Lee 4-20 Pot Plugs Up, Why? How do I stop that?

Got a problem I need your help with. I have a Lee Pro 4-20 bottom pour pot. When it works it works great. I smelt ingots and wheel weights in a Lyman Big Dipper. I do not mix COWW and SOWW. I assume the ingots from others are marked correctly. The process I use is a two step process = First the Lyman to melt the wheel weights then the Lee bottom pour to make bullets. Ingots are assumed to already have had the melting and fluxing process completed. In the Lyman I flux them with pine sawdust. I've run across about 20 pounds of ingots poured by someone else marked PB into Lyman 1# ingot molds that have left a coating on my Lee Pro 4-20. It also stopped up the bottom pour valve. It seems to have a brown, rusty interior that, when hot, is almost sticky, but, scrapes off quite easily as a black residue on the molten metal surface. I skim that off and toss it out. When it is hot the interior looks like caramelized sugar. I use the Lee for bullet pouring only.

The last ingots from someone else batch was heated in my Lee pot to under 700 degrees (measured by a digital thermometer). The fully heated alloy was silver on top, never had that blue or yellow sheen develop. I fluxed the alloy and had the same results. My Lee pot was stopped up in less than a dozen pours. I noticed that as the temp dropped below 600 degrees the alloy quickly became mushy. Took the Lee apart and cleaned it out. I'm ready to try again with COWW I melted, fluxed and made ingots from, not this stuff.

I don't have much experience with melting pure lead. I assumed the ingots were pure lead (after all they were stamped PB) so I added 3% tin with the same results. My thinking is my sawdust flux material is leaving a resin on the interior of the pot and that is what is stopping up the valve. The material most likely is pure lead (now with 3% tin). What do I have here? SOWW or pure lead or what? What is causing the Lee pot to plug up?

My 4-20 pot would do the same thing all i did was clean it empty all the lead out let cool fill a little above half way with water add a little dish soap have water on hand to add as needed and a brush that will fit in side the pot and a scraper to help clean the sides turn on let it boil
add water as needed will look like new



https://leeprecision.com/parts/bulle...-4-20lb-parts/ i just saw that you said that the temperature would drop i would give lee a call phone (262) 673-3075

I think you need this https://leeprecision.com/thermostat-110v-20lb.html

Are you sure your thermometer is reading correctly? The common 621 degree temp for lead is the point at which all the lead is liquid, below that point only some is liquid until the temp falls to the freezing point. Even adding 3% tin does not lower the melt point very much, thus the mush. Also the pour spout tends to be colder than the pot and will freeze up. Try pouring at a full 700 degrees or if not sure of the temp turn the pot temp up until it pours properly. My experience has been that somewhere between 700 and 750 degrees is the sweet spot for casting with a bottom pour pot. I have smelted at lower temps between 650 and 700 degrees but it was done in a pot over a turkey fryer burner using a ladle .

The softer the alloy the higher the melting temperature.
sometimes the lead cools in the spout if your rythem is to slow or the room is too cold.
I use a small torch on a can with a self-igniter to warm it back up.

bbogue1

Wholeheartedly agree with Rich/WIS....in my experience the Lee 4/20 pots are well capable of handling most temps and will generally allow good pours but please understand you need to accurately control your temperature - the dip-in non digital thermometers (only ones I have used) generally do not give accurate readings depending on where they are placed in the pot plus they take ages to settle on a value.......take your pot to bits one day and see exactly where the elements are situated as immediately next to them gives the hottest readings - cooler elsewhere so stirring is advised..it's not a big temp difference but there all the same...

Likewise with an IR sensor.....you will get some 'signal bounce' from the beam due to the reflective nature of the melts and the angle it's aimed at plus it will not tell you what the core temp is, only the surface.....I've never had accurate consistent readings using both methods in comparing them to each other.......don't try to regulate the temp with just the Lee built in potentiometer...its a cheap and crude temperature on/off switch; and next to useless for accurate temp control...

