Governance by those who do the work.

Friday, December 19, 2014

Precision Roughness Plate

John Cox has completed the difficult job of milling the aluminum plate to make a precision rough surface!  Its average (also the root-mean-squared) height of roughness is 3 mm.  Cutting the MIC-6 aluminum broke several end mill bits.  Reducing the depth-of-cut to less than 1mm, it took 6 hours on a ShopBot CNC mill.

While MIC-6 turned out to be difficult to machine, its cut surfaces are highly reflective and should hold radiative heat transfer to a minimum.

Next, I will attach the heating elements and temperature sensor to the plate and program the microcomputer to take measurements and store them.  The first measurements will be of natural convection.  After that it will be suspended in the wind tunnel for measuring forced convection.

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