Regulating pot temperature

[leadmonkey]

I finally fired up my new Lee Pro 4 20 today for the first time.

When I got all the ingots melted, and stuck a thermometer in the pot, the temp shot up to nearly 800 before I could get it stopped. I finally got the temp stabilized at 700. I got the flow rate adjusted, and tried to cast a few boolits. I had all the usual beginner's problems on that, no usable boolits to show for it, but I'll deal with that later. My main problem was trying to keep the pot temperature stabilized. The temp started dropping when I started trying to cast, and I had to stop and try get the temp back up and stabilized. And by then, my mold got cold. Seems that I spent a lot of time chasing the right temperature. I was casting outside, and the slight breeze didn't help any either. I'm sure that plenty of others have figured out how to deal with the heat control on that pot. I guess it's typical noob troubles. Here's why I'm telling you all this.

If you notice the construction of the pot, the temperature sensing thermostat is located in the aluminum housing adjacent to the pot. It's not even close to the actual heated section. No way that part actually gets up to the same temp as the pot. I'm guessing it gets up to about 300- maybe 400 degrees or so. That thermostat has to operate in the same temp range as the aluminum housing. I have to guess that Lee has figured out how hot that aluminum housing will get relative to the actual pot, and specified that thermostat accordingly. I'm sure that Lee made this that way because it was inexpensive to do, and although it doesn't work well, it works within some usual acceptable limits.
I'm thinking that there could be a simple modification that would improve temperature regulation, without going to the extreme and wiring in a PID controller.
Maybe someone has found a suitable thermostat and mounted it directly on the lead pot?

[nodda duma]

There is no thermostat in the Lee pot. It's just a simple rheostat (look up the definitions).

If you do your homework and search, all the parts you need to make a PID controller will be about the same cost as a thermostat ( which is basically the same thing)

[leadmonkey]

Negative. There is definitely a thermostat. It cuts on and off. It is not a rheostat, which varies the voltage.

[jsizemore]

The secret to the temperature controller on the Lee pot is.........don't use it. It's actually an instrument of frustration. Mine actually kept temperatures pretty consistent for the first 5 or 6 times I used it when it was 60% or more full. When the level got low temps shot up and down without control. So I could cast 6-8lbs of boolits with pretty good consistency and then with age it got unpredictable and frustrating. Did the pid thing and then ran up on an old Lyman Mold-Master and used it for a while. It has the same type of temperature controller but a much better bottom pour linkage. Finally got a RCBS Pro-Melt with a better thermostsat and it's a little better then the other 2 from full to 20% capacity but still has a wide margin around the set temp. Very good when new but wide undershoot/overshoot with age. I built a PID for universal use and just leave the temp controller full on or bypassed when hooked up to the PID. Life is more better.

You may be smarter then everybody that's come before you and figure out the Lee pot secret. Maybe you share'll that and the secret to make it not drip. We will call you genius. Good Luck

[bangerjim]

There is no thermostat in the Lee pot. It's just a simple rheostat (look up the definitions).

If you do your homework and search, all the parts you need to make a PID controller will be about the same cost as a thermostat ( which is basically the same thing)

You are wrong, sir. There is a bimetallic strip type thermo-sensor in the aluminum housing that is fairly repeatable! If you listen, you can HEAR it click. I set mine at 5.5-6 all the time and get perfect boolits every time.

Using a "rheostat" as you stated would be way too expensive, as the 700 watt rating would burn up all but the most very expensive devices like that. And using variable resistors like that would lead to more of an electronic control, like a PID controller so many drool over on here. You KNOW LEE does not do that.

Hey.......it's just a lead pot, not an industrial control process. The simple bimetallic thermostat LEE uses has worked for many thousands of us for many decades. Why mess with it?

bangerjim

[Mike W1]

The Lee control does work - a PID just does so much better a job of it!

[rsrocket1]

Jim is right, the bimetallic strip in the Lee pot is a cheap "thermostat" just like the dial thermostats that were in house heaters for decades. The problem is that it isn't calibrated to an absolute temperature so your setting won't be the same as mine. Unless you get a PID, don't worry about absolute temperature. Just get into a good pace of pour, freeze, cut and dump. With a few casting sessions of at least an hour each, you'll find the right pace which will give you boolits that are neither wrinkled nor frosted and without having too tough a cut on the spure nor smeared lead on the top of the mold block.

