proper temp for Steel mold

[glassparman]

OK, been using Lee Aluminum molds for a while with fairly good outcome. I just keep the pot at the right temp and keep the mold on a hot plate during pours if I'm feeling slow.

I recently picked up a couple older Lyman steel molds and I cant seem to get it just right. I'm using one of those crazy digital "Laser" point and shoot thermometers to check the steel mold temp and I seem to have to keep the mold at about 180 degrees F. If I go too fast, the mold drops frosty stuff so I think it is too hot. Never had that problem with the aluminum.

The other thing I noticed is that the side of the mold with the holes for the pins seems to not maintain the same temp as the other side of the mold. I'm just guessing this, as that side of the bullet always looks different when I drop even though the mold itself looks nice on the inside.

Is there a sticky here for a new guy that can give me pointers on working with steel vs. aluminum molds?

Thanks!
Mike

 

[RBHarter]

Iron moulds have to run slower , you don't have to "work so hard/fast" to keep them up to temp . In singles and doubles anyway . Little bullets in 4C are harder .

 

[462]

For whatever value it may be, I read somewhere that iron moulds work best with a temperature in the 400-degree range. Don't know the truth of that, but if you trust your digital point-and-read thermometer, the mould is too cold. For sure the mould halves are not at the same temperature, otherwise the bullets would have a uniform appearance.

I use a hot plate and "mould oven" to pre-heat moulds, while the pot is coming up to temperature. With practice, and knowing the foibles and nuances of each mould, the first cast will produce keepers.

Michael here too. Worked with so many Mikes -- once there were three of us Mikes on a three-man crew -- that I kind of morphed into a Michael.

 

[Rick]

Everyone that learns casting using one mold material and then starts with another has a learning curve. That's all it is, a learning curve. Aluminum sheds heat far faster than either steel or brass, thus your using the hot plate between pours. Once your steel molds are up to casting temp they will maintain that temp much better than aluminum. The key is mold temp and not pot temp. Unless your casting pure Pb keep the pot at or close to 700 degrees and adjust casting cadence to achieve the correct mold temp. As RB said, you won't need to cast as fast with iron (or brass) molds.

 

[Joshua]

Panini press. It’s one of the best things that I’ve accidentally discovered. I wanted a hot plate. They didn’t have any at the thrift store. But, they had a panini press for five bucks. I thought why not. It doesn’t get too hot. It heats evenly top and bottom. I’ve got no idea how hot it runs, it just works. I start heating my molds when I turn on my pot. Molds are well preheated, when the lead is ready.

 

[Mike W1]

I ditched my HF thermometer long ago. Saved the below post as one of the reasons. I've drilled the moulds I use for a TC in conjunction with my multimeter. I like my iron moulds around 420-30 °F. I did neglect to save the posters name for reasons I don't remember now but regret not having done so now.

Before I retired from Zeiss, at least 2-3 times a year I had to engineer systems that would measure the exact temperature of machined parts prior to measuring their dimensions. (Engine blocks, heads, etc. in Big 3 auto plants.)

So I've done more than my share of study of temperature measurement methods. Let me say categorically that these non-contact "laser" measurement systems are almost worthless. They measure infrared radiation from the target, and that radiation varies wildly with what is called the "emissivity" of the
surface.

The industrial suppliers of these things claimed that they could tell me a temperature within 2-3 percent of displayed value, IF we sent a large number of samples to them so they could measure the emissivity and calibrate their sensors. Any time a sensor required replacement, they had to go through the whole rigamarole again. Any time the surface finish changed, ditto.

Without calibration, and given unknown surfaces, they wouldn't guarantee accuracy to better than 25% of the displayed value! And that's industrial grade equipment costing thousands of $$. Bottom line, if you calibrate a Harbor Freight instrument against an accurate contact thermometer, you may be within 5% for the exact object you calibrated for. Any other object, you can be wildly off.

BTW the laser has nothing to do with the measurement process. It's just an aiming aid.

Best method is a low-mass thermocouple or RTD device, (thermistor). These are not expensive. Some under-$100 Volt-Ohm-Meters come with a thermocouple probe. I have had two of these, and they worked pretty well. I've never stuck one into melted lead, but there are versions that are encapsulated in ceramic which I would.

 

[fiver]

if you got one half of a mold doing one thing, and the other doing something else, the one that ain't keeping up is dirty.

anyhow... 375.

 

[STIHL]

You can cast yourself to death with aluminum. Once you get them to temp you have to keep a fast pace. Frosty boolits are not an issue. Hell some of my Lee moulds won’t throw a good book it until they get frosty with my alloy. Ive sent many frosted boolit down range with no issue.

 

[Mike W1]

I've arrived at several opinions after doing a LOT of temperature measuring as well as weighing bullets. First off I cast in a shop that's wood heated so I'm warm and comfortable whatever the weather outside. I built a "hut" to put the moulds into while on a hotplate, even insulated it. Conclusion: pain in the bottom and of no value for inside casting at least.

