Lee 4-20 ProMelt conversion (image heavy)

[zubrato]

Before I begin, let me say this entire thing began as one g-damn screw, the shoulder bolt on the Lee 4-20.

Latest update: this is where I stand today. (updates to come very soon)


It's not yet done, as I've got materials to paint the frame black, and install a mold guide.

From the beginning: I began with ideas for the frame, and drew up schematics for what I wanted, using square steel tubing, and angle iron. Using an old welder my dad bought, and sat in the crawl space forever.

This is sort of my first weld for practice, but I went over it once by accident because I couldnt see JACK out of my welding mask. Hated the damn thing till I flashed myself once on accident while setting up to weld. Wished it was darker after that


The completed frame. Some welds are nice, some are snotty because I'm uh not so good with tight corners in cramped spaces. They're all strong welds, but not all of them are pretty.
Still my first time, so I get a bit of a break (I hope.)


Me welding away. it may look as though the project is welding itself, but do not fear it's because I'm well camoflaged.

Now, the spout pin. I kiiinda broke the slotted tip, and it has always felt junksy to me so I decided to replace it. I found this thing in a spare parts bin, and I cant remember just what the hell it's for. I assume breaking up concrete, because I couldnt drill through the damn thing it was so hard. It just happens to be a perfect fit for the spout though, and matches the OD of the Lee Spout pin!


I cut up some old aluminum signs for the splat plate, and the top that would hold the whole rim edge of the casting pot. Here you can see I used smaller angle iron as borders, so I wouldnt have to drill and screw it together. I feel this looks cleaner. Once the whole thing is painted and ready to go, then I'm going to shim that plate into place so it won't move.



huh, only 10 img's per post. stay tuned!

[zubrato]

part two

Electrical box. I'm no good at electronics, and neither fabricating as you can tell from the pictures. Looks like it was drunkenly broken into, twice.
However, I had to get creative here if this thing was supposed to look like I wanted it to. I pounded the old aluminum plates flat, and bent them into a box shape by eye. Box too small. Used the old Lee pot curved sections that go around the heating elements, cut off the end that stuck up, and drilled/screwed it all together with machine screws.


The paperclips taped to wires you see are my handiwork, I put them on before disassembly and took pictures so that I could let everyone know that yes, I'm stupid enough to mix up three wires. Again, all im trying to do is contain the magic smoke that powers electricity here. Once the smoke gets out, you done messed up.

I dont have pictures of the handle process, but what I did is called "bending flat steel the hard way (or edgewise)"
The BEST way to do this is clamp the end in a vice, heat a small section ahead of the clamped part and push up. Once it begins to S shape from the compression (outside gets thin, inside gets thick) stop, put that section in the vise and clamp down. Continue until you have the angle you want.


Clevis nuts are expensive. I found a few coupling nuts, and got to work with a hacksaw. Got some clevis pins, and had some cotter pins lying around.
While I kept the spout, I put a nice big washer underneath the lip of the old spout to lift it up and give the dirt a bigger curb to prevent drips and the pot clogging up.


Moment of truth: the water test.
No leaks! great flow!


I'm going to be honest and say at this point I stop documenting, because it kinda burned me out over a few weeks, thinking over solutions and sketching up diagrams.
I used rockwool for insulation, and aluminum sheet and secured it with worm gear hose clamps.


but does it work?

yup! a quick test cast confirms this! too tired to cast much, pooped after fitting every piece to one another.

The last part of the project is a mold guide using shelving track, brackets, and brass lifting rods. Stay tuned for updates!

[Mica_Hiebert]

cool project!

[Walter Laich]

nicely done.

[zubrato]

Thank you for the kind words! I feel I spent a lot of time on the project, and wasn't sure it was all that well spent until I started casting with it, and it worked like a dream.
I know it isn't a promelt by any stretch, but imitation is the sincerest form of flattery!

I plan on adding a few fun and useful features, like opposing coat hooks to wrap the power cord around, and carrying handles. I used aluminum for the top plate that secures the pot so that I could preheat ingots (and it works great for that) but it isn't quite so easy to grab and move it, unless its by the rear support legs.

I had been looking for a nice quality looking dial face plate, but short of paying 15$, I figured I would just sharpie in the same scale as previously until I found a nice faceplate I like.
I could have used the Lee one, but I had put too much heart into the build to slap a Lee label on it.

[jmort]

This is a seriously good thread. What a great way to utilize the guts of the 4-20 and make it way better.

[Sheldon]

Nice work! I especially like the ledge in the back. Been thinking of welding something like that to my pot to warm up lead ingots.

[Catshooter]

Nice work.

The piece you used to stop the spout, pointy on one end and threaded 1/4x20 on the other is 'nail' for powder actuated concrete fastening tools. The pointy end is fired into the concrete, and that's why it's very hard. Hilti is one brand name for them. Used in construction.


Cat

[2wheelDuke]

Nice work. I'd look into PID control and just do away with the knob.

[Mal Paso]

Nice work. I'd look into PID control and just do away with the knob.

I'll bet he gets better heat control with "infinite switch" where he put it. Although it's not a thermostat heat from the pot does affect it. I'll bet you see PID on the next one.

Great Build !!!!!

[BwBrown]

I have two Lee pots, the 20 pounder and its little brother. Based on my experience, I long ago concluded that "Lee" is short for "LEAKS".
After cleaning up nearly 20 pounds of molten lead one night (I had turned my back during warm-up) cost me a kitchen table, I went with another less troublesome brand (Green is good - much higher cost, but should have made the change decades ago).
The design of the "bottom leak valve" increasingly became a major stumbling block for me.
I did use them for nearly 40 years, just was never happy with them. And I tried all manner of fitting, grinding, lapping with little improvement.
I'm going to revisit my pots with ideas from this post.
Thanks.

[zubrato]

Huge Thank you to everyone for the kind words!

I knew the threaded pin looking thing was for breaking up concrete, but forgot exactly what it was; thank you Catshooter!

Took a bit more work than I expected since I had to fab so much of it.

Going to install a mold guide, sand and spray paint the frame with high temp black paint as soon as it stops raining.

I definitely wanted a PID, and it's the next project for sure. I just didnt want to bite off more than I could chew all at once.

However, the knob definitely works better now, and I could live with it along with my cheap cabelas deep drier thermometer. Lots of insulation between the knob and pot helps, the knob is controlled by resistor which heats the bimetal strip

Thank you guys again, i put a lot of heart and thought into the project to the point where I just wanted to get it over with so I could resume casting.

If anyone has questions I'd be glad to help answer. I sort of trudged through because I tried a lot of different solutions before I found what worked, and what could potentially be a thorn in the butt when using it later.

[HB0708]

Super cool!