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Elysium Max Exoskeleton

Exoskeleton suit replica from the movie Elysium in Autodesk Inventor, 3D printed and investment cast out of Aluminum

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The motivation was to create several exoskeletons for band members of my next (industrial metal) music project. I like the "hacked together" look of the exoskeleton worn in the movie by Max Da Costa, so I chose to replicate that one. In the future I would like to create and sell original pieces, like what http://www.bionicconcepts.ca/ is doing.

Electrical parts include two fans in the chest piece and lighting setup throughout various exoframe bones. I decided not to worry about actuators due to movie-look and time constraints (it has taken 3 years just to get to this point), so this remains an advanced replica prop.

I 3D-printed and finished all of the parts last year, machined pistons on a metal lathe, and sewed a harness. Since then I've been working on casting all of the plastic parts out of Aluminum using the investment casting process. There is no paint on the plastic parts since they are only used to make the wax positives, but the finished suit will be gloss black.

The printable STLs are available here and on GitHub. See the assembly instructions if you want to put together one of your own. Since many of the parts are large, they will have to be sliced into halves and quarters in your 3D printing software and glued together after the job completes.

Here's what metal casting this beast looks like:


Standard Tesselated Geometry - 45.85 MB - 02/11/2017 at 18:56

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  • Getting rid of bubbles and inclusions. Automation.

    Valeriy Novytskyy10/09/2017 at 06:37 0 comments

    To fight bubbles embedded in the casting I got a spray bottle to apply VacuFilm on the wax models more evenly - this worked and I got a thin mist layer instead of large drops as when using the brush.

    I also got a new large vacuum chamber for degassing before and after investing the wax model. I tried to do that with the vacuum oven for a long time (it was large enough), but after using it for wax, it no longer pulls full vacuum unless it's hot. With the new chamber, time to full vacuum is short enough that I can vacuum twice, all while agitating aggressively with the vibratory tumbler.


    The resulting casts no longer have bubbles stuck inside concave geometry. There are actually a few bubbles on convex geometry (perhaps just a spot I missed with VacuFilm) but those tend to be simple to just grind away.

    The last problem are the inclusions - and I noticed that making sprues that are bent several times before reaching their target may be the answer. Kind of like the bent leg of a kitchen sink where all the garbage ends up, they seem to catch inclusions before they get to sensitive geometry. The model that had two of these bends next to each other had the least inclusions of the entire batch (almost perfect).

    Lastly, I automated the investment/water weight calculation to save myself some time & trouble. I wanted to experiment with Preact and Recompose for a while for building small but potent web apps, and I also wanted to see how simple it would be to build a site that's pre-rendered while being very interactive, and hosted in a static S3 bucket on the Amazon cloud. I published the app and it works amazingly well - now I am taking a UI design class and learning Sketch to design the graphics to go with the functionality


    Of course I will mostly be using it on my phone, so I have the mobile comp as well:

  • VacuFilm

    Valeriy Novytskyy09/18/2017 at 15:46 0 comments

    Success in metal casting is achieved through ever-tighter process control. This week I spent many hours on chasing the wax models to remove any small concave geometry left from removal of sprues & scaffolding required to cast in silicone. When wax is steamed out in the pressure canner, any small concave negatives become small investment positives. Even though UltraVest is high quality, a few bits of the material hanging on a thin neck will always break off due to gravity, shaking, or by force of metal entering the mold.

    To take care of bubbles getting stuck in concave corners (the ones I have to leave in because they are part of the design) VacuFilm can be mixed with Methyl Alcohol and brushed on, almost like mold release when silicon casting:

    Here's also a botched test cast from this week - still encouraging because almost the entire model came out this time.

    It's interesting to note that the butt of the model (with the square cross) is blurry compared to the rest of the model because it was partially exposed to the surface. That means to achieve good results throughout, the model needs to be as deep inside the mold as possible, with only a thin sprue leading out. Otherwise it must be mixing with hydrogen from the atmosphere and failing to fill.

  • Casting a large part

    Valeriy Novytskyy09/03/2017 at 18:23 0 comments

    In this one I get to use my new automatic kiln and extra-tall vacuum flask welded out of two smaller flasks. I made too many mistakes because I haven't done casting for some time while improving my tools, but I am seeing small improvements from process control.

