Page:Popular Science Monthly Volume 89.djvu/316

 302

��Popular Science Monthly

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��Drilling Square Holes

THE drawings relate to work that is drilled in the lathe. The piece is shown in Figs, i, 2 and 3, Figs, i and 2 showing round and square holes. They are the formers and are used for drilling square holes in round stock, such as would be used for socket-wrenches, etc. Let us say we need an inch-square hole. The stock is put in the lathe chuck and drilled with a one-inch round drill. Then the former (Figs, i, 2, 3) is slipped over the stock and fastened with the set screw, C. This brings the one-inch square, B, against the one-inch round drilled hole. The tool. Fig. 5, is then inserted in the back-center of the lathe and fed to the round hole, the three-sided drill, D, cutting the hole one inch square.

This is caused by the square in the former going around the drill, and the drill having a pla^- in all directions.

The play of the drill is pro\-ided for by the simple means of something like a modified universal joint, E and F, Figs. 4 and 5, the pin E fitting loosely in part F. Being rounded, the part F has a movement that works two ways and the pin E makes the other two move- ments. Hence we see that this provides for a limited circular movement.

If the work (flat stock or otherwise) is

���Fig. 6. Former, to be held in tool post of lathe when drill is running and work is on back center

��needed to be drilled, the tool (Fig. 4) is inserted in the lathe head, and the tool (Fig. 5) is used in the tool post, the former part / being brought up to the work, which is secured by an>- ordinary means to the back center. The position of the drill in cut- ting square hole is shown in Figs. 7 and 8. It must be understood that the former must be as close to the work as possible. The former should be hardened and the drill edges slightly rounded.

The cutting end of the drill should be slightly rounded, similar to a reamer

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���Fig. 7 Fig. 8

Showing two positions of three-sided drill

about to cut the round hole square

edge. Of course the drill has not much work to do — simply taking out the round corners. It can be used in the drill press, the work and former being strapped to the table. — Edgar Hoi.dcroft.

A Remedy for Jarring Bottles

���^^x TN order to keep bottles from jarring

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��Fig 2 Fig.3

Formers for round stock that is held in lathe chuck

��from being knocked oft" a shelf which may be remote from the lathe, a tin can is nailed down to the shelf and about iK "IS. of shavings and sawdust placed in it to keep the bottle from being broken when dropped into it.

���Fig. 5. Same as Fig. 4, but assembled

��The bottle can not slide or jar off

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