Introduction: Thor's Hammer Pendant (Stargate Version)
The first engraving job I did with my workshop laser was to put a traditional version of Thor's hammer, Mjölnir, on the side of a wooden mallet, and I have caught many students, when they think I'm not looking, holding that mallet aloft and trying to summon lightning.
So, when I needed a project to demonstrate designing pewter molds of varying thickness, I was naturally drawn to Mjölnir again. This time, though, I decided to broaden my students' nerdly awareness, and use the version of Mjölnir seen as a symbol of Stargate's alien Asgardians.
Throw in a useful, but often neglected knot, and this educational project produces a gift suitable for Stargate's Fandom and pagans alike.
Step 1: Needful Things
As well as a laser cutter, you will need:
- 3mm thick MDF
- 2mm thick MDF
- PVA glue (or glue stick)
- One or more clamps
- A means to safely melt and pour pewter*.
- Safety goggles and tough clothing.
- Tin-snips, toe-nail clippers or wire-cutters.
- Strong knife, such as a box-cutter
- Fine file.
- A couple of feet of dark cord or thin leather thong.
*For this project, I am using a "proper" pewter furnace made for a school setting. If I was doing this at home, I'd use a large metal spoon and a decorating heat gun (check out my first attempt at pewter casting to see how)
Step 2: Create Your Image
It's not hard to find screenshots of most TV-based objects online.
Working in Inkscape, I produced a 2D outline of the hammer icon as used in Stargate.
(That step looks short, but it actually took about half an hour...)
Step 3: Layers
Looking at the screenshot, it is obvious that is is basically two thicknesses: The thicker head, and the thinner handle.
This requires a mold of five layers:
- Two outer layers, holding everything in (also carrying the pattern on the side of the head). In the image and files, they are layers A & E
- Two layers to give the extra thickness of the head, and carry the pattern of the handle (layers B & D).
- A single layer to give the thickness of the handle (layer C)
In these images and files, black lines cut all the way through the material, and green lines enclose areas engraved away. An engraved area in the mold produces a raised area on the final object.
I made the layers by starting with the complete drawing scaled to my desired size, and enclosed within a rectangle to show the outside dimensions of the mold.
Make four identical copies of the complete mold, then remove from each one everything except the parts needed on that layer.
I also added a wedge shape to the three central layers to act as a funnel to pour in the pewter, and a notch in the central layer to allow air out as pewter pours in.
Finally, layers D and E will need turned over when assembling the mold, so they need to be flipped vertically. This is a vital thing to remember if the object you are casting is not symmetrical.
Step 4: Cut
The Instructables system wouldn't let me upload the actual Thunder Laser file, but you can use any of the files from the previous step to create a useful file in the appropriate software for your own cutter.
Make sure that:
- The lines drawn in black cut all the way through the material.
- The areas drawn in green are engraved away.
- The letters drawn in blue are lightly vector-cut to help you get them stacked correctly.
Cut layers A, C and E from 3mm MDF
Cut layers B & D from 2mm MDF (the head is thicker than the handle, but not three times thicker).
Keep an eye on the parts of layer C - there is a small wedge-shaped piece that can easily drop down into the bowels of your laser cutter. Don't lose it, you need it!
Step 5: Assemble the Mold.
Once you have rescued that small piece from beneath the cutting bed, you assemble the mold.
Stack layers A, B & C on top of each other. You should be able to look through the holes in the layers and see the engraved pattern.
Use a tiny drop or smear of glue to tack the wedge-shaped piece into place on layer B. If you use too much glue, the water in it can flash to steam as the molten pewter hits the mold, ruining your cast and the mold.
Turn layer D over, line it up on top of layer C, flip layer E and add it to the stack, then firmly clamp the whole stack together.
Step 6: Cast
Use your preferred method to melt your pewter, and set up your mold on a stable and heat-proof surface.
It's not obvious in the photos, but the clamps are tilted slightly downward - the handles rest on the work surface to provide balance.
Make sure you wear goggles and long sleeves during casting - liquid pewter seems to splash further and more easily than water. Depending on your casting method, the molten metal will be three to six times times hotter than boiling water.
You should wear clothes made of thick cotton, as synthetic fibres can melt and fuse to your skin.
Obviously, you are responsible for your own safety, but if you don't act safely in my workshop, don't expect to be allowed near tools - clothes and goggles can be replaced, but burst eyeballs cannot.
Using the appropriate tools for your method, quickly and smoothly pour the molten pewter into the mold.
Leave the mold at least five minutes to cool and set, then turn in out onto a heat-proof surface.
Beware! The solid pewter is still hot enough to burn and blister your skin, so leave it a few minutes more.
Step 7: Clean Up
The cooled piece is not finished, since it still has an ugly sprue sticking out of the handle.
Snip off the sprue as close to the handle as you can, or use a fine-bladed saw to cut it away (in my school workshop I have a powered scroll saw that can cope with pewter if you go slow) then use your strong knife to shave off more of the excess.
Finally, use a fine file to clean off the sprue flush to the handle.
Step 8: Add Cord
The observant among you will have noticed that there is no hole in Mjölnir for you to add a cord. That does not stop you sharing your Stargate fandom!
You are going to knot the cord to Mjölnir, using what is known as a Constrictor Knot, Tied On The Bight. I've shown you it in paracord, because that's a lot easier to see in photos than the cord I actually used.
- Lay out your cord in front of you, and find the middle.
- Pull the cord into a flat "S" shape.
- Lift and turn the two loops over the top of the rest of the cord. It should look like a figure-eight.
- Put finger and thumb through the loops of the "8" and pick it up.
- Make sure the two loops droop down, flat against each other.
- Slip the handle of Mjölnir through all the loops at once, and pull tight.
Tie the ends of the cord with a reef knot (see step 3 of one of my older projects), and you are good to go!
Participated in the