I keep wanting to build a Tesla coil. Something on the scale of the one Tesla had in Colorado Springs:

I don’t really see that happening.  I am working on a smaller, more transportable one. The lathe at the ITP shop was a helpful fixturing tool for winding this small secondary coil on a piece of PVC.  It could have been wound more comfortably sitting in a chair at home. But in my mind it was an excuse to use the lathe.

 

Capacitors were discovered in 1745 by Ewald Christian von Kliest and Pieter van Musschenbroek.  There is a lot of text out there about the discovery.  Most of it is very interesting:

“When the globe D is made of English glass there is no effect, or almost none; German glass must be used, Dutch doesn’t work either; D does not have to be a globe, a drinking glass will do; nor does it matter if it is large or small, thick or thin, tall or short, or of any particular shape; but it must be made of German or Bohemian glass. The globe D that almost killed me was of very thin white glass, five inches in diameter.”

This is another important example of the discovery of a subatomic phenomena which affects our daily lives by individuals who were not a part of “big science.”  Experimentation and observation have always been keys to discovery.

I’ve been making glass jar capacitors since I was in fifth grade (no, I am not certain if plastics had been developed then.  Yes, we had electricity.). Here’s the basic formula for calculating the capacitance for Leyden Jar Capacitors (DIY’s or those found in museums):

C = 0.224 Π K D (H +0.25D) / 1,000,000 T

C = capacitance in microfarads
K = dielectric constant
D = diameter of jar in inches
H = height of jar in inches
T = thickness of jar in inches

I’ve been making plate glass capacitors for projects since.  I’ve had a desire to make larger capacitors using plastic to reduce weight and resist breakage.  I settled on relatively easily available materials.  These include polypropylene (8 mil carpet liner) as a dielectric, PVC pipe for the housing (pulled from the dumpster at ITP after a recent Maker Fair), Aluminum foil, and some hardware that I just knew I would need (?) that I brought from my studio in San Diego.  I used hardware larger than was really needed for issues of mounting safety:  There is little to be gained in underbuilding an experimental object.  This is especially true for me as I am extremely clumsy.  Aside from the availability of the polypropylene, the material is a homopolymer whose heavier mass and density are useful for the higher voltages I will be using.

Images below show the PVC caps drilled and prepped for hardware.  Next steps in the assembly are rolling the Aluminum foil and polypropylene, and the decision to use wax or mineral oil to fill the tubes.  Each has its advantages and disadvantages.

My studio is filled with tools of different types. Organizing them in a non-distracting, space saving, efficient manner, is a constant challenge. I keep most of my small hand tools in two cabinets of drawers.  These were a great find while walking back from Canal Street through off New York City’s SoHo sometime early in the 1980’s.  I carried them back to my studio space at 135 Fifth Avenue (22nd Street).  They have been an integral part of my work flow ever since.  Yes, I brought them and their contents in order to have the tools which I use at ITP.   After all; aren’t tools the fingers of imagination?

In order to present a personal version of aesthetic harmony, it has always been important for me to be able to accurately measure and arrange parts when constructing work of any kind. A unified, consistent aesthetic which you like is always a good way to build support for an idea. Having access to a laser – even if it cannot cut metal is an amazing resource to have available!In another class I decided to create a universal proto-typing fixture for microcontrollers.  My thought was to use only parts which I had brought with me.  Measuring switches, LEDs, jacks, plugs, with my calipers was time consuming and (as it turned out) often inaccurate.

I decided to make a hole pattern which I could easily use when designing this (and future) project’s faceplate.  By drawing a series of one to forty millimeter holes in Illustrator, and then using the laser cutter to fabricate this new measurement tool, I was able to eliminate “operator error” of the digital caliper as well as errors in tolerance within the caliper.

The potentiometer fit nicely into a ten millimeter hole, the arcade switch a twenty-nine millimeter hole, the nut driver handle a twenty-five mm hole.

While on the subject of using software and hardware tools to create new tools, the other tool which I made is similar to the hole pattern, It is a thickness gauge to better determine material dimensions for box assembly:

Before cutting final parts out of acrylic on the laser, I test what I design in Illustrator first as a drawing on cardboard, and later cut out of that or another piece of cardboard.  This gives me multiple opportunities to adjust spacing/layout as well as to correct dimensionality of parts prior to final assembly which helps to reduce both frustration and waste.  Waste has costs associated with the concept.  These include dollars, time, and space in landfills.

The image below is an example of drawing with the laser to check for layout and then burning a cardboard base to be used as part of a Calder mobile.

Many of the tools which I use when working on small, table-top scaled projects are the same: nut-drivers, solder tools, ice pick blades (seriously; very useful), small and large screw drivers, etc.  No matter how much I don’t want to see a mess where I am working beating a realized thought into reality from tools and materials just makes a mess.

In building the spark-gap transmitter and assembling the microcontroller interface I had need of multiple sizes of nut drivers and screw drivers.  I do not know about you, but I cannot tell the size of the nut driver I need by glancing at the handle.    Since the business end of the nut driver isn’t sharp (thinking of the delicate veins and arteries of the underside of my wrists),  I decided to make a bench top tool holder where I could have many common tools neatly available; including my nut drivers with their business end up for easy identification.

The image below is a laser drawing on material prior to burning through.Solvent bonding of acrylic – in spite of its hazards to health – is  another kind of magic.  Solvent bonds are often stronger than the original material.

I use blocks of Ultra-high-molecular-weight polyethylene (UHMWP or UHMWPE) to aid in the fixturing of parts for gluing.  Teflon blocks are also good, but the material has other issues and it is more expensive than UHMWP.  The great thing about these materials is that most adhesives will not adhere to them.  UHDWP is the same material that industrial quantities of cyanoacrylate adhesives are packaged in.  The material is so inert that it is now being used as an implantable material for joint replacements.

For the relatively mundane miracle of successful solvent bonding, plenty of moving air, flatness , right angles, and creative fixturing are keys to assembly.

Here is version 1.0 of the tool holder in use:

Other items which are being prepared for the spark gap transmitter include the wonderful $5 motor from eBay, a neon sign transformer, and some salt-water Leyden jars.

While the high temperatures of the plasma during discharge will erode the brass spheres shown in the image below, they look cool and they aren’t going to evaporate.  Then there is the fact that I would be hard pressed to find a better use for these items which I have had waiting for such a purpose for at least twenty-five years.

[quicktime]https://www.terezakis.me/video/arc-2.mov[/quicktime]

First test of pivot, weights, fulcrum(s)

[quicktime]http://www.terezakis.org/itp/video/calder-1.mov[/quicktime]