Mold temperature?

[John Hill]

I am a new caster and have trolled all over this great forum and have learned a lot. I have a Lee aluminum 2 cavity mold 358 158 to cast .38 spl semi-wad cutters. I am getting wrinkling near the tip area and have read that my mold may not be hot enough even after casting 30 or so boolits. I have a single element hot plate to pre-heat the mold and also have a Harbor Freight infrared thermometer so I can tell the temp of the mold. What is a good range of temp to get good flow and help eliminate the wrinkles?
As long as I am asking, what is a good temp for my Lee Pro 4-20 pot to cast boolits from mixed wheel weight ingots?
John

[462]

Mould temperature: 375 to 400 depending on material and other variables.

Alloy temperature: 575 and up, depending on ambient temperature and other variables.

[theperfessor]

Don't expect an IR thermometer to be very accurate. Aluminum molds need to be run a little hotter than steel. The point I try to reach is to have the sprues freeze in about three seconds. Cut sprue with gloved thumb.

[Echd]

Dip that sucker in lead and let it heat up.

Worst thing that happens is that it gets so hot your boolits don't cool and solidify for a bit. If that happens, then you can wait a bit and you should be at just about the right temp.

[prs]

There are different kinds of wrinkles. Sometimes the little wormwood like wrinkles are due to a poorly vented mold or a mold that may perform better with a different pour rate or pour at a different angle. A slightly loosened sprue plate may let "breathe". If it is the larger wrinkles, the mold could benefit from cooling, recleaning, repeat sessions. Getting the alloy hotter and casting rapidly to get very frosty boolits mat bring it around to your way of thinking, then back the heat down to cast as you prefer.

prs

[Sgtonory]

Set your pot to between 7 and 8. Break the spru 3 sec after it has frosted and keep it going untill you get nice boolits. May also still have some lube in the cavity, try and clean the mold again and see if this helps.

[Clay M]

I set my hotplate to read about 550 with my casting thermometer.The mold heats up and cast good bullets.I use cast iron molds,I don't know about the temp for aluminum.

[geargnasher]

Aluminum loses heat more quickly than ferrous metal and may require a more brisk casting pace. I run my aluminum moulds at about 400-420 which puts a nice, light "dusty" satin frost on wheel-weight boolits when they cool. Wipe it right off with a rag and they're shiny underneath. I get better fillout that way.

As long as your alloy is hot enough to come out of the spout, it's hot enough to cast with. Oil will cause wrinkles as well as venting and mould too cool. Hot alloy and too-cool mould won't make good boolits, focus on casting 4 pours a minute minimum and don't overheat your alloy. 700f should be plenty for alloy temperature unless you're casting near pure lead.

A IR temp gun can work fine on a Lee mould if you use some BC aluminum black on the side and 'shoot' that with your temp gun. Those Lee moulds usually cast better on the third or fourth session than the first two anyway, even with a thorough initial cleaning, so don't sweat it, just keep trying. If all else fails, a light coating of smoke from a butane lighter in the cavities helps, but only if all else fails. I hate smoking moulds and preach against it for a variety of reasons, but sometimes it does work when nothing else seems to.

Gear

[detox]

Infra Red thermometer is very accurate when used on moulds...including silver aluminum moulds...no need to coat. My cheap Radioshack version reads up to about 400 degrees.

Hobbiest use infra red thermometers to check aluminum cylinder head temperature of two stroke engines. Too hot you are running too lean, too cold you are running too rich. About 280 degrees was perfect running temp for my two stroke land engines.

Propane torch is much better preheat source

375-400 degrees sounds way too hot for any mould. My various brand cast iron moulds run between 150-300 degrees while casting. This is easily checked using infra red thermometer.

Look here: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXEMG5&P=7

[Bret4207]

I don't know how long you've been using the Lee, but I've found, over the course of 35 or so Lee moulds, that they often take a few casting sessions to straighten out and fly right. I've always put it down to machining oil contamination in the mould burning off.

[theperfessor]

I'll stick with my comment that IR thermometers aren't very accurate. I have shot cast iron molds with my own IR gun and also instrumented them with a thermocouple and digital readout of known accuracy and gotten exactly what detox got. The IR reading is way off compared to real thermometer. It may be repeatable, but it is not very accurate.