Read as much as you can here on casting preparation and techniques and you'll save a lot of time and frustration. I did and started casting good boolits with my Lee 6 cavity molds on my first session with a stock Lee 4-20. I have since built my own PID (for $0 with parts from my electronic parts bin). It's convenient, but not 100% required.

[Beagle333]

I could get mine to a happy place and cast with it for a while, using the thermometer and chasing the dial. So it is quite useable, just within a 50 degree swing. I guess I'm one of those who drools over my PID. I am completely spoiled now. I use it for my luber warmer too, and have already thought of several more <1000W uses for it around the house!

[jsizemore]

For some folks "good enough" is good enough. If on target accuracy is important to you then eliminate as much error as your capable.

[6bg6ga]

Jim is right, the bimetallic strip in the Lee pot is a cheap "thermostat" just like the dial thermostats that were in house heaters for decades. The problem is that it isn't calibrated to an absolute temperature so your setting won't be the same as mine. Unless you get a PID, don't worry about absolute temperature. Just get into a good pace of pour, freeze, cut and dump. With a few casting sessions of at least an hour each, you'll find the right pace which will give you boolits that are neither wrinkled nor frosted and without having too tough a cut on the spure nor smeared lead on the top of the mold block.

Read as much as you can here on casting preparation and techniques and you'll save a lot of time and frustration. I did and started casting good boolits with my Lee 6 cavity molds on my first session with a stock Lee 4-20. I have since built my own PID (for $0 with parts from my electronic parts bin). It's convenient, but not 100% required.

You are correct it is a primitive bi-metallic switch AKA thermostat. I will point out that the number on the dial will change with ambient temperature change. They are not known for their accuracy thus the PID comes into play for those demanding some type of precisian control. The comment that it has been used by many thousands for decades doesn't hold much water . The model T was used for a long time and people wanted change otherwise we would still be driving them.

[leadmonkey]

The metals in thermostats have limitations. They cease to be consistent durable at temps much above 750 degrees. I've looked, and I can't find any thermostats designed to work in any temperature much beyond that. That's why Lee didn't attach a thermostat directly to the lead pot.

The limitation of the thermostat in the Lee pot is that it is not directly reading the temperature of the lead pot. It is reading the temperature inside the aluminum housing adjacent to the pot. It's a very indirect way of sensing the pot temperature. This makes it slow to react to genuine temperature changes in the pot, and it also makes it susceptible to external wind drafts.

On this particular pot, if there is no draft around the pot, and I'm not drawing or adding lead to it, the pot temp will stabilize at about 700 degrees with a setting between 3 and 4.

If I start casting and dumping sprues back in the pot, the pot temp will fall to 600 or so before the thermostat will begin to compensate. That is obviously a characteristic of the remote location of the thermostat. There is a delay before the temperature change in the pot changes the temperature of the aluminum housing and the thermostat.

If there is a wind draft, the pot the temp will rise, and depending on how much draft is around, it can rise to 800 degrees or more, even with the thermostat setting on minimum. That is also obviously a characteristic of the remote location of the thermostat. The draft cools the aluminum housing more than it does the lead pot itself.

I guess I'm not telling anyone here anything new. Based on the popularity of these pots, I'm guessing that you can learn to predict these variations, and make timely corrections to the thermostat setting to compensate.

[6bg6ga]

All very good points and all the reasons why I got rid of mine. Start out with a pot full of lead and start casting. Anticipate the need for more heat...crank up the control. Add more ingots.....take a break because you won't be casting anytime soon. Windy day.....you'll be casting in the garage. Timely corrections....no not with this kind of pot.

These cheaper pots are the reasons that guys diy their own pots out of LP tanks or they weld up something suitable for their needs. Bottom line is this.....if you cannot afford anything better or you simply don't shoot that much or you love to punish yourself you stay with this type of pot. Want something better, bigger, the ability to control the temp ? They you enter the dark side and start construction on your super pot.

