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Step 1: Photoshop!
This step is pretty simple. I needed to create a nice, clear reference image to trace in 3d. All I had to do here is increase the contrast and clean up an image of the Bioshock logo I found online. I started by resizing the image so the logo filled the canvas. Then I pulled up the image>adjustments>levels menu and slid the two tabs in towards the center of the histogram (the little graph in the middle.) This is to increase the contrast so I can isolate the areas of the image that I'll pull out into 3d. Ctrl+shift+u will turn the image monochrome and a little bit of magic with the wand, bucket, and brush tools will get you an image that's ready to trace in SolidWorks.
Step 2: Solidworks!
Solidworks is an incredibly complex and incredibly powerful program for designing parts for anything from cars, to rockets, to blow driers, to buildings. I can't get into nearly enough detail to show the entire process of playing and tweaking to get it just right but I can give a pretty clear outline. If you want to learn the program in more detail there are a bunch of goodvideotutorials on youtube.
I've been using the program for a while so I find it pretty intuitive but it's really hard for a first timer. If you've never heard of it you might consider trying simpler programs like VectorWorks, Blender, or Google Sketchup before hunting around for SolidWorks. That being said SolidWorks is what I've got and what I know so it's what I used.
I started by importing my drawing on the top plane with insert>dxf/dwg. Then I created a new sketch on that drawing and traced over the shapes with the sketch tools. From there it was just a few simple cuts and extrusions to create the logo in 3d. Now all I had to do was scale it down to the right size and save it out as an STL (a common 3d format to deliver to the CAM program.)
Step 3: DeskProto
DeskProto is a nice, simple, inexpensive program for turning 3d geometry into a path a CNC machine can follow. You can even get a free 30 day demo on their site. It takes a lot of practice and experience to get CNC machines exactly as you want them to but they are well worth the effort.
The cool thing about DeskProto is that you can have a wizard take care of most of the work. As long as you're not doing anything super complex you can create just about any simple part in a few steps. When you open a new document the wizard (pic1) will start up automatically. I picked the "Basic 3D Milling" option and then selected "Load Part" (pic2.) After finding the STL I loaded up from Solidworks I rotated it to lie flat along the XY plane (pic3). The next menu I cared about was the "Cutter" menu. I use a special tool for cutting out wax called a profile mill. You can find these at jewelry supply websites and specialty machining tool sites like Bits and Bits. The one I used was called a 15deg conic engraving tool. After selecting that tool I hit "Next" and then "Calculate Toolpaths." That's it. It will calculate how the CNC machine will run to cut out this part with the tool you specified and then you save the NC file it creates to a thumb drive and put it on the machine.
Step 4: Machining!
Ok, so this is it, almost done.
Using the Tormach, or any CNC machine is a matter of trial, error and experience. The part I made was pretty simple so setting up the machine was fairly easy. I started with a piece of purple machinist's wax. I stuck it down to a wooden plank using some contact cement. This means I don't have to worry about the profile tool messing up the table if I accidentally cut through the wax. The machine needs a coordinate on the corner of my wax to set up the path, so I just maneuver the too there, call it the origin and load up the file I just made in DeskProto. The cutting took about an hour and afterward I had to brush all the little wax chips and dust out of the cracks in the finished wax. From here I made a box around the wax and poured in some RTV Silicone. This gave me a mold I could make some copies with. I used red wax (a medium-soft easy to cast wax that's super common and super cheap) to make some duplicates. After cleaning these up a bit it was off to the metal caster.
Step 5: Casting!
I think it's easier to pay to get a part cast in metal than to try and do it yourself. I teach a class on aluminum sand casting, but the devil's in the details. If you want a high quality part it's usually better (and sometimes cheaper) to go to the professionals. I use a small metal casting studio called JR Casting. They're in the bay area, so it was really easy for me to visit their shop to talk about how they did what they did. Check for a lost wax or investment casting house near you. You'd be surprised at how many there are in the world.
I drove the waxes down to JR, they cast them in metal and I got them back a few weeks later. The metal took a little cleaning up and sanding down but it was soon looking pretty sharp. I brazed a pin and some rings on the back to attach the whole thing to a belt. After that I made the metal look old and worn to match the Bioshock aesthetic with gun blue. You'll need some kitchen gloves, a disposable container and some sand paper to do this process. You put your part in the container and let it soak in a little of the solution. After the metal has darkened you rinse it off and can restore some of the shine with the sandpaper to help bring out the detail. If you can't find gun blue around you, you can use a bunch of other solutions. Mine just took some polishing and sanding and...
