I had been thinking about giving one of the Gingery injection molding machines a try for a long time. I was hesitant to try because I didn't know how well it would work (I hadn't seen any of the machines online). I also didn't have a good method of creating molds for the machine. After I purchased my CNC milling machine (Sieg X3) I had a tool to produce molds of significant complexity to make it really interesting so I decided to give it a try.

- The injection molder attachment is designed to be used with a drill press with a spindle travel of at least 3 inches. I use a drill press stand that was originally intended for mounting a hand held drill. My drill press stand does not have a stroke of 3 inches but I found that if I set the stand height so I have to lift the injection cylinder over the mold I can still eject the last bit of plastic from the cylinder. - In the book when the depth of holes is given the depth is to the point of the hole not the depth of the full diameter. - So far I have made all of my molds out of aluminum using a CNC milling machine but the description for the injection molding machine book states that molds can be made with castable epoxy or plaster of paris. There are not any details of how to make molds out of these materials in the injection molding attachment book. The injection molding machine book may have more details (I don't know). The description of the book does say that it has instructions on how to make a knob mold (used for the adjustable table in the injection molder) and a mold that creates a small plastic container with a snap lid. These items are not in the injection molding attachment book. - The video shows that I used a toaster oven to preheat the mold. I have found that preheating the mold is not required for the parts I have been making. All of the parts pictured on this page have been made without a preheated mold. I am guessing that for longer thinner parts preheating the mold will help prevent the plastic from hardening before the mold is filled. - A lot of my molds look spotted and the parts I make have little nubbins sticking out of them. The material I use for most of my molds is aluminum that I have melted and cast into billets. The billets tend to have porosity in them. When I inject the plastic into the mold the small pores in the aluminum are filled with plastic resulting in the nubbins that stick out from the plastic parts. Since I use scrap aluminum for the molds and scrap plastic for the parts all of the material I use for plastic injection molding is free. Dial Caliper Thumb Wheel Hook with Nubbins - For the hockey stick shaped pen cap below I used a long removable insert to form the inside of the pen cap. The insert proved very difficult to remove for the first molded part. I had to heat the insert with a torch to partially melt the plastic before I could get it off. After the first mold for this part I started rubbing wax from a candle on the insert prior to molding and that worked like a charm. As long as I use wax as a mold release the insert comes out without any difficulty.

Gingery publishing has two books on plastic injection molding: Plastic Injection Molding Machine and Plastic Injection Molding Attachment for the Drill Press. The first book details the construction of a full injection molding machine including the mechanism used to push the ram into the injection cylinder. The second book features a smaller machine that relies on an existing mechanism from a drill press to push the ram. Using the drill press attachment design reduces the complexity and space required for the project. For these reasons, I decided to build the drill press attachment injection molder. The temperature control for the heater is also different in the two books. The drill press attachment book uses a purchased PID controller, thermocouple and purchased cartridge heaters. I do not know the details of the other controller because I do not own the book.