[dragon813gt]

Construction of a super pot? It's a lot cheaper to add a PID. As much as I wish I had a larger pot. A PID controlled Lee pot works great.

I don't get why members here don't like change. It really shows you age. It's the whole you can't teach an old dog new tricks thing. Adding a PID means you don't have to worry about chasing temps. You set it and it stays there. The Lee thermostat varied to much based on how much lead was in the pot for my liking. It really went up in temp as the level lowered. It's great not having to constantly adjust the knob.

[leadmonkey]

Okay, I know I can probably get by with this setup by learning when and how much to turn the knob, but I'm now leaning toward a buying PID temp controller. It looks like a piece of cake to kluge this together.

So I'm looking at the Mypin PID controllers and kits like are found all over evilbay and Amazon. Many even come with a 25 amp SSR and K thermocouple. It will cost me maybe $35 - $40. Sounds like pretty much everything I'll need except maybe a housing and some hardware. I almost pulled the trigger on one of these, but I thought maybe I'd run that by the experts here first. You guys have a better idea?

[6bg6ga]

QUOTE=dragon813gt;2662833]Construction of a super pot? It's a lot cheaper to add a PID. As much as I wish I had a larger pot. A PID controlled Lee pot works great.

I don't get why members here don't like change. It really shows you age. It's the whole you can't teach an old dog new tricks thing. Adding a PID means you don't have to worry about chasing temps. You set it and it stays there. The Lee thermostat varied to much based on how much lead was in the pot for my liking. It really went up in temp as the level lowered. It's great not having to constantly adjust the knob.[/QUOTE]

You don't get why members here don't like a change? Thats simple.... Its the "Thats the way I've always done it" attitude. If it works then don't change.


The MYPIN PID controller. Is it a good deal? Having two of them right now one as a back up. The other being an Auber unit. There is night and day difference between the two programing wise and function wise. Sure, you pay more for the Auber unit but you end up with a unit that will probably outlast the cheaper MYPIN. I have a bullet caster with a MYPIN unit on it now. Its the second MYPIN that has been on it.

The probe... make sure it is able to submerged.

[leadmonkey]

Well, based on all the glowing praise for the Mypin controller in one of the sticky threads, I just ordered one, with SSR. I found another vendor with the correct thermocouple at a good price. I may be sorry at some point that I didn't get the Auber unit, but maybe this will get me started. I fished an old ATX computer power supply out of the junk box for the cabinet. What I put together probably isn't going to be original or elegant, but it should work. I'll take pictures of the project when I get started on it.

BTW, I just noticed something interesting about the Lee pot. I had wondered how Lee got by without putting a grounded power cord on a metal appliance. UL approval would have required it to have a grounded cord. But it has no UL sticker on it. Just an observation.

6BQ6A, I have to guess you were once into CB linear amplifiers.

[6bg6ga]

Well, based on all the glowing praise for the Mypin controller in one of the sticky threads, I just ordered one, with SSR. I found another vendor with the correct thermocouple at a good price. I may be sorry at some point that I didn't get the Auber unit, but maybe this will get me started. I fished an old ATX computer power supply out of the junk box for the cabinet. What I put together probably isn't going to be original or elegant, but it should work. I'll take pictures of the project when I get started on it.

BTW, I just noticed something interesting about the Lee pot. I had wondered how Lee got by without putting a grounded power cord on a metal appliance. UL approval would have required it to have a grounded cord. But it has no UL sticker on it. Just an observation.

6BQ6A, I have to guess you were once into CB linear amplifiers.

Maybe the reason the MYPIN have a following is because a former member was putting kits together using the MYPIN PID. The MYPIN is attactive because of the price point and at the same time there weren't the choices there are now for PIDs. I also used a computer power supply case. Its a cost efficient way of putting a project together. I figured I would buy a better grade of PID and scrimp on the chassis. I believe you will find a thread of a number of members PID's completed pictures if you hunt.

6BG6GA is simply a Hi Fi tube and I'm a Hi Fi nut. If you guess I have all tube gear.

[bangerjim]

Construction of a super pot? It's a lot cheaper to add a PID. As much as I wish I had a larger pot. A PID controlled Lee pot works great.

