In Fig. 167 is given a view of one of the electrically driven lathe grinder attachments made by the Cincinnati Electrical Tool Company. It may be held in the tool-post or tool-clamping device, and is entirely self-contained, the emery wheel being attached to the shaft of the small electric motor within the metallic case. It is driven by the current coming through an ordinary incandescent lamp cord. Its movements are regulated by the crank seen in front of the case, as well as by the cross and lateral feeding mechanism of the lathe.

Fig. 167.   Tool Post Grinding Attachment, made by Cincinnati Electric Tool Company.

Fig. 167. - Tool-Post Grinding Attachment, made by Cincinnati Electric Tool Company.

Its compact form, portability, and the convenience of attaching, using, and detaching, render it a very useful lathe grinder. It can be set at any angle so as to grind taper work as well as straight, and the centers of the lathe in which it is used.

Figure 168 is of a center-grinding attachment made by the Hisey-Wolf Machine Company, and is shown attached to a lathe in the proper position for grinding the head-stock center. Like the last example it consists of an electric motor whose shaft carries the emery wheel. The shaft is arranged to travel endwise as is necessary in center grinding, and is operated by means of the double crank shown at the left. It is driven by the current from an ordinary lamp cord.

Fig. 168.   Lathe Center Grinding Attachment, made by the Hisey Wolf Machine Company.

Fig. 168. - Lathe Center Grinding Attachment, made by the Hisey-Wolf Machine Company.

Figure 169 represents a larger grinding attachment made by the same company and designed for larger and heavier work than either of the above devices. It is arranged to be bolted down upon the lathe carriage, or a block attached to it so as to bring its center at the same height as that of the center line of the lathe. It is driven in the same manner as the last two devices.

The entire motor and case is attached to a square block having a vertically sliding surface planed upon it, and fitting the bolting-down and supporting bracket upon which it slides vertically, being adjusted as to height and held in any desired position by the double crank seen at the top.

By extending the shafts of these motors, either temporarily or by having them so constructed when built, to the proper distance so as to carry the emery wheel at a considerable distance from the motor, they may be used for grinding the inside of cylindrical work, the longitudinal feed of the lathe being made use of to give the required travel for the wheel.

Fig. 169.   A Larger Lathe Grinding Attachment, made by the Hisey Wolf Machine Company.

Fig. 169. - A Larger Lathe Grinding Attachment, made by the Hisey-Wolf Machine Company.

Should the inside work be conical it is entirely practical to attach the grinder to the compound rest, set at the proper angle and the wheel fed back and forth quite as readily as on straight work.

Being electrically driven the device may be set with its shaft at right angles to the center line of the lathe, and face grinding may be conveniently performed.

In fact there are hardly any of the ordinary grinding operations that are required to be done on centers that may not be performed by one of these grinders, even to cutters, reamers, and the like, by a little ingenuity in arranging for them.

These points make such grinders of a great deal of value in ordinary machine shops and manufactories, and almost indispensable in the smaller shops where it is not always possible to get a regular grinding machine.

The Rivett-Dock thread-cutting attachment, shown in Fig. 170, may with propriety be classed as a tool, but from its importance in design, use, and effect it seems to deserve being classed as an attachment and so it is made a part of this chapter.

Its construction and operation is as follows: The angle plate A is adapted to be bolted down on the tool block of the lathe, and upon its upright face is fitted the horizontal slide B, which may be moved forward and back by means of the lever C. The slide B has pivoted to it the circular cutter D, whose ten teeth are shaped in the form of the thread. However, the full form of the thread is only given by the last one used in cutting the thread, the others being gradually cut away so that the first one hardly more than marks the location of the cut, the design being to cut the full thread at ten cuts, each successive tooth of the cutter cutting a little deeper until the tenth tooth shall have but a trifle to cut to finish the thread.

Fig. 170.   The Rivett Dock Thread Cutting Attachment.

Fig. 170. - The Rivett-Dock Thread Cutting Attachment.

It will be noticed that the tooth marked 0 in the engraving rests upon a projection E, which supports it in its cutting position to act upon the piece F which is being cut. The cutter having made one cut is withdrawn from contact with the work by the handle C, by which motion the pawl G, pivoted at the top of the angle plate A, engages in the space between the teeth of the cutter D, and causes it to rotate to the left just far enough to bring the next tooth into the cutting position. The withdrawal of the cutter from the support E permits its revolution. The cutter is then thrown forward and the next tooth is ready for the cut. This operation is repeated until all the teeth have been brought into the cutting position and made their cut in succession, and the thread is completed.

The important point accomplished by this device is that as there should be ten cuts made to complete a thread, the keen edge of the tool for finishing is liable to be lost in the earlier roughing cuts. With this device the roughing cuts are made with teeth designed for that work particularly, and the thread is brought to a state of completion by what is practically ten different tools. Hence a saving of time, both in cutting and in grinding tools, and the production of a smooth, accurately finished, and perfect thread.