US2578163A - Plasterer's darby - Google Patents

Description

Dec. 11, 1951 E. A. WHALEN PLASTERERS DARBY Filed July 9, 1949 &

Patented Dec. 11, 1951 PLASTERERS DARBY Edward A. Whalen, Chicago, 111., assignor to Wha-Lite Products, Chicago, 111., a copartnership composed of Edward A. Whalen and Sidney F. Lundberg Application July 9, 1949, Serial No. 103,886

1 Claim. 1

The present invention relates to plasterers darbies. By the very nature of its intended use a plasterers darby is a tool which is exposed to substantial abrasion and frequent wetting and drying. These tools have traditionally been made of wood, and to the best of my knowledge are still exclusively so made. Because of these unsatisfactory working circumstances, however, many disadvantages inhere in this wooden construction, the correction of which would result in better plaster coats, reduced expense, and asubstantial saving of tool maintenance labor to the plasterer. Because of the alternate wetting and drying, warping of the implement almost inevitably occurs unless extraordinary precautions are taken such as nailing the tool to a flat surface while drying it and periodically redressing the working surfaces. Since a darby is relied on to create a plane surface in a plastering operation this warping obviously will destroy its basic utility. Second, through the continuous wetting to which it is subject, a wooden implement will gradually soak up increasingly more water to make the tool heavy and awkward to manipulate. Although it might be suggested that a wooden darby could be covered by a Water resistant surface such as paint, the abrasion to which it is exposed in Working with plaster will quickly wear off or destroy any such coating and the tool would again be subject to the material disadvantages suggested above. The abrasion also results in splintering of the wood, requiring frequent planing to correct, and furthermore produces a roughened surface on the tool which is most difficult to clean.

My invention has, therefore, as one of its objects the provision of a novel darby which is light in weight, not subject to warping, inexpensive, and simple in construction.

Another' object of my invention is to provide a darby formed in novel fashion of light metal which offers a relatively indestructible working surface.

The use of metal, however, in the fabrication of a darby involves the two contradictory requisites of lightness and rigidity. Thus solid metal stock may attain rigidity equal to that of a wooden darby but only by increasing the depth to a degree which will add substantial weight. The reconciliation of these requirements forms apart of my invention and a further object thereof is, therefore, to provide a darby which, though made of light metal and is exceedingly light in weight, has equal or superior rigidity to a darby formed of wood.

Other objects and advantages of my invention will be apparent from the following description and drawings, in which:

Fig. 1 represents a perspective view of the back side of a darby constructed in accordance with my invention;

Fig. 2 is a cross-sectional view which may be considered as being taken along the line 2-2 of Fig. 1 looking in the direction of the arrows; and

Fig. 3 is a sectional view which may be considered as being taken along the line 3-3 of Fig. 1 looking in the direction of the arrows.

According to the present invention the darby is composed generally of a longitudinal blade Ill which is preferably formed of a light metal extrusion and two handles l2 and 14 mounted on the back side of the blade ill, the first [2 being a longitudinally extending centrally disposed handle, and the second M a centrally disposed cylindrical handle. As illustrative of the possible methods of mounting the handles, the longitudinal handle may be secured to the blade by screws 16 extending upward from the working surface [8 thereof, the heads of the screws being countersunk therein as at 20. The cylindrical handle may, likewise, be secured to the blade by a nut and bolt 22. However, since the back side 24 of my blade is preferably planar, some abrasive material 26 such as sand may be deposited between the back side of the blade and the abutting end 28 of the handle I4 to prevent rotation of the handle with respect to the blade. It also is possible that the back side of the blade and the abutting surface of the handle be formed so as to provide for some other means of mutual engagement'to prevent rotation between them, so avoiding the requirement of the abrasive.

The blade, in which my invention primarily resides, is basically a long narrow strip of light metal which may be formed by several processes but which will preferably be formed by extrusion. An appropriate metal would be a lightweight structurally strong magnesium or aluminum alloy. The approximate outside dimensions of the blade would be a length of about three and one-half feet, a width of three and three-quarter inches, and a thickness of three-eighths of an inch. If extruded stock is to be employed in its fabrication, the desired length, of course, will be achieved by a simple cutting to length.

The strip of which this blade is formed is characterized by the presence of two cavities 30 extending longitudinally therethrough and lying side by side between the working surface 18 and the back side 24. By this fabrication a central rib 32 remains in the blade through which the screws l 6 or bolt 22 may pass to provide a secure anchorage for the handles 12 and I4, without distorting the working surface l8, the rib also serving as a strengthening element in the structure and contributing to the rigidity of the blade.

The durabilityof themetal blade makes possible a feature which is wholly impracticable in the case of the wooden darbies; namely that of providing serrations on at least one longitudinal r edge of the Working surface in order to rake the wet plaster, to spread it more smoothly, and also to provide a keyed surface to which a subsequent coat of plaster may be applied to adhere-rmore effectively. The present darby therefore "may be serrated on one or both longitudinal edges of the Working surface [8 as at 34 bya notching of the edge. The vertical depth of these'serrations may be on the order of a quarter of an inch. v.To permit the formation of'these serrations and to prevent plaster from flowing into the cavities 3 ll to-load up the interior thereoL-theouter walls 36 of the cavities are formed to slopedownwardly and inwardly thereby to provide agreater thickness of metal on the longitudinal edges.

An implement constructed in accordance with myin-vention provides a darby which islight-and easy to use, which, being made :of metal, afiords 5 Number a long lasting smooth surface and a blade which is proof against warping, and, by virtue of the tubular structure, offers rigidity characteristics equal or superior to the conventional wooden darby.

Having thus described one embodiment of my invention, what I believe to be new and useful 'anddesire to obtain by Letters Patent of the United States is:

A substantially rectangular tubular darby blade, a central longitudinal rib connecting the front'and back walls thereof, outer corners of the tube being internally beveled to provide thickened corners-said outer corners being ext'ernally serrated, and handles on the back wall of said darby blade and secured thereto by countersunk bolts extending through said central rib.

EDWARD A. WHALEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Taggart June 24, 1919 Williams July 21, 1936 Mosel J an.'2, 1940

Images