Low Temp Metal Casting via the Glowforge

Hi all, I’ve been working on a custom product for my business and have had some decent success in using the Glowforge as a primary component in producing pretty intricate metal castings. Following is a brief overview of my process.

First, I used the forge to do a relatively deep engrave in acrylic of a design. In this case I reproduced one of my playing card designs into a “mini-deck” size. This went through a few variations to get the right level of detail (this early one proved to be a little too much detail for my process).

After creating the blank it was time to make the silicone mold. I mounted the blank into a shallow plastic box with superglue and then used a 2-part silicone from Amazon (Alumilite High Strength 3). This material works really well, is easy to mix and has proven quite durable.


Once the mold cured, I used a tin-bismuth metal (also from Amazon) melted in a small hot-pot and once the metal got up to temp I poured it into the mold. This is the trickiest part of the process and it took a few rounds to get a technique of pouring/jiggling to make sure all the air bubbles are out. Luckily, if you mess up just toss the piece back into a hot-pot and try again.


After a few rounds of revisions I ended up with a very cool little casting. With a few pretty cheap ingredients and a little time and creativity, I think this general process could be used for all kinds of unique items!

77 Likes

Very cool!

Does the surface of the casting lend itself to finishing, i.e. could it be sanded then polished?

2 Likes

This is outstanding!

1 Like

yes I think you could. I have used a basic sandpaper on a few edges just to knock down some tiny casting remnants and it sands easily and looks quite shiny. I imagine with a little more hand work you could get a very polished look.

3 Likes

Very cool!

1 Like

Oh man, I do not need another craft, but it looks like I might have one! SO COOL!!!

6 Likes

Thanks so much for sharing your process! It looks like another thing I might have to try. Best of luck with your decks–I remember their artistry and uniqueness!

1 Like

awesome work. Next step: centrifugal casting. lol I got to do this back in college. You’re bringing back fond memories.

1 Like

That’s a really great process. Well done.

1 Like

I did the same thing a while back to make some challenge coins then used a paint pen to color them.

24 Likes

Are they double sided? If so, I’d love to know the technique…

I had a lot of that material to bend silver tubing. You fill the tubing with it and then it all bends like it was wire. After which you heat it again all all the low melt flows out leaving round tubing for stuff like hollow earrings,

I wonder if you could Electroform on it and then melt out the low temp leaving a hollow shell that could be light enough as earrings while looking massive. I had always felt the low temp metal too low melting to use on its own

5 Likes

Yes, both sides are identical. I engraved them on wood, dusted them with talcum powder and laid them into a box just a little bigger. Then I built a thin dam (plastalina modelling clay) around the edges of each coin (I did 2 at a time) to prevent the silicon from wicking under them. I then poured about an inch of silicon mold max 60 over the top and let it harden. Then I removed the silicon and the dam and dusted with talcum. After pouring an inch or so of silicon on top I separated the 2 halves, removed the wooden plugs and cut a channel for the pour and one for the air to escape (in a V shape to keep them apart) from one edge down to each coin . Of course when the metal coins are removed there is a bit of hack sawing and filing to get rid of the excess metal “sprues”. Then I lapped them on sand paper to smooth the surfaces a bit.
Oh, the metal I had on hand is tin.

7 Likes

Sounds great. Would you mind posting a pic of your mold? Thanks.

1 Like

Here is a pic of the wooden plugs plus the mold I made:



I forgot to mention in the previous post that I also made the registrations bumps for alignment of the 2 halves using the modeling clay.

15 Likes

This is neat and relevant to my interests.

One thing that I think would help a lot in these projects is eliminating or reducing the laser char texture that we always get when doing a deep engrave.

image

I wonder if there is a good trick for that.

1 Like

I think some folks have done purposefully de-focused passes to smooth out the engrave. Not sure precisely how you do that and maintain detail where you want it to be crisp though.

2 Likes

That may also be partly due to my choice of wood for the plugs. It’s hardboard from HD. It also might have a smoother background if I had maxed out the LPI? They are pretty small to try sanding out the low spots and I actually kind of like them like this.

1 Like

I was going to ask if you used an image to create that cool background texture! :slight_smile:

1 Like

You can also use cold casting techniques, using metal powders with casting resins instead of metal/heat.

2 Likes