My molds are at the 350 to 425F range and yet read much cooler with an IR thermometer. I'll post the link later to a very well run test that a member here performed and published concerning IR thermometers.

If you're happy with the results of yours that's fine, to each their own. Just don't confuse what it tells you with the truth.

IRguns are fine for a lot of things, but reading melt temp and mold temps aren't among them.


Edit to add this link:http://castboolits.gunloads.com/showthread.php?190209-Infrared-Thermometer-Test&highlight=IR+thermometers

[Garyshome]

Pour speed is important also. If the lead doesn't get into the mold fast enough then strange stuff happens.

[GARD72977]

Great thread. I have had some inconsistent results with my brass molds. Now I think I can make them work all the time. Thanks for all the info guys!

[mold maker]

Any non contact temp reading is suspect, and just a number.
The preformance of any mold is determined by many variables.
A well heated Lee mold on which the sprue freezes at from 3-5 sec is about right. Don't take time to inspect the results untill you have cast for several minutes at about 4 rounds per minute.
If your still getting wrinkles you probably still have some kind of oil or wax in the mold. It's awfully easy to use too much sprue plate lube that migrates into the cavities. A serious cleaning with break cleaner and a tooth brush should remove whatever remains.
A 358 WC boolit shouldn't be hard to sucessfully produce, although finding the right combo of variables can be a strain for a beginner.
Just keep trying. We all had to start just like you, although when I started ther was no forums, and I didn't know any other caster.
If you can ask specific questions, with more experience, we'll be able to give you more specific answers.

[462]

A reading of 150-degrees on a mould that is at its optimum casting temperature (well defined, non-wrinkled boolits) indicates the shortcomings of using an infrared thermometer on a reflective surface.

I use a Tel-Tru thermometer*, graduated to 1000-degrees, and have found that a mould with a temperature of less than 375-degrees** does not drop well defined, non-wrinkled boolits. (*Maker of RCBS and Lyman thermometers.) (**Mould pre-heated in a mould oven and thermometer probe inserted in a mould cavity.)

Swede Nelson, of NOE Molds (aluminum), recommends a temperature of 400-degrees.

+1 to what the perfessor said "If you're happy with the results of yours that's fine, to each their own. Just don't confuse what it tells you with the truth.".

[bhn22]

Infrared thermometers only measure the objects external temperature. The temperature internally would vary a bit. I set my molds on top of the pot to warm them, them I dip the mold blocks in the alloy for several seconds just prior to casting, making sure that approximately the same amount of each block half is in the alloy, with the hope that the blocks will heat evenly, even though I've never, ever seen warped blocks. Then I lube the pivot pin slightly and go at it. I cast hot, around 700- 750 degrees unless the mold has a history of requiring lower temps.

[John Boy]

What is a good range of temp to get good flow and help eliminate the wrinkles?
As long as I am asking, what is a good temp for my Lee Pro 4-20 pot to cast boolits from mixed wheel weight ingots?
John, it's really simple ... bring your pot melt & mold to a temperature so the sprue puddle frosts in 5 - 8 seconds using a 5 second pour with your ladle. Keep the ladle spout stuck firmly in the sprue hole.

And spend 20 bucks for a quality bi-metal thermometer that measures the temperature IN the pot, not ON TOP of the pot melt ...
http://www.amazon.com/Tel-Tru-LT225R-Replacement-Thermometer-degrees/dp/B0055777EU/ref=wl_it_dp_o_pC_nS_nC?ie=UTF8&colid=27UO44IFJYUFC&coliid=I3IC3M6K4UXVM3

[detox]

OK repeatable. I allways find the sweet spot when casting. Then i record outside temperature of mould with infrared thermometer. I allways pre heat my molds to this reading before casting for perfect boolits with less culls. Each mould reads different exterior temp from 150-300 degrees. This works verywell for me...very repeatable.

BTW...Accurate moulds does not recommend going higher than 325 mould temp when casting. Especially when using brass moulds.

[theperfessor]

detox, it sounds like you have a good system. I won't argue at all with the concept of an IR thermometer giving repeatable readings that a careful person such as yourself could use to dial in everything to get good bullets during the first few pours.

