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Over the last few months I've been developing a construction technique for my entry in a design competition. I can't share the actual design itself, sadly, but I can share the process. So I did the whole thing again, this time with a couple polyhedral dice models.

First, a tessellated shape is created in a 3D design tool such as Blender. This is exported and opened in Pepakura, which takes 3D models and "unfolds" them so they can be printed and cut out as papercraft. Instead of paper, however, we're going to get it waterjet cut out of 14 gauge steel sheet -- including the score lines to get it to bend into shape properly. Then we'll weld it together, grind it up all pretty like, and do a surface treatment.

Step 1: 3D Design

I did my designs in Blender, though any 3D design tool could be used as long as it can export STL files. Because we're working with steel sheet, the shape needs to be made entirely of flat surfaces -- it should be tessellated like something in an early 3D game.

The final object will be slightly larger than the shape you designed. Following this process, we basically wrap the design in steel, so the final product ends up being larger by twice the thickness of the metal you end up using. On more complex designs, this can be important to remember, particularly if you have to 3D print jigs to help with assembly.

Once you are satisfied with the design, export it as an STL and import it into Pepakura Designer. (The free Pepakura Viewer won't work, I'm afraid.) Unfold it, turn off tabs, and export the result as a DXF. There are a lot of guides for Pepakura, so I won't get into the details here. If your design has to be split into smaller pieces, you'll probably want to make sure they are symmetrical. which Pepakura won't do by default. Sometimes Pepakura will add cut lines in weird places, due to the model having faces that are even slightly non-planar. I usually find it easier to fix that in the DXF afterwards with a tool such as LibreCAD, rather than fight with Blender and Pepakura.

I've attached all the files used for the dice as an example, both the original objects in Blender and the final, cleaned up DXF files.

Some general guidelines I've learned after many rounds of testing:

