Journal - Franklin Institute of the State of Pennsylvania (1826)
Franklin Institute, Philadelphia, Franklin Institute (Philadelphia, Pa.) · [Philadelphia : Franklin Institute] · leaf 52
corundum or diamond-dust ismixed with oil and applied to the flat surface of the lap by means ofa flat steel instrument, upon which pressure is applied in order to forcethe corundum or diamond-dust into the copper, thereby making a cut-ting surface. The irridum to be ground is held against this… … means of the stoel instrument as described ; this operation is continueduntil the grinding is complete. After the slabs are ground to a surfacethey are then drilled. In the drilling operation, the iridium ij firstcountersunk by means of a diamond drill, consisting of an uprightspindle suitably…
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