My only argument with IR thermometers is that there are better, cheaper, and more accurate tools for measuring melt and mold temperatures.

I use mine to find hot air leaks around the house during the winter, and to find hot spots on machinery. Even then I don't trust the absolute temperature as much as I trust the contrast and difference in temperatures as I scan something.

[bangerjim]

I had one Lee mold that just would NOT give me non-wrinkled slugs no matter what I did to the mix, temp, or filling technique. Then I tired pressure casting. A miracle!

Your 4-20 spigot is shaped to fit in the sprue hole of your mold. Get the mold hot on your plate or propane burner and stick the sprue right against the spigot. On a 38, it will fill in about 2 seconds with a full pot. Try it! Amazing results were obtained when I did it. Perfect boolits every time from that bad boy.....only mold I need to pressure cast with, but all of mine work very well with the technique also!

I have 2 different IR's and neither one will read a shiny liquid or aluminum. I use them for all kinds of temp measurements in my work and hobbies......but not lead or casting temps! One is a HF cheeeepy and the other is a $250+ pro unit. Surprisingly, they both read fairly close.

bangerjim

[detox]

I just cast a few linotype boolits from my Lyman 358429 mould. Temp on front face of Mould measured 190 degrees using the IR thermometer. Melt temp in pot measured 650 using RCBS thermometer. The next time i cast using this mould i will preheat mould to 190 degrees using propane torch...while checking temp with IR thermometer measured at same spot on front flat outer face.

My digital thermostat in my house reads 70 degrees. Everything else in my house from glass, Chrome bread pantry, air, reads 70-72 degrees using IR thermometer. Objects inside my freezer reads from 17 to 28 degrees using IR. My skin/flesh measures 86 degrees. Exterior of my 358429 mould reads 190 at sweet spot...core temp is probably hotter. You guys must have bad IR

What is the boiling point of water? I can check if you like.;)

[theperfessor]

There is a property called emissivity that must be taken into account. It is expressed as a numerical value between 0.0 and 1.0 and is used as a multiplier to adjust the measured heat value to the actual heat. If the material you are shooting matches the emissivity the meter is programmed for your temperature readings will be pretty close. If not they won't be. The energy transfer through radiation depends on the difference in temperatures taken to the fourth power. The greater the temperature difference and any error in emissivity would give a greater error at extreme temperatures.

The next time you get your mold at a good solid 190F on your IR meter dunk one corner into a little bit of water. If it bubbles what conclusion will you draw?

[detox]

I am not saying you are wrong...i think? As long as i get repeatable readings from my mould's face i am happy with that. Repeatable... remember.

[detox]

Boiling water test. Depending on altitude, water has a boiling point of about 212 degrees. My IR reads 214 as soon as water started coming to a good boil.

[bangerjim]

You can point that thing at darn near every know object, but I can tell you for a fact, an iR tnermometer will NOT measure molton lead! I have one that costs a whole bunch more than that little RS toy you have and I have checked it against a bunch of things. It is very accurate on "black body radiation" type of measurements....most things in your house like you listed. A black body does not have to be "BLACK" to be classified that way. But it does not work on shiny hot things. Can you say emmisivity?

Believe what the professor & I are trying to tell you.......it will not give you accruate measurements on molton lead! Buy a standard bi-metallic rod style dial thermometer to measure molten lead.....down INSIDE the pot, and not on the surface. And keep the little "hand job" IR thermometer for checking furance duct temps and other things like that around the house.

Your boiling water temp test was mesuring the temp of the BOTTOM of the pot thru the water!

banger

[detox]

I never said i read molting lead with it...Only moulds... Jesus. Exterior of my black lyman 358429mould reads 190 degrees. That is all i care about. I have some moulds that read as high as 300 degrees...is this wrong?

This toy only reads to 400 degrees. Is there any other test that you guys would like for me to try.

[detox]

Your boiling water temp test was mesuring the temp of the BOTTOM of the pot thru the water!

banger

If IR thermometer reads the bottom of pot accurately...why would it not read exterior of mould accurately.

I was using Linotype alloy (melt temp 600-650) which will cast perfect boolits at much cooler temps than some other alloys. Which is maybe why mould reads only 190 degrees. I have to cast hotter using Lyman #2 alloy so i am sure mould will read hotter using IR thermometer.

