Lee Valley & Veritas
Woodworking Newsletter
  Volume 8, Issue 3 - January 2014    
Featured Patents
Let's Bash the Tin Box
Hexdall hammer
In terms of the rapid rise in the high-tech world, there have been consistent references to the "two guys in the basement" and how innovation and determination changed and shaped how information is stored and transmitted. But what about the ordinary things? The new improved mousetrap with more than 7,000 approved patents? And of course the lowly hammer, sitting at more than one million patents. These are examples of how constant revision is the driving force for any new concept. The same principle applies in the tool world with the working tradesperson who "sees the light", so to speak, and makes an improvement to an everyday working tool. Such is the case with this item. First the patent and then the story.
Hexdall hammer   Hexdall hammer
Andrew M. Hexdall of Morris, Indiana, sought with patent #2,606,468 dated April 29, 1949, to improve the methods used and the quality of work done by those in the sheet-metal trade with the construction of the purpose-built tinner's hammer. His distinctive approach resulted in a hammer head that, upon manipulation, could work into square recesses. It also provided a large striking surface for working the flange in rectilinear joints, as normally found in ductwork. As with most regulated and apprentice-driven trades, change is most difficult. The appearance of a new tool to supplant the old is never well received unless there is a possibility of reaching a wide group via mass marketing and effective distribution. Strangely, some 50 years later, this hammer has merit and could probably be widely accepted as a first choice in the respected tin-banger trade.

  Hand-written note
  A hand-written note, included in the box, explaining the history of the item.
In the mid-1990s, this item was offered on a popular website and made its way into the Lee Valley collection. Upon receiving the hammer, it was a most pleasant surprise to find that the history had been carefully recorded by a Mrs. Dale Hextell (note spelling) and was included in the original packing box. The photo shows a copy of the original handwritten note, as found, with its full explanation as to the source and manufacture of the hammer. On a separate sheet, the seller (who was not Mrs. Hextell) indicated that there were about 25 units available in this new old stock (N.O.S.) condition. I surmise that these sold rather quickly, as hammer aficionados would jump at the chance to own such a limited-production hammer with an American patent and history. Normally by the time tools such as this are rediscovered or sold, there is no record as to where and how they came to be marketed. It is rather pleasant to know the back story of this innovation.

D.S. Orr

D.S. Orr has been a collector, user and student of woodworking and metalworking tools and practices for more than 40 years. Recently retired, he has devoted even more time to these endeavors.

Patented Aug. 12, 1952
United States Patent Office


Sheet Metalworking Hammer

Andrew M. Hexdall, Morris, Ill.

Application April 28, 1949, Serial No. 90,085

2 Claims. (Cl. 81-15)
This application is a continuation-in-part of my copending application Serial No. 14,661, now abandoned.

The invention relates to hand hammers generally, and more particularly to an improved hammer for sheet metalworking.

The general object of the invention is to provide a hammer especially suited for the various operations involved in the fabrication and erection of sheet metal structures and which is constructed so as to afford a feeling of balance and a resiliency or bounce that makes it easier and less fatiguing in use.

A more specific object is to provide a hammer particularly well adapted for completing Pittsburgh joints in sheet metal structures, which can be used effectively in confined spaces and which is universally adaptable for seating the driven flanges of either right or left-hand joints and for other joint finishing operations such as the lapping over of the second or locking flange.

Other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiments illustrated in the accompanying drawing, in which:

Figure 1 is a perspective view of a hammer embodying the features of the invention, showing it in the left-hand position in seating the driven flange of a Pittsburgh joint.

Fig. 2 is a perspective view of the hammer showing it in the alternate or right-hand position.

Fig. 3 is a perspective view showing the use of the hammer in lapping over the locking flange to finish the joint.

Fig. 4 is an end view of a modified form of the hammer shown in Figs. 1-3.

Fig. 5 is an end view of a modified form of the hammer.

Two embodiments of the invention have been shown by way of illustration, but it is not intended to thereby limit the invention to the precise forms illustrated. On the contrary it is the intention to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Referring to the drawing, the improved hammer has a head 10 which may be fashioned as a steel forging or may be milled from bar stock, as desired. The head is centrally apertured as at 11 to receive the end of a wooden handle 12. Such handles are commonly formed with a gripping portion 13 of generally oval contour to conveniently fit the hand of the user. Preferably, the end or shank portion of the handle and the aperture 11 in the head are of circular cross section so that the handle may be turned on its axis to orient the gripping portion for the convenience of any user. The handle may be anchored to the head and located in adjusted position by any suitable means, such as a set screw 14 (Fig. 4). Alternatively, a conventional wedge 15 may be utilized for anchoring the handle to the head, as shown in Fig. 5.

In accordance with the invention, at least three specially shaped striking faces are provided on the head 10. One of these is a relatively long striking face 16 fashioned on a side of the head and terminating or blending into noses 17 of smoothly rounded contour at each end. To provide the resiliency or bounce desirable for reducing the shock and jar transmitted to the hand of the user, the face 16 is preferably crowned or formed with a contour a contour arcuate about an axis substantially parallel to the axis of the handle and off-set therefrom and on the opposite side thereof from the face. In general, a relatively small curvature is all that is required and in practice it has been found that such curvature may conveniently be formed on a radius in the neighborhood of four inches.

