GB2245509A

GB2245509A - Plasterer's trowel

Info

Publication number: GB2245509A
Application number: GB9112520A
Authority: GB
Inventors: Geoffrey Betts
Original assignee: Betts & Sons Ltd
Current assignee: Betts & Sons Ltd
Priority date: 1990-07-06
Filing date: 1991-06-11
Publication date: 1992-01-08
Anticipated expiration: 2011-06-11
Also published as: GB2245509B; GB9112520D0; GB9014973D0

Abstract

A method of making a plasterer's trowl comprises welding a plurality of upstanding studs 16 at controlled spacing on one side of a steel blade element 10 and subsequently securing a reinforcement element 12 thereto by the use of an adhesive in apertures 22 in which the studs 16 are received. So that the securing of the reinforcement element to the blade element does not induce tensile stresses and distortions in the blade element, the method includes the forming of the reinforcement element 12 to which a handle 24 is connected, with an elongate aperture or apertures 22, the studs being an interference fit widthwise in said aperture or apertures. <IMAGE>

Description

Plasterer's trowel.

The invention relates to plasterers' trowels and to an improved method of making a plasterer's trowel.

It is known to manufacture a plasterer's trowel by a method involving the welding of a plurality of upstanding studs on one side of a steel blade element, a handle subsequently being secured to the blade element by means of said studs. For example, an all metal handle has been secured to the blade element by riveting over the free ends of the studs after they have been caused to extend completely through a part of the handle. However, with this known method a particular problem is that any induced tensile stresses in the blade element, brought about for example by variations in the spacing of the studs, will produce distortions of the blade element.Since it is essential for the working surface of the blade element to be perfectly flat, such distortions have to be corrected by a subsequent surface grinding operation which adds to the cost of production (although in fact this is not a complete answer to the problem because induced stresses can become relieved over a period of time so that a trowel which has initially been made perfectly flat by surface grinding can sometimes become distorted after prolonged use).

The invention has for its object to provide a method of making a plasterer's trowel by means of which the problem referred to will be at least alleviated.

According to one aspect of the invention, a method of making a plasterer's trowel includes the steps of welding a plurality of upstanding studs at controlled spacing on one side of a steel blade element; forming a reinforcement element with a planar surface and with either an elongate aperture or a plurality of apertures at the same nominal spacing as the upstanding studs of the blade element, in this latter case said apertures being of greater length than width, but in either case the width of the or each aperture being such that the studs of the blade element are an interference fit between the side surfaces thereof; charging the or each aperture with an adhesive; and uniting the blade element and reinforcement element together by forcing the studs into the elongate aperture, or respective apertures, as the case may be, of the reinforcement element whereby the two are held together initially by the interference fitting of said studs in the aperture or apertures, the clearances formed between the studs and/or between the studs and the ends of the aperture or apertures being filled with the adhesive. Preferably, the reinforcement element will be made of elongate form and be produced as a metal casting integrally with a handle root portion, a handle being subsequently secured to said handle root portion. The method may include the further step of moulding a handle sleeve portion for fitment on a spindle part of the handle root portion, and fitting said handle sleeve portion non-rotatably with respect to said handle root portion.The method will preferably include the initial step of forming screwthreads on the studs which are to be welded at controlled spacing on the one side of the steel blade element, the screwthreading of the studs subsequently assisting the interference fitting of said studs in the respective apertures of the reinforcement element.

According to another aspect of the invention, there is provided a plasterer's trowel which has been made by the method described above.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which:- Figure 1 is an exploded view showing the main elements of a plasterer's trowel embodying the invention, Figure 2 is a sectional view on the line 2-2 in Figure 1, drawn to a somewhat enlarged scale, Figure 3 is a scrap view of a part of a die in which an element of the trowel has been cast, and Figure 4 is an exploded view illustrating a handle part of the trowel.

Referring now to the drawings, the plasterer's trowel there illustrated includes three main parts, that is to say a steel blade element 10, a metal reinforcement element 12 and a handle, generally indicated 14, which is connected to the reinforcement element.

The steel blade element 10, which is of rectangular outline shape, has a plurality of upstanding metal studs 16 welded to it on one side along a line equidistant from its longitudinal edges. The studs 16, which are screwthreaded studs for a purpose which will be hereafter explained, are provided for the securement of the blade element to the reinforcement element 12, the underside of which is perfectly flat and straight.

The thickness of the steel blade element is such that, until united with the reinforcement element, it is fairly flexible.

As shown in Figure 1, the reinforcement element is of elongate form, having been produced as a metal casting with a planar surface 18 against which the blade element 10 is to be secured and with an integral handle root portion 20 for the securement of the handle 14 thereto. A number of apertures 22 are cast in the reinforcement element, said apertures opening from the planar surface 18 and being spaced at the same nominal spacing as the metal studs 16 upstanding from the surface of the blade element. However, the apertures are not cylindrical apertures but are of elongate form.As shown in Figure 3 each core piece of the die in which the element has been cast has been formed from a somewhat oversize cylindrical pin with flats formed down each side to suit the diameter of the metal studs 16. (Each core piece will in addition be provided with a very small degree of taper to facilitate the release of the cast component from the die but this is not shown since this is a conventional requirement). The arrangement is such that as the blade element 10 and reinforcement element 12 are united together, the metal studs 16 are an interference fit between the side surfaces of the respective apertures, a clearance being formed between the studs and the opposite ends of said apertures. Consequently, any slight variations in the spacing of the studs along the length of the blade element is catered for and the working surface of the blade element remains perfectly flat.

