Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.


  1. Advanced Patent Search
Publication numberUS197933 A
Publication typeGrant
Publication dateDec 11, 1877
Filing dateApr 20, 1877
Publication numberUS 197933 A, US 197933A, US-A-197933, US197933 A, US197933A
InventorsHaywaed A. Haeyey
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Improvement in wood-screws
US 197933 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)


Patented Dec I 8 Zim? 2.




Specification forming part of Letters Patent N0. 197,933, dated December 11, 1877; application filed April 20, 1877.

To all lwhom t may concern:

Be it known that I, HAYWARD A. HARVEY, of Orange, New Jersey, have invented a certain Improvement in Wood-Screws, of which the following is a specification:

My improvements relate to the formations of threads upon wood-screws.

The chief feature of my invention consists in forming such threads with a differential pitch and a variable depth, the pitch and the depth having a constant relation to each other, due to the fact that the core is of the same length between any two threads, whatever may be the pitch. Owing to this peculiarity I am enabled to cut a thread of differential pitch with a tool having a single fixed lead-in other words, without varying the character of the lead given to the tool in making the series of cuts -necessary to finish the thread to the vproper depth.

I form my thread with a gradually-increasing pitch from its point of commencement upon the shank of the blank, which, for con venience, I call the heel7 of the thread. I may gradually increase the pitch from the heel to the point of the screw, or increase it for only a portion of the distance and cut the remainder of the thread upon a uniform pitch. The latter mode, especially, I contemplate adopting in the case of very long screws.

rlhe accompanying drawings represent central longitudinal sections of screws exhibiting my invention in the two forms I have mentioned.

Figure 1 shows the diiferential thread commencing at the heel on the line a@ .r and ter- 'minating at the line y y, from which line the thread has the ordinary uniform pitch to the point of the screw. Fig. 2 shows the differential thread having the pitch gradually increasing from the heel to the point. Fig. 3 is l a drawing showing the contour of the threads and exhibiting the relation of the depth to the differential pitch.

It will be seen that all the threads are nished to a sharp edge by the same tool. In cutting the thread the lead of the tool is gradually increased in speed, and at the same time the tool is fed inward toward the axis of the blank.

I determine the character of the motion required to be given to the tool by dividing the which the differential thread makes. For example, in Fig. l the differential thread makes only four turns around the core. To find the motion for the tool in this case, I lay out a single thread, as in Fig. 3, and then draw, at equal distances, four lines, a b c di, parallel with the bottom line c, which represents the length of the core. I make the. lines a b c d of the same length as the bottom line e, measuring from their respective points of intersection with 011e of the inclined sides, A, of the thread. Three inclined lines, b, c', and d', are then drawn parallel to the opposite inclined side e of the thread. The distance from the line b to the line a. indicates the depth attained by the thread at one revolution. The distance of the line b from the point a indicates the gain of the lead while the blank ismaking a single revolution. The distances between the lines a, b, c, d, and e, respectively, indicate the gain in the depth of thread at each of its revolutions, and the disstances between the point a on the line a and the respective points where thelines bf, c', d', and c intersect the line a indicate the increase in pitch at each revolution, or, in other words, indicate the amount of increased lead required to be given to the tool for each of' the four successive turns of the blank.

It will be seen that the lines representing the core in Figs. l and 2 are inclined to the axis of the screw.

In measuring the depth of the thread preparatory to laying off the pitch of the diiferential threads, as I have described, I measure on the dotted lines Z, which indicate the averageV depth of the deepest thread. In Fig. 2 there are twelve turns of the differential thread, and I therefore divide the greatest depth into twelve equal parts.

It will, of course, be seen that the principle of laying out the differential threads as I have described, for the purpose of measuring the pitch, is capable of application for any variety of pitch required.

I claim as my invention- A screw having `a thread which, for any portion of its length, has a differential pitch and a correspondingly variable depth', substantially as described.


Witnesses Ask FARE, Enwn. PAYsoN. A

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2427216 *Jan 20, 1944Sep 9, 1947Gen Tire & Rubber CoTire mounting rim
US5120171 *Nov 27, 1990Jun 9, 1992Stuart SurgicalBone screw with improved threads
US5226766 *May 21, 1992Jul 13, 1993Stuart SurgicalBone screw with improved threads
US5417533 *Jul 13, 1990May 23, 1995National Medical Specialty, Inc.Bone screw with improved threads
US5492442 *Feb 24, 1994Feb 20, 1996National Medical Specialty, Inc.Bone screw with improved threads
US5871486 *Jan 10, 1997Feb 16, 1999Acumed, Inc.Variable pitch bone screw
US5964768 *Mar 3, 1998Oct 12, 1999Acumed, Inc.Tapered bone screw with continuously varying pitch
US6030162 *Dec 18, 1998Feb 29, 2000Acumed, Inc.Axial tension screw
US6299615Aug 16, 1999Oct 9, 2001Acumed, Inc.System for fusing joints
US6468277Apr 4, 2000Oct 22, 2002Ethicon, Inc.Orthopedic screw and method
US6527777Mar 13, 2001Mar 4, 2003Ethicon, Inc.Device for repairing a soft-tissue tear and method
US6811552 *Jul 1, 2002Nov 2, 2004Depuy FranceDevice for securing bits of bone together
US6984235Jun 3, 2002Jan 10, 2006Acumed LlcSystem for fusing joints
US6989014Jul 25, 2002Jan 24, 2006Ethicon, Inc.Orthopedic screw and method
US7235079Nov 18, 2004Jun 26, 2007Acumed LlcComposite bone fasteners
US7578836Jan 24, 2006Aug 25, 2009Depuy MitekOrthopedic screw and method
US8070786Jan 9, 2006Dec 6, 2011Acumed LlcSystem for fusing joints
US8197511Mar 4, 2009Jun 12, 2012Miller M ToddSuture anchor having a suture engaging structure and inserter arrangement
US8439946May 21, 2012May 14, 2013Stryker CorporationSuture anchor having a suture engaging structure and inserter arrangement
US8632568Sep 24, 2007Jan 21, 2014Stryker CorporationSuture anchor having a suture engaging structure and inserter arrangement
US8858596Mar 20, 2012Oct 14, 2014Stryker CorporationSuture anchor having a suture engaging structure
US9161793Mar 27, 2013Oct 20, 2015Acumed LlcAxial tension screw
US20030014054 *Jun 3, 2002Jan 16, 2003Huebner Randall J.System for fusing joints
US20030040751 *Jul 1, 2002Feb 27, 2003Weil Lowell ScottDevice for securing bits of bone together
US20040249381 *Jul 8, 2004Dec 9, 2004Depuy FranceDevice for securing bits of bone together
US20050227320 *Oct 14, 2004Oct 13, 2005Massachusetts Institute Of TechnologyRationally designed polysaccharide lyases derived from chondroitinase B
US20050233419 *Oct 14, 2004Oct 20, 2005Massachusetts Institute Of TechnologyRationally designed polysaccharide lyases derived from chondroitinase B
US20060122612 *Jan 24, 2006Jun 8, 2006Justin Daniel FOrthopedic screw and method
US20080167660 *Jan 4, 2007Jul 10, 2008Nathan Ryan MoreauSuture anchor and inserter arrangement
International ClassificationF16B25/00
Cooperative ClassificationF16B25/00, F16B25/0015, F16B25/0057, F16B25/0047
European ClassificationF16B25/00G1C, F16B25/00C1, F16B25/00G1A, F16B25/00