lee molds so can't say how they handle the heat

[bluebird66]

Thanks for the photos everyone!

[OS OK]

For a long time I used to use a small block of wood to hold the handles at the correct height to keep the mould flat on the heating plate & to keep the mould from falling off the plate. That made it rough to preheat 2 moulds, I was always knocking one mould off when grabbing the other one...



Then one fine day I found one of my feed buckets that had been broken (plastic junk-O-bucket) and just as I started to toss it...I saw a solution to my preheating problems...a rail made from a bail ...to support the mould handles...

[Retumbo]

I had a bunch of these lying around, work well

https://www.omega.ca/en/industrial-h...B&gclsrc=aw.ds

[kevin c]

Ouch, I'm not sure I'd be willing to spend that much. Glad you had them already.

[Rich/WIS]

Instead of the #10 can I use the bottom of a Danish Butter cookie tin, notched for the mold handle. Used a wire coat hanger to fashion a bail handle to make it easier to remove and use the top of tin inverted on the hotplate to put ingots in to pre-heat. My hotplate is the solid type from WW. Don't have a tippng problem with the molds as they are all either Lee six cavity or NOE five cavity. The cookie tin is shorter and keeps the heat around the mold better than a tall can.

[tacofrank]

Howdy Casters,
I took the advice from several folks here a few weeks ago and bought a cheap hot plate from a thrift store ($3.50). All can say is do it. Damn! I've been casting for 50 years and casting dozens of bullet before getting good ones. I cast from three different molds this afternoon and got great bullets from the first pour with all three molds.
This site is awesome!!
TF

[kevin c]

Well, I just tried out the aluminum strips on my 1100 watt coil, with the bread pan mold garage. The garage I went a little crazy on: it's two bread pans nested, sandwiching a layer of pink Fiberglas insulation, with one end cut off for mold insertion.

TOO HOT!!! A few minutes between medium and high (I used to use the maximum setting before) had the mold smoking when I rubbed a two stroke oil soaked swab over the sprue plate, and the first pour of 720° alloy (PID controlled pot) the sprue would not solidify at all; it just ran off the top of the plate and left little puddles in each sprue hole. The blocks and plate were so hot that even after a minute and a half the lead in the sprue channels was liquid, and when I relaxed my grip on the handles I discovered the lead in the cavities was the same as it drained from the cavities out between the mold faces.

Starting with another mold cold, even medium heat settings caused smoking and little frosted BB's. This is going to need more work...

[OS OK]

Well, I just tried out the aluminum strips on my 1100 watt coil, with the bread pan mold garage. The garage I went a little crazy on: it's two bread pans nested, sandwiching a layer of pink Fiberglas insulation, with one end cut off for mold insertion.

TOO HOT!!! A few minutes between medium and high (I used to use the maximum setting before) had the mold smoking when I rubbed a two stroke oil soaked swab over the sprue plate, and the first pour of 720° alloy (PID controlled pot) the sprue would not solidify at all; it just ran off the top of the plate and left little puddles in each sprue hole. The blocks and plate were so hot that even after a minute and a half the lead in the sprue channels was liquid, and when I relaxed my grip on the handles I discovered the lead in the cavities was the same as it drained from the cavities out between the mold faces.

Starting with another mold cold, even medium heat settings caused smoking and little frosted BB's. This is going to need more work...

Can you put the thermocouple from the PID in the garage to see how hot it got?
If you had been warming ingots on the top of the enclosure, that might not have gone too well?

[kevin c]

Good thinking, there, OS OK. Thinking out loud:

The rigid PID probe is too long to sit in a cavity and go through the opening. I could drill a hole through the top; it's not like heat loss is going to be an issue. Or, easier, I could use a flexible wire thermocouple hooked up to my multimeter.

I just need to find the setting that'll get the blocks to 400° and keep them there until casting time, right? I'll report back.

[bangerjim]

Howdy Casters,
I took the advice from several folks here a few weeks ago and bought a cheap hot plate from a thrift store ($3.50). All can say is do it. Damn! I've been casting for 50 years and casting dozens of bullet before getting good ones. I cast from three different molds this afternoon and got great bullets from the first pour with all three molds.
This site is awesome!!
TF

Hear us now and believer us later! It does work and saves hours of throwing back bad castings while getting up and running.

banger

[DaveN]

I suggest getting an infrared thermometer. Not expensive, I think I paid $25 or so.

[kevin c]

Update on temp measurement and my insulated mold garage.

I now use a k type thermocouple in one of the cavities, figuring the temp of the mold block at the cavity surface is really what I want to know, not so much the air temperature in the garage or the top of the sprue plate. I'm finding that for my 8 cav aluminum molds, a cavity reading of 428 to 446 °F (220 to 230 °C) drops good boolits with a light matte frost (95-3-2 alloy), though ambient temp and wind affect that.

With the probe I just leave the coil hot plate set at max, and pull the mold off when the probe approaches the temp I want. That does mean monitoring the temp, though. I've also learned to preheat the preheater if I want to get to casting faster: it takes a while for the garage and the heat diffusing aluminum strips under it to warm up, even at max, and that slows warming up the mold.

[243winxb]

Heat molds by casting. https://support.leeprecision.net/en/...le-cavity-mold

The aluminum molds will not overheat by simply casting but can be overheated by preheating with a hot plate, torch, setting on top of the pot to heat up or immersing in molten alloy for an excessive amount of time.

https://flic.kr/p/2myVqhb

[Mike W1]

I'm one that goes the easy route I guess. If it gets electrical heat applied I use a PID and control things. Experimenting with my moulds for the temperature they cast well at as well if the hot plate will maintain it there when I set it there for a break without overheating I came up with what works well for me. Both pots also have PID's as well as my lube/sizer. PID's take all that guesswork and I like turning things on and KNOW they'll be just where I want them to be. A litttle ebay shopping makes having multiple units pretty inexpensive. Be sides being fun to assemble!

Here's how my hotplate setup is. Used a 1/4" aluminum piece for that.