Regarding fluxes and assorted mixes......they will cause stains to the aluminium frames if in contact but some say that adds to the character of your pot :) .....Sawdust and non Borax fluxes will stain readily and the 'sheen' you refer to could be a result of factors such as residual flux traces still there, the lighter metal rising, a higher temperature, oxidation of the metals plus other minor ones like humidity etc...all contribute with the main culprit being temperature.....hence stir it and control the temp...

I have found that using pure ingredients other than wheel weights or materials of unknown compositions gives less fouling and a much more consistent pour without the need to flux as often. On average I would only flux once per full pot if at all..as generally not needed....just using a bent steel spoon to skim the top......you will find also that as you stir the brew, dross and other bits float up and can be removed

My 4/20 seems to prefer different temps for different alloys but if you are just using the standard Pb/Sn combination (stress pure metals used - not wheel weight or other) then anything from 1-4% addition of Sn will cast and pour best from a range between 690F to 730F ..once I go over the 720F mark then I start to notice a blue sheen on the brew so that's a good indicator you are near your max temp mark for that alloy........

The cast pills will also get a shinier finish with higher temps and should drop around the 10BHN...don't go higher temp as you will start to degrade the brew and makes it harder to get decent casts even though it pours easier, plus it can gum up the pour hole the closer you get to the bottom..that may be a reason for one of your concerns.....also heats up the moulds too much and the pills start to wrinkle .....I usually settle on 3% but it doesn't make a whole lot of difference to the pour as I found the temp is more critical.....if you want them a tad harder then water quench but there are limits to how hard you can go with just Sn added.......

Cannot stress highly enough, if you want to get a consistent brew and less casting issues then it becomes much easier if you eliminate as many variables as you can...hence use pure metals, borax flux, clean your pot between brews but most importantly install a temperature mechanism to control your temperatures as desired....a PID is a good investment.....

So hope my experiences helps you along and remember to please keep it safe and use all the proper safety......so take care and good shooting

My Lee works all the time, never leaks or plugs, What I do though is NEVER melt scrap in it & NEVER run it dry. That is when crud gets into the valve. I run a PID on mine but you still need 650deg or so for good flow with most alloys.

Trash and crud clogs the opening.

Clean the pot and hole

Flux more. Flux more when casting the ingots and flux more in the pot. Get the alloy clean before you start casting.

if you can pick up one of these setups, you can smelt larger batches of alloy and do a more aggressive flux. this is a 10 inch dia. cast iron dutch oven sitting on a turkey fryer burner.

Take a propane torch and heat the spout if it solves the problem your lead isn't hot enough.

few thoughts here.if your bottom pour pot is clogging up with **** you need to do a better job of cleaning your lead.I try and keep my smelting pot as clean as my casting pot.If you are using ingots you did not make and get a lot of **** in your casting pot stop and remelt and clean the lead.i have both a lee 20 and promelt either will have the spout freeze at about 680i have never had my spout clog with ****.as mentioned above the propane torch is the test.I have stoped doing 2 things with the casting pot.i do not use anything wood in the casting pot.wood if for cleaning the lead in the smelting pot.all you need is a bit of wax to get any oxidized stuff back into the mix.i no longer flux several times in a casting pot full of lead.i only flux when I fill or refill the casting pot.over fluxing just take more time and cruds up the pot faster.the mix will not separate that much in the time it takes to drain the pot.this is what works for me ymmv

bbogue1, sending you a pm

Thanks for the photo triggerhappy and the help everyone. I smelt the dirty COWW in a different melter usually wood fluxing twice. In my casting Lee 4-20 I have spread a bit of wood over the top to prevent oxidation. I did empty the pot, scrub it well with wire brushes then filled it with soap and water and boiled while again scrubbing the sides and bottom. I ended up with a small pile of rust, lead and a brown crumbley dust before the water bath. I found the Lee pot is a steel pot which would explain the sloughing off of oxidized material (rust). Take a look at your BBQ it deteriorates the same way. After cleaning the pot I took some measurements while the pot was still empty. With the pot set at 5 Mid way up the side the empty pot was 752-770 the spout was 580-590. When I raised it to 6 the pot went to 701-703 while the spout 575-585 and a setting of 7 showed the pot to be an average of 825 while the spout was an average 648. Since the pot is usually half full while casting I am assuming the heat transfer will be better and a setting of 6.5 most likely will be appropriate.