[theperfessor]

Well, first let me state that I am not trying to be adversarial to anyone, just pointing out from a scientific and technological point of view the reasons why IR thermometers aren't accurate when used for some purposes. And I acknowledge and understand their usefulness in reestablishing certain conditions that lead to making a successful product.

But I bet your mold surface at a measured 190F using your IR thermometer is actually hotter than that. Even blackening the mold may not get you a more accurate reading. You now know that your meter is within 2F at the boiling point of water when it reads the IR output of H2O molecules going through a phase change at the surface of the pot. That's not he same as putting a drop of water on an aluminum object at a measured 190F to see if it will bubble off.

Again, I'm not trying to be contentious, I'm just trying to help explain the good and bad features of certain tools.

Edit to add: It's the emissivity. The emissivity of materials depends on a number of factors. But shiny metals and molten metals have emissivities that are pretty far off from what most fixed resolution IR meters are calibrated for. It's just the nature of the universe.

[bangerjim]

I, like theperfesser, am not here to "punish" anyone! Far from it.

I am a graduate engineer with over 40 years of professional experience in process ccontrol instrumentation, including temperature monitoring and control. I love to share my knowledge and help others out. I also keep an open mind to new ideas. "The day one quits learning is the day they nail on the coffin lid."

I have discovered thru many field trials ( and tribulations) the many in's and out's, do's and dont's of measurement.

banger

[bangerjim]

I never said i read molting lead with it...Only moulds... Jesus. Exterior of my black lyman 358429mould reads 190 degrees. That is all i care about. I have some moulds that read as high as 300 degrees...is this wrong?

This toy only reads to 400 degrees. Is there any other test that you guys would like for me to try.

I would recommend to just cast away and do not get lost in the "mold temp weeds". I never measure the temps of any my 2 or 6 banger molds. I heat them on a lab electric hotplate that has a variable temp dial (0-10) I know the approx settings for......but not that accurate. I know at a setting of ~6.5, my molds are ready to go in ~10 minutes. That all hinges on the intimate contact of the mold with the dead flat surface of the plate.

I cast and check the drops. (I drop into water so I can immediately check them so the mold will not start cooling off while waiting for air cooling.) If problems, I keep casting to get the mold up to temp, not worrying about the actual temp of the mold. I normally (fortunately) drop good boolits the 1st time, occasionally the 2nd time. That just comes from experience and guestimation.....and holding my mouth right.......HA....ha!

Good Casting!!!!!!!!!

banger

[Driver man]

I dip my mould in the mix and when hot enough the mix doesnt solidify around the mould. That usually cures the wrinkly boolits. A stout bristle brush on the mould face helps also.Keep the pins lubed.

[dragon813gt]

The thread I posted about my tests w/ a cheap handheld spot IR thermometer and a FLIR camera tell the tale of the technology. With that being said there is no reason you shouldn't be able to attain repeatable results when shooting a mold. A number is just a number. If detox is taking the temp when the mold is raining bullets then he has acquired the value he needs. As long as its repeatable that's all that matters. If the IR is reading 220 but the actual mold temp is 375 it won't matter because you only care about the value the tool you're using gives you. Repeatability is the key which is why I keep repeating it ;) This isn't precision work by any stretch. I learned that trying to explain emissivity on this forum is a fools errand :D

[detox]

theperfesser, How good is the IR thermometer at reading cold, shiney, metalic objects? If i put my mould in the freezer overnight, shouldn't the mould read below freezing just like the shiney aluminum foil wrapped hamburger meat.

I will remove my mould from freezer in the morning then check temps away from freezer. I will also use fan to blow away cold air surronding mould so that the cold air emitting from mould will not be read.

Maybe IR thermometer is just reading hot radiating heat or hot air from mould while casting
insted of actual surface temp. I could use fan to blow away hot air surrounding mould before taking reading.

No flames...just learning. I hope you get to feeling better soon.

Keith

[Slow Elk 45/70]

Me thinks some of you good old boys are working this Temp thing into the dirt.....no offence indented....I have been doing this a long time, if I'm concerned about the temp of the mold, I set it in the top of the lead pot and as the man said, when the lead drops off the mold , your close enough. As you can tell I'm just an old red neck and prone to do what ever works for me. If you feel the need to make an engineering project out of casting a boolit, more power to you and good casting.

