Hot Mold or Cold Mold

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Wm Cook posted this 5 weeks ago

There’s no judgement one way or the other. I’m just curious about the importance you place on mold temperature and why you think that way.

Does anyone even monitor mold temperature? Are there any experiences you’ve had that makes you lean that way.

I consider “hot” north of 400, “cold” south of 380. To give it some reference I’ll add that the alloy is PID controlled at 700.

Gonna take a wild guess here and predict most will say that you don’t monitor mold temperature and adjust your cadence on bullet appearance and sprue cut. Bill C

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Glenn R. Latham posted this 5 weeks ago

 You're right, Bill, I don't monitor (measure) mold temperature, although I got a pyrometer recently.  Just the usual, if it's frosting, cool it down.  Wrinkly, warm it up.  I do have one 22 cal. aluminum mould that is VERY PICKY on temperature, even with linotype.  It has a very narrow window where it will cast good bullets.  One spot on the edge of a band won't fill out if it gets too warm.  It's a pain to cast with.

Glenn

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Aaron posted this 5 weeks ago

I do not monitor mold temperature with a primary means. I use a secondary method; cadence. I run a hot alloy and adjust cadence if bullets get too frosty. It doesn't take too long to cool a mold down depending on mold material. Just need a slightly longer dwell time before refilling. If I am going to cast a lot from the same mold, I may decrease alloy temperature slightly once mold is hot and cadence established. That works well with "normal" bullets. When I cast the larger bullets for 58 caliber rifles, which George (linoww) refers to as "ingots", I run out of alloy too fast to worry about much other than getting tired arms.

So, I have no idea what the actual mold temperature is. I know if it's too hot or not hot enough.

 

 

 

With rifle in hand, I confidently go forth into the darkness.

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Aaron posted this 5 weeks ago

One spot on the edge of a band won't fill out if it gets too warm.  It's a pain to cast with.

I have a few mold that are fussy like that too. Temperature of alloy and mold has to be just right.

 

With rifle in hand, I confidently go forth into the darkness.

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Tom Acheson posted this 5 weeks ago

It might be NOE that offers a threaded opening in the mold block to be used to screw-in a temp reading gizmo (thermocouple).

I’m in the cadence and visual monitoring camp.

Tom

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pat i posted this 5 weeks ago

The day I have to stare at a thermometer attached to a mold to cast bullets is the day I give up casting bullets. Just as was said, another gizmo with no value in the real world.

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Wm Cook posted this 5 weeks ago

I don’t know if I could navigate a thermocouple with the leads going to a digital display. But I never tried it so I’m ignorant as to its how it would work. There’s always something to learn, right.

30 years ago I was just happy to have something that looked like a bullet come out of the mold. In 2022 I learned about cast BR and that led to a reevaluation on how I was casting. The first thing I focused on was casting consistency and the only yardstick for that was bullet weight. I agree with John that +/- x tenths means little to nothing but weighing can be used to evaluate your casting consistency.

Yesterday I cast a couple hundred 30 cal bore riders with a mold temp about 30 degrees cooler than the previous cast. Two things stood out, the first being that the bullet (single cavity brass) fell out of the mold readily and the second was that I had lost some nose diameter. Enough diameter that I couldn’t feel the nose dragging on the lands.

My habit is to check mold temp every tenth drop to keep me somewhat consistent. If you drop 5 or 8 in a row that jump out of the mold the temperature will creep up 5, 10 degrees if you don’t watch yourself. Same same if you have a glitch and your cadence is hampered. If you know what you’re doing you can throttle back or speed up on the time it takes from the bullet coming out of the mold to when you start the next pour.

With this mold I go to frost then do the “count” (1 Mississippi, 2 Mississippi …) then hand cut the spruce. The time between bullet drop and starting the next pour was tweaked to keep the mold temp at the target 385.

Will it win a match? No. Too many other things can ruin your day. I was just curious as to what others were doing. Bill C.

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TRKakaCatWhisperer posted this 5 weeks ago

THE best thing that I did to ensure CONSISTENT results was to WEIGH each bullet after making it - while it was still hot and the mould cooling from having just been filled.  It showed me, by variation in weight, that I was doing something different.  Get the rhythm down [to ensure bullet to bullet consistency] and weigh 10 or so at cool temp and repeat for hot temp. 

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OU812 posted this 5 weeks ago

Watching and judging how long it takes for sprue to cool and solidify works for me. I use RCBS instructions and preheat mould by dipping mould end in melt few seconds...maybe 45 seconds before start casting.

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OU812 posted this 5 weeks ago

Easier to start with mould that is too hot than cold. Waiting for sprue to solidify just takes longer with mould that is too hot, but it will cool down.

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Bud Hyett posted this 5 weeks ago

The best investment I've made is a PID controller. Each mold has its own attributes dependent on alloy, ambient temperture, and how I feel that day. This has driven me to cast one mold at a time. 

Farm boy from Illinois, living in the magical Pacific Northwest

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RicinYakima posted this 5 weeks ago

I have just one pace and cast with one mould. Then I adjust the PID until we are all happy. 

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Wm Cook posted this 4 weeks ago

I know I should leave this alone but risking the wrath of some of the members (take a deep breath Pat) I'll take a chance and offer this up.

If you've been casting 50 + pounds of alloy a year for the past few decades none of this makes sense.  For those with less experience there are tools that can improve your consistency.  Bud and Rick mentioned the PID.  Its one of the few things that I could not do without.  The only pot I have with its own temp control (Lyman Mag 20) is off by 30 degrees.  What do you think that would do to a new-be caster.

