As anyone with access to a 3D printer knows, it's relatively easy to print off custom designs from the printer in a few minutes or hours. However, many people come up short in how to translate these fragile plastic pieces into actual working parts on a budget. This instructable is courtesy of our friend, Evan Daniel, who teaches metal pouring at Techshop RD. All credit for an awesome Saturday goes to him. We took the pictures and generally got in the way. If you are interested in following more of his work, simply click his link to view the latest Instructable he's put together. To make a 3D metal piece from plastic, you will need a few simple tools:

1) Plastic part or model master
2) Sand
3) Molding Box
4) Raw aluminum or other metal
5) Kiln or furnace to heat the metal  (We used Techshop RD's)
6) Cold water to cool off the metal afterwards
7) Baking oven (you can use your oven at home or any oven that heats up to an even 400 degrees)
8) Tongs
9) Protective metal gear: gloves, helment, and apron

        Now, you're ready to make a real cast from plastic in a few short hours without breaking the bank. We cover simple medallions, complex 3D prints like this owl, and compound machine parts. Hopefully this will allow you to do 3D casts of anything you can dream up at home or your local hackerspace/techshop.

Step 1: 3D Print Your Plastic Model

         This first part is pretty simple. Plastibot, Instructables, Techshop, Shapeways, and a number of other services in our area offer competitive rates for 3D printing. If you want ideas or are looking for something fun, I encourage you to check out Thingiverse. We used Plastibot to do ours as we find they have the most detail for the price when doing 3D prints, better than even MakerBot. Plus, they use PLA which bakes out more evenly.
          Again, for your print use PLA, not ABS, as you want something that melts cleanly and is non-toxic. If you have any specific questions, Luis Freeman (owner of Plastibots) who runs our local 3D printer meet-up group every two weeks here is very knowledgeable. These are a few pictures from our March Workshop Event on How-To-Make-3D-Printers from scratch. Lots of fun all around.
         So print in hand, what do you do next?
<p>If I'm trying to cast a set of accessory drive brackets for an engine, which will need to have bolt holes lined up fairly precisely, should I scale up? or just print actual size?</p>
<p>For an even easier burnout, there is also a 3D printer compatible wax filament available. This would allow you to use a hot knife for final smoothing/shaping and makes for pretty surfaces if you employ an investment to the burnout mold before casting. A quick Google search will bring up a couple suppliers.</p>
<p>Woah. I know what I'm spending my next paycheck on.</p>
<p>game changer!! Thanx!!!</p>
<p>Forgive me if you answered this, but what about scaling the master up for size loss during the process? Is there a formula or rule for how much greater in scale the master should be for a perfect replica? Great 'ible btw. TechShop Rules! Come to Philly!!!! </p>
<p>the standard formula for patternmaking in aluminum casting is to allow 1.08 to 1.12 oversize plus machining tolerances. This website is helpful for the calculation for other metals that you may cast as well:</p><p>http://www.shelmetcastings.com/shrinkage-allowance-for-metal-casting.html</p>
<p>They should be 1 to 1 ratio for this type of sand casting, and if not, the change in factor would pretty much be negligible. If you're needing that level of precision, you'd need to use a completely different method. </p>
<p>Great. Thank you!</p>
<p>Could anybody help me out real quick? I am looking for greensand to use for my molds as I am a real beginner at casting, but I dont know where to buy a good type or what I could DIY it from.</p>
<p>https://www.youtube.com/watch?v=tH-PaNugz9w Use playsand</p>
<p>This is something I really want to get into (as a Lostwax casting Bronze artist, and 3d modeller). Something that occured to me; It wouldn't be hard at all to add feaders/ sprues and vents at the modelling phase, for diffucult pieces. </p>
<p>No, it is very easy. We hoped that this instructable would help fellow artisans like ourselves in their craft.</p>
<p>Thank you for the awesome instructable. You answered a lot of my questions that I had prior to casting and successfully pouring my first time. Thanks again. </p>
<p>Good luck. We have fun. Hope you do too.</p>
<p>Hey, have you considered vacuum forming the PLA before you do lost PLA? You could keep all that hydrophilic PLA out of the sand; I have a suspicion that chunks of PLA aren't completely exiting your molds during the baking process causing gaseous bubbles to show up on your metal. If you vacuum form the positive and add the vacuum form to a green sand or a plaster, you can then carefully pinch out the PETG easier than PLA. This is my method which works decently for convalescent shapes. </p><p><a href="http://www.thingiverse.com/thing:247363" rel="nofollow">http://www.thingiverse.com/thing:247363</a></p>
