Cast Pewter Robot Badge

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Introduction: Cast Pewter Robot Badge

About: The answer is lasers, now, what was the question? If you need help, feel free to contact me. Find me on Reddit, Tumblr and Twitter as @KitemanX

So, I had just published a pewter-casting Instructable, when I suddenly realised I was missing a trick: detailing.

I had to spend a few hours driving, and cogitated as I drove, working out a way to do it: engraving.


Welcome to another step in me learning how easy it can be to cast pewter...

Step 1: Materials, Tools and Brain Damage

Materials:

  • Pewter
  • 3mm MDF
  • Butterfly badge-pin

Tools:

  • A hot air gun
  • Tongs or pliers (more than one pair)
  • Clamps
  • Something to cut MDF (I used my laser cutter, because I can, but ordinary hand tools are absolutely fine)
  • Ladle.
  • A heat-proof surface over which to work. I used an old baking tray.

The "ladle" needs to be steel, but beyond that there are many options - you could use an actual soup ladle, use a serving spoon or cut a clean food can into shape. I found a set of measuring spoons - the smallest turned out to be perfect for the ingot of pewter I bought, and had a flat bottom (so balancing was a lot easier).

There are lots of suppliers of pewter online, but I always recommend supporting a local physical craft store if you can. Use lead-free pewter - the presence of lead doesn't really affect the use of the finished item if you're making a something nice to look at, but you don't really want it on your skin, and (worse) you don't want to breathe in hot lead fumes. Lead is a cumulative neurotoxin - each exposure damages your brain a little more.

If you are working indoors, please make sure that you have plenty of ventilation - open windows and doors, have fans maintaining an air-flow away from you (and especially away from any children or pregnant or nursing mothers).

Step 2: Design Notes

I took the image of Robot from this old forum topic - I imported the image into Inkscape, and the drew over the picture to make a slightly simpler vector image.

Drawn in thick lines, I then turned each thick line into a pair of thin lines (Path -> stroke to path), and created the mould files from that (attached in several formats)

If you use my ECP file, notice that the actual drawing of Robot is doubled up: the lines are engraved, and then vector-cut.

Making the mould needs three layers of MDF.
The central layer is the outline of the Robot, with a small notch at the top to let you pour in the molten pewter. The front layer is just a rectangle of MDF with a hole to pass through the pin of the badge-back, and the back layer includes the engraved detailing.

The pin for the badge was a bit too wide for the mould, so I just clipped off the sides with tin-snips.

Step 3: Clamp

Just what it says - get the parts lined up, and clamped as firmly as you can.

I didn't push the spike of the badge-back all the way through the hole in the mould - the plan is for pewter to flow all around the pin & hold it firmly in the metal.

You want the parts clamped as firmly as possible, held vertically over a surface you don't mind spilling molten pewter over.

Step 4: Melting Your Pewter

The joy of using pewter is that you do not need a furnace, just a ladle.

If you have a small metal ladle, then you're good to go. You could also use a large spoon (with a pouring lip bent into the side of the bowl), or cut down an empty can to make a ladle.

One advantage of using the measuring cup I used (or an old can) is that it has a flat-enough bottom to stand without spilling. I put my pewter ingot in the ladle, and blasted it with the heat gun until it was melted. Standing the ladle on the part-open vice meant I could heat it from above and below.

Don't forget that metal conducts heat, and the handle will get hot - use the pliers to pick it up and pour.

Step 5: Pour Your Pewter

With the mould propped firmly in a vertical position, gently and carefully pour molten pewter into the funnel-shaped cut-out of the mould.

The design I was making needed only a small fraction of the pewter in the ladle - the mould filled quickly and over-flowed.

Step 6:

After the pewter has had time to solidify (officially just 2-3 minutes, but I give it five), release the clamps of the mould.

The pewter seemed to glue the layers of MDF together - I had to slip a knife blade between the layers to prise them apart.

Resist the temptation to immediately pick the badge up with your bare hands - despite being solid, it might still be hot. It will only take a couple of minutes to cool enough to handle, though.

Unlike the smooth rocket badge, the textured surface of the mould seemed to "grab" the pewter - parts of the MDF got pulled off the textured layer, and I had to break the central layer to extract the badge.

Step 7: Finishing

Once the pendant is set, you may have excess material, known as a sprue.

These need trimmed off - a mall pair of tin-snips easily removed the bulk of the sprue, and then a pair of toenail clippers removed most of the rest. Final trimming was done with a Stanley knife and a fine file.

MDF is really just thick paper, so the last scraps of adhered material came off after soaking in hot water and scrubbing with a stiff-bristled brush.

Dry it off, and you're ready to wear it - just remember, it's a bit heavy for a thin shirt, but ideal for a jumper or suit or coat lapel.

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    16 Comments

    Very cute! I wonder if you could add some color, possibly painting it, or adding enamel... interesting project :)

    5 replies

    Enameling sounds interesting, but don't you need to bake enamels? I worry that the pewter would melt again.

    Ah, I hadn't even thought that far...

    Polyvine make acrylic enamel which is basically thin nail varnish that you can paint onto pewter with an acceptable level of shine without needing a kiln.

    Thanks for the info :) Good to know

    You have introduced me to the concept of pewter! Fantastic, thanks!

    1 reply

    You're welcome!

    Please, post pictures of what you make!

    Haha, I don't know about "master", I'm still getting good tips off folk. I'm wondering next about more complex shapes that might need vents...

    I know - I've been meaning to try this for well over four years, maybe five or six. I'm glad I did now, Robot looks very good on the lapel of my dark grey suit!

    It looks great, even with the details. And it does not seem that difficult to make, maybe I'll give it a try!

    1 reply

    You ought to - once I'd worked out how to do the detailing, it was less than an hour from switching on my laser cutter to wearing the finished badge.