Cryogenic Machining: Custom Rubber Parts

Cryogenic Machining Custom Rubber Parts

Fashioning a custom, one-off rubber part for your project isn’t usually an option, but [Ben Krasnow] has an alternative to injection molding and casting: machining frozen rubber.

As [Ben] points out, you can’t exactly pop a sheet of rubber on your mill and CNC the needed shape; the bit will push the material around rather than cut it. Freezing the rubber first, however, allows you to carve into the now-hardened material.

His initial setup consisted of a sheet of aluminum with water drizzled on top, a square of neoprene placed on the water, and a steady stream of -60 to -80C alcohol flowing directly onto the rubber. The water underneath freezes, holding the neoprene in place. This proved problematic as the ice-clamp gives way before the milling is complete. [Ben] later adds some bolts to clamp the pieces down, allowing the milling process finish as planned.

A small plastic tray sits underneath this assembly to capture the alcohol as it runs off, feeding it back with some tubing. [Ben] recommends against a submersible aquarium pump—his initial choice—because the pump stopped working after a few minutes immersed in the chilly alcohol. An external, magnetically-driven pump solved the problem although it does require manual priming.

Stick around after the jump for the video and check out some of [Ben's] other projects, like his quest for the perfect cookie, or CT scanning a turkey.

[Read more...]

Cold climate solar water heater

Here’s a solar water heater setup that augments your home’s water heater instead of replacing it. The system monitors a solar collector panel on the roof for temperature. If the temperature is warm enough, a photo voltaic cell powered pump circulates cold water through the system. The heated water returns to the top of the home’s water heater. Unlike the warm-climate solar heater we saw earlier, this one can withstand freezing because it uses silicone tubing in the collector.

[Thanks Marius]

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