<p>Haven't tried vacuum forming, our machine for that is a bit temperamental for that. It's easier for us to print multiples than use vacuum forming.</p>
actually waiting for abut 4 hours is a safe bet. u dont wanna burn thro on your gloves. i was a union welder. 4 a few years. an burn thro is pain in the butt.
<p>Thanks for that, we waited an hourish, but I think that a longer wouldn't hurt. Cooling time is always a problem in industrial operations.</p>
waiting over night if your not in a rush to crack your piece. or if your in a rush put the item in to a fridge to kool off.
where are the safety glasses he supposed to be wearing.
I would think that an IR thermometer would be a great addition to your toolbox at this point. Suggestions?
An IR thermometer is overkill for this. All you need is a metal stick to swirl around in the molten steel and check that it's melted like making candy consistency($1-2 at any Lowes or Scrap Yard). We've had the same stick for daily pours for almost 3 years running now. You can see it in a couple of pictures.
I just meant to make sure that it is cool enough to handle at the end as an extra safety precaution for those that would want such a thing. Just as a suggestion reinforcing the whole &quot;hot aluminum looks just like cool aluminum&quot;. <br><br>I agree that for melting, surface temperatures of the molten metal are useless.
Hey guys love this, im trying to cast some arrowheads this method, but i cant get a 3d print of what i wants, can you guys help me??
Shoot me an e-mail at: gnpage3@lisashay.com with specifics. I bill hourly for spec design work, we can discuss details to see if I'm in your price range or not for the job.
I have not tried this with PLA masters, but with wooden masters you can lightly coat them with a thin film of PVC/PLA glue which smooths out the gaps and lines. This should work on a 3D printed master. <br>
Interesting, I normally just sand them down, but will have to try this. The model here has not been sanded as wanted to be as realistic as possible to the quality you can get starting out on a budget.
An important notice to users new to aluminum casting is that hot aluminum looks just like cold aluminum. It does not change color like many other metals.
Excellent instructable! I have one comment to add though: While it very likely doesn't matter for a visual/artistic application, quenching non-ferrous metals (i.e. Aluminum, as used here) makes them softer than simply allowing them to cool naturally, which could be beneficial if you have sanding or further machining to do, but could cause problems if the cast parts need to withstand some stress. This is the opposite of what occurs in most steels/cast irons, because the martensitic reaction, as it is called, has different results in non-ferrous metals. Then again, by the time the casting is free of the mold it has probably already cooled enough to avoid softening, but for those high test applications even a little extra strength can help. Hope that helps!
Nice work. For the pitting in aluminum you might try cedar chips in in the smelted metal. A tip I learned from an old geezer who really knew his metals.
Very well done instructions and great pics! Do you add anything special to the sand to get it to keep its shape, or does just getting it wet do the trick?
It is definitely not just sand and water. The water-based sand for casting is known as &quot;green sand&quot;, and typically consists of a sharp sand, bentonite clay, and water. Green sand is a major staple of the casting industry.
Hey Tomdf, just getting it wet does the trick for us. However, casting sand comes in two types water based and oil based so you should look at the directions on the back of your bag to see what you have. Oil sand generally is ground finer and has more detail to it as a result, but more expensive and requires more maintenance. Not as easy for the beginner. You can compare and contrast the detail on the two here: http://www.foundry.ray-vin.com/k-bond/k-bond.htm
Very nice. <br>I notice that even the detail of the printing layer line (scale) do show on the finish product. <br>So I guess it's a good idea to send the printed model before sand casting. <br>Tony
Mmmm, actually I find the metal is easier to work with as it does not break as easily as plastic. The metal will clean up nicely after you cut off the sprue and polish it. What you are seeing here is a raw form pulled directly from mold before cleaning. See this other instructable on bronze casting if you want an idea of what it will look like after cleaning: https://www.instructables.com/id/Bronze-casting-your-3-D-print/step19/Final-Product/. If fine detail is important to you, you should see about using oil based sand instead of water. It can generally pull the details off a quarter and is used in jewelry work. You can buy a pretty big bag for $25 off ebay.
However, if you want to sand beforehand, it is a perfectly respectable way to go. Just realize you will have to do it twice.
Very good work!

About This Instructable




Bio: Hi, we're Dara and Nash. Industrial designers, tinkers, and mayhem builders. Follow our travels.
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