International library of technology; a series of textbooks for persons engaged in the engineering professions and trades, or for those who desire information concerning them Volume 138 - International Textbook Company, Paperback

• Release Date   9/13/2013
• ISBN-13   9781230007953 | 978-1-230-00795-3
• ISBN   1230007954 | 1-230-00795-4
• Format   Paperback
• Author(s)   International Textbook Company
• 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. 1920 edition. Excerpt: ...the rod to be threaded is held in a vise. The die is then well oiled and screwed down on the end of the rod until the desired length of screw has been cut. Some pressure will be necessary to start the die. but after a few threads are cut it will feed itself along as it is revolved. The die shown in Fig. 52 is adjustable within certain limits. Fig. 54 shows it with one half removed. The parts a and b compose the cutting die proper. The part c is a guide that slips on the end of the work and holds the die true when starting the thread. Adjustment is made by the tapered-head screw d. When screwed into the lower guide, it forces the halves of the die apart slightly, thus causing them to cut a larger thread. When in use, the two halves of the die are kept from springing apart by being held in the die stock. 97. Inaccuracy of Pitch.--Hand threading is slow, as it requires nearly as much time to remove the die from the work as to cut the thread. Hand-cut threads can never be depended on to be true with the axis of the work, as the guide does not fit with sufficient accuracy to start the die perfectly true. Worst of all is the inaccuracy of pitch. It is not uncommon to find dies that would cut a thread which, if continued for a foot in length, would be in error inch. With care, dies can be made that will cut short threads with sufficient accuracy of pitch for ordinary commercial purposes. BOLT CUTTERS 98. General Description.--For rapid screw cutting, special machines are used, called bolt cutters, that rotate the dies while the work is held in a chuck. Fig. 55 shows a type of double-head bolt cutter, so called because it carries two heads or die stocks. The work is clamped horizontally in the machine in the jaws or chucks d by means of the large...