Introduction: Custom Thermoplastic Battery Holder.
In the last few years, Thermoplastic has become popular in the maker community. It is cheep, strong, easy to work with and provides a quick solution to prototyping. It's known by it's brand names Polymorph, Shapelock, Instamorph and a few others. I recently used it to create a 9V battery holder because I needed one with a smaller clearance and footprint than any available in a store. This project may be nothing special, but I feel the technique I used is worth sharing. By rolling out sheets of thermoplastic, cutting out shapes and "welding" them together, I found an effective and unique approach to this material than that of the classic solutions. I hope you think so as well.
Step 1: Materials and Tools You'll Need:
-Thermoplastic (I use a brand called InstaMorph.)
-Rolling pin (I use a silicone coated one, but wood is fine.)
-Heavy cutting board (Any large flat heavy object. A dictionary might serve quiet well.)
-Pan (The wider the better.)
-Fork (Tongs, Spatula or any kitchen tool for retrieving things from hot water.)
-Rolling pin guide (Any pair of thin long objects used to roll dough, I mean plastic, to a uniform thickness. I used identical strips of stained glass I had laying around. You can use strips of Plexiglas, wooden rulers, BBQ skewers, etc.)
-Pen and paper (Graph paper is most handy, but isn't it always?)
-Wood or silicone cutting surface (To protect your counter and to keep your plastic from cooling too quickly.)
-Heating gun (It might make the welding portion of this tutorial easier, but hot water will also work.)
If this is your first time with thermoplastic, you will find it comes as very small beads (or "nurdles" as they say in the biz). Do yourself a favor and melt about a tablespoon of them at a time into larger pieces and store them that way. This will make a much smaller mess if you knock over the canister.
Step 2: Roll the Dough:
Boil the Water:
-I seriously am not going to waste your time with how to boil water. I am going to say that you don't need the water to boil at all, just be a little hotter than hot faucet water. Fill your pan half way and set the heat to low. Thermoplastic becomes workable at about 140 to 160 degrees F. You can't really damage thermoplastic by boiling it too hot, but it will be dangerous for you to handle, so keep the temperature down.
-Add the plastic to the water. The reason I used a wide pan is so that I can spread the plastic out and it will melt faster. It also helps that as you roll it out and reheat the plastic, the "slab" will fit back into the water and not fold on you. Melted thermoplastic will stick to itself very very well and not let go. This may have unintended consequences and ruin your project.
-Once all the plastic has become transparent, remove the "clump" of plastic with a fork and place it on your counter top or cutting surface. Start rolling it out like pie crust. You'll find you can get a few good rolls in before it cools enough to not want to flatten any more. At this point, return it to the water and reheat.
-After two trips to the water, you'll get close to the desired thickness and you will want to starting using your rolling pin guides. Keep rolling and reheating until the entire slab is uniform in thickness.
-When you're happy with the thickness, reheat the plastic one last time to soften it just enough to be pliable. Place the slab on your counter and let it cool completely underneath a heavy flat object. This will keep the plastic from warping as it cools and provide a level surface from any portion you choose to work with later.
The only material I have found thermoplastic to really stick to is other plastics like PVC. Granite, wood and Formica are safe surfaces and the plastic will release nicely from them. I have also found that you can roll this stuff very thin until it becomes tricky to work with. After about 0.5 mm (0.018 inches) it becomes difficult to keep it from bunching up on itself in hot water. Also, the thinner it is, the more it will warp when cooled.
Step 3: Take the Slab to the Lab:
- A 9V battery is 1.8 x 1 x 0.7 inches. To accommodate this, my battery holder will have 4 parts: a base, two side holders and a back-stop.
-The base will be 30 x 40 mm.
-The two sides holders will be 22 x 28 mm.
-The back-stop will be 15 x 15 mm.
-Draw these squares onto paper (or print them out if you have a graphics program that allows you to do this accurately.) Cut them out and use them as templates to trace the pieces onto the plastic.
I do tend to flip flop from inches to millimeters. When I make small things, I use millimeters so I can get a more accurate resolution of measurement. But I always convert so I don't "wreck myself" at the very end of projects, wondering why two pieces just don't line up. (Again.)
Step 4: "Welding" Thermoplastic:
-For this step, I used a heat gun. I found I had great control over heating just the parts I needed to this way. You could also use a candle for a small point of heat or simply dip the edges of the pieces to be welded back into the hot water.
-Heat the edges of the pieces to be welded until they turn clear. You will want to heat both pieces at the same time. The weld will be much stronger if conjoining pieces are melted when joined.
I know in my photos I am only melting one piece at a time. This is only because I needed my other hand to take the picture.
-Carefully press the edges together gently but firmly. If both sides are still clear when joined, they will weld even if you simply touch them together. Make sure you have lined up the two pieces as you need them to be when joined. Melted thermoplastic is not very forgiving if you mistakenly put two pieces together wrong. You also don't want to apply too much pressure as this will deform the plastic and make your fabrication look "bulgy". This can be fixed later, but try to minimize it at this stage.
Try welding two scrap pieces first so you can get familiar with how thermoplastic behaves when being welded. This will save you from having to roll out, trace and cut new pieces.
-Once you have all the pieces together, you can clean up the edges with a little heat, a craft knife or scissors.
-Place the battery in the holder. If it's a tight fit, heat the inside of the holder with the heat gun or dip the holder into hot water for just a second or two. Put the battery back in the holder and shape the plastic around it.
-Heat the two side pieces and wrap them around the body of the battery. Let the whole thing cool with the battery in place. Once cooled, pop the battery out. This may take a little work, but the battery will release. Don't worry about breaking the holder; this plastic is incredibly strong.
Step 5: Done. Enjoy.
-You can drill holes in the base for screws if you like. If you make something much thicker then this, be careful drilling. Thicker thermoplastic tends to heat up from the drill and melt around the bit. If this is a problem, try a cooling agent like water.
-I have tried to spray paint this stuff, but everything just flakes off when scratched. You can dye thermoplastic in the melting phase with color nurdles if you want a color other than white.
-It becomes difficult to cut with scissors at thicknesses greater than 1/4 inch (6.5 mm). It is very difficult to saw as well. If you need to make something of this thickness, it may be your best best to shape it while it is melted.
-This plastic is very tough. As I mentioned before, I rolled it as thin as 0.5 mm (only twice as thick as 110 weight card stock) and I cannot tear it with my hands yet it is extremely flexible.
Step 6: Other Projects:
As I mentioned earlier, thermoplastic sticks very well to PVC. Using the rolling technique, I made bottoms for PVC tube tool holders. I drilled holes in the tops and used them to organize my peg board. I also made pen and desktop tool holders this way, adding to a project put forth in an instructable by jacco1997 PVC Desktop Organizer. Here's the link: www.instructables.com/id/PVC-Desktop-Organizer/
Thermoplastic is a must have for the maker arsenal. Please share with me and the rest of this community if you have other tips and tricks to make it even more versatile and fascinating!