Author Topic: Spin up your own thermowell or metal temperature probe.  (Read 457 times)

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Offline SLOweather

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Spin up your own thermowell or metal temperature probe.
« on: March 04, 2016, 02:36:41 PM »
For a project, I decided to use LM34s for the temperature sensor. The TO-92 package is a 3 lead plastic transistor type. I need something more durable, a way to protect it.

After some thought and research, I decided to try spinning a brass tube closed. I got a length of 1/4" hobby tubing at Ace, cut it into some 2.5" lengths, and started playing with the drill press. I made a form by drilling a shallow hole in a piece of steel plate After watching a YouTube video, I realized the lowest speed (500 rpm) was too low, and sped the press up to 3,100 RPM.

It took some trial and error but I found a method that works. I started rounding the end over with an oiled steel block pressed against the end of the spinning tube at an angle, working it up and down. Then, I finished it by pressing it into the oiled hole in the plate.

After it was done good enough , I drilled a 1/4" hole through a threaded 3/8" brass plug and inserted the tube. Here it is before sealing the end with solder, and sweating the tube to the plug.

Before I make any more, I think I'll polish the hole form and smooth off the sharp edge.

You could leave off the plug and just make probes if desired.