Summary

I went through a phase on YouTube where I got really into metal working. Summer during the pandemic was weird like that. Anyway, I got into a metal casting rabit hole and I saw enough questionable set ups that worked reasonably well that I decided to try it out for myself.

I can say pretty confidently that this is one of my favorite projects right now, and I'm really looking forward to trying to cast a ton of different things.

I'm going to showcase a bronze dagger that I cast here because it's easily the coolest thing I've done so far, but the process is more or less the same for every casting.

Smelter

To smelt my metal bars I set up one of those DIY Mini Foundries that are so common on YouTube now.

My system is pressure fed from a propane tank into a high temperature, plaster lined steel bucket. The plaster is reinforced using stainless steel wool, similar to how fiberglass works. The air inflow is regulated using a simple steel sheet over an induced flow port.

Inside the smelter I use a graphite crucible to contain the molten metal.

Flask

I used some leftover pine I had laying around to make my flask. To help the sand adhere to the walls of the flask, I cut several grooves on the wood using my circular saw set to a shallow cutting depth.

I added some handles and played around with different ways of locking the two halves together. I really need to add some good luggage latches to it, but for the time being I'm just using some aluminum rods.

Green Sand

Making my own green sand was actually the hardest part of this entire endeavor. Had I known how long it would take I would've just ordered some.

My mix was a majority fine grain sand, with 11% bentonite clay, and about a quart of water. For the sand I had to finely sift about 30 lbs of sand with a flour sieve. For the clay I had to blend up absorbent clay kitty litter with a thrifted blender, and then sift that as well. For mixing I jerry-rigged a large steel spoon onto my cordless drill, which had... mixed results.

Safety

Obviously this is one of the more dangerous things I've worked on so I took my safety very seriously.

To try to protect myself from spills and bubbles I wore all cotton clothing, which burns rather than melts, leather boots, and stainless steel boot covers I cut up and folded with my dremel.

To protect myself from the fumes I bought a respirator rated for foundry work, and to protect my eyes I used my safety goggles from my chemistry course several years ago.

For my hands I wore leather welding gloves which do a great job of insulating the heat.

I would have prefered to have a leather duster as well, but I couldn't find one at the local thrift stores.

Pouring

To pour I used a combination of cheap stainless steel tongs and some actual crucible tongs to remove the lid of the smelting pot and lift out the crucible.

I kept the crucible very low to the ground in order protect myself from spills, and I kept the smelter very close to the flask so I wouldn't have to travel very far.

This is where things went wrong for this particular cast. I poured the molten bronze into two of the three sprues, so gas could escape the third. Still, I believe I poured a bit too fast which trapped some pockets of gas in the cast you'll see further down the page. For future castings I introduced a sprue basin to slow down the metal on its way into the void.

Initial Result

Immediately upon pulling my casting out of the flask I knew I had a pretty good result. You can see how close the unprocessed cast is to the 3D printed pattern I used to make the mold cavity.

There's some flash here and there, some voids due to trapped air, and clearly some spots where the mold broke up prior to the pour. Fortunately, none of these were very serious issues.

Processed Result

Here's the final result! Well not entirely I still had to sharpen it after this photo was taken, but I really like this photo.

Yeah there are some voids but overall it came out really nice for a first attempt. Since bronze weapons had to be fairly thick, this dagger has a good heft to it and it feels pretty satisfying hold. If I had to lug it around on some ancient campaign though I'd infinitely prefer a less cumbersome steel weapon.

Currently I have this dagger on display in a shadow box over my desk. It looks great and people seem to take interest in it when they spot it. I think this will be one of the personal projects I look back on the most fondly.