Before the blade element and reinforcement element are united together, an adhesive is injected into the apertures 22 so that as the metal studs are entered into them the adhesive fills the clearance spaces at the opposite ends of said apertures. (Various adhesives may be used but it has been found that an adhesive which is available under the trade mark ARALDITE 2001 is very suitable for this purpose). It will be understood that the degree of interference of the metal studs between the side surfaces of the respective apertures is sufficient to hold the parts tightly together until the adhesive has fully set. The fact that the studs 16 are screwthreaded studs assists the interference fitting of said studs in the respective apertures.It will be understood that screwthreading is a convenient method of forming what is, in effect, a serrated configuration down each side surface of each stud.

As shown in Figures 1 and 4, the handle root portion 20 is provided with an integral spindle part 24 on which a handle sleeve portion 26 of moulded plastics form can be fitted. Said sleeve portion is secured on said spindle part by a nut 28 which engages a screwthread formed at the end of said spindle part. The handle sleeve portion can abut against a shoulder 30 formed on the root portion 20 through an adaptor washer 32. The adaptor washer has a pair of holes 34 on one side which can receive a pair of protuberences 36 standing proud of the shoulder 30. The other side of the adaptor washer is formed with a spigot 38, on which the generally cylindrical end portion of the handle sleeve can register, and with a pair of oppositely disposed key pieces 40 which can be received in complementary slots (not shown) in the end of said handle sleeve.The arrangement is such that the handle sleeve can be clamped non-rotatably with respect to the handle root portion.

Thus there is provided a method of making a plasterer's trowel which has been found to overcome the problem previously referred to. The provision of the clearance spaces at the opposite ends of the respective apertures has been found to avoid the imposition of induced tensile stresses in the blade element as the blade element and reinforcement element have been united together, thus allowing the blade element to remain perfectly flat.

However, various modifications may be made. For example, instead of the reinforcement member being formed with a plurality of apertures at the same nominal spacing as the studs upstanding from the blade element, it could be provided with a single elongate aperture extending almost the full length of the element, or only a very few apertures each one extending a distance to receive two or more of the studs. In this case the single elongate aperture, or the very few apertures each extending a distance to receive two or more of the studs, as the case may be, will be charged with adhesive before the blade element and reinforcement element are united together.However, as in the first described embodiment, the interference fit of the studs between the side surfaces of the single aperture, or the very few apertures, as the case may be, will be sufficient to hold the parts tightly together until the adhesive has fully set.

The metal studs 16 need not necessarily be screwthreaded studs; any other form of stud could be employed but a screwthreaded stud is particularly convenient to use because of its ready availability and the fact that the point contacts provided by the screwthreads is ideally suited to the provision of the required interference fit.

The studs could however be specially serrated studs if preferred. The required number of the metal studs and their spacing can be determined by trial and experiment.

The handle sleeve portion 26 and adaptor washer 32 could be replaced by a wooden handle if desired; in this case the end of the wooden handle would be pierced by the protuberances 36 as the nut 28 was tightened on the end of the spindle part.

Claims

CLAIMS:

1. A method of making a plasterer's trowel, the method including the steps of welding a plurality of upstanding studs at controlled spacing on one side of a steel blade element; forming a reinforcement element with a planar surface and with either an elongate aperture or a plurality of apertures at the same nominal spacing as the upstanding studs of the blade element, in this latter case said aperture being of greater length than width, but in either case the width of the or each aperture being such that the studs of the blade element are an interference fit between the side surfaces thereof; charging the or each aperture with an adhesive; and uniting the blade element and reinforcement element together by forcing the studs into the elongate aperture, or respective apertures, as the case may be, of the reinforcement element whereby the two are held together initially by the interference fitting of said studs in the aperture or apertures, the clearances formed between the studs and/or between the studs and the ends of the aperture or apertures being filled with the adhesive.

2. A method of making a plasterer's trowel according to claim 1, the reinforcement element being of elongate form and having been produced as a metal casting integrally with a handle root portion, a handle having been subsequently secured to said handle root portion.

3. A method of making a plasterer's trowel according to claim 2, including the further step of moulding a handle sleeve portion for fitment on a spindle part of the handle root portion, and fitting said handle sleeve portion non-rotatably with respect to said handle root portion.

4. A method of making a plasterer's trowel according to either one of the preceding claims, including the initial step of forming screwthreads on the studs which are to be welded at controlled spacing on the one side of the steel blade element, the screwthreading of the studs subsequently assisting the interference fitting of said studs in the respective apertures of the reinforcement element.

5. A plasterer's trowel which has been made by the method claimed in any one of the preceding claims.

6. A method of making a plasterer's trowel, substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

7. A plasterer's trowel, constructed, arranged and adapted to be used substantially as hereinbefore described, with reference to and as illustrated by the accompanying drawings.