Plastics Mold

The mold shown in the pictures is an aluminum tube that can be filled with scintillating plastics and then screwed together to create an airtight chamber. The top lid can then be removed and the plug in the bottom can be taken out. By opening up the mold, the puck can then be pushed out through the hole in the bottom. To create the mold with such tight tolerances I had to make sure that I was very careful when using my tools so that the parts would just barely slide together.

With a difference of 0.0005″ between the tubes inner diameter and both of the plugs outer diameter, it was crucial that these parts were machined to be extremely smooth and evenly cut across all surfaces. To create a cylindrical part I needed to use a manual lathe. As far as tools, I used a boring bar which is a metal bar with a wide asymmetrical blade attached to it. To get a smooth finish on the part I would make a cut so that the wider part of the blade would make contact with the part. By doing this action the insert would drag across the surface and create a smooth finish. The only problem with this method was if the tool began to chatter, or bounce around, during the cut. Chatter would create a lattice pattern in the part and would make the cut uneven. However, chatter can be avoided by taking small cuts and being smooth with the cutting motions.

After using the lathe to create the shapes of these plugs I then had to drill and tap the holes into them. These holes allow all-thread to come in and secure the lid to the tube, as well as the tube to the base. The base was an aluminum block with a large hole drilled into it, which was then counter-bored so that the base plug could rest in it and be flush with the base. In the base I also had to drill out three holes, two to be tapped and one to be reamed so that a dowel pin could be pushed in to help locate the mold. The final few pieces to this project were the thumbscrew on top and the rig to hold it to the threading. These were fairly simple to make since the only critical piece was to make sure the two threading holes were a set distance apart. Once all of the parts were made and fit together, two final holes were drilled into the body of the mold at 45° angles so that gas could be added into the chamber without undoing the entire mold.

This project was very time consuming due to the exact nature of the dimensions and the critical spacing between the top and bottom plugs. I learned a lot about patience from this build since each cut had to be taken with slow and shallow cuts and forced me to take my time, being extremely diligent and careful with my decisions. While this project may seem straight forward, the nature of the material we were working with and the machines we were using helped me understand how you can do a lot of things quickly but it is important not to sacrifice the quality of the product for the sake of speed.