  • If at all possible, make sure that only 3 planes meet at each vertex (point). This makes assembly far easier, as there is only one way to fold them together. With 4 or more, this isn't true.
  • Minimize long, narrow faces. (I.e., highly acute triangles.) They're hard to bend into shape because you can't get a good grip with pliers on the very end of the tip where it is the narrowest.
  • We can bend a piece down to any angle we want, but we can only bend it up by about 45 degrees without extra work. Try to minimize bends like that in your design. (See the next section for more discussion of this restriction.)
  • Complex designs will most likely have to broken into multiple sections when unfolded. Think carefully about how they will be assembled to choose where to make the breaks. Those seams are likely to be wider and more obvious, so try to hide them if possible. This is another good way to deal with highly acute creases which are greater than 45 degrees. If you put the join between two sections down there, it's a lot harder to see.
  • Also for very complex pieces, getting the angles of the bends exactly right is critical, as any errors build up and result in huge gaps very quickly. I found the best way to solve this was to 3D print a version of the final shape, and use it to test each angle as you bend it. You can also do something similar to create jigs that fit on the outside, with press-fit magnets holding different sub-assemblies in the correct alignment for welding.
<p>Love these but those of us with no access to a water jet or cnc plasma cutter will have a hard time making them. Doesn't mean I won't try...</p>
<p>I've made basketball sized versions of these using a bandsaw, and painters tape to hold the pieces together.</p><p>I have a gallery of a D10 I welded up here:</p><p><a href="https://krux.org/gallery/index.php/events/Defcon/Defcon-22" rel="nofollow">https://krux.org/gallery/index.php/events/Defcon/D...</a></p>
<p>Also made up a set of D20s which were trophies for a contest I run at DEF CON called Crash and Compile (this the programming languages vs numbers on the side)</p><p>I MIG weld these, but looking to learn TIG welding in the future. I leave the millscale on there, since I like how it looks.</p>
<p>TIG isn't so hard, combination of MIG and Brazing only with a much thinner stick. I am out of practice but its pretty easy to learn. Allows for a huge array of materials to weld</p>
<p>change your metal to a copper or brass plate, and use a jeweler's saw. </p>
<p>Yeah, that would definitely slow things down. I don't have either myself, I just work with a local small shop for a lot of my projects. It can take a couple tries to find someone willing to work with you on weird little projects, though, and it's never very cheap.</p><p>I bet you could get acceptable accuracy with a handheld torch or plasma cutter, at least for simple, regular shapes like these. If you skipped the crease/bend aspect, you could even cut them out with a metal shear if you really wanted to. With the 3-face constraint, you could just tack the pieces together to get a similar bendable joint to figure out the final angles with.</p>
<p>These are stunning, and I totally wish I'd seen this Instructable <em>before</em> I made my <a href="https://www.instructables.com/id/TIG-Welded-Steel-Bowl/" rel="nofollow">stainless steel geo bowls</a>! Your tip about exporting to Pepakura is brilliant -- it would have saved me a lot of time. After creating my 3D model, I <em>manually</em> recreated the dimensions as a vector drawing in Illustrator, ugh.</p><p>Have you tried TIG welding? I think you'd love it for projects like this! It would save you a lot of time grinding because you can just fuse the seams without actually adding any filler rod (no filler = less material to grind down). Have you tried <a href="http://www.amazon.com/3M-SandBlaster-9682-Assorted-Conditioning/dp/B002DUCIZU/ref=pd_sim_hi_8?ie=UTF8&refRID=1CJ1MC7FCXKA1KXXFVPV" rel="nofollow">these 3M Sandblaster pads</a> on the angle grinder? They're my favorite for getting a super silky finish after using an 80-grit flapwheel disc.</p><p>Absolutely love your design, the process details you shared, and how you finished the dice (gun blue is so rad). Thank you for this kickass writeup! </p>
<p>Oooh, I love the stainless look! Very nice.</p><p>I've done some TIG and really enjoyed it, but I've yet to invest in that for my shop. I was originally thinking I'd need one this year for a big project, but I ended up leaving the raw waterjet score lines and just tacking it from the inside. That design had a lot of concavities, so grinding things clean after wasn't going to be an option. Even with TIG, it was going to be super hard to get the welds clean enough to be presentable! Anyway, yes, I totally want one, but I think a real mill will be my next big upgrade. :)</p><p>I'll check out those pads. I definitely need to get better at finishing on pieces. Thanks!</p>
<p>Whoa, I just checked out some of your projects on your website -- loved the GMBLMZ videos! Super rad!! Will you have anything on the playa this year? </p>
<p>Thanks. :)</p><p>Not this year. I already have a big commission due in August, and hopefully I'll be starting an artist residency right about then as well. Maybe in 2016!</p>
<p>would you ever consider making these for people to buy?</p>
Possibly? They'd be pretty expensive, though. The waterjet cutting alone was over $100.
<p>I want these so bad. Great work!</p>
Like papercraft with metal - this is fantastic!
They look great! Maybe you could preserve the open edges if you glue the inside edges with epoxy before you close the last piece. Or weld all before the last bend and fix only the last one with epoxy.
<p>You did there a realy nice polishing job after welding. Very cool project.</p>
<p>Those look <em>very</em> cool - do they actually work as dice, though? How noisy are they?</p>
<p>it would be cool if there an instructables to make your own water-jet cutting instructbles</p>
<p>Awesome Idea !</p><p>the Finish on all three pieces is really nice and crisp, nice grinding ! Also nice to see that you finished it all off with a clear coat. I'm curious if you could slip an Led inside?</p>
<p>Adding a light would be a lot of fun, though I'll have to think a bit about how the battery could be changed. :)</p>
<p>Well something this nice may need a display case :)</p><p>maybe you could build some lighting from underneath?</p>

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Bio: A kinetic sculptor known as Fish. He is currently making a slow, terrifying transition from computer professional to full-time artist.
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