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Hi Asa,
> Don't many people use primitive methods of faceting, like the
> device seen on
> http://www.rockhounds.com/rockgem/articles/laplap.html ? Its
> basically a simple device thats held by hand over a lap, used much
> like sharpening gravers. What did people use like 100 years ago?
> 500 years ago?! What do those in the third world use? Are there
> any good books covering primitive faceting/lapidary?
There's a unit made called the 'Lap Lap' that uses a simple pyrimid
type device to hold the stone. The cutting media is silicon carbide
paper on a piece of glass. For polishing other materials are used.
It's a very slow way to facet a piece of rough.
As far as 3rd world countiries are concerned, a device called a 'Jam
Peg' faceter is used. It's basically a table that has a rotating
flat lap similar to the faceting machines you've seen in the class
room & a mast with a board attached. The board has holes drilled in
it from top to bottom. One end of the quill, to which the dopped
stone is attached, is inserted in on of the holes. The hole selected
causes the stone to contact the rotating lap a a given angle.
Changing holes results in different angles. The indexing about the
circumference of the stone is done, for the most part by judicious
hand & wrist placement.
It's not uncommon for the lap to be larger than the 8" lap usually
used on the Facetrons & UT's. In some cases it may be as much as 18"
in diameter. If this is the case, & it's a production shop, 2 or 3
facetors sitting around the lap may be using the same lap
simultaneously.
While many of these facetors turn out respectable stones, the odds
are that there's a wide variation in angles between the various
facets. As the accuracy & proportions of a stone vary from an set
of values that are determined by the laws of physics, the light
return, sparkle & other optical characteristics of the stone suffer.
A well cut stone will out preform those cut by jam peg machines.
Sorry, I can't help you with any books on ancient lapiday.
Dave
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