Interchangeable parts

* Eli Whitney not really being the hero of the industrial revolution
* Interchangeable parts - what they really mean is the repetitive manufacture of standard and precise duplicate artifacts
* What I really think of when I hear the term "interchangeable parts"-- legos.

http://en.wikipedia.org/wiki/Lego
"""
The company's flagship product, "Lego", consists of colorful interlocking plastic bricks and an accompanying array of gears, minifigures and various other parts. Lego bricks can be assembled and connected in many ways, to construct such objects as vehicles, buildings and even working robots. Anything constructed can then be taken apart again, and the pieces used to make other objects. The toys were originally designed in the 1940s in Europe and have achieved an international appeal, with an extensive subculture that supports Lego movies, games, competitions, and four Lego-themed amusement parks.

Lego pieces of all varieties are a part of a universal system. Despite variation in the design and purpose of individual pieces over the years, each remains compatible in some way with existing pieces. Lego bricks from 1963 still interlock with those made in 2008, and Lego sets for young children are compatible with those made for teenagers.

Bricks, beams, axles, mini figures, and all other parts in the Lego system are manufactured to an exacting degree of precision. When snapped together, pieces must have just the right amount of strength and flexibility mixed together. They must stay together until pulled apart. They cannot be too easy to pull apart, or the resulting constructions would be unstable; they also cannot be too difficult to pull apart, since the disassembly of one creation in order to build another is part of the Lego appeal. In order for pieces to have just the right "clutch power", Lego elements are manufactured within a tolerance of 2 µm.
"""

Wikipedia has good information on lego CAD and the manufacture of lego parts:
http://en.wikipedia.org/wiki/Legos#Design
http://en.wikipedia.org/wiki/Legos#Manufacture

Some properties of legos:
* precise repetitive manufacturing of the same artifacts
* a "universal system" [within their company at least :-)]
* each piece remains compatible in some way with (all) existing pieces

With legos, not only can you replace red block with red block, but you can replace red block with green block slightly extended. There is more than one type of part that is compatible with each other part, and each part can be remixed into other constructions the designer comes up with. In manufacturing and design engineering, there is an opportunity to design to pre-existing standardized parts, esp. see screws and other little parts. And it's my understanding that this (albeit primitive) form of standardization was brought about by parts catalogs and part identifier numbers/names. You can generally only replace parts in machines with exact duplicates, whereas with legos there's a set of available parts that are options for solving the same 'problem' (lego designs don't really face all of the issues of mechanical design, so the problem is usually aesthetic). Apparently the definition of 'interchangeable parts' in manufacturing is more related to the precise repetitive manufacture of artifacts for essentially standard replacement parts constrained to measurements and tolerances. It's easy to see how I could feel betrayed by "interchangeable parts". It's a fairly good encapsulation of an important concept. Legos have some sort of intricate link to my childhood (I still play with legos), so the natural feel of having both exact duplicate replacement parts but also a sort of quasi-*functional* interchangeability/compatibility must have transferred when considering the concept of "interchangeable parts". Maybe that's how many others think of interchangeable parts too, it wouldn't be a longshot-- legos are but one of the many concepts that 'interchangeable parts' could be associated with. 

With the example of standardized naming of parts and components, I'm pretty sure that I'm wrong and that there are many manufacturable artifacts that are interchangeable with other parts for solving basically the same functions, but my guess is that these are in isolated instances throughout product catalogs. In electronics, the golden standard for standards and compatibility, there are many replacement parts from different manufacturers, and thousands of different types of LEDs, or 555 timer chips that can be dropped into a breadboard without sweating it - even the individual pin pathways are standardized. The other day I was excited to find ECIX, "Electronic Component Information Exchange":

http://archives.si2.org/si2_publications/

EC PinPak XML example: http://archives.si2.org/si2_publications/pinpak/SampleInstances/KM736.xml
http://archives.si2.org/si2_publications/pinpak/Parts/Samsung_KM736V687A/KM736V687A.pdf
((wonder if I should go hack out some code and submit to gEDA for ECIX file support.))

Basically that's an XML representation of the Samsung KM736 datasheet (PDF above). Thomasnet.com and Globalspec.com both have 'datasheets' for some of the products on their site, but it's hit-and-miss since some products within the same category don't have all of the information filled out and so on. Amazon is terrible at doing datasheets, but NewEgg at least has a wizard-like sidebar that guides users through picking specific stats and numbers for the items to search for, so I'm guessing NewEgg put the squeeze on manufacturers or is manually entering data with hired kids.

Anyway, there's far from an available "datasheet spec for standard artifact engineering," except for electronics. The reason I bring this up is because of some of the code I commited to the repositories the other day, and for the interface between packages/artifacts I was just using a Measurement object plus a string for material identification, encapsulated in an ingredient class, which is far from a good idea. It's hardly sufficient for its task, and so will be thrown out with the trash once the better ideas spontaneously turn into code.

So, something that I've been thinking about recently is the "industrial revolution" and in particular the theme of interchangeable parts. For some reason this phrase started propagating since the onset of the concept of the industrial revolution, and in particular it seems to be traceable back to Eli Whitney. 

http://books.google.com/books?id=pkhVAAAAMAAJ&pg=PA54&dq=%22interchangeable+parts%22+date:1-1910&lr=lang_en&num=100&as_brr=1&as_pt=ALLTYPES&ei=JixZSd61MJWyyQSdl8DAAg

"Thus where years ago the skill and ingenuity of the mechanic were monotonously and patiently utilized in the hand production of a number of parts of great accuracy to a certain attainable degree of duplication they are now directed to the devising and constructing of one part or tool or a set of tools which will produce other parts or tools in endless repetition."

http://en.wikipedia.org/wiki/Interchangeable_parts
"""
Around 1778, Honoré Blanc began producing some of the first firearms with interchangeable parts. Blanc demonstrated in front of a committee of scientists that his muskets could be assembled from a pile of parts selected at random. Other inventors who began to implement the principle included Henry Maudslay, John Hall, and Simeon North.

In the U.S., Eli Whitney saw the potential benefit of developing "interchangeable parts" for the firearms of the United States military, and thus, around 1798, he built ten guns, all containing the same exact parts and mechanisms, and disassembled them before the United States Congress. He placed the parts in a large mixed pile and, with help, reassembled all of the weapons right in front of Congress, much like Blanc had done some years before.

The Congress was immensely impressed and ordered a standard for all United States equipment. With interchangeable parts, the problems that had plagued the era of unique weapons and equipment passed, and if one mechanism in a weapon failed, a new piece could be ordered and the weapon would not have to be discarded. The hitch was that the guns Whitney showed congress were made by hand at great cost by extremely skilled workmen. Whitney, however, was never able to design a manufacturing process capable of producing guns with interchangeable parts. Historians Merritt Roe Smith and Robert B. Gordon have demonstrated conclusively that Whitney never achieved interchangeable parts manufacturing.
"""

An interesting reference to read on this subject:
* Woodbury, Robert S. (1960). "The Legend of Eli Whitney and Interchangeable Parts." Technology & Culture 1.
Woodbury mentions that Eli Whitney was really struggling for money, and generally argues that Whitney was scamming congress at the time because he didn't really have "interchangeable parts".