Cutting oil grooves in bearings with a chisel is not always a satisfactory method and considerable time is lost in the operation. The proper method is to utilize an oil grooving machine, but these are not common in repair shops. An attachment for an ordinary lathe which the repairman who constructed the device states can be utilized to groove any size bush or bearing is shown at Fig. 339. The drawing is practically self-explanatory but the chief points to be considered are that the arrangment should be bolted firmly to the lathe body and that the adjustable arm connecting the carriage with the horizontal disc should be parallel with the lathe bed at each end of its stroke.

Fig. 339.   Attachment for Grooving Bearings on Lathe.

Fig. 339. - Attachment for Grooving Bearings on Lathe. A - Grooved Brass in section. B - Arrangement of Drive. C - The Work in Chuck. D-Disc Drilled to Give Various Strokes. E - Adjustable Connecting Rod. F - Screw Which is Removed to Allow for Free Travel of Tool.

The screw in the carriage holder must be withdrawn before commencing operations, so as to enable the carriage to slide easily in either direction. The drive must be so proportioned as to enable the chuck to make one revolution while the tool is traveling the whole length of its stroke. An oil groove, after the outline of that shown in the small sketch, will thus be made to feed oil equally all over the bearing.

For example: Assume that a bush 1.5 inches long is to be grooved. The pin on the horizontal disc is set .625 inch out of center; the connecting rod adjusted and the main carriage bed locked. The transverse screw is then removed from the tool carriage and the grooving tool set about .125 inch inside the bush, and the lathe started.

The carriage being free to slide, the connecting rod will cause the tool to travel just 1.25 inches, and the gearing being so arranged that the chuck will make one revolution during the complete travel of the tool, an oil groove of the required length and pitch will be cut into the bearing.