Problem with bottom pour pot...need ideas.

I have a 20 pound Lyman lead pot that I have upgraded to a home built electronic temperature controller. This works so well it is scary. +/- 5 degrees F is very east to maintain. The probe is calibrated via the software so that the top of the melt and the bottom of the melt are the same temperature.
The problem I have is that the the bottom pour drain keeps cooling and blocking the flow of the alloy which is at it's ideal melting temp of 680 Degrees F.
If I crank up the temp above 725 degrees my alloy separates and no amount of fluxing / mixing will prevent it from doing so. The cast bullets at this higher temp are frosted as well.
The drain is very close to allowing a flow and a one second blast of torch heat will free it all up again,only to happen a couple of minutes later.
The melt is not clogged with crud,it has solidified due to being cooler than the lead in the pot. The drain and its valve are cooler than the melt.
I'm using a bullet ladle now from the top and it works just fine. The sprue is larger than I'd like. The bottom pour has very little sprue when used.
I'm open to any helpful ideas you may have on how to not overheat the melt, but have the bottom pour drain not solidify up ?

My 2 bottoms pours from Lee work just fine with out any digital PID controllers. Excellent temp control. Perfect pours from the 1st drop! (Preheated molds on an electric hot plate to FULL casting temp).

Don’t know what your problems are, but you should get excellent results. You may be over-thinking this temp control situation! This is not rocket science....just simply melting lead. I have had no problems with the standard bi-metal temp controls on my 2 pots for years. I do NOT use a thermometer either! Just plain old common sense and experience.

680F......720F.....makes no difference. I just adjust the pot dial to where I get perfect drops from the 1st one. Everybody is into this PID technology and it is not really needed! I design and sell digital control systems (for temp and everything else) and do NOT use any PID controllers on my simple little Pb melting pots.

Try going back to basics and your problems may be solved!!!!!

Bangerjim

I've been casting for 50 years now. The bi-metal "thermostat" was in need of replacing. Rather than have a poor temp control I did build a PID to control the temp.
The LEE does work well but has too little volume for my needs.
Thanks for the reply.

i have never seen the need to control the temp to this degree. i also use lee pots and a variety of molds some like a hotter melt than others but i see no difference in + or minus 50 degrees. i have to agree with bangerjim just use commonse if it cast good then go with it. i don't rember who it was but a fellow on here comimeted that he sold pids and other equipment for living and wouldn't waste his time putting one on a lead pot. sometimes i think people get carried away ( i am one of them on quite a few subjects ). just keep it simple is the best advice.

[QUOTE=Rapidrob;4411016]I have a 20 pound Lyman lead pot that I have upgraded to a home built electronic temperature controller. This works so well it is scary. +/- 5 degrees F is very east to maintain. The probe is calibrated via the software so that the top of the melt and the bottom of the melt are the same temperature.
The problem I have is that the the bottom pour drain keeps cooling and blocking the flow of the alloy which is at it's ideal melting temp of 680 Degrees F.
If I crank up the temp above 725 degrees my alloy separates and no amount of fluxing / mixing will prevent it from doing so.

From the LASC site:
It is a common misconception that because they are less dense than lead, antimony and tin may undergo gravity separation from the melt. Nothing could be further from the truth. In the absence of oxygen or oxidizing materials, melted lead alloys will remain stable and mixed virtually forever. And from Lyman, [3]Perhaps the single most significant error in all the bullet casting literature is the misconception that lead-tin-antimony alloy melts gravity segregate.

"I have a 20 pound Lyman lead pot that I have upgraded to a home built electronic temperature controller. This works so well it is scary. +/- 5 degrees F is very east to maintain. The probe is calibrated via the software so that the top of the melt and the bottom of the melt are the same temperature."

First off I doubt very much that the temperature is the same at the top as it is at the bottom of the melt. Am wondering what kind of software you have that makes you think this. You might let us know what kind of controller you have as well as where you have the TC (TC's?) placed. The majority seem to place their TC about 1/2" from both the side and bottom of the pot. But perhaps you have your TC mounted permanently somehow which might be a whole different ballgame. And as said above the alloy isn't separating, that's an old myth. More info is needed to be of any help.

If you can do it try moving the heating coil a little closer to the bottom of the pot. It wont affect the melt much but the steel pot will transefer this added heat thru it to the spout. Sounds like you don't need much to make it a runner

If there is air movement where you are casting or if you are casting outside in a breeze, then the pour spout can be susceptible to freezing.

I have a Lyman Mag 20 that's about 30 years old. The the tip of the probe from my PID ended up a quarter inch from the side and a quarter inch from the bottom of the pot with the bracket I made for it. 90 % of my casting is at 685 degrees and the spout NEVER freezes up. I dump the sprues right off the sprue plate back into the pot and the temp still never varies from 5 degrees +/-. In 20 lbs. I only flux about twice and end up with a nice satin finish on all my boolits, never frosted. This is with a 70/30 mix of coww and lead.