My hotplate is PID controlled as are the pots of coursel First I went the warming shelf route. Couldn't get the moulds to actual casting temperature. Mine like 310° F but release better at 320° F. In order to have the mould at that temperature and be able to lay it back on the hotplate and figure it's gonna be that temperature after say a 5 minute rest I think I set the hotplate at 480° F. I'd have to go out to the shop tonight in zero weather to verify that but am sure that's what I came up with.

Only have the one Lee and not sure if I measured temp's on that or not. If I did I need to do some consolidation of my notes, getting a little hard to sort out. BTW, having always used iron moulds I never had any consistent luck with the Lee's UNTIL I got a hotplate and actually got one up to temperature. Another investment in making life easier and as I always say, my wife says "you like toys". But I EXPECT the first bullets out are gonna always be good ones.

 

[STIHL]

Interesting, it takes me 8-10 pours after preheat on a hot plate to get my lees to throwing good boolits. Then, I can Run 2-3, 2 cavities, balls to the wall for a while until I run out of lead. I found if i pre heat the lead on the hot plate and I can keep on getting it. Fairly well anyway.

 

[Petrol & Powder]

I think it's easy to get lost in the tall weeds and forget what's important.
The goal is to produce large quantities of adequate bullets. Not PERFECT bullets.
Well filled out, sharp definition, no voids. We're not making jewelry !

Most of my molds are iron. They take a bit more time/heat to get up to temperature when compared to aluminum molds. But once you get them hot, they work just fine.
I purchased a thermometer for the lead pot. I think I've used that thing 2 times? maybe 3? It was sort of useful to get some idea of temps but not useful enough to be bothered with.
I get the mold blocks hot enough to drop nicely filled out bullets. If they start to come out with a frosted finish, I back the heat down and slow my pace.

Perfection is the enemy of adequate.
My goal is to make decent bullets, not works of art.

 

[Winelover]

Decent bullets might be adequate at handgun distances. Might not be, at rifle distances.

 

[Petrol & Powder]

You can spend 2 hours making 20 perfect rifle bullets OR you can spend 30 minutes making 60 rifle bullets and 15 more minutes culling out 20 perfect bullets from that pool of candidates.
What you do with that extra 1 hour and 15 minutes is up to you

 

[Winelover]

IMO, bullet casting isn't a race. For me, it's something to fill up, otherwise wasted time. It's not about quantity, it's about quality. Besides, only accurate bullets are interesting.

We as casters can, just toss questionable bullets, back in the pot. No great loss.

 

[Bret4207]

My advice is stop overthinking mould temp. Start casting and get the mould dropping decent looking bullets. Yes, you want them as nice as you can get, but you will never cast an absolutely perfect bullet. Frosty bullets, within reason, ususally are better filled out and shoot better for me than pretty shiny ones. If you hate the frosty look, you can swipe them with 4/0 steel wool after seating and they'll shine. As far as the "perfection" of the bullets, you look at that after they've cooled, not while you ahve a good rhythm going. Turn out 500 bullets, pick out the nasty ones and remelt them.

I don't think there is ONE MAGIC temp for steel, alum or brass moulds. I'm pretty sure a single cav and a 10 cav are going to be at different temps. Might be within 50 or 75 degees of each other maybe, but it may be more than that. What matters is what the mould seems to want on that particular day, with that particular alloy. That's the "art" part of this game.

 

[Rick]

I can say that in all the decades I've been casting not once, not ever have I turned on the pot to see how many how fast.

 

[Winelover]

Been casting for 40+ years. Never used a thermometer or a hot plate, until maybe 10 years ago. Learned by doing, no mentor. No internet, not much reading material on the subject, back then.

Hot plate's advantage is to get mould up to casting temperature, quicker. I use to do that with judicious application of a propane torch. Outcome is the same. Only my newer pots have PID's. Just another crutch, IMO. Cast enough, you develop a feel, after a while.

 

[Winelover]

I judge the proper temp for any mould material, is when you can open the sprew plate with only a gloved hand, with little to no resistance. Mould mallet, is just another crutch.

 

[dale2242]

I find the hot plate and thermometer to be of great help.
I don`t care how accurate my thermometer is, within reason.
I can go back to a certain temp on it and know how well the mould will cast.
As far as casting jewelry, I want all my cast bullets to appear perfect in my eyes.
My rifle bullets will be weighed, the handgun bullets will not.
Too each his own.

 

[Petrol & Powder]

Bullets from the same mold, cast during the same session, with the same alloy, that have sharp bases, sharp driving bands and weigh the same - are probably about as good as it gets.

You can try to make those good bullets by casting; say....20 near perfect bullets ? that all weigh the same and have well defined features...
OR
You can cast say......60 bullets? in a fraction of the time and select 20 good bullets out of those 60 that weight the same and have well defined features.
You will end up with exactly the same result.

While it is a hobby and not a race, my time is still valuable. I just cannot see myself spending an inordinate amount of time attempting to cast 20 perfect bullets when I can achieve the same result in a fraction of the time and just toss the rejects back in the pot.
To each his own.