Saw blade tension mechanism for frame saws

Aug. 22, 1950 A. A. HENDRICKSEN ETAL 2,519,904

SAW BLADE TENSION MECHANISM FOR FRAME SAWS

Filed Nov. 18, 1946 2 Sheets-Sheet 1

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ATTORNEYS

Aug. 22, 1950 A. A. HENDRICKSEN ET AL 2,519,904

SAW BLADE TENSION MECHANISM FOR FRAME SAWS '

Filed Nov. 18, 1946

Sheets-Sheet 2

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ATTORNEYS

Patented Aug. 22, 1950

2,519,904

UNITED STATES PATENT OFFICE

2,519,904

SAW BLADE TENSION MECHANISM FOR

FRAMESAWS..

Allan A. Hendricksen and Francis F. Hendricksen,

Adams, Oreg.

Application November 18, 1946, Serial No. 710,542

Claims.

This invention relates to improvements in saws, and more particularly to the provision of means for tensioning saw blades in frames.

Heretofore, in saws of the type herein considered, the blade has been attached to a frame by means of a pin and wing nut. In a job where it is necessary to change saw blades frequently because of wear or breakage, or because of the necessity of using different types of blades on different metals, the wing nut method of attaching blades causes a considerable loss of time in changing blades. Also, the wing nut method of attaching blades does not provide the proper tension each time a blade is changed.

It is, therefore, an object of this invention to provide a spring tensioning device for saw blades which enables blades to be changed quickly and which maintains the proper tension of the blades when changed from time to time.

The above and other objects are attained by the novel construction and arrangement of parts hereinafter described and illustrated by the accompanying drawings, forming a part hereof, and in which:

Fig. 1 is a side elevational view of a saw with a blade tensioning means in a closed position.

Fig. 2 is a side elevational view with the blade tensioning means in an open position.

Fig. 3 is a sectional view taken on the line 3—3 of Fig. 1.

Fig. 4 is an end view of the device.

Fig. 5 is a longitudinal sectional view of the device.

Fig. 6 is a plan view of a compression lever.

Fig. 7 is a plan view of an operating lever.

Fig. 8 is a sectional view taken on the line 8—8 of Fig. 5.

Referring to the drawings, the device is shown to include a saw frame 1 which is attached by rivets 2 to a hollow handle 6. Mounted in the handle 5 is a guide block 3 having a square hole through which passes the square end 4 of a tension rod 4' having a round section 5. The portion 4 has an extension 7 from which projects a pin 8 to which one end of a saw blade 9 is attached.

Attached to the handle 6 are pins 10 which pass through apertures 11 in a compression handle 12, which has apertures 13 receiving pins 14 on an operating lever 15, the latter having straps IS adjacent the end remote from the pins 14 whereby the lever 15 is slidably received on the round section 5 of the tension rod 4'. The end of the lever 15 outwardly of the straps 18 bears against a washer 17 loosely mounted on the round (Cl. 145—33) section 5 of the tension rod. A compression spring i 8 bears against the washer 17 and against a nut 19 on the threaded end 20 of the rod 4'. Access to the nut 19 for adjusting the tension of 5 the spring is attained through an opening 21 in the end of the handle.

In operation, to attach a blade, the compression lever 12 is moved to the position shown in Fig. 5 which relieves the pressure on the spring, 10 allowing the tension rod 4' to be moved longitudinally. The lever 12 is then moved to the position shown in Fig. 1 which applies pressure on washer 17 and provides the proper tension on the blade 9.

To move the blade to a horizontal position as shown in Fig. 2, the compression handle 12 is moved to the open position, and the tension rod 4' is moved so that the round section 5 is in the square hole in the guide block 3. The rod is then ²⁰ rotated to the horizontal position, and the blade attached as above described.

When the compression handle 12 is in the closed position as shown in Fig. 1, the pivot pins 14 of the operating lever 15 are above the pivot ²⁵ pins 10 of the compression lever 12, which causes the spring to exert a pressure to hold the operating lever or handle up against the hollow handle 6.

The device enables blades to be quickly changed 30 and adjusted to different positions, and provides the proper tensioning of the blades at all times.

The above description is to be considered as illustrative and not limitative of the invention of which modifications can be made without depart35 ing from the spirit and scope of the invention as set forth in the appended claims.