US42475A

US42475A - Improved wood-screw

Info

Publication number: US42475A
Authority: US
Publication date: 1864-04-26
Anticipated expiration: 1881-04-26

Description

WO OD SGREW. l

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UNITED STATES ATENT OFFICEO H. A. HARVEY, on NEW YORK, N. Y.

IMPROVED WOOD-SCREW.

,To aZZ whom it may concern:

Be it known that I, HAYWARD A. HAR- "VEY, of the city, county, and State of New York, have invented a new and useful Wood- Serew; and I do hereby declare that the following, taken in connection with the drawings, is a full, clear, and exactdescrption thereof. a

In the drawings, Figure l is' a longitudinal central section through the screw. Fig. 2 is an elevation' of' the head'and part of the shank, and Fig. 3 is a plan of the lower side of the head.

Tle improved wood-screw herein descrihed has been devised i order to 'secure a firmer hold in Wood, and to prevent in a measure, if

not Wlolly, all the tendeney of the screw to i The improvements are bs'ed upo'n'tle well known property of exjar out ot' the Wood'.

pansion of Wood after eompression.

The sc'ew is to be cut -in -any nsual or propermaehine, and the chaser s to be caused t) cut deeper than usnal at some part of the barrel of the sorew between the end of the 1 point and the place` Where the thread comn'ences, as from A to B. [his operation will leave the pitch of the thread the sameas in the ordinary screw, but the thread willhave greatest projection where the barrel of the screw is smallest indiameter; and also be thinner or cone more nearly to an edge at its peiphery, as may be clearly see-n in the dran iugs. The barrel of the-screw will alsobe curvcd longitudinally; so that its diameter near the point is greater than its dianeter farther up the shank or barrel, and it is clear that it' the barrel were gripped at the small part that it could not be pnlh'd out of the 'grippcr or grasping* body it' the 'same were rigid, even-ifit had no thread. This longitudinal curve in the barrel making the serew bnlbous--ointed, is theflfirstfeatnre of the invention, and such bulbous-oointed screws nay be made witlfia thread of Varying pro jection, as shown in the drawings,or with a thread which at all points projects the same distance from the barrcl. The former plan is preferred.

The under side of the screw-head'represented in the drawings is cut into teeth like ratchet-teeth, so that the screw can be turned easily in one 'direction-wl'en in contact with Wood, and cannot be turned except With diffieulty in theother. These teeth are so formed With reference tothe twist of the screw-thread that their inclined faces compress the wood and pass over it when the screw is screwed in. When a screw such as is described is forced into Wood, the latter will expand after the point has passed and grasp firnly 'around the small part of the barrel; and :when the thread draws the under sideof the head down upon the Wood the teeth will conpress the wote, and when the screw is hotne the wood expanding Will` enter into the ratchet-teeth and prevent unscrewing,` except b breaking or cutting the Wood by the straight sides of the teet I prefer to 'make these screws with the entering part ot" the point formed substantially 'as shown in the drawings, where the convolutions ot' the 'thread are represented as extending down the entvring part of the point; a

but stopping short oi' the extreniity thereof. By. this nethod of .construction a center point is forned which forns a guide, causing ,the scre'w't'o enter eXactly-a t the desired location, and also opens the' way so that the screw may be screwed in withcut the necessity of boring a ho'e, thereby causing the expanding Wood to grip firnly around the small part of the barrel. But the extrenity of the point may be of any forn and the screw still remain bulbous-pointed so long as the barrel is smaller atsome part of its length than it is at another part between that small part and the extrenity of the point, thereby bringing into action the expnding quality of the wood to secure the screw in place irrespective of the hold of the threads.

l claim as of ny own in\'ention- 1. -A bulbous-pointed screW, substantially -such as -is hercin deseribed.

2. 'A bulbous-pointed screw with the thread projecting'unequally, so that its periphery \villoccupy the same position that it 'wouldin a screw ottheordinary form of barrel, 'substantially as described.

. 3. A bulbous-pointed ratchct'headed screw, constructed and having the mode of operation herein set forth. 4

4. A bulbous-pointed serew provided with a center point without any thread on-the extremity thereot, substantially such as is herein specified.

In testimony whereof I have hereunto subscribed my name;

H. A. HARVEY.