Exoskeleton suit replica from the movie Elysium in Autodesk Inventor, 3D printed and investment cast out of Aluminum
I designed and printed all of the parts, machined pistons on a metal lathe, and sewed a harness. Now I am working on casting all of the plastic parts out of Aluminum using the investment casting process.
The printable STLs are available here and on GitHub. See the assembly instructions if you want to put together one of your own.
Here's what metal casting this beast looks like:
I've been working on a custom vacuum assist chamber for casting large parts:
I also got a 360 camera so now I can video blog & live stream the work on this project in VR. The editing should also be fun.
Lastly, I am continuing to make rubber molds for the remaining parts:
More two-part molds for chest plates. Casting them in metal will require welding a custom steel flask because they are the biggest parts I will have to cast yet.
Started a new two-part mold for shoulder connector heads:
A batch of four flasks with connectors & wrist clamps:
New vacuum setup with fixtures still working well:
Last week I re-cast two parts with better detail and completed four other parts I already had molds for.
I also started working on casting some of the largest parts: hip and chest plates
Left chest plate two part mold (probably just the first draft, as I am still learning how to make these)
I also ordered a new batch of risers with inline ceramic filters.
Finally, I started working on an investment casting article. I want it to be the best reference for DIY investment casting on the Internet, so I'm taking time with reviews, edits, and graphics. Seeking feedback from anyone here:
I've achieved the highest quality casting results possible with my setup, so I am learning how to use a FlexShaft this weekend to finish parts after cutting them off the sprues:
Also casting wax parts to begin another metal casting batch:
I did a detailed inventory this weekend - I am going to cast between 16 and 26 parts (out of 245) and fast-track the rest through CNC. I am glad I built out my foundry infrastructure, but I still want to finish this project in no more than a year. So far I have 3-4 casts ready to cut off the sprues and start polishing.
The last two fixtures got fused together because the metal filled the cavity where pipe diameter didn't quite match the flask. I managed to beat the chunk of metal out of one of the fixtures, but both got destroyed in the process.
Just when I was in talks with a plant that manufactures custom riser/filter combinations from CAD drawings, one of the engineers here at the hackerspace got interested in the problem and helped create a fixture that worked to increase casting quality:
The new fixture uses a ceramic blanket and more precisely machined & welded pieces (now I know how to weld!)
This weekend I finally completed fixtures to increase the casting quality. After refractory which cracked and fell apart, clay which exploded in the kiln, CeramaCast which fell apart despite the high price, and finally a cost-inefficient CNC quote, I iterated onto something that works.
I estimated the CAD model used for the CNC quote with steel pipes of diameters stocked by the nearest steel yard - features like bevels, tapers and 1-piece construction had to be given up but the resulting cost was around $90, down from $900 from the CNC process.
The inner pipe sized to accept the riser is held inside the outer pipe that connects to vacuum flask lip with 1/2" screws. The holes took two weekends to drill and tap, but the result is holding well. The cavity between the pipes is filled with refractory. which no longer needs to hold together by itself.
The original model quote (it would be two of those):
Ceramacast.
Caramacast after hardening. Those broken pieces are worth $300, pretty unpleasant.
The experiment with ceramic fixtures made out of pottery clay failed because the clay shrinks when drying (and especially during firing) - I mounted the clay onto steel flasks to try to imprint the flask surface on the inside which meant the fixtures had no available space to shrink and blew up in the kiln.
Plan B - I am going to try a quality ceramic casting compound for dense and high-detail casts with 1% shrinkage: Ceramacast. This time I will use wax cores cast from silicone molds to create the inside detail - after hardening, no firing is necessary and the wax core can be steamed out.
I found out that the last problem I have with inclusions occurs due to thermal shock weakening the investment (inside the mold) and vacuum then breaking weak pieces off so they end up being embedded in cosmetic surfaces. To shorten the working time I decided to try making ceramic fixtures that have riser & filter pre-inserted. That way I can take 5-6 minutes it takes me to attach riser & filter down to 20 seconds (which is the max time before the thermal shock event).
The idea is to have the crucible and the vacuum rig already in the kiln room, so all I have to do is take the flask out of the kiln, close the kiln door, place the flask in the vacuum chamber, and attach the fixture. Can this be done in 20 seconds? We'll find out, but first I have to fire the fixtures themselves and glaze them. So, I have some involuntary clay art to do :)
Tire polish pictured here is used as mold release for clay.
Assembly Instructions in PDF format: Hackaday (Dark) | Default (Light)
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.
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.
You are casting, right? The alloy is completely different for CNC/machining, 6061.
See https://www.metalsupermarkets.com/7-things-consider-choosing-aluminum-grade/
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.
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?
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 :)
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!
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.
The build was split between Viper for SLA (http://www.agile-manufacturing.com/product/used-3d-printers/viper-sla.html) and sPro for SLS (http://www.agile-manufacturing.com/product/production-3d-printers/spro-sls-series/spro-140-230-sls-center.html). Parts ordered from ProtoLabs (https://www.protolabs.com/3d-printing/).
Valeriy Novytskyy
jupdyke
mclien
UkiyoWeee
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.