ISBN: 9781236842329

RareBooksClub.com. Paperback. New. This item is printed on demand. Paperback. 104 pages. Dimensions: 9.7in. x 7.4in. x 0.2in.This historic book may have numerous typos and missing text.… Mehr…

RareBooksClub.com. Paperback. New. This item is printed on demand. Paperback. 104 pages. Dimensions: 9.7in. x 7.4in. x 0.2in.This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1907 edition. Excerpt: . . . motions upon the leading screw only; and when this is the case, its original accuracy (as previously stated) cannot long be maintained. This is to some extent due to the greatly increased strains to which it is subjected when used for turning heavy work instead of for cutting the threads of screws only. But, even if every possible care be taken in this respect, a still more fertile source of error remains, from the fact that the bulk of the work in almost every lathe is performed within a short distance of the mandril, so that this part of the screw becomes much more rapidly worn and deteriorated than the remainder. This has led to the introduction of self-acting apparatus for giving motion to the slide-rest by means of the longitudinal rack, to which, in its application to handtraversing, attention has already been directed. The gearing required for this purpose gives an additional appearance of complication to lathes which are provided with it, which are known as Self-acting, Surfacing, and Rack-traversing lathes; the tools attached to their slide-rests being capable of being driven with a slow traversing motion parallel to the lathebed, at right angles to it for surfacing, or diagonally, by an ingenious combination of the two, for taper turning. For these purposes a longitudinal Back-shaft is placed behind the bed, being supported (at its ends only) in the same manner and in much the same position at the back, as that in which the leading screw shown in Fig. 175 is supported in front. But this shaft, instead of having a screw-thread cut directly upon it, carries a short worm, which, whilst it can slide freely in the direction of its length, is compelled always to revolve with it, the shaft being provided with a longitudinal. . . This item ships from La Vergne,TN., RareBooksClub.com<