US2016620A - Method and apparatus for dovetailing articles of wood - Google Patents

Description

Oct. 8, 1935. v c. P. ASPELUND 2,016,620

METHOD AND APPARATUS FOR DOVETAILING ARTICLES OF WOOD Filed July 5, 1953 2 Sheets-Sheet i 75 73 74 72 79 7'2 flr 0. P a e/m6? METHOD AND APPARATUS FOR DOVETAILING ARTICLES OF WOOD c P. ASPELUND 2 Sheets-Sheet 2 Filed July 5, 1955 I I l I I I I I Patented Oct. 8, 1935 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR DOVE- TAILING ARTICLES OF WOOD Carl Pedersen Aspelund, Reykjavik, Iceland 7 Claims.

The present invention relates to a method for dovetailing articles of wood and the invention is mainly distinguished in that the dovetail slots may be cut in a single operation simultaneously in both halves and half or wholly concealed as desired.

The invention also comprises a machine by which the method may be carried into effect and said machine is illustrated in the accompanying drawings in which:

Fig. 1 is a front view of the machine.

Fig. 2 is a side view of the same.

Fig. 3 is a vertical section through the driving mechanism of the machine.

Fig. 4 is a plan view of the same with parts broken away.

Fig. 5 is a front view of two wood pieces during the dovetailing operation.

Fig. 6 is a cross section and Fig. 7 a plan view of the same.

Fig. 8 illustrates a cross sectional view of the pieces assembled,

Fig. 9 is a view corresponding to Fig. 6 illustrating a somewhat modified embodiment.

Figure 10 is a detail view of the eccentric mechanism shown in cross section, and

Figure 11 is a plan view of the same.

In the drawings denotes legs which support a. table 2 in which a slide 3 is arranged movable in the longitudinal direction of said table. The slide 3 is provided with rests 4 and 5 (Figure 3) and clamping devices e. g. screws 6, 1, by means of which two wood pieces 8, 9 may be secured at right angle to each other as shown.

On the front side ofthe table 2 are secured bearings It for vertically disposed shafts H to the upper ends of which are secured plates l2 each provided with bearings l3 for a cutter shaft M. The shafts H! are each, on the end which is situated nearest to the shaft I I, provided with a pulley l5 which by means of a belt I6 is driven from pulleys H on a shaft |B journalled in the legs I. The shaft I8 may be rotated in any convenient manner.

The shafts M are at their inner ends provided with cutters IS, the shape and use of which will be described below.

On the front side of the table 2, at the middle between the bearings I0, is secured a bearing 50 for a vertical shaft 2|, which on its lower end is provided with a worm-wheel 22, coacting with a worm '23 on a horizontal shaft 24, which is journalled in the legs I. The shaft 24 is driven by means of a pulley 24' and belt 25 from a pulley 26 on the shaft I8.

of the catch 3| is provided a stopper 33 swing- 10' ably supported on a pin- 34 connected to the table 2. The stop-per 33 meshes with the rack 32 and serves to prevent undesired displacement of the slide 3 to the left in Fig. 1. In order to hold the slide 3 pressed into engagement with the stopper 15 33, the slide is acted upon by a weight 36 suspended by means of a wire 35.

On the pin 30, which is secured to the arm 29, are pivotally secured two arms 31, each of which by means of a pin 38 is pivotally connected with 20 the outer ends of arms 39, 39, the other ends of which are secured to the swingable plates |2, |2 respectively.

The edge portions of the work pieces 8 and 9, which are to be dovetailed, are rounded to a radius which approximately corresponds to the radius of the cutters l9, and the pieces 8, 9 are clamped in position into the machine with the rounded surfaces, facing each other as shown in Fig. 6. With the pieces clamped in said position, the axes of the cutter shafts coincide with the plane in which the pieces touch each other.

In rotating the shaft IS, the shafts M with the cutters H! are rotated and simultaneously the shaft 2| is rotated by means of the worm 23 and 5 worm-wheel 22 in the direction indicated by the arrow in Fig. 4. During this operation the excentric pin 30, by means of the arms 31 and 39, swings the plate i2 and thereby the cutters I4 towards the work pieces 8, 9, whereby inclined 40 slots are cut in the same. One of the cutters I9 produces inclined slots a and the other cutter corresponding slots b, which are inclined in a direction opposite to that of the slots a. 1 In order to obtain slots of the necessary depth the cutters must be moved towards the work pieces until the middle point of the cutter coincides with the foremost limitation line of the pieces, as shown in Fig. 6. The distance at between the cutters I9 (Fig. 7) corresponds to the pitch of'the slots or a multiple of the same and the inclination of the cutters determines the proportion between the inner and outer width of the slots. In order to make the bottom of the slots as even as possible the teeth of the cutters are bevelled outwardly corresponding to the inclination of the cutters in relation to the work pieces.

