A vacuum chamber from a pressure cooker

[Allan] needed a small vacuum chamber to get all the air out of clear casting resin. Degassing is a simple step in casting that improves the finished product immensely. The problem, though, is building a vacuum chamber. [Allan]‘s chamber seems easy enough to build, and pulls enough air out to get to 0.1 atmospheres.

After a hole was drilled in the side of the pressure cooker, [Allan] installed a 15mm “speedfit” plastic tank connector. The seal around the connector is neoprene self-adhesive foam. This foam was also taped around the lip of the pressure cooker for the top.

A thick-walled pressure cooker is more than capable of handling the outside pressure when under vacuum, but [Allan] cautions against using acrylic plastic for the top. Acrylic has the tendency to fail catastrophically, so he used a thick sheet of Lexan. Check out the demo video of [Allan] sucking the air out of shaving cream after the break.

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Hacking a better pressure cooker

This pressure cooker hack on [Dave Arnold]‘s great cooking blog was sent into us (thanks, [techartisan]!). Most pressure cooker recipes are written for pressure cookers that can go up to 15 PSI or 250° F / 121° C. At these temperatures, a lot of interesting chemistry happens in the food. The popular Cuisinart electric pressure cooker doesn’t reach these pressures and temperatures, so [Dave Arnold] set out to make his Cuisinart better.

After measuring the temperature with a thermocouple, [Dave] deduced that the Cuisinart cooker only reached 237° F and 9 PSI. After having a look at the electronics, he realized that adding a resistor to the temperature sensor circuit would give him the pressure he wanted. After soldering in a trim pot, everything went swimmingly and the cooker was able to reach 15 PSI.

[Dave] isn’t sure how his modifications will hold up – he doesn’t know how the cooker will hold up to overheating (and there are a few concerns about non-stick pressure cookers in the first place). That being said, it’s a great mod to get some more capabilities out of a Cuisinart.