Today I'd like to show you an interesting idea I had while tackling an issue with another project (not published): custom pipe fittings made from polymer clay.
Polymer clay is a type of modeling clay that hardens when baked. It typically uses PVC plastic particles suspended in a plasticizer. It's water proof, weather resistant, and quite hard like PVC. It also doesn't droop/deform during heating, meaning that little to no support is needed while hardening.
These properties inspired me to test the feasibility of using it to make pipe fittings for strange connections.
Now, onto the instructions!
Step 1: Tools & Materials
1. Polymer clay (I used the Premo Sculpey brand).
2. Corn starch, talcum powder, etc. (Trust me, it makes things much easier).
3. The piping you want to make a fitting for.
4. Whatever you want to connect the pipe to. (In my case, small check valves)
1. A drinking straw.
2. A kabob skewer.
3. An oven safe pan to bake the clay.
4. An ink pen (or any long narrow cylinder, really).
1. Glue, if you intend to permanently attach the fitting.
2. Heat resistant supports: it's not required for most things, as long the the clay is thick enough. Thin, or complex parts could benefit from these.
3. A set of clay working tools: the "tools" I listed above will work, but a real clay tool set would be easier and more reliable.
4. Parchment paper: powders work fine for getting the mold to release, but these do sink into the clay's surface. This can potentially alter the clay's properties.
5. Polymer clay glazes: these can be used to create different finishes and fill imperfections in the surface of the clay. I didn't use any, but they do have useful applications.
6. A seperate oven for baking the clay: Most polymer clays aren't harmful as long as you DON'T OVER BAKE THEM. While still relatively safe, burned polymer clay can release compounds that can linger in an oven. A small toaster oven might be a wise investment.
Step 2: Preparing the Clay
Polymer clay starts out rigid and brittle; it requires kneading (called conditioning) before it can be shaped.
Now that our clay is conditioned we start by rolling it into a sphere. Next, we gently press the top and bottom of the sphere flat, while also smoothing the side; basically we should have a thick, wide disc. Finally, we use our ink pen to press matching grooves into each side of the top, leaving a raised middle part.
Note: the last part isn't necessary, but it uses less clay than other shapes.
Step 3: Shaping the Details
Begin by cutting a hole straight through the part on top, using a drinking straw. Then use the straw to expand the holes on either side by gently rotating the end of the straw in a small circle inside the clay, pushing the clay outward into a larger circle; do the same on both sides if necessary. Test fit your parts, carefully pressing the clay around them for a tight fit.
Now with the parts still in the clay (to maintain shape), place the bottom of the clay against the open end of the pipe.
Gently smooth the clay down the sides, being careful to keep the thickness roughly even all the way around. Smooth over any cracks or creaves in the clay, as these will be point if weakness after baking if you don't. Carefully remove the pipe from the clay, being cautious about not warping the opening (if the clay is nice and thick, this is only a minor issue).
Now we make our final cut with the straw, pushing into the center of our pipe connection side so that we intersect with the hole leading to the other connections. If the clay doesn't neatly come out of the hole use a kabob skewer to prod the left over clay out of the way.
Note: You may need to apply talcum powder (or corn starch) to the pipe and other parts before they are inserted into the clay to insure they slide back out easily.
Step 4: Baking the Clay
This brand recommends baking at 270 degrees fahrenheit (132.222 degrees celsius). The length of time is based on the thickest part; 15 minutes for every 1/8 inch (3.175mm) of thickness. So since the center of my fitting was about 1/4 inch thick vertically, I baked it for 30 minutes. Once baked allow the clay to cool down on the baking pan. Moving it before it has cooled sufficiently may damage the clay (it could still be setting).
Once completely cooled it's ready for use; attach your pipe and other connections, and off you go!
Step 5: Conclusion
I hope you found this instructable interesting and useful. As you can probably tell I've only just started experimenting with this technique and as such it's a little rough. I'm confident that with some refinement and better methodology this will prove to be extremely useful in future endeavors.
Thanks for reading, and if you have any feedback I'd love to see it!