Category Archives: fabrication

CNC Bubble Iris Article Released

http://www.instructables.com/id/CNC-bubble-machine
Photo of the CNC Bubble Iris taken at Autodesk’s Pier-9 facility by Nathan Hurst, Editor at Make Magazine.

 

It is a real pleasure to see Make Magazine,  Hackaday, and Adafruit #ArtTuesday all re-blog the publication of the apparatus I’ve built to bring new precision, repeatability, and automation to the craft of giant soap bubble making.  Stay tuned for all the interesting things I’ll use this instrument for!

May your life be as smooth as Silicon-Bronze TIG brazing.

small heptagon with square tubing at 45 degrees from flat, after welding and wire brushing.
An experiment in jig construction, TIG-brazing, and symmetry. This took about an hour from conception to completion, much of which was locating the V-blocks for clamping the tubing at 45 degrees during cutting.
Small heptagon with square tubing at 45 degrees from flat, as tacked together, showing fit-up.
Tacked at ID and OD. The fit of the bevel cuts is sublime! not a sheet of paper could be inserted at ID or OD of any joint. Spot on 64.3 degree (=90-(180/7)) bevel!

IMG_5670IMG_5682
Next step:  make four of these with the tubing’s face to table’s face angles sampling intervals of 0, 22.5, 45, and 67.5 degrees (or generally, angle increments of ([0:(n-1)]/n) * (360/(number_of_tubing_facets_equals_4_if_square_tubing)) degrees rotation from flat.   Make a jig to photograph them at consistent position,  then make looping stop motion animation of toroidal ring rotating around it’s minor axis…

Then,  perhaps, I will also incrementally crush each ring as I’ve done to destructively test prior similar experiments,  and register each frame,  so the animation might suggest continuation of the rotation throughout the increasing deformation.

Animated Retroreflective Safety Signage

I’ve been playing with a new process in which I remove the silvering of mirrors in detailed patterns,  leaving optically clear glass.

A zone plate made of mirror and optically clear glass zones will focus images in both reflectance and transmission.  The focal length of this plate, at visible wavelengths, is too long to be practical though.  I'm experimenting with shorter focal length, finer ring spacing, zone plates.
A zone plate made of mirror and optically clear glass zones will focus images in both reflectance and transmission. The focal length of this plate, at visible wavelengths, is too long to be practical though. I’m experimenting with shorter focal length, finer ring spacing, zone plates.

My first experiment was to make a Zone Plate,  but my current process didn’t have enough resolution to make fine enough lines for a zone plate of short focal length at normal visible wavelengths around 600nm:

However, the process is fantastic for barrier grid a.k.a. moiré a.k.a. ‘strip’ animations,  and for an afternoon project this has borne incredible fruit:  only about a dozen promising directions to go from here!  I decided to focus first on making an animated cautionary text and moving image safety sign for vehicles, especially bicycles,  especially helpful for night-time visibility.

 

US Patent #8154279 Issued To Gordon Kirkwood &co. for Non-Destructive Magnetic Sensor of Graphitization Corrosion

Grey Iron and Ductile Iron Pipe are the dominant conveyances of water and sewage in American infrastructure.    These types of iron have carbon and iron constituents whose relative distribution and crystal sizes determine their mechanical properties.    Over time,  this material are susceptible to ‘graphitization corrosion’ in which either graphite particles migrate and aggregate (typically at temperatures above 800F)  or in which local electrochemical corrosion at room temperature results in preferential loss of the iron / ferrite constituent of the matrix. When this happens, the pipe becomes brittle, and mechanical insults like vibration  or thermal stresses can exceed the flexibility of this now brittle material,  leading to brittle failure and cracks. However, this corrosion can be invisible,  because the remainder graphite particles are cohesive and the pipe appears physically unchanged.

US08154279-20120410-D00001
Illustration from the patent, indicating changing composition of portions of a grey iron pipe wall, in cross section.

During road work, construction, and maintenance operations, these pipes are visually inspected,  but because pipes experiencing graphitization corrosion often look physically unchanged – the graphite material remains in the same contour as the original material,  a method of detecting the change in properties of the pipe was needed which did not depend on visual changes, or subjective “bang on it with a hammer” subjective methodology,  as was the state of the art previously.  We needed a non-destructive method of detecting the changing properties of the pipe.

The insight of this patent is that the changing microstructure of the graphitized material has reduced magnetic properties due to the loss of iron.   This could be sensed by measuring the magnetic permeability of the pipe,  or it’s consequential magnetic measurements like inductance or the force developed within a fixed magnetic field.   At the urging of my mentor Dr. Mehrooz Zamanzadeh,  President and Principal Scientist of Matco Services,  and with my assistant Sam,  I developed a prototype sensor and confirmed that magnetic flux concentration,  magnetic force, and inductance measurements are all viable methods of non-destructive detection of changed microstructure and ferrite loss in grey iron and ductile iron pipe.     US Patent 8154279 was issued on April 10th 2012 for “Non-destructive testing apparatus for the detection of graphitization of iron”
US08154279-20120410-D00004 US08154279-20120410-D00005