Polycaprolacton (also known as InstaMorph, ShapeLock and maybe other brand names) is a plastic that becomes workable at 150 deg. F. It's hard at room temperature. It's a great material for inventing and prototyping. This Instructable shows you how to make plastic bolts. I made a 1/4 inch bolt for these instructions. I think this is close to the smallest bolt you could make with this material and process.
Step 1: Gather Materials
- 1 x 1/4" bolt
- 1 x 1/4" nut
- a source of 150 degree heat. (stove, microwave, hot plate)
- 1/8 - 1/4 cup Polycaprolactone pellets
- Thermometer (optional, but handy)
- Waterproof work surface that won't stick to the Polycaprolactone.
- Sharp knife or razor blade.
You don't have to use a 1/4" bolt exactly. Any nut and bolt that match could work. I don't think you can make a bolt much smaller than 1/4 inch that's very long and works.
Polycaprolactone will stick to plastic, so test a tiny bit on your work surface before you get going. If you overheat Polycaprolactone it gets stickier. That's a useful trick for other projects, but don't let it get over 150 deg. F in this project.
Step 2: Make the nut
Step 3: Make the bottom mold
Step 4: Take the bottom half impression of the bolt
If you mess with the block it may pull away from the bolt, but you may need to gently work the top surface to get it right. Let the mold cool and make sure you have a good impression and the bolt isn't more than halfway in. Try again if you pushed it in too far or the block pulled away when you worked the top surface.
Step 5: Make the top half of the mold
Step 6: Complete the mold
Put the top half of the mold into the hot water and let it get warmed to 150 deg. F all the way through. It will be completely clear. Take it out and quickly push it down on top of the bolt and bottom mold while it is still very soft. Push the sides down a bit around the edges to get a good seal. Don't work it too much. Walk away while it cools completely.
Step 7: Open and inspect the mold
Step 8: Make the bolt
Step 9: Cast the bolt
When you remove the bolt, there be some extra plastic from the seam in the mold. See the second image. This is also known as a sprue. It's normal and we will fix it next.
Step 10: Clean up the bolt
Don't overheat the bolt while touching up the threads. If you do melt it, just go back to the molding step and try again.
Let the bolt cool and make sure the nut can turn all the way on and off.
Step 11: Testing the bolt
Congratulations. You now have a plastic nut and bolt. The bolt won't be as strong as a nylon bolt of the same diameter. But you can easily make all you need.
Let me know if you find a good use for these bolts. I plan to use them to close project boxes I will also make out of Polycaprolactone.