  • Burnout kiln hooked up

    Valeriy Novytskyy08/17/2017 at 19:43 2 comments

    The new burnout kiln has finally been hooked up to 30 A / 240 V outlet, which I routed to a fusible safety switch, which then goes across the wall and the ceiling to the breaker box. After so much time spent routing EMT (electrical metallic tubing) conduits, my brain is randomly focusing on them everywhere I go and naming the components. I also had to cut off the kiln's power plug and replace it with another, NEMA 10-50.

    The homebrew ventilation visible here was a result of intense labor to make a 3D model of the duct in Inventor, unfold it using sheetmetal functionality, export the sketch to Illustrator, and finally print it at 5% size. I projected the print using a tracer projector and got it to a focus state where 1" on Inventor drawing was equal to 1" on the wall, then traced on sheet metal and cut the patterns out with sheet metal scissors. Common sheet metal screws were used to assemble the final patterns after re-folding them with clamps.

    Finally the switch was pulled and nothing exploded. The kiln emitted a long beep and the Sentry controller came online, burning with a demonic red glow. Today I am starting the first over-night (13-hour) burnout.

  • Updating Tools

    Valeriy Novytskyy08/02/2017 at 15:29 0 comments

    This week I got the vacuum oven back from service and went to a trucking company warehouse with an axe and a crowbar to retrieve my new burnout kiln (they failed to deliver 3 times). I broke down the box in their parking lot and dragged it into my car, finally making it to the hackerspace to place both on the new fireproof desk that once belonged to National Guard.

    The extra-long flask fits inside the programmable kiln! Now I need to complete a custom VAC duct system and we have to put in a new electrical system for power requirements of the burnout kiln.

  • New Tools

    Valeriy Novytskyy07/29/2017 at 22:08 0 comments

    I love new tools, especially ones that improve the process. After consulting with a jewelry teacher, I got a pressure cooker for steaming wax out of invested flasks:


    The steamer collects the wax on the bottom as a large disc that looks like a vinyl and you throw the disk away (or re-melt) after a 2-3 hour steam cycle on hi. Flasks go in the kiln with wax already removed, and the only thing left to do is get the water out of investment so there is no scary fire or heavy black smoke.

    I also contracted a welder to make two tall 4" flasks out of four short ones. This takes care of all the long parts in the suit, mostly arm bones. I will still need custom box flasks welded for the chest piece and the hips because those are tall and wide at the same time.


    Since the major reason I still have defects are internal mold fractures, I got jewelry waxing tools to perform detailed cleanup on the wax parts before they are invested:


    ...another reason was that water still left in the investment if not completely evaporated during the 300 F step will start boiling at 700F and generate steam that will push its way out of investment pores and take pieces of surface detail with it, destroying cosmetic surfaces. For larger parts, 300 F has to be held longer.

  • Quest for quality and repeatability

    Valeriy Novytskyy07/18/2017 at 19:47 0 comments

    Looks like there are still a few issues with repeatability left to solve but I got pointed to new tools and processes which might help. I also had a lengthy discussion with a Rio Grande dealer about how I am doing my investing, so I think I have a good chance of increasing the number of good casts out of each batch.

    Some interesting things that came up:

    - When putting sprues on, both the sprues and the model have to be very clean (i.e. trim all imperfections with hot knife and exacto knife). Investment will get in those and then break off during burn-out, fall on cosmetic surfaces as dust and jagged particles and get imprinted in the casting.
    - Fewer sprues is actually better, because that will create less turbulence of streams of metal mixing together and possibly destroying more investment on the inside.
    - More investment & less water for heavy pieces.
    - Instead of doing the complete burn out inside a kiln (which so far has cost me $300/month due to having to replace burnt out coils, not to speak of black smoke that gets everywhere), flasks can be boiled in a pressure cooker/canner, which gets most of the wax out in a very clean way. It can then be collected from the bottom of the cooker in one piece and thrown away
    - Jewelers use flex-shaft tools for chasing and finishing work, which are stronger than dremels - got one to try it out
    - Got sticky wax and a wax warming pot (that looks like a little food tray with sections and a built-in hot plate). Apparently sticky wax, besides helping to put the sprues on quicker, is a much stronger bond after cooling (not flexible). Got a hot knife also (waxer pen with tips and a wire going to the power supply with potentiometer).
    - Got more pre-made sprue sizes
    - Longer burnouts are necessary both for larger flasks and for detailed parts. The longer burnout will harden investment more and not let metal destroy small details when swirling inside.
    - It's good that I've been using risers, that still helps even with vacuum casting

  • Metal casting success

    Valeriy Novytskyy06/02/2017 at 05:22 0 comments

    After a very long year of experimenting with metal casting techniques, I finally got perfect casts using the vacuum process. Now it's a matter of shotgunning all 300 parts of the exosuit using the same method, and then a few more months of finishing and painting.

