Books › Violins and other stringed instruments : how to make them ; with numerous engravings and diagrams, 1906 › scan 25
Scan 25
Violins and other stringed instruments : how to make them ; with numerous engravings and diagrams, 1906
2 lines. Read by computer on 29 August 2026. Printed page 21. See the scan on archive.org.
1callipering, during which a careless stroke with the tool or an error in reading the callipers may spoil all the results of the labour. To obviate these objections the thickening appliance shown in Figs. 28 and 29 has been devised. It reduces enormously the time spent in thickening the plates, and at the same time ensures accuracy. The motive power may be a lathe treadle and fly-wheel, in which case the appliance is bolted down to the lathe bed in the position occupied by the mandrel head, which is temporarily removed, the appliance being allowed to hang over the bed to the left so as to leave the regulating screw free. An old sewing-machine stand may be used, the flywheel lying along instead of across the stand, thus allowing the appliance to be placed with the drill towards the operator, and hanging a few inches over the front of the table. A 1/8-in. gut band is used as a driving belt, with hook and eye fastenings as used on lathes. The two guide pulleys p (Figs. 28 and 29) are grooved, and are 1 in. in diameter; they may be got ready bored at the ironmonger's for a few pence, and are set at such an angle as to be in a line with the rim of the flywheel, the axles being common screw nails. The block which carries the pulleys also supports a hinged lever used for pressing down the drill, the lever having a small metal plate screwed on it to bear on the top end of the drill. The drill is made from a piece of drill steel 4 in. long and about 3/16 in. thick, as sold by watchmakers' furnishers, and on it a pulley, the same as the guide pulleys, is driven tight about 1/2 in. from the top end, the cutting point being formed on the other end. Heat and then hammer flat about 1 in. of the end, which may then be twisted with pliers and filed into a diamond point with rather sharp cutting edges, and tempered to a straw colour, the top edge of the flame of an ordinary bat's-wing gas burner being used for heating. The drill is journalled in a 2-in. length of brass tubing driven tightly into the upper wooden arm. The positions of the guide pulleys and the driven pulley are so arranged
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