Examples of Box-tool Turning.—Box-tools are not only used for cylindrical and taper turning on the end of a bar, but for many other operations. [Figs. 9] and [10] show a number of box-tools of different designs, with examples of the work for which each is intended. While these tools are designed for some specific part, they can, of course, with slight modifications be adapted to other work.
A box-tool of the pilot type that is used for finishing, after the surplus stock has been removed by roughing tools, is shown at A, [Fig. 9]. The work, which is the cone for a ball bearing, is shown at a by the dotted lines and also by the detail view to the right. The pilot b enters the work before either of the cutters begins to operate on its respective surface. The inverted cutter c, which sizes the flange of the cone, is held in position by a clamp d, which is forced down by a collar-head screw. The cutter is further secured against a beveled shoulder at g by the set-screws f, and it is adjusted forward by the screw e. By loosening the screws f and the collar-head screw, the cutter may be removed for sharpening. The cutter h is adjusted to cut to the proper diameter, by the screws l, after which the clamp k is made level by the screw j. The collar-screw m is then used to secure the tool in place. The cutter is made from drill rod and it is slightly cupped out on the cutting end to give keenness to the cutting edge. The adjusting screw o, which passes through plate p, prevents the cutter from backing away from the work. This adjusting screw plate has its screw holes slotted to avoid removing the screws when it becomes necessary to remove the plate and cutter for sharpening. Pilot b is held firmly to the tool body by set-screw r. The hole s through the shank makes it easy to remove the pilot, in case this is necessary.
A pilot box-tool for finishing another type of ball bearing cone is shown at B. The shape of the work itself is indicated by the dotted lines a and by the detail view. This tool is somewhat similar in its construction to the one just described. The cutters b and c are inverted and are used to face the flange at d and to turn it to the proper diameter. These cutters are held by the clamp f and screws g and are adjusted forward by the screw h. The cutter j, which operates on top of the stock, rests on a bolster, of the proper angle and is adjusted up or down by the screws k. The clamp l, which binds against this tool, is beveled to correspond with the angle of the tool. This clamp is secured by the collar-screw shown and it is leveled by set-screws s. The adjusting screw p prevents the cutter from slipping back. The holes in the adjusting-screw plate are also slotted in this case so that it will not be necessary to remove any screws when the cutter has to be taken out of the holder.
A box-tool for finishing a treadle-rod cone for a sewing machine is shown at C. This tool is also of the pilot type. The cutters in it operate on opposite sides of the cone a. The inverted cutter b sizes the cylindrical part of the cone, while the front cutter d is set at the proper angle to finish the tapered part. The rear cutter b is held in place by the clamp g and a collar screw. It is adjusted forward by the screw h in the plate i which is held by screws as shown. The pilot is retained by a set-screw, and it is easily removed by inserting a small rod in the hole l which passes through the shank. The cutter d is held by clamp m and is adjusted by screw n which passes through a tapped hole in plate o. The screw holes in both the adjusting plates i and o are slotted to facilitate their removal.
Fig. 10. Examples of Box-tool Designs
The box-tool illustrated at A, [Fig. 10], is used for finishing the bushing of a double-taper cone bearing a. The cutters are so arranged that they all cut on the center; that is, the cutting edges lie in a horizontal plane. The inverted cutter b at the rear forms the short angular surface, and the cutter c in front forms the long tapering part of the bearing. The large diameter is turned, to size by cutter d. The pilot e has a bearing in the bore nearly equal to the length of the work and it is provided with oil grooves, as shown. The taper shank of this pilot is tapped for the screw i which extends the whole length of the shank and is used to draw the pilot back to its seat. It is not necessary to remove adjusting-screw plate k to take out the cutter b, as the latter can be drawn out from the front after the collar-screw m is loosened. The cutter c is removed by taking off the adjusting-screw plate s after loosening the collar-screw n. The cutter d is held in a dove-tailed slot by two headless set-screws q. It is also backed up by an adjusting screw in the plate s. These adjusting screws should all have fine threads, say from 32 to 40 per inch, and be nicely fitted so they will not loosen after being adjusted.
The box-tools shown at B and C, [Fig. 10], are for turning the sides of a loose pulley for a sewing machine. This pulley (shown by the dotted lines) is finished in two operations. The box-tool for finishing the side of the pulley on which the hub projects beyond the rim, is shown at B. The inverted cutter a, which faces the end of the hub, is held by a clamp c (clearly shown in the end view) from the under side and it has no adjustment. The collar-screw d is tapped into this clamp, which is prevented from getting out of place by the dowel-pin f. The pilot g is made small in the shank, so that tool a can be so placed as to insure the removal of all burrs around the bore of the hub. The pilot is held by a set-screw and it is provided with oil grooves. The cutter j sizes the outside of the hub, and the cutter k faces the side of the pulley rim. These cutters are both held by the clamp l and the collar-screw m. No side plates are used on this tool, and the cutters are all easily removed.