Something I learned last weekend, about temp

I'm using a Lee Pro 420 (220v, heats up really quick, glad I went that way) and Lee molds at this time, and a Lyman thermometer. @800 on the therm, just wasn't getting good pours, lots of wrinkles, bad fillout, even with preheating molds and being very careful.

No signs of frosting, so I just started cranking the temp up. Therm is reading over 1000 deg and the lead starts really flowing well. It is now a fine stream instead of like pouring syrup. Mold fillout gets really good, real square consistent driving bands and still no frosting.

Obviously my thermometer is off by a couple hundred degrees at least. And I bought the Lyman because it was more expensive than Lee so it should be better, right? :veryconfu

But it was like a whole new level when those molds started filling out like that. Like a light came on.

Who makes a good, accurate thermometer?

I bought the RCBS because the customer comments regarding Lyman were not complimentary. I mnever calibrated the thermometer but it reads 700 degrees with good fill out.

Sounds like you need to turn it up a little more. Is it cold outside where you live? That may be keeping your mold too cool to produce good, frosted bullets. It they're filled out like you say, then they are probably good enough, but a little frosting tells the story of a good bullet.

Not real cold down here in FLA, just really humid!

I would just continue to use the Lyman but it stops at 1000 so I'm guessing past that...

I have had two dial thermometers over the last few decades and one was as bad as yours and the other was off about 75F around melting temps.....I went to thermocouples and digital readouts. I do other things that require very fine temp. management so I justified expensive equipment. Nowadays I have found new stuff that is cheap to be amazingly accurate in the 500-800F range. Even many multimeters (volts, ohms, amps) often have a j-thermocouple input.

Consider the possibility that the thermometer could be correct and you have still to learn the lesson about the importance of adequate MOULD temperature.....and find how to achieve it without pouring thousand-degree alloy.

Gear

Gear: I have considered that, being a relative noob, but would not the boolits be frosty at over 1000*? And, the pour just seemed to magically get way easier, like pouring syrup straight out of the microwave rather than straight from the cabinet. It just seemed like "hey, this is how it is supposed to work".

OuchHot: tell me more about this "new stuff that is cheap" of which you speak!

I have a Lyman thermometer, used it for years with Lee pot and it seemed good. When I bought an RCBS pot and used the thermometer, it showed 450* when the pot was set at 750*. Don't use the Lyman any more. Funny thing is, both pots yield great boolits.

A thermometer is a standard. If your shows water boils @ 300 F it isn't accurate. That doesn't keep you from noting you get your best bullets when it reads XXX and taking your melt to that point. Accuracy isn't really needed for most boolit making just repeatability. Pure lead melts @ 621.5 F so get some pure and see what it does with your t/stat. make sure it is pure but those are your reference points.

Quote:

---

Originally Posted by Quiettime

Gear: I have considered that, being a relative noob, but would not the boolits be frosty at over 1000*? And, the pour just seemed to magically get way easier, like pouring syrup straight out of the microwave rather than straight from the cabinet. It just seemed like "hey, this is how it is supposed to work".

OuchHot: tell me more about this "new stuff that is cheap" of which you speak!

---

"Frosting" is an effect caused by two things in combination: The presence of antimony in the mix, and a very hot mould.

The temperature of the metal going into the mould has zero to do with whether or not the boolit surfaces will have the "frosted" appearance, that is 100% a function of mould block temperature and cooling rate, or rather the SLOW cooling rate, of the alloy. The more slowly an antimonial alloy cools, the more time the antimony dendrite crystals have to form lattices, and the appearance of a textured surface becomes present.

For example, I can literally pour 800-degree wheel-weight metal into a 200-degree mould and get shiny, wrinkled boolits with rounded edges. I can also pour 650-degree wheel weight metal into a 450-degree mould and make boolits that are so frosted and undersized that they appear as rough and dull as freshly-broken cast iron, or appear as if they were sand blasted. The difference is the temperature of the MOULD, not the alloy. And, of course, the presence of some antimony in the mix. Tin/lead alloy or pure lead always casts fairly shiny, regardless of mould temperature or alloy temperature.

The general rule for most of the ternary (lead, antimony, tin) alloys that we scrounge up for making boolits is to run the pot below 750 degrees F., or really about 100-150 degrees hotter than the fully-liquid point, and to preheat the moulds somehow (dip a corner in the melt for a while, set across top of pot for a few minutes, or improvise a "mould oven" using a hot plate and metal box) so they come up to casting temperature faster or start out at casting temperature. THEN, as you cast, maintain a pace that is brisk enough to keep the mould hot enough for good fillout.

Casting good boolits is all about consistency. Constant pot temperature is important, this is what your thermostat and thermometer are for. Constant mould temperature is even more important, and that is controlled simply by adjusting the timing of the various pouring, waiting for sprue to set, cutting, opening, dumping, closing, and refilling operations. Casting boolits is like driving a car on the highway, you have to constantly make slight corrections to steering, throttle, brake, etc. and watch your mirrors, the road, anticipate hills and valleys to keep the speed consistent and in the "zone" that you want to be.