[dragon813gt]

Maybe IR thermometer is just reading hot radiating heat or hot air from mould while casting
insted of actual surface temp. I could use fan to blow away hot air surrounding mould before taking reading.

That's impossible for the thermometer to do. It reads surface temps only. Otherwise when I shoot a ceiling diffuser it would read 48(typical temp of air in AC) instead of the normal range it reads of 55-60. As far as shiny metals go they don't work well at all. Again, for me this shows up when shooting copper pipes. A clamp on thermometer will give me actual temp. I can get close if there is a piece of dark tape wrapped around the pipe. Otherwise a pipe that is at 180 will very likely read 120. And that's with the thermometer being put right on the surface. The IR thermometers have limited uses.

[detox]

theperfesser, How good is the IR thermometer at reading cold, shiney, metalic objects? If i put my mould in the freezer overnight, shouldn't the mould read below freezing just like the shiney aluminum foil wrapped hamburger meat.

I will remove my mould from freezer in the morning then check temps away from freezer. I will also use fan to blow away cold air surronding mould so that the cold air emitting from mould will not be read.

Maybe IR thermometer is just reading hot radiating heat or hot air from mould while casting
insted of actual surface temp. I could use fan to blow away hot air surrounding mould before taking reading.

No flames...just learning. I hope you get to feeling better soon.

Keith

I removed mould from freezer and tested temperature away from freezer in front of fan:

Blued Lyman Mould temp on shiney flat front side 36-41 degrees. Rough cast handles 26 -36 degrees.

After about 1 minute a dull non reflective White frost developed on mould and handle. Reading was a consistant 21 degrees on all surfaces.

So you were correct. Now I believe temp readings are more repeatable than they are accurate using the IR on hot BLUED moulds.

[masscaster]

Work faster, and don't stop to admire the boolits. This is what culling is for.
Even if it's got a little oil in the cavities it'll burn off.
I use my sprue lube for the mould temp check. If you touch it with lube and it doesn't smoke, it's not hot enough.
Also, if your casting really fast, and the boolits aren't frosting it's a good sign your melt is a bit cool.
The smaller the boolit, the faster you should be casting.
As you can tell i use no Thermometers.

Hope this helps,
Jeff

[John Hill]

I started this thread by asking some general questions about "how hot" and 36 replies later I have a pretty good handle on how to proceed. I figured that using my IR thermometer would be less painful than licking the mold and watching for steam. I now understand that it should be "hot" as in if I had let the mold sit on the surface of the molten lead in the pot for a few seconds or longer. I also learned that pour rate could be a factor. I learned that WW pot should be around 650-700 degrees, more or less.
Thanks to all for all of the info. Now I'll make one change at a time to see how I do.
John

[bangerjim]

I started this thread by asking some general questions about "how hot" and 36 replies later I have a pretty good handle on how to proceed. I figured that using my IR thermometer would be less painful than licking the mold and watching for steam. I now understand that it should be "hot" as in if I had let the mold sit on the surface of the molten lead in the pot for a few seconds or longer. I also learned that pour rate could be a factor. I learned that WW pot should be around 650-700 degrees, more or less.
Thanks to all for all of the info. Now I'll make one change at a time to see how I do.
John

John........you got it........SWAG! Just go at it and use common sense.

banger

[Echo]

I dropped out of my EdPsych doctoral program (my incompetence), but still call myself a measurement person, so I'll add a little trivial info to the thread.
In Measurement, we call repeatability Reliability - a steel tape is a very Reliable measurement device. An IQ test is a fairly reliable measurement device. An IR thermometer is a very reliable measurement device. But there is another aspect of measurement, and that's Validity.
Validity means, Does it measure what it says it measures? The concept is 'Validity of Use'. The aforementioned steel tape is a very reliable device - but one wouldn't use it to measure Intelligence. It has no validity measuring intelligence. Can't do it - just as an HF IR thermometer (I have one) can't validly measure certain surfaces, depending on their emissivity. It can measure those surfaces reliably - gets the same answer every time, it's just not the correct answer.
So we can use the HF IR thermometer, taking into account that with experience we can depend on the reading to tell us when we are at the point where we wish to be, that is, where the mold will be turning out the best boolits. The actual temperature may be unknown, but we are making boolits!
Pedantry over. Echo out.

