US335480A - Eick edwaeds - Google Patents

Description

(No Model.)

J. L. RAWBONE.

KEYLESS CANVAS STRETOHER. No. 335,480. Patented Feb. 2, 1886.

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JOSEPH LOXTON RAWVBONE, OF TORONTO, ONTARIO, CANADA, ASSIGNOR OF TWVO-THIRDS TO WILLIAM GEORGE RAVBONE AND CHARLES MER- RICK EDWARDS, BOTH OF SAME PLACE.

KEYLESS CANVAS-STRETCHER.

PECIFICATI IC forming part of Letters Patent No. 335,480, dated February 2, 1886.

Application filed June 22, 1885. Serial No. 169.447.

T 0 all whom it may concern.-

Be it known that I, JOSEPH LOXTON Raw- BONE, a subject of the Queen of Great Britain, residing in the city of Toronto, in the county of York and Province of Ontario, Canada, have invented certain new and useful Improve ments in Keyless Stretchers; and I do hereby declare that the followingis a full, clear, and exact description of the same.

My invention relates to a keyless stretcher for artists use, as hereinafter set forth.

Figures 1 and 2 show the method at present in voguein the manufacture of artists stretchers. Figs. 3 and 4. illustrate the operation of my improvement. Figs. 5 and 6 are a section and plan, respectively, of the clamping-plate used by me. Figs. 7 and 8 show an alternative method of forming the clampingplate.

Referring to the drawings, A A represent two sides of the frame or stretcher, such sides having heretofore been joined by means of tenons, and expanded by wedges or plugs a a, as shown in Figs. 1 and 2.

It will be seen on reference to Figs. 3 and 4 that the sides of the frame are out at each end to an ordinary miter or angle offorty-five degrees. Over this miterllay aplate, B, made of wrought-iron or other material having tensile strength. This plate B is provided wit-h diagonal or converging slots 1) b. I then attach the plate B to the sides A A of the frame by means of set-screws, as shown, or by nails 1) b. It therefore follows that on the plate B being thrust forward in the direction shown by arrow by any kind of pressure or by a blow on the larger or convex end of said plate, the miterjoint will be opened, the edges of the miter, however, stillremaining parallel. This plate B being placed on the back of the frame or stretcher, and the canvas being tacked on the front of such frame, it follows that on the opening of the miters the whole frame will be expanded and the area occupied by the canvas will be increased, the canvas being caused to stretch quite evenly on each of the four sides. The economy of this method of constructing the stretcher is not its only advantage. It has (No model.)

always been noticed that the canvas, being strained over a frame joined by means of tenons, (see Figs. 1 and 2,) will show a distinct line or edge caused by the inner edge of such frame. To obviate this, it has been the practice to bevel off theinner edge, so as to remove it from contact with the canvas. It will be found that by using my improved plate the force created by blows orpressure on the said plate will have the effect of opening the miters at the back of the frame, while thefront of the miter will remain closed, thus causing the sides of the frame to cant outward toward the rear, (see Fig. 4,) so that the only point of contact of the canvas with the frame will be at the outside edge of the front of the frame. the canvas being in these drawings denoted by the letter The material of which the plates B are made allows of their bending sufficiently for this purpose.

The shape of plate which I prefer is shown in Fig. 6, and it will be seen that by driving up these plates at each corner of the frame an equal expansion is secured, allowing of no wrinkles whatever in the canvas.

A great advantage in my invention is that by its application the corners of the stretcher are left square and solid, with no tenons or other projections to interfere with the tacking on of the canvas.

I am aware of the patents to A. D. Shattuck, Nos. 272,162 and 320,300, in which a key is employed. I do not, however, claim the construction shown in said patents, nor do I broadly claim a diagonally-slotted metallic plate in connection with a stretcher-frame.

\Vhat I claim as my invention, and desire to secure by Letters Patent, is-- An artists stretcher consisting of the frame A, having separable miter-joints, and the keyless metallic plate B, having converging slots b b, and adjustably secured to said frame by set-screws b b, as set forth.

JOSEPH LOXTON RAW BONE.

\Vitn esses:

GEORGE EARL, M. WILLS.

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