Patent GB-647538-A (GB)
Title: Improvements in or relating to apparatus for polishing precious stones
Inventor: WEST CHARLES
IPC: B24B9/16
Filed: 1948-12-06
Abstract: 647,538. Polishing precious stones STONE, L., and OLIVER, H. Dec. 6, 1948 No. 29372/47. [Class 60] An apparatus for use with a flat-faced polishing element 46 for polishing precious stones comprises a flat-faced member 14, an arm 11, a head at one end of the arm to carry a dop, a fulcrum 13 on the arm slidably engaging the flat-faced member and permitting the arm to swing in an up and down direction, a stop 20 fixed to the flat-faced member and underlying the arm, and means for adjustably securing the flat-faced member against movement to a bench 70 so as to locate its face accurately parallel with the face of the polishing element. The head comprises a sleeve 10, Fig. 2, which receives a stem on the dop and is threaded at 40 to engage a graduated nut 41 free to rotate in a member 34. The nut is prevented from moving axially in the latter member by a split sleeve 43, while the sleeve is secured against rotation by a key 38. The arm 11 has a cup-shaped aperture 31 to receive a spherical portion 33 of the member 34 which is secured to the arm by bolts 35. Thus the member 34 can be angularly adjusted and the sleeve 10 vertically adjusted with respect to the arm 11. The means for adjustably securing the member 14 comprises bolts 69 which pass through plugs 65 in threaded engagement with rods 66. These plugs are independently adjusted until the face of the member 14 is parallel with that of the polishing element. The support 20 is adjustably secured to a post 17 and carries a spring- loaded lever 22 whose upper end is in contact with the arm while its lower end functions as a switch with an adjustable terminal 26 insulated from the remainder of the apparatus. The lever is deflected by the movements of the arm during the abrading operation to energize a warning device, such as a lamp 29. The arm 11 may be loaded by weights or by means of a loading arm 49. The latter is pivoted at 51 and carries an adjustably mounted weight 50 which loads the arm through a pivoted member 53 having a pin 55 in engagement with a ledge on the arm. This pin is withdrawn axially to free the arm and is re-engaged by lifting the weight 50 by means of a second pivoted member 52 having a cam surface 58 at its lower end in contact with a fixed plate 59. When the pin has been lifted high enough to engage the ledge it is pushed inwardly allowing the second-pivoted member to be swung into a position in which its cam surface is not in contact with the plate 59 so that the load is transferred to the arm 11. In operation, the support 20 is adjusted until the axis of the sleeve 10 is perpendicular to the face of the polishing element. The sleeve 10 is then downwardly displaced by the amount to be ground off the diamond by turning the nut 41. Grinding now takes place until the descent of the arm 11 is arrested by the support 20, in this position the upper end of the lever 22 is flush with the upper surface of the support while its lower end is in contact with the terminal 26 to operate the warning device. During grinding, the arm is moved towards and away from the scathe, lateral displacement being prevented by a ledge 16 and the post 17. Pockets 62 are provided for cut and uncut stones.