By the continued rotation of the shaft 2| the plates l2 with the cutters l9 are swung outwardly at the same time as the catch 3| moves to the left on the rack 32 and during its return meshes with a tooth and carries the slide 3 to the right a distance corresponding with the pitch of the dovetail slots, whereupon the whole operation is repeated. During the return of the catch, the slide 3 is held resting against the stopper 33 by means of the weight 36. At the start of the operation the slide 3 may be released and carried to the left by releasing the stopper 33.

The width of the cutters I9 are preferably chosen corresponding to the narrowest width of the dovetail slot and when both cutters, by the above described displacement, in succession are inserted in the work pieces at the same point, they will, owing to its inclination, form in cross section dovetail-shaped slots, the bottom of which are bounded by arcs of circles.

When the pieces 8, 9 have been worked in their entire length by both cutters, the pieces may be locked together, as shown in Fig. 8.

In order to make the concealing or covering thicker the pieces 8, 9 are removed somewhat from each other asshown in Fig. 9, the axes of the cutter shafts then coincide with the middle plane between the pieces.

In dovetailing wood pieces of different thickness it may be suflicient in connection with minor variations to shift in new cutters and adjust the cutter shafts, as the width of the slots and the angle of inclination may be altered to some extent without replacement of the excenter mechanism and the rack. For greater variations in wood thickness the excenter mechanism and contingently also the rack must be replaced. The feeding movement of the catch 3! may be adjusted by an adjustable cover plate which limits and determines the point of engagement between the catch and the rack.

As will be understood the details of the machine shown and described may be varied in many Ways without departing from the scope of the invention, if only the described relative movements between the cutters and the work pieces are provided in the longitudinal direction of the pieces as well as at right angle to the same.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. A method for treating a structure member to provide slots for dovetailing purposes, consistin in providing the member with a convexly arcuated edge, then cutting slots with concavely arcuated bottom surfaces, one slot being cut in the edge of the member at an acute angle to one side of a line normal to the edge of the member and another slot being cut entering the member coincidental with the first slot at an acute angle to the other side of a line normal to the edge of the member to form a single dovetail slot.

2. A method for treating a structure member to provide slots for dovetailing purposes, consisting in providing the member with a convexly arcuated edge, then cutting slots with concavely arcuated bottom surfaces complemental to the convexly arcuated edges of the members, one slot being cut in the edge of the member at an acute angle to one side of a line normal to the edge of the member and another slot being Cut entering the member coincidental with the first slot at an acute angle to the other side of a line normal to the edge of the member to form a single dovetail slot.

3. A method for treating a pair of wooden structure members to provide slots for dovetailing purposes,'consisting in providing the two members with convexly arcuated edge portions for making dovetail slots therein, said edges being rounded according to a circular arc with the same radius as that of the cutters to be used, then placing the members at a right angle to each other with their rounded edge portions directed towards and symmetrically in relation to the cutter axes, then cutting the slots in said edge portions simultaneously, the cutters being during the cutting operation arranged in such an angular relation to the longitudinal axes of the edge portions that slots of a dovetailed crosssection are formed, said slot bottoms being defined by a cylindrical surface with the same radius as that of the first-named rounded edge portions.

4. A method for treating structure members to provide slots for dovetailing purposes consisting in arranging two members at right angles to each other, moving said members intermittently in a longitudinal direction, moving a cutting tool in a direction toward said members so as to cut a slot in the edges of the members at an acute angle to one side of a line normal to the edges of the members when the members are stationary and finally moving a second cutting tool toward said members to successively enter the slots at the same acute angle to the other side of said normal wherebyto provide dovetail slots.

5. A machine for cutting slots into the edges of structure members for dovetailing purposes comprising a table, a pair of disc-shaped cutter wheels mounted on the table in opposite relation to one another with their axes at an acute angle to the member edges and at an obtuse angle to one another, a slide for carrying and supporting a pair of structure members at right angles to each other mounted on the table, means for periodically moving the cutters in a horizontal arc toward and away from the members at coincident spots and means for actuating the cutters.

6. A machine for cutting concave slots into the edges of structure members having convex edges for dovetailing purposes, comprising a table, a pair of relatively inclined cutting wheels mounted on the table, means for carrying and supporting the structure members at right angles to each other mounted on the table, means for periodically moving the cutting means in a horizontal arc toward and away from the structure members at coincident spots and means for actuating the cutting means.

7. A machine as claimed in claim 5 comprising dual means for synchronously operating the slide in a longitudinal direction and for moving the cutters toward and away from the members.

CARL PEDERSEN ASPELUND.

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