    The last problem turned out to be the lack of control over the mold burnout and baking process which is very crucial to obtaining quality. Ultravest instructions need to be followed to a T, especially the part where you hold it at 1350 F for two hours to ensure there is no water left in the mold, which otherwise turns into steam and destroys the metal surface.

  • Vacuum metal casting

    Valeriy Novytskyy05/28/2017 at 17:27 0 comments

    I thought vacuum metal casting would require a giant rig the size of my car, or that jewelry casting machine that can only do tiny parts like rings. Turns out it's both cheap and easy to build one for your application! DavidF from AlloyAvenue forums was nice enough to share the details.

    All that's required is a trip to a steel yard to get a pipe and a base plate. I also got a barbed fitting (MPT) to connect to my vacuum pump. After drilling a hole in the large steel pipe I threaded it with an MPT tap, screwed the fitting in, then used RTV (high temp silicone sealant 300 F) to attach pipe to the base plate and put some RTV around the fitting as well. Flanged perforated flasks (ordered from jewelry supply or custom-built) go in the pipe. The flange lip hits the top of the pipe and a silicone gasket (also bought, or you could use RTV again) provides a vacuum seal. When investment mold is inside the vacuum flask with wax model already melted out, just start the vacuum before pouring metal. Hydrogen and other gases that cause porosity are sucked out through dried investment walls, and the metal fills all the details.

    As you can see I still have issues with temperature control, and possibly the way I melt the metal and the alloy I use, but results are markedly better, especially the fill.

    To summarize here:

    - Go through the models you want to cast, and note bounding box dimensions

    - Buy or build (if on budget) perforated vacuum casting flasks with flanges, that would fit those dimensions. Rio Grande offers a variety of pretty big (up to 8") diameters. Anything bigger, you would have to weld & drill a custom vacuum flask.

    - Buy silicone gaskets along with vacuum casting flasks, or just use a layer of RTV sealant if on budget. I also recommend graphite gaskets on top of silicone (for the side that touches the very hot flask) and a rubber button base for wax models, because it creates a super nice funnel shape for pouring.

    - You will need a fairly strong vacuum pump (~7 cfm), Rio Grande has those too, or you can restore a used one if on budget.

    - A silicone tube to connect vacuum pump to the vacuum rig

    - Build the vacuum rig as above. Use steel pipe & base plate dimensions to ensure flasks can slide into the rig with minimal clearance. I got three sizes to be safe: 3.5", 4" and 8" to fit 95% of all exosuit parts.

  • Better metal casting results

    Valeriy Novytskyy04/17/2017 at 00:58 2 comments

    It's still very early in the game, but after reading & following some advice I got the next jump in quality:

    • Keep metal cooler. The hotter the metal is at the time of pouring, the more it will bind with air & water in the atmosphere to create hydrogen inclusions, which results in a horrible looking surface.
    • Keep metal from getting too cool. Wrap the crucible and/or the ceramic mold into a ceramic blanket to curb heat loss on transfer.
    • Pour slowly (just like with wax) to let gasses escape from the vents while metal is going into the sprues.
    • Maintain a large thermal mass of metal just above the mold, to increase the force pushing the metal inside the mold. This is a low-tech alternative to vacuum casting or spinning centrifuge. The result is improved fills on thin and intricate mold cavities.
    • Carefully degass with tablets just before the pour
    • Fire ceramic molds as long as possible (but not higher than 500 F) to remove all water. Any remaining water will convert into hydrogen upon contact with molten metal and result in gas entrapment.

    Parts being extracted and quenched:

    Wax casts prepared for box molding:

    Another batch: parts attached inside respective boxes for pouring UltraVest investment:

    Removing from boxes after investment solidified overnight:

    Wax burnt out and investment de-watered:




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Discussions

Dan DWRobotics wrote 07/29/2017 at 22:22 point

Very interesting project. I really enjoyed that film. Interesting to see that you are casting your own parts from aluminium. The actual casting part is really difficult, I know because I have tried it. Since you are putting in so much effort into making it from metal, are you not tempted to make some of mechanisms function like a real robotic exoskeleton? With assistive actuation and motors? great project, will follow with interest.

