[Illustration: Fig. 9. A Lathe Taper Attachment]
=The Taper Attachment.=--Turning tapers by setting over the tailstock center has some objectionable features. When the lathe centers are not in alignment, as when set for taper turning, they bear unevenly in the work centers because the axis of the work is at an angle with them; this causes the work centers to wear unevenly and results in inaccuracy. Furthermore, the adjustment of the tailstock center must be changed when turning duplicate tapers, unless the length of each piece and the depth of the center holes are the same. To overcome these objections, many modern lathes are equipped with a special device for turning tapers, known as a taper attachment, which permits the lathe centers to be kept in alignment, as for cylindrical turning, and enables more accurate work to be done.
[Illustration: Fig. 10. Sectional View of Taper Attachment]
Taper attachments, like lathes, vary some in their construction, but all operate on the same principle. An improved form of taper attachment is illustrated in Figs. 9 and 10. Fig. 9 shows a plan view of a lathe carriage with an attachment fitted to it, and Fig. 10 a sectional view. This attachment has an arm _A_ on which is mounted a slide _S_ that can be turned about a central pivot by adjusting screw _D_. The arm _A_ is supported by, and is free to slide on, a bracket _B_ (see also sectional view) that is fastened to the carriage, and on one end of the arm there is a clamp _C_ that is attached to the lathe bed when turning tapers. On the slide _S_ there is a shoe _F_ that is connected to bar _E_ which passes beneath the toolslide. The rear end of the cross-feed screw is connected to this bar, and the latter is clamped to the toolslide when the attachment is in use.
When a taper is to be turned, the carriage is moved opposite the taper part and clamp _C_ is fastened to the bed; this holds arm _A_ and slide _S_ stationary so that the carriage, with bracket _B_ and shoe _F_, can be moved with relation to the slide. If this slide _S_ is set at an angle, as shown, the shoe as it moves along causes the toolslide and tool to move in or out, but if the slide is set parallel to the carriage travel, the toolslide remains stationary. Now if the tool, as it feeds lengthwise of the work, is also gradually moved crosswise, it will turn a taper, and as this crosswise movement is caused by the angularity of slide _S_, different tapers are obtained by setting the slide to different positions.