Thursday, February 20, 2014

Lapidary Work 1854

This lapidary table is very interesting:

and a rim rises about two inches above the top to catch the waste emery and water thrown off by the mill. In the left hand compartment are a hole and a collar through which passes the vertical spindle of the driving wheel a the lower conical end fitting in a rail of the frame. The driving wheel is about eighteen inches in diameter and works just below the under surface of the bench top it is worked by a horizontal handle c.

In the right hand compartment the spindle d carries the mill which is about eight or nine inches diameter and revolves about an inch above the surface of the bench but it may be adjusted by means of a flange and screwed nut to a greater or less distance according as the edge or side of the mill is required to be used.

In the figure the lower centre is a square wooden rod passing through a mortise in a transverse rail of the frame and kept to the desired height by a side wedge. By this contrivance lap spindles of various lengths may be accommodated. The top end of the spindle also works in a wooden centre screwed into a hole near the end of a horizontal iron and e which slides upon a perpendicular bar and is retained at the proper height by the binding screw g. The pulley is about four inches in diameter and is fixed on the spindle just below the bench top.

A little to the right and in advance of the lap is an iron support h called a gim peg or germ peg about eight inches high and in the form of a crank it is secured below the bench by a wing nut so as to allow the peg to be moved round to different distances from the lap as may be required. Its use is to support the arm of the workman in grinding the edges of small stones and also to serve as a guide for the vertical angle in cutting facets for which purpose a wooden socket shown in the figure is slipped over the upper part of the rod and held in its place by a wedge. Holes or notches arranged round the sides of the socket serve to determine the inclination of the stick upon which the stones to be cut are cemented.

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