[Of obscure etymology; perh. a use of prec., as the original tool may have been a ‘lap’ or wrapping of cloth or leather.] A rotating disk of soft metal or wood, used to hold polishing powder in cutting or polishing gems or metal.
1812–6. J. Smith, Panorama Sci. & Art, I. 35. In the manufacture of cutlery, the use of the stone is followed by that of the lap or glazor.
1833. J. Holland, Manuf. Metal, II. 29. The blade being properly ground, is then glazed … by applying it to the lap.
1884. F. J. Britten, Watch & Clockm., 212. A soft steel lap at first and afterwards a zinc one are generally used.
1888. Sheffield Gloss., Lap, a wooden wheel with a leaden surface used to glaze razors.
b. Gun-making. (See quots.)
1881. Greener, Gun, 238. The lap is fixed into a head revolving 650 times a minute. The barrel is moved backwards and forwards upon the lap.
1886. Walsingham & Payne-Gallwey, Shooting, I. 71. The polisher, or ‘lap,’ as it is called, consists of an iron rod round which is secured a leaden plug the exact size of the tube.
