Methods of machine shop work : for apprentices and students in technical and trade schools (1914)
Halsey, Frederick A. (Frederick Arthur), 1856-1935 · New York : McGraw-Hill · leaf 219
Fig. 189.—Multiple spindle drill heads. mounted eccentrically in the main spindle. This constructionpermits the spindles to be grouped together more closely thanany other, the limiting center distance being two diameters ofthe drill. 208 METHODS OF MACHINE SHOP WORK … DRILLING 209
Machine-shop practice
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