  Are you sure? yes | no

Valeriy Novytskyy wrote 07/30/2017 at 04:25 point

The secret reason I am spending so much effort on this prop is that my next project is a BD Cheetah clone, so this is a great opportunity to explore mechanical engineering and industrial design. I am not into bipeds at the moment, just want to build quadrupeds, but we should connect since we are both into robotics

  Are you sure? yes | no

Liam Mason wrote 07/12/2017 at 14:16 point

What grade Aluminium did you cast it from? I'm intending to make my own exoskeleton design. However, I'm not sure on the best choice of Aluminium from the extensive variety available.

  Are you sure? yes | no

Valeriy Novytskyy wrote 07/12/2017 at 14:42 point

I am using this right here (closest to 356 alloy):

http://www.ebay.com/itm/ALUMINUM-INGOTS-43-lbs-26-to-30-ingots-Casting-alloy/182166261652

The quality is a lot better than you would expect - I originally bought this as practice stock, but then realized it's actually top-shelf casting stock sold cheaply :) I get as-cast surfaces that are literally polished with no further work required.

Lastly, I did consult with two mechanical engineers here at the hackerspace (one who works at Intel and one who works in a local machine shop), and they both pointed me to 356.

  Are you sure? yes | no

Liam Mason wrote 07/12/2017 at 14:47 point

Thank you for the help :)

  Are you sure? yes | no

Valeriy Novytskyy wrote 07/12/2017 at 19:20 point

You are casting, right? The alloy is completely different for CNC/machining, 6061.

See https://www.metalsupermarkets.com/7-things-consider-choosing-aluminum-grade/

  Are you sure? yes | no

Liam Mason wrote 07/13/2017 at 00:45 point

Ah right. No I haven't decided yet on whether I would cast or CNC/machine it out, while CNC is much more expensive I don't really have the appropriate tools/location to cast. 

  Are you sure? yes | no

Liam Mason wrote 07/13/2017 at 01:12 point

I've also been looking around for months but can't seem to find those type of pistons/hydraulics used in the joins of your exoskeleton. Is there a specific name or site I've missed? Or did you get those custom manufactured? 

  Are you sure? yes | no

Valeriy Novytskyy wrote 07/13/2017 at 03:53 point

I manufactured the pistons, see page 6 of my RPF build thread:

https://www.therpf.com/showthread.php?t=212832&page=6

...through middle of page 7:

https://www.therpf.com/showthread.php?t=212832&page=7

I don't regret learning how to use a metal lathe, but in retrospect this was the wrong decision for the project. Lathe was $500, tube stock I ordered was around $500 as well, and I spent 2.5 months, about 45 hours per week, machining until late night and coming home each day looking like a coal miner. Then I spent another $100 taking them to a painting plant not to mention I had to wake up in the middle of the night to make it back in time for work.

Knowing what I know now, I would say either low-tech them if you are going for appearance and use a convenient size of pipe (2 diff. diameters cut & inserted into each other), or post for help on a CAD forum to learn how to make drawings and submit them to a machine shop (and have them do high-detail matte/gloss indoor electro-coating). Price will likely be the same for machine shop as doing it yourself, BUT you get to spend all that time hanging out with friends instead of machining and crying :)

  Are you sure? yes | no

joe wrote 04/04/2017 at 15:10 point

So with these files being online.   I want to ask first.  Is this design an open source design.  I think it is amazing looking and would like to make one myself.  I  don't think i can come close to getting this level of detail.  Also this suit looks amazing!

  Are you sure? yes | no

Valeriy Novytskyy wrote 04/08/2017 at 15:22 point

Prop replicas are never completely open source, since Sony owns the right to the movie and all props (you are always a voicemail away from Cease and Desist). However, all the files have been created from scratch and a few parts differ from on-screen appearance (thus it's not an exact copy) so as long as nobody's crazy enough to sell it they will likely let it slide.

  Are you sure? yes | no

ConsultingJoe.com wrote 02/26/2017 at 14:50 point

what 3D printer did you use

  Are you sure? yes | no

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