My findings prove you guys know your stuff. Yes, with the Lee pot set on 5 my pot melted the alloy, but, the spout was much colder than I thought it would be and the alloy froze up. Didn't help that I introduced wood into the casting pot which is now a no no. I also am mixing more to keep the alloy at a more consistent temp top to bottom.

Next I melted what I knew to be clean alloy on a setting of 6.5 and it was so clean, poured nice, but, I had tried to drill the spout on an earlier attempt so it dripped like crazy. I have ordered a new spout. I have a PID and it does a marvelous job. Up till now I use it to smelt COWW at 700 degrees to prevent zinc from accidently slipping in. After I get the new spout I may try the PID on the Lee 4-20 to keep the put at a more consistent temp. I like the idea of the torch for heating the spout, When using the torch do you heat the spout and raise the pot temp or heat the spout whenever the pour gets sluggish?

Get a set of HF dental picks, use the angled ones to push up the spout to clean., while the spout is hot. The Lee spout has a 'chamber' of larger dia than either the valve or spout that will capture some junk and release it when you least expect.

I have the same problem now and then especially on cool or windy days when casting low weight bullets like the Lee 356-120-TC's. The problem is the spout doesn't heat up when filling six 9mm 120g cavities as it does when filling six 45ACP 230g cavities so it cools down below the freezing point if I wait too long for the next pour. I keep a propane jet BBQ lighter on the table to jump start the spout if it ever freezes up but I usually don't need it if I set my PID about 25 degrees warmer for the small bullets.

Mine will get sluggish if I allow the pot to get less than half full. The added pressure from a full pot helps a lot. If it stops up for no apparent reason I'll take a bent jumbo paperclip and holding it with pliers I'll clean the spout. I'll also periodically twist the spout plug rod to help keep it clean.

Quote:

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Originally Posted by Tom W.

Mine will get sluggish if I allow the pot to get less than half full. The added pressure from a full pot helps a lot. If it stops up for no apparent reason I'll take a bent jumbo paperclip and holding it with pliers I'll clean the spout. I'll also periodically twist the spout plug rod to help keep it clean.

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I try to find a nail which barely fits into the pour spout when new. I clamp the nail in vice grips and use it to remove debris from the pour spout.

I found a ribbed paneling nail the right size then bought a cheap large bamboo spoon and cut the end off. I drilled a hole slightly smaller than the nail and taped in the nail. then I secured the nail in place.

If your alloy is solidifying in the spout, if the alloy is not up to temperature or you just added more to the pot, the easiest way I have found to get the spout flowing again is to use one of those BBQ lighters with the long extension and heat the spout up with it. It will soon start flowing again and once it starts to drip open the valve wide open for a few seconds and the heat of the lead in the pot will take over. I hope this is clearer that mud.


Ken

The PID will tell you where you are and you will see where the spout freezes.I have never asked what other do but with the PID I keep my pot control wide open and let the PID do its thing.The temp should be an even temp from top to bottom once you see the temp settles in to where you have the pid set.I use propane torch with he auto lite,with a low flame it only taks a few sec to get things going.

Another tip when you get you new spout clean off the valve rod and Lap the rod on the new spout seat this stopped most of my dripping.

I may have missed it.what bullet are you casing and what mold?o think it was mentioned befor but I cast my pistol molds form 700 to 750

I try to pour between 700-750 shooting for 720 and I pour the whole thing and clean it if I don’t the junk that builds up around the spout will plug it off guaranteed, especially if the pot is full.


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