Building the Platen
The Platen. This is one of the key ways that you get a really good vacuum form. To produce a good high definition product from a vacuum form you need high pressure. Or really very low pressure. About 25″ hg. You can’t get that from a vacuum cleaner. They only get about 6″. So you need tanks and you need to pull the vacuum from underneath allowing the normal atmosphere pressure to press down on the hot plastic, forming it into the details of your mold. The Platen makes that possible. By keeping the volume of the Platen down you reduce loss during the process. So these two sheets of aluminum with a very small gap and 450 holes do that.
Here is where you need LOTS of time and a good drill press doesn’t hurt. Clearing the burs by hand was the toughest part of this job. Building this one 2 x 2 platen took most a weekend and every night for a week. I still need to build the 2×3 and a 2×4. If anyone knows of a better way to make 600 – 900 holes without burs, let me know.
There are lots of photos of this step. I think the photos tell the story and I don’t have much to add. Take your time, don’t rush.