[bhn22]

I feel backwards somehow. I use a Lyman thermometer to keep track of alloy temperature, and pretty much wing everything else. I preheat my molds as mentioned above, I dip both block halves evenly in the melt until the allot doesn't stick to them. I pull them out and wipe any lead residue off with a cotton cloth. Then I touch the sprue pivot with an LBT lube stick, along with the alignment pins, and off I go. I figure mold temps will vary under different circumstances, and as long as everything fills out properly, and I don't have too many culls that I'm good.

[theperfessor]

I successfully cast hundreds of pounds of bullets before I got any kind of a thermometer. At one point in my life I needed more accurate control of temperature so I built a dual PID controller. I also have a HF IR thermometer and have compared the two. The IR thermometer isn't even close to being accurate for reading mold blocks and molten metal.

The average caster can get by fine with even the cheapest analog thermometer or even no thermometer at all as long as you take a few notes and pay attention to what works. I love my tools and use the best I can afford, but I recognize you can do a good job with a lot less.

[bangerjim]

I just had a long conversation with one of the engineers from Fluke....you know.....the guys that make the best test equipment in the market. He concurred with my (and others here) statement that an IR....ANY IR thermometer, no matter how cheeeeep or expensive, will NOT read shiny hot surfaces due to the emissivity factor and black body radiation effect.

If you must read those kind of temps, use a direct contact K t/c or a bi-metallic rod style analog dial thermometer.

I, like theperfessor, have cast many many boolits successfully with NO temp monitoring at all....only close observations and good common sense.

banger

[detox]

What if I painted the "exterior bottom" of mould using Flat White, High Heat, Header paint, will the Infra Red Thermometer read more accurately if measurement was taken on this painted area only?

[dragon813gt]

Flat black paint will work best. I use the black grip tape on pipes at work. Shiny and light colored are what you don't want.

[bangerjim]

What if I painted the "exterior bottom" of mould using Flat White, High Heat, Header paint, will the Infra Red Thermometer read more accurately if measurement was taken on this painted area only?

Please do not take this wrong, but I think your getting way too deep in the weeds on this mold temp thing. It is not THAT critical. I have NEVER EVER checked the temp of any of my many molds with a temperature device of any kind. Save your IR for heating & A/C register temp checking.

The easiest way is.....(I use a hot plate to heat molds)......

1) dip the mold end into the top of your pot. If the lead sticks & clumps, the mold is not hot enough. If it clumps a bit and falls off, you are good to go. If it does not stick at all, you are above temp, but go anyway!!!!!!

2) Your boolits should "cure" in 4-5 seconds in a mold at temp. The lead on the sprue plate should turn slightly frosty in the same time. If the sprue plate cuts hard, you are below temp. If the lead takes more than 5-7 seconds to harden, you are overheat. Just touch the bottom on a wet rag a few times to cool a bit. (I rarely ever have to to this.) I just slow down my fill rate a bit to allow the mold to cool a little.

That is ALL the temperature "measurement" I ever do. I try to keep it simple!

Flat black paint is what you want if you must use the IR tool. Just smoke the bottom with a candle flame.

Good casting!

banger

[detox]

Just smoke the bottom with a candle flame.

Good casting!

banger

That is the best advice i have heard so far.

BTW propane torch is most simple way to preheat and will heat mould more evenly. To prevent warpage Do Not concentrate heat on just one area. About 1 minute may be enough, but i use the repeatable IR to check...very simple

[220]

If you want accurate temp readings with IR just paint the surface matt black or purchase a thermometer that has programmable emissivity value.

[detox]

The IR works poorly on aluminum moulds shiny surface...so i must smoke the bottom of mould with candle to get close to actual reading. The IR works verygood with blued moulds (no smoking required)...the temp may not be axact, but are repeatable and closer to actual. Once while casting I opened then dropped bullets from mould and read temp at bullet cavity...reading was around 290. This was higher than the exterior reading of 250.