Step 6: Finished! (and FAQ)
I know you have questions. There are always questions. I'll try and answer as many as I can and provide as many resources for you to explore if you're still curious about all the parts:
- Q: Where did you get the silicone? How did you cast it?
- A: I got mine at Douglas and Sturgess in SF, but you can order it online at smooth-on, freeman, and even Amazon. It tends to be rather expensive but has a long shelf life and is a great mold making material. You can even cut up old silicone molds to use as a filler when you cast new ones. The casting process was super simple. I just built a box around the wax part with some paint stirrers and poured the silicon on. I've got some more detailed tutorials about casting silicone here and here.
- Q: What kinds of wax did you use?
- A: What I cut out was a hard, easily machinable, fine grained wax called machinist's wax. It's pretty cheap and is an awesome material for CNC especially if you want to test out something super fast before doing the final version in metal. I get mine from Progress Tool. To do the duplicates, I heated up red casting wax from Douglas and Sturgess in a coffee cup in a toaster oven and poured it into the silicone mold.
- Q: How do you get metal parts cast?
- A: Feel free to build your own home forge to cast metal parts. I don't really have the time or inclination to do all that just for some buckles, but it's still on my list of life goals. You can mail wax parts to almost any small investment casting studio and they'll duplicate them in metal. You lose the wax (that's why it's called lost wax) but you get back a really high resolution metal part. Be sure to call and ask what kind of metal they cast, if there are any limitations on the dimensions of your part, how they cast it (if you have to make special allowances for sprues) and try to supply them with as much information as you can so they can give you an estimate on cost. I have used JR Casting for several of my projects and have been really impressed. They cast silver, gold, brass and bronze there. The cost of your part will vary on how big it is (how much space it takes up in their casting container or flask), how much labor it takes to get it set up, and how massive it is (how much metal they have to pump in.)
- Q: What is Techshop? How do I get access to a CNC?
- A: Techshop is a kind of gym for nerds. You sign up for a monthly membership and they give you open access to a huge selection of industrial machines, hand tools, workshop space, and cool people. For the more complex machines like the Tormach you have to take a class. Getting time on CNC machines is kind of hard. Although the technology's becoming cheaper and more ubiquitous every day it's still not common to find a CNC machine available to use at the rec center or your local library. Chances are you won't be able to get time on one unless you buy one, build one, have a TechShop near you or know how to get in touch with machine shops and beg your way inside.
- Q: What is CNC? What is the Tormach?
- A: CNC is short for Computer Numerical Control. This means a computer handling something by numbers, coordinates, or vectors. Often this is used to talk about machines that are driven by this architecture. Wikipedia has some pretty good articles. If you really want to learn more there are really good videos on youtube and forums all over the place. Instructables even has several CNC projects as well as Thingiverse and RepRap. The Tormach is a fairly powerful CNC machine, especially at its low price tag of $7000. It lives at TechShop, but was previously employed on Prototype This.
- Q: Steampunk? Bioshock?
- A: Steampunk is an ethos and fashion trend that has really caught on with geeks and makers from across the globe. It's essentially an interpretation of an imagined past where steam technology was never replaced by electronics, therefore you get mad ideas like steam powered helicopters and spaceships. Bioshock is a videogame made in this style. It's a bunch of fun to play.
- Q: What is brazing?
- A: I used a torch and some bronze filler rod to weld on the rings and pin that make this a belt buckle. The process is called brazing. It happens at a lower temperature than steel or aluminum welding but is still very strong.
- Q: Why did you cast it in bronze? I thought brass was the quintessential steampunk metal.
- A: I originally wanted it cast in brass. I like the green verdigris brass gets with age. Unfortunately a lot of metal casters won't get many brass orders so will wait until they can fill a whole flask with parts before casting. I decided I didn't want to wait the month or so it would take to get it cast in brass so I just opted for bronze, which is apparently more in demand.
- Q: How do I get my own?
- A: You can't. At least, you can't now. You'll just have to suffer in envy.