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Originally Posted by RED BEAR

i have never seen the need to control the temp to this degree. i also use lee pots and a variety of molds some like a hotter melt than others but i see no difference in + or minus 50 degrees. i have to agree with bangerjim just use commonse if it cast good then go with it. i don't rember who it was but a fellow on here comimeted that he sold pids and other equipment for living and wouldn't waste his time putting one on a lead pot. sometimes i think people get carried away ( i am one of them on quite a few subjects ). just keep it simple is the best advice.

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I am the fellow you refer to. The engineering firm I own designs and sells control systems for industrial applications, many of which use digital proportional integral derivative control algorithms for accuracy and repeatablilty as well as data historian functions for government needs. I am talking BIG processes, not teeny 20# lead pots. If one gets warm fuzzies from 5F temp control, go for it. I personally do not want all the extra trappings for a controller needed to melt little bits of Pb. I get perfect boolits from the 1st drop every time “by the seat of my pants”.

Happy Casting......no matter how you melt it!

Bangerjim

bangerjim i am right there with you. bought a thermometer for melting wheel weights. not real sure i needed it for that. bullets come out just fine from first to last one cast!

I drained the 20 pound pot and dissembled the weir. I found the weir had crud caked onto the end. It's as hard as a rock. I replaced the weir and coated it today with 'Drop Out" and fired up the pot again. I was able to cast several hundred bullets with no more issues.

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Originally Posted by Rapidrob

I drained the 20 pound pot and dissembled the weir. I found the weir had crud caked onto the end. It's as hard as a rock. I replaced the weir and coated it today with 'Drop Out" and fired up the pot again. I was able to cast several hundred bullets with no more issues.

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It's your turn to educate me now! Just what in heck is the weir? Hadn't ever heard that term around casting circles before.

a WEIR is a purpose built drain or drain with a built in overflow. A weir plugs the drain until it is lifted.

I use weirs all the time. Only difference, my applications are in waste treatment plants. They are a V-notch in a fixed length of pipe or trough that allows a know amount of liquid to pass thru it. You measure the height of the water behind it and that is the flow in GPM. There several weirs/flumes out there with specific math formulas behind them.

A weir is a concrete or masonry structure which is constructed across the open channel (such as a river) to change its water flow characteristics. Weirs are constructed as an obstruction to flow of water. These are commonly used to measure the volumetric rate of water flow, prevent flooding and make rivers navigable.
1. Types of Weirs based on Shape of the Opening
•Rectangular weir
•Triangular weir
•Trapezoidal weir

2. Types of Weirs based on Shape of the Crest
•Sharp-crested weir
•Broad- crested weir
•Narrow-crested weir
•Ogee-shaped weir

3. Types of weirs based on Effect of the sides on the emerging nappe
•Weir with end contraction (contracted weir)
•Weir without end contraction (suppressed weir)

https://theconstructor.org/water-res...r-weirs/11873/


Let's let him explain how he is using a weir on a lead pot! Got my curiosity up also!!!!!

bangerjim

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Originally Posted by Rapidrob

a WEIR is a purpose built drain or drain with a built in overflow. A weir plugs the drain until it is lifted.

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Perhaps you might want to rethink your definition of a weir?

No, it is what it is. After working for 45 years in photography, the automated film processors used three to six tank weirs that drained the tanks as well as worked as an overflow device when plugging the drain hole. The height of the weir was the level of the chemicals in the tank.
There are several uses of the weir in all applications.

So for just us new and old bullet casters around the world that have no commercial photography experience, you just cleaned off the build up on the shut off rod and valve seat. That is just normal deposits built up over time.

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Originally Posted by Rapidrob

No, it is what it is. After working for 45 years in photography, the automated film processors used three to six tank weirs that drained the tanks as well as worked as an overflow device when plugging the drain hole. The height of the weir was the level of the chemicals in the tank.
There are several uses of the weir in all applications.

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That is actually the definition of a weir.....a v-shaped (or other) restriction in a tank, vessel, or pond that restricts the flow to maintain a certain level or allow measurement of said level. A weir does NOT shut off flow, it restricts it by a certain pre-calculated amount.

I too have been in a much broader industrial environment for the past 45 years than just one industry. I have sold weirs to any industrial market you can name for measuring open channel flows of any liquid you can name. From 2" to 96", I have done them all. To shut a weir off, you install a vertical sliding knife gate valve on it that ceases the flow when let down across the notch in the flow stream .

Weirs really do not have any place in boolit casting, unless you are melting tons of lead and want to measure the flow of it going into another vessel. Being 750F+, that is about the only technology you CAN measure flow with - deriving the flow value from the polynomial formula for the specific weir and measuring the level behind the weir with radar or ultrasonic non-contacting sensors.

Thanks for your input to this "potpourri of knowledge" on here.

bangerjim