The surface finishing of the striking face 16 is also important in giving the hammer a well-balanced feeling and the correct swing in use. More particularly, it has been found that the best results in this respect are obtained when the striking surface is finished by an abrading operation or the like which leaves the surface slightly roughened and with a grain defined by shallow ridges. The abrading tool is applied so that the grain or ridges extend across the face in the direction of its narrowed dimension or parallel to the handle. This enables the pounding face to draw on the metal or hold back just enough to impart a live feeling, which is highly desirable in metalworking hammers.

Two additional striking faces 20 and 21 are fashioned on opposite ends of the head. These faces are disposed in substantially parallel planes at right angles to the first-mentioned striking face 16. The striking faces 20 and 21 are crowned similarly to the face 16 and are finished with an abraded surface having the grain extending across the narrow width of the face, in this instance transversely of the axis of the hammer handle. Preferably, the corners of these faces are rounded as shown in Fig. 4.

To facilitate the use of the hammer in oppositely disposed crevices or corners, the striking faces 20 and 21 are terminated at their ends remote from the striking face 16 in abrupt shoulders 22 and 23. The intermediate portions of the head 10 on the side opposite the face 16 are recessed as at 24 so as to present the shoulders 22 and 23 in laterally projecting or off-set relation with respect to the central portion of the head. Thus ample clearance is provided for inserting the head into a corner. At their other ends, the end striking faces are separated from the side face 16 by the noses 17 which terminate inwardly from the faces or are off-set so as to form narrow shoulders 171 substantially normal to the respective striking faces.

The facility with which the improved hammer may be used in confined spaces will be readily seen by reference to Figs. 1 and 2 of the drawings. Thus, in hammering in a left-hand corner (as viewed from the handle end of the hammer) such as shown in Fig. 1, the striking face 20 is used. The narrow shoulder 22 permits the striking face to be applied relatively close to the edge of the surface being pounded. In an oppositely disposed or right-hand corner, the hammer head is turned through 180° about the longitudinal axis of the handle from the position shown in Fig. 1 to the position shown in Fig. 2 and the striking face 21 is used. This reversible characteristic of the hammer greatly aids the worker, especially in confined quarters, when working overhead or in the various awkward positions that a sheet metal installer has to assume.

Pittsburgh joints are, of course, commonly used in sheet metal duct work. As is well known, the sheets for such joints are performed so that one sheet 25 has a first or driven flange 26 which must be hammered into a groove formed by a reverse bend 27 in the other sheet 28, as shown in Figs. 1 and 2. Finally, a second or locking flange 29 at the edge of the sheet 28 must be bent or crimped over and smoothed down over the sheet 25 to complete the joint, as shown in Fig. 3.

Such seating of the driven flange 26 and lapping over of the locking flange 29 has to be done on the job by hand during installation of the sheet metal structure. The hammer here disclosed is especially suitable for the performance of those operations. The peculiar shape and location of the reversible end striking faces 20 and 21 make it possible to get into the corners between the sheet 25 and flange 29 and drive home the flange 26 wherever the work is located. It can be done by this hammer with clean, sharp blows without either marring the upstanding flange 29 or buckling or distorting the sheet 25 at the root of the flange 26 or elsewhere. Moreover, with the flange 26 driven home, the long striking face 16 makes it possible to lap over the locking flange 29 in a neat, workmanlike manner and with a relatively small number of strokes of the hammer. Because of the surface contour and finish of the striking face 16, the feeling of balance and the draw against the work enables the workman to attain maximum production with less effort and with maximum fatigue.

In some instances it may be desirable to provide the hammer with a fourth or auxiliary striking face 30, which additionally serves as an anvil or backing surface against which a metal sheet or the like may be pounded to remove irregularities. The face 30 is formed on the side of the head 10 opposite the face 16 and is preferably flat and smooth as shown in Fig. 5. In this case the end faces 20 and 21 are merged into the face 30 by gently rounded corners 31. Since all four sides of the head present pounding faces in this instance, the handle 12 is anchored to the head by means of the wedge 15.

I claim as my invention:
1. A sheet metal hammer comprising a metal head apertured centrally to receive a handle, said head having an elongated generally flat lateral surface disposed in a plane approximately parallel to the axis of the handle aperture, a pair of generally flat end surfaces substantially shorter than said lateral surface, said end surfaces lying in planes laterally offset from and substantially parallel to the axis of the handle aperture, said lateral surfaces merging at opposite ends into said end surfaces by way of smoothly curved corner portions which are offset inwardly with respect to the end surfaces, the end portions of said head having lateral extensions at the side opposite said lateral surface defining shoulders projecting substantially beyond the portion of the head between the shoulders.
2. A sheet metal working hammer comprising, in combination, an elongated head defining abrupt shoulders at opposite ends thereof at sides opposite from said side face, said end faces being substantially commensurate in width with said head and extending from said respective shoulders to extremities disposed somewhat inwardly of the adjacent ends of said side face, and two curved nose portions on said head disposed in bridging relations between said respective end faces and adjacent ends of said side surface.
Andrew M. Hexdall.
References Cited

The following references are of record in the file of this patent:
United States Patents
Number Name Date
Feb. 3, 1880
Jan. 21, 1890
May 21, 1901
Jan. 11, 1910
May 17, 1910
Aug. 23, 1910
Sept. 8, 1931
Mar. 1, 1932
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