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Background

I want to build a drip-style coffee maker for fun. My "design" features a sealable cylindrical housing for the water and heating element. Silicon tubes will carry boiling water from the cylinder to the coffee grounds. I plan on using a cheap water heater element that I can power using a 120V household outlet. A valve will be installed on the side of the cylinder to allow steam to escape. By partially closing the valve, I think I can modulate how quickly boiling water is pushed through the silicone tubing to the coffee grounds.

sketch

Question

What material can I use for the cylinder? Right now I'm looking for easy and cheap. I have access to a drill press and welding station, but not a mill/lathe.

Options that I'm considering:

  • 3D printing using a food-grade filament. Not a great option. It seems there aren't a lot of good filaments that can withstand boiling water for long periods of time.
  • CPVC piping. I think this would work, but I'm seeing mixed answers online. A few answers say CPVC is rated for 200 F, not 212 F. Another resource rated CPVC for much higher temperatures.
  • Copper tubing. This would be safe, but it's an expensive option. And I guess I would need to worry about welding/threading the top and bottom.
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  • $\begingroup$ What are plastic kettles made from? $\endgroup$
    – Jonathan R Swift
    Commented Jan 3, 2021 at 9:17
  • $\begingroup$ First step - See what commercial units are made with . Step 2 - Buy a commercial unit. $\endgroup$
    – blacksmith37
    Commented Jan 3, 2021 at 17:57
  • $\begingroup$ @blacksmith37 I guess part of the challenge for me is to not scavenge parts from a commercial unit $\endgroup$
    – EssentialAnonymity
    Commented Jan 3, 2021 at 18:03

2 Answers 2

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Stainless tube with end caps that clamp on using threaded bar - no welding and easy to seal.

Easy enough to find in 2" or 3" or 4" diameter, plate for the end caps as well. Drill holes and get some threaded rod.

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  • $\begingroup$ What's the best place to buy small amounts of tubing like that? $\endgroup$
    – EssentialAnonymity
    Commented Jan 3, 2021 at 17:42
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    $\begingroup$ As a student, my first move would have been going to an engineering company and asking to look in the scrap bin... worked when I needed some stainless tube, but it’s also handy to be an engineering student in a city that does a lot of engineering and manufacturing. $\endgroup$
    – Solar Mike
    Commented Jan 3, 2021 at 17:52
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Buy a pressure cooker, drill holes as needed for tube and electric connections .It will have an approved safety valve and a second vent that usually allows for a couple different pressures . This should protect you from yourself. Steam - boiler explosions prompted creation of ASME over 130 years ago . I believe a government agency let manufacturers know if they did not make boiler rules , the government would. So ASME was founded and wrote the boiler code , generally known as the "code". Then ASTM was formed to write specifications for materials to use to build boilers conforming to Code. Basically anything larger than a home hot water heater must conform to Code. Generally anything that can generate steam pressure follows the guide lines. The point is when you build something that can make steam pressure ,you should be careful.

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