US2013749A - Wood joint - Google Patents

Description

Sept. 10, 1935. D RE 2,013,749

WOOD JOINT Filed Oct. 20, 1935 INVENTOR.

ATTORNEYJ;

Patented Sept. 10, 1935 UNITED STATES some @FFIQE 7 Claims. (Cl. 20-92) This invention relates to an improved mortiseand-tenon joint involving more particularly the use of an improved metal anchor which not only expands the tenon within the mortise but also is forced into both tenon and mortise by the movement of inserting the tenon. No special formation or preparation is required either for mortise or tenon, and the anchor itself has the advantage of being simply and cheaply constructed and easily positioned.

To the accomplishment of the foregoing and related ends said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

The annexed drawing and the following description set forth in detail certain mechanism embodying the invention, such disclosed means constituting, however, but one of various mechanical forms in which the principle of the invention may be used.

In the accompanying drawing Fig. 1 is a transverse vertical section through a mortise, tenon and anchor, all parts being in the position immediately preparatory to assembly; Fig. 2 is a view corresponding to Fig. l but showing the completed assembly; Fig. 3 is a larger scale perspective View of the anchor; and Fig. 4 is a central vertical section through a modified form of anchor.

In making up the joint, a mortise I and tenon 2 are formed precisely as though no anchor were to be used. The anchor 3 consists of a tubular metal ferrule, the length of which may be varied according to the hardness of the wood and other features, but which in general will be somewhat longer than its diameter. Prongs 4, slightly flared, are formed on the bottom, and the top is preferably, although not necessarily, directed slightly inwardly, as at 5. The diameter of the circle in which the points of the prongs lie is just slightly less than the diameter of the mortise bottom, so that the anchor drops in easily and is self-centering. In the event that the mortise is of other shape than round, the diameter of the prong point circle would be such as to be inscribable within the transverse section of the mortise.

In Fig. 4 a modification of the anchor is shown in which the top 6 is not inwardly directed.

The joint is most readily constructed when the mortise opening is vertical. The anchor is dropped into the mortise opening, points down, as shown in Fig. l, and centers itself by reason of having a fairly large diameter relative to its height and having a spreading base. The tenon is then forced down on the anchor into the position of Fig. 2, thus forcing the prongs i out and into the mortised member, and at the same time completely seating the anchor in the bottom of the tenon. The relative degree of penetration of the points 4 depends partly upon the hardness of the wood, both of mortised member and tenon and partly upon the relative sharpness of the points and of the upper edge 5. For example, a tenon made of soft wood, for insertion in a mortised hard wood block may indicate the use of the form of anchor shown in Fig. 4 rather than that shown in Fig. 3, so that the resistance between the top of the anchor and the tenon is great enough to force the prongs properly into the walls of the mortise.

The assembly of the joint, using this anchor, may be made either with or without glue, although it is contemplated that ordinarily glue will not be necessary to the formation of a thoroughly tight and secure joint. The expansion of the tenon within the mortise due to the entering of the upper part of the anchor therein, and the intrusion and expansion of the teeth 4 into the wood below and beyond the bottom of the mortise combine to give out a powerful locking action. Where the upper edge of the anchor has a slight inward tendency, the engagement with the wood of the tenon is especially secure as at 7, due to an inward compressing effect upon the wood fibers. It will frequently be found however that the expansion of the bottom of the tenon due to forcing the mass of the anchor thereinto is sufiicient, and consequently, where the character of the wood admits it, the straight-topped anchor shown in Fig. 4 is satisfactory.

It will be observed, particularly from Fig. 2, that the prongs 4, in the completed joint, extend only about half their length into the mortised element. The relatively wide angle of these points, best seen in Fig. 3, prevents any further penetration than is necessary to secure holding and thus avoids splitting the mortised element.

Although the usual application of this invention will be to a wood joint, as indicated by the title and the foregoing description, and the ferrule or anchor is to be made of metal in the ordinary instance, it will of course be understood that the invention may be applied using any materials having physical characteristics which enables such use to be made.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invention:

1. A mortise-and-tenon joint including an anchor element, said anchor element comprising a hollow member with transverse ends, one of said ends being adapted to expand into the mortise walls and the other end being adapted to penetrate and expand the end of the tenon.

2. A mortise-and-tenon joint including an anchor having an open-ended hollow cylindrical body, thin edged, the lower end of said anchor being expanded transversely to the axis of the tube to a diameter slightly less than the mortise diameter, whereby said anchor element will be self-centering in a mortise opening, the upper end being adapted to penetrate a tenon.

3. An anchor adapted for use in a mortise-andtenon joint comprising a cylindrical tubular body inwardly directed at one end and serrated and. outwardly directed at the other end.

4. A mortise-and-tenon joint comprising in combination a tubular anchor having a spread end further expanded into the mortised material and having the anchor body centrally embedded in the tenon material within the depth of the mortise.

5. A mortise-and-tenon joint comprising in combination a unitary tubular anchor having one end expanded into the mortised material and having the anchor body embedded in and contracted upon part of the tenon material.

6. An anchor adapted for use in a mortiseand-tenon joint comprising a hollow cylindrical body and the wall sharp at each end, one end being splayed and the other inturned.

"1. An anchor adapted for use in a mortiseand-tenon joint comprising a tubular body of stiff but thin material and a series of outwardlydirect'ed points around one end, said body being short and of relatively large diameter.

FRED A. DUNIVIIRE.

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