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A brief backgrounder thread on Precision to help interpret the EDM artwork and sample videos that have been floating around twitter following last week's precision machining industry day in the Far East.
What you are seeing in these various videos are artworks, product samples (examples of what a company can do) and in many cases apprentice machining tasks - yes - apprentice!
They are in the main not cut-outs but separately machined parts, precision drilled and cut to fit each other like a glove with the surface polished to provide that "invisible join".
Before the advent of CNC and computerised machining, precision tasks were frequently assigned to apprentice mechanics, engineers and machinists to practice and demonstrate their precision skills.
It was common to see an apprentice, especially one seeking Journeymanship, working late after a workshop closed on an insertable cylinder or triangle with no visible gap to demonstrate their hand-crafted precision.
Radius Gauges (Gage's?) and other precision measurement tools were also set as tasks and compared against the Engineers set - or if lucky - an actual standard set. 
Although precision interlocking (often in woodworking) prior to the industrial revolution, it was with the birth of metrology that precision manufacture exploded.
The father of metrology combined with machining is arguably Sir Joseph Whitworth, a genius of precision measurement and manufacturing.
Whitworth is best known for producing incredibly flat surface plates for basing measurements, invention of the three plates method for their production and proliferation of screw making machines.
Military buffs will also recognise his name from the helical Whitworth Rifle.
Whitworth was also known for introducing the concept of the "Thou" (one thousand of an inch, 0.001" == 0.025mm) and the thread standard known worldwide as the...
...the British Standard Whitworth.
...the British Standard Whitworth.
The precision machining you've seen over the last few days isn't a far cry from the lathes and drills of Whitworths day but are mainly produced by different Spark Erosion and Electrical Discharge Machining (EDM) devices.
EDM works by passing a current from a source (e.g. drill, tube, or wire) through a dielectric (usually a fluid such as distilled water) and into a completing circuit which is often the material being cut itself.
The spark is carefully calculated and can cut, drill or polish to within a micron or two of precision or 25-50 "Thou".
Intricate shapes are produced with multi-axis EDM Drills...
(Photo: EDM Precision Ltd)
(Photo: EDM Precision Ltd)
...and EDM Wire Cutters...
(Photo: Cheshire Wire Erosion Ltd)
(Photo: Cheshire Wire Erosion Ltd)
...most machines commonly movable in 4- to 5-axis although other "world record setters" are out there.
The beauty of EDM methods isn't just in the precision but also in the variety of materials that can be cut from softer stainless steels all the way through the tungsten carbide.
The process is skilled, uses precision equipment and as such there is very little "cheap labour advantage" to seeking companies outside of either the UK or the US.
Applications vary from bearing F1 cars to bearing holes to british rocket gimbles to F-35 parts to drain holes without stressing material to micro gas turbine blisks spinning on self-generated air bearings.
(Photo: Bladon Jets)
(Photo: Bladon Jets)
If you need precision metal cutting consider Cheshire Wire Erosion Ltd and EDM Precision Ltd (Silverstone). Reliable EDM in Houston are also a great supplier and have even released a free book on EDM!
The supply chain for the UK companies also includes high quality and *consistent* standards tested materials as an added bonus.
(Photo: Cheshire Wire Erosion Ltd)
(Photo: Cheshire Wire Erosion Ltd)
But the samples coming out of the Far East look cool too.
/FIN
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