Sunday, March 29, 2015

Kickoff of Dabblers Lair

For some time I've been thinking about a blog that describes my various tech-centric (mostly) activities.  Done not in the vein of trumpeting the victories but as a process of taking a concept or thought and making it real.  Or analyzing it and concluding it's impractical or impossible.

My interests have a broad range.  Here is an incomplete list.

Machining, as a process of learning how to shape metals and plastics accurately, with few-to-none of those "oh s**t" moments when you figure out you just blew several days of machining.

Nitrogen vacancy centers (NV centers) in diamond.  An elegant quantum-mechanical system that could find its way into applications like quantum computing, supersensitive magnetometers, MRI, etc.  A system that is relatively easy to experiment with (I think), given a few items available off of Ebay, Amazon and Edmund Optics.

Mathematics.  Example:  I recently have become interested in the mini-Kossel type of 3D printer.  It is elegant in its own way, because the XYZ movements are accomplished by combining 3 identical actuator mechanisms.  Conventional XYZ printers use an XY table, with all its foibles, and a Z gantry, also with interesting issues.  However, mathematical analysis of the Kossel has shown that its resolution depends on the current position of the printer head.  I think the specifications shown for Kossel-based 3D printers are best-case and don't necessarily reflect what users will experience.

Chemistry.  I ran across a reference to "magnesium oil", which is used as a topical source of dietary magnesium.  If you browse the 'Net for health supplements you will find information which suggests that everyone is short of every element under the sun (literally).  My interest was picqued because I was not aware of any benign organo-magnesium compounds.  A lot of organo-metallic compounds do things like spontaneously combust in air (like diethyl zinc), or are horribly toxic, like methylmercury.  So what is magnesium oil?  Turns out it is a fairly concentrated solution of magnesium chloride.  Applied topically, it is easily absorbed through.  Turns out that it is easy to make using table salt (sodium chloride) and epsom salt (magnesium sulfate).

Here's how it is done.  Make two saturated solutions of table salt and epsom salt.  Mix the "right" volume of each one so each magnesium ion has two chloride ions available to it.  This can be done by looking up the solubility constants for each, calculating the molarity of the resultant solutions and....the rest is left as an exercise for the student <heh>.  Now throw the combined solution in your freezer and wait a day or so.  The magnesium chloride crystallizes out of solution because its solubility greatly decreases at low temperature.  Working quickly, strain out the crystals.  Voila, magnesium chloride, which can be redissolved & used for "magnesium oil".

And on and on.

MK 3-29-15

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