Elysium Max Exoskeleton

The past three weeks have been a living hell of trying to cast two large plastic parts with complex geometry and thin edges out of rubber. Today it ends!

I used SmoothOn Brush-On 40 to make the mold and shore 70 hardness rubber along with a black pigment to cast the parts.

In the past 3 weeks I cast the remaining parts for the spine as well as shock plates/armor that will be attached to boots:

Just before that I cast two extra parts I was missing before, a shoulder connector with some extreme detail and an unsightly hip connector. One of the parts here is repeated above.

My sheet metal order of bent spine connectors and arm bracelets came in:

I decided I might as well make those in 2mm stainless steel after prototyping with paper and cardboard:

Last week I finished two more molds for shin shockplates. The only other "required" part left is the chest plate, one of the biggest and coolest-looking parts of the exoskeleton. There are a bunch of optional parts I would like to cast as a stretch goal, notably the tiny details placed on the hands, the vacuum tube holders with light-up tubes, and some tech gribble for the face to complete the cyber ninja look.

Fig. 1: Finished making the first part of a two-part mold with 3D-printed model suspended in clay

Fig 2: Preparing to pour the second part of both two-part molds

Fig 3: Resulting two-part molds I will use for casting wax positives

Fig. 4: Resulting wax positives that will be shell-cast by adding 10 layers of ceramic shell and melting the wax out before pouring metal

I successfully cast the chest plates this fall (see Shell Casting Success), but after many casting attempts on hip bones this winter, I finally ran out of slurry. I can't order more because it would arrive frozen, resulting in permanent chemical damage.

Issues included areas that cooled too fast, porous surface, and pieces of the mold breaking off prematurely:

So, I am switching back to box casting. Here's the breakdown of the parts I have left to cast:

Shell casting with SuspendaSlurry

• Hip Left
• Hip Right
• Chest Base
• Shin Snockplate Left
• Shin Shockplate Right

Box casting with UltraVest

• Hip Bottom Connector
• Spine Top
• Spine Bottom
• Spine Middle Left
• Spine Middle Right
• Foot Upper Shock Plate (2)
• Foot Shock Plate (2)

I also started working on polished sheet metal bracelets to attach arm bones without using elastic belts or gauze (like in the movie).

The prototyping session:

The parts I uploaded to RSM RapidQuote:

I have some mixed news from my attempt this weekend. I got all the data, but the act of observing the temperature and filming combined with more trouble from my regulator caused a decline in casting quality. I suspect it mostly came down to metal that got too hot, thus absorbing more gas from the atmosphere. I also had to move the camera and take laser temp readings, so I didn't remove the mold from the kiln as quickly as last time, and didn't pour as quickly.

First three attempts on the graph was me messing with camera and lights to try and raise "production values" so I left the crucible in the kiln for too long. The last attempt the crucible was in the kiln for about the right amount of time, but the kiln was over-fed by propane.

This week I am sick, so next week I will retry all of this and hopefully have some video worth publishing. I took some time to setup lights, and the video quality was significantly better - next time I will already have that experience so I can setup lighting quickly and before doing anything important to the casting process.

I got a USB temperature logger that works with my K-type thermocouple, so I can overlay a live temperature feed on my next metal casting video.

Here's what the output text file looks like when opened in the app that comes with the logger:

...and this is the raw output. CSV with sample ordinal, date/time, temperature in F, high alarm, and serial number

Today I nailed down the shell casting process (with a great amount of help from The Home Foundry) I can use to finish off remaining parts.

...without pre-heating:

...with pre-heating:

I followed advice on building more shell layers, pre-steaming the pressure cooker before putting in the shell, steaming for a short time (30 mins instead of 2 hours) and repairing cracks /adding another shell layer after vitrification. I have one final problem with a frozen surface in parts of the cast. Here's the video of this attempt:

Here's the frozen effect. I poured at 950-970 and I skimmed a film of metal off the top, but it filmed over just as I was pouring.

Another iteration of sprue planning for the chest pieces: https://github.com/01binary/sprue-planning/blob/master/chest-sprues.stl