This plastic molding project started when I could not find a plastic toroid
(i.e., a hollow donut-shape) part I needed for one of my new projects. First, I
needed to build a mold. I used my lathe and my lathe duplicator to build the mold's
inside and outside pieces.
This video shows turning the inside mold piece and cutting out the outside mold piece. I used white oak for both mold pieces. The outside edge of the mold is 10 inches in diameter. The mold is built to produce half a toroid that is 1 inch in diameter. | ||
Next, I molded a plastic test strip to get an idea of the heating time, temperature, and pressure needed to make a plastic molded part. The plastic I used was purchased from Home Depot. The pictures on the right show the complete mold and mold press I used to make the first test piece. This test piece taught me that I did not heat the plastic long enough. Two of the test piece's edges cracked under the pressure of the mold press. I also learned that I would not need any kind of release agent applied to the mold because the plastic did not stick to the mold. | ||
This part of the process involved preheating my barbeque grill to 300 degrees and then heating the plastic on the opposite side away from the direct flame. I used an aluminum cookie sheet and a piece of parchment paper to keep the plastic from sticking to the cookie sheet. I heated the 12 inch square piece of plastic at 300 degrees for 10 minutes until it became soft and malable. Next, I slid the plastic sheet off the cookie sheet and pressed it with the mold. The video on the left shows this process. The parchment paper and The 'Ove' Gloves are a helpful tip. | ||
Finally, after waiting about 10 minutes to let the molded plastic cool, I removed the molded piece from the mold. The video on the right shows the removal and completed formed piece of plastic. I molded several of these plastic pieces. I put each molded piece in the bottom half of the mold and trimmed them using my router duplicator. I then attached two halves together to finish making the plastic toroid. |