You'll have to experiment with timing operations and pouring stream adjustment, technique, sprue puddle size, etc. while watching for frosting, rounded edges, filled bases, air bubbles/voids in the bases, wrinkles, shiny spots, frosted bands/shiny noses, sprue flashover time to give yourself clues about what is working and not working with a particular mould, alloy, and atmospheric condition.



Here's a quick and dirty method that works every time. Turn on the pot and start melting your alloy. Stir it with a spoon as soon as it starts to get mushy and watch the thermometer. Once the metal thins out like thin porridge, keep a close eye on temperature, it should remain constant as the phase changes. Once the last bits of grainy metal go away, the temperature should start to rise again (the metal is past the phase platau). Record the phase plateau temperature and add, say, 150F to it. Allow the alloy to reach this temperature and adjust the pot to maintain it. Spoon in a layer of pine sawdust on top of the melt and stir the alloy gently to flux and reduce oxides. Skim if you want, or not. Dip a corner of your mould down int he metal and hold it there until the alloy no longer sticks to the blocks when you withdraw it, this could take anywhere from 30 seconds to two minutes. Dip the tip of the sprue plate in the alloy too, for about ten seconds, then close the mould and start casting. The mould should suck the pot temperature down 50 or so degrees depending on the size of the mould. Fill, cut, and dump the first few castings quickly and glance at the boolits. If shiny and wrinkled, keep casting culls as fast as you can until they start to fill out and get an even, satin frost all over. From this point on, you can play with the timing and sprue puddle size to control mould block and sprue plate temperature to keep the mould temperature and boolit quality even from nose to tip.

This works with any alloy, any pot, any pouring technique, and any mould (except non-antimony alloys won't frost, you just look for sharp edges and good fillout with those) and any weather. Don't forget to glance at the pot temperature once in a while and make sure it stays 100-150 above the fully-liquid point that you recorded first thing. It's all up to mould temperature and technique after that, and trust me, quit dinking around with pot temperature, it is not going to do you any good.

One more thing, to emphasize what MT Gianni wrote, IF your thermometer is off even 200 degrees, if you do as I described above, it won't matter because you only want to obtain an alloy temperature that is a certain amount above fully liquidus with ANY alloy, and your thermometer is good enough to give you that valuable reference point even if it is not giving you an exactly accurate temperature reading.

Gear

This is why this sight is of such value. Good stuff Gear.

Gear, I'm not sure what others extracted from your post but I would like say I was very nicely written. I've been casting a long time with great success and I picked a ton of good useful information from your post.
Thank you, Jeepyj

Thanks Gear. Succinct and well stated.
I've used single round ball molds, Al and brass, even a Lee 1 Oz. slug mold with no difficulties. Recently branched out to a 2 holer in .44, 250 gr. and experienced wrinkled boolets. Actually better success with a 6 banger casting 200 grain boolets.
Mold temperature is critical.

Can we get a "Sticky" on that post gear? "Frosting - more than just sugar!" (hehe).

I have been a member for ~2 years, and in that time I have not read a more thorough description.

Sticky! This is just one of many fine posts by Gear. It would be nice if they were all in one place.

Long posts often turn me off, but after reading all the at a boys I went back and read Gears post, glad I did. Dennis

Since the OP thermometer is reading over 1000 degrees and hard to take a reading as there are no numbers past 1000 it might help to adjust it so it reads within the scale on the face.
My older Lyman thermometer was off also so I gently grabbed the probe and turned the head and set it this way. The head turns on the probe to adjust the needle.
And Gears post was a very good one.

Gear,

A tremendous post from which i learned a lot. Thank you for taking the time to write it. i am sure it will help a lot of members.
Be blessed.

I struggled for 15 years and many buckets of wheel weights before finding this site, some well-written books on the subject that I didn't know existed before, and was finally able to sort fact from myth for myself. It is a hundred times more difficult to figure this out if you have to sort the misinformation from simple fact as opposed to simply getting the facts in the first place. I see people getting fed the wrong information constantly and know where that road will lead: Frustration and probably giving up the hobby because there is too much "witchcraft" involved with it. My aim is to distill the facts as I see them and stop the wive's tales that pervade this hobby to the detriment of newcomers. I wish someone had done that for me 20 years ago, I'd be a lot further along by now.

BTW, most of what I explained above is outlined in The Lyman Cast Bullet Handbook, third edition, but the style is more academic than technical and somewhat difficult to distill if you don't already have a general idea of the factors involved with casting metal.

As for long posts, I don't really like them either, but if one can only condense information/instructions to a certain point before it loses value.

Gear

Gear,
Great job, I liked the article.