I don't get why members here don't like change. It really shows you age. It's the whole you can't teach an old dog new tricks thing. Adding a PID means you don't have to worry about chasing temps. You set it and it stays there. The Lee thermostat varied to much based on how much lead was in the pot for my liking. It really went up in temp as the level lowered. It's great not having to constantly adjust the knob.

Well I certainly am a tech-savvy guy, and an instrument & process control engineer and know ALL the in's and out's of digital PID loop control & their functions. And I still do not want a controller on my lead pot. I could do it for free because I sell all the stuff in my company, but choose to use the Lee knob. It has always worked 110% for me. I do not experience this "change the temp or add lead an go out and have a beer" waiting for the temp to stabilize. Temp is not that critical!!!!!! Our fore-fathers did it over a camp fire. My grandfather did. They cast good boolits (that their lives depended on!!) without the use of a sooper-looper fuzzy logic PID digital controller. I just keep casting perfect boolits with the knob set at ~6.

I certainly would not begrudge anyone that wants all the wires and cables hanging out of their pot to do it. My pot is portable. I take it outside my loading shop to the patio and cast away, clamped on a Workmate. One single cord to plug in. Simple. Effective. Perfect Boolits. Always have been....always will be.

The choice for a digital loop controller is totally yours, my friend. Enjoy.

banger

[jsizemore]

^ what do you use to check your temp?

[dikman]

Banger, it's all about having new toys! :grin:. I'll be the first to admit I don't need a PID - my Pro-melt is perfectly adequate as it came out of the box. But reading about PIDs all the time was gnawing away at me, and I just knew that sooner or later I was going to have to build one. So I did.

I call it FUN.

[nodda duma]

Negative. There is definitely a thermostat. It cuts on and off. It is not a rheostat, which varies the voltage.

WHOOPS my mistake and my apologies. You are correct. Internet posting, beer, and thinking about work don't mix lol

[Handloader109]

One reason why the. Mypin controller is used is it is the cheapest I found that can be changed to Fahrenheit. And it is still portable

[blikseme300]

QUOTE=dragon813gt;2662833]Construction of a super pot? It's a lot cheaper to add a PID. As much as I wish I had a larger pot. A PID controlled Lee pot works great.

I don't get why members here don't like change. It really shows you age. It's the whole you can't teach an old dog new tricks thing. Adding a PID means you don't have to worry about chasing temps. You set it and it stays there. The Lee thermostat varied to much based on how much lead was in the pot for my liking. It really went up in temp as the level lowered. It's great not having to constantly adjust the knob.

You don't get why members here don't like a change? Thats simple.... Its the "Thats the way I've always done it" attitude. If it works then don't change.


The MYPIN PID controller. Is it a good deal? Having two of them right now one as a back up. The other being an Auber unit. There is night and day difference between the two programing wise and function wise. Sure, you pay more for the Auber unit but you end up with a unit that will probably outlast the cheaper MYPIN. I have a bullet caster with a MYPIN unit on it now. Its the second MYPIN that has been on it.

The probe... make sure it is able to submerged.[/QUOTE]

Consistency and repeatability are the 2 things a PID allow regardless of the pot. The cost difference between the Mypin and the Auber unit is negligible in the big picture of time availability and quality in my case. I work 60-80 hr weeks for most of the year and don't have time to waste if a tool does not work well every time. Same with hand tools - I buy Snap-On and not Harbor Freight. Some folks have time but limited funds and I respect their efforts in creating the perfect boolit. I just don't appreciate the comments that I waste money on over priced tools just because cheaper solutions exist.

If I had to start over with boolit casting the first item will be a PID controller for a pot.

[goofyoldfart]

My PID controller is called "personally interfacing dippering". Years ago while working in the Steel Mill, I made a 3/4In thick melting pot that holds 50 lbs of lead and has flat bottom. I use this on a chicken (turkey, too) fryer burner and stand and It has worked very well for me. I only have 1,2and 3 cavity molds so it suffices fine. I also tend to set my flame heat to give me slightly frosted boolits and have had no problems with my bullets accuracy and leading. Blikseme: I understand what you are saying and you are perfecly correct. Time counts--especially when one does not have a lot of it to spare. God Bless to all and theirs.
Goofyoldfart.