But using a mold is a learned behavior that can only be gotten by putting a lot of time in front of a furnace.  Those in the CBA that are in the top 10% of users of alloy don't need a crutch like this.  However, my guess is that there are probably 30 or 40% of the users that could use some help to sort of keep them in the middle of the road with their casting ability.  

For those casters a means to measure the temperature of their mold makes sense and keeping the mold at a consistent temperature tightens up the ES of the bullet weights.  Not that .3 tenths will be seen on the target but face it, we would all like to see single digit velocity standard deviations but we can live with what we got.    

Setting up a thermocouple in a fixed position is simple and adds no time to the cadence process.  My sprue's take about 6, 7 seconds to reach frost, then depending on the mold I take another 0 to 4 seconds or whatever is necessary to allow a clean cut (no tears, no divots) as the sprue is cut.  When I'm casting I catch a mold temp every tenth drop and it doesn't interfere with my cadence.  Its like glancing at your speedometer once in a while when you're driving through Kansas.  Be honest without yourself here.  Would you drive highway 70 through Kansas with the speedometer on your car taped over.

With ladle or bottom pour Linotype I can usually hit about 95 - 97% +/- .1g when I'm making a long run (160 to 200 bullets).  

If someone had shown this to me back in 22 when I first heard about cast Benchrest I would have saved my self a lot of time.  But they say its the trip, not the destination.  Right?  Thanks for tolerating the rant.  I won't live long enough to be as good as most of you.  Bill.

 

 

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pat i posted this 4 weeks ago

Bill I don't need to take a deep breath because how people do things is their own business. Personally I just don't find what amounts to pouring piss out of a boot overly complicated. My PID is that thermometer left in the pot all the time. Temp goes above 750 I turn the temp knob down. Goes below 750 I turn it up. 750 degrees has always worked for me no matter what the molds made out of. No idea what the mold temperature is and really don't care as long as it's throwing good bullets. When I start seeing the use of PIDs and mold thermometers showing up on people's targets I might change my mind but as of now there's a lot of records that were set before either came down the pike. 

 

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Wm Cook posted this 4 weeks ago

Pat, whose pot is that and how much does it hold. Bill.

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Wm Cook posted this 4 weeks ago

Pat, I have a couple questions. The first is whose pot is that and much does it hold.

The second is whether you ever checked the accuracy of your thermometer. And the reason I asked about checking the accuracy of the thermometer is that I had my first Lyman thermometer give false readings (off 20 degrees one way or the other, I forget which) back in the 90’s. When the replacement came in, it was off as well. That’s when I went digital. Verification for accuracy is now is done with two different thermocouple thermometers. Even my mag 20 failed. 740 is actually 710. Since going to the independent K style thermocouples I haven’t had any failures.

And I’ve always understood that prolonged temperatures over 725 degrees can reduce the tin content. I can’t speak directly to “750 degrees “ because I don’t run that hot but I have had success in destroying the tin properties when I left a pot unattended and the drip leak turned into a 5 pound mass of alloy that had me resort to using a butane torch to clean up.

Pat, I have no doubt you’re casting match grade bullets and that your skill level places you in the top 10% of CBA casters with the methods and equipment you’re using. My concern is that if you turned that arrangement over to a new caster the outcome would not be the same.

My thoughts were directed to those with lesser skills. Bill.

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pat i posted this 4 weeks ago

Pat, whose pot is that and how much does it hold. Bill.

Its a 20 pound Lyman Bill.

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pat i posted this 4 weeks ago

I don't know if the thermometer is 100% accurate and don't care. I'm getting good bullets out of wheel weights at a reading of 750 degrees so if in actuality it's 730 or 770 it doesn't mean squat to me and I'm certainly not going to stick my finger in the lead or squirt some in my mouth like a baby bottle to find out.

I don't know if I believe that tin burning out routine at the temps we cast at, at least I haven't noticed anything although I don't know how I would. I'm not a marathon caster so the lead isn't hot for that long and if I was unless I just kept casting and remelting the same bullets over and over again your adding tin and everything else back to the pot every time you refill the pot.

I don't know if I'm in the 10% of anything or at least I've never been told I am. As to your comment about new casters. I'm a firm proponent of the KISS principal. Start telling people that their alloy has to be at an exact temperature or anything along those lines I think it throws them off. Let people learn the important parts first and then they can start adding equipment and become more exact later, or not. Being were a bunch of old guys we learned by doing it the old fashioned way. Might have made some mistakes and had problems but we figured it out. Like I always say....this ain't rocket science.

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Tom Acheson posted this 4 weeks ago

Interesting subject.

I’m a lot like Pat on the attitude of trying “over tech” ourselves. I had a PID and used it a couple years, the concept sounded reasonable, but then it developed an “attitude”. Since then, without it, I’ve made many good bullets.

Alloy composition, pouring cadence and sprue condition are the guiding parameters to producing quality bullets.

No offense intended here but I’m of the old school crowd, not the over-evaluating herd.

FWIW

Tom

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Lee Guthrie posted this 4 weeks ago

Glenn, how did you get my mould ???

Unfortunately, quite a few of my 100+ moulds have that irritating problem.  Sometimes a very light application of hard lead pencil only on the offending portion of the band helps.  

 

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Aaron posted this 4 weeks ago

 I tend to keep it simple like frying bacon. Taking too long? Turn up the heat. Don't like curled up bacon? Turn down the heat. The PID is my Mark-1 eyeball. smile

 

With rifle in hand, I confidently go forth into the darkness.

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