US948184A - Blackboard-eraser. - Google Patents

Description

H. W. MITCHELL., BLAGKBRD ERSEP.;

APPLIGATION FILED MAB. z5, 1909..

Patented Feb. l., i910.

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I-IOW'ARDv W. MITCHELL, OF SAN'BORN, MINNESOTA.

BLACKBOARD-ERASER.

To all whom it may concern:

Beit known that I, HOWARD W. MITCHELL, a citizen of the United States, residing at Sanborn, in the county of Redwood and State of Minnesota, have invented certain new and useful Improvements in Blackboard-Erasers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention has for its object to provide an improved blackboard eraser which is capable of being taken apart, easily cleaned and again put together.

To the above ends, the invention consists of the novel devices and combinations of devices hereinafter described and defined in the claim.

In the accompanying drawings, which illustrate the invention, like characters indicate like parts throughout the several views.

Referring to the drawings, Figure l is a plan view of the complete eraser; Fig. 2 is an end elevation thereof, some parts being broken away; Fig. 3 is a perspective view of the frame of the eraser, the sections thereof being separated; and Fig. 4 is a detail in plan, showing a portion of one of the members of the eraser frame on a larger scale than in the other views.

The body of the eraser is made up of a plurality of heavy bars of felt l, preferably cut rectangular, and provided near their ends with alined perforations 2.

The frame of the eraser is made up of two parts that are adapted to be interlocked and to be separated. One member of the frame is made up of a light metal bar 3 which is bent upon itself to form parallel laterally eX- tended arms l and 5 located inward from its extreme ends. The end of the arm Ll is notched to form a T-shaped head 6 and the arm 5, near its end, is provided with a perforation 7. The other member Iof the frame is in the form of a clamping bar and is also formed from a light metal bar 8 bent upon itself into parallel arrangement and provided with ends 9 turned inward near one end of said bar. A lock bolt 10 is slidably mounted in perforations formed in the inturned ends 9 and in the adjacent bowed exn Specification of Letters Patent.

Application filed March 25, 1909.

Patented Feb. il, i910. serial No. 485,681.

holds said boltin its operative position shown in the drawings. The inner fold of the clamping bar 8, near one extremity of the clamping bar, is formed with a longitudinally extended slot or perforation 13,

through which the T-head 6 is adapted to be inserted when the clamping bar 3` is turned at a right angle to the clamping bar S.

l/Vhen the component parts of the eraser are to be assembled, the arms 4f. and 5 are passed through the coincident perforations 2 thereof with the T-head 6 and with the perforated end 7 of the said arms 4 and 5 projecting therethrough. Then the bar 8 is turned at a right angle to the bar 3 and to the eraser sections l, the lhead G is inserted through the slot 13 then said bar S is turned into a position parallel to the said clamping bar. Then the lock bolt l0 is retracted against the tension of the spring 1l, the perforated end of the arm 5 is inserted in the seat between the bent ends 9 and then said lock bolt is released and permitted to pass through the perforation 7 of the said arm 5. In this way, the sections of the eraser are tightly clamped together and the eraser is ready for use on either side. The eraser, of course, is taken apart by a reverse operation. When the eraser sections l are removed from the holder, they may be very easily cleaned and quickly reu assembled within the holder. One way of cleaning the eraser would be to clamp a multiplicity thereof between the jaws of a pair of tongs and to beat` the same against some hard object. The eraser sections may, however, be cleaned by any suitable means and might be run through a cleaning machine provided for that purpose. W'hen the eraser sections are too badly worn for use, they may be thrown away and new sections substituted therefor in the holding frame. The frame itself is practically indestructible and under ordinary usage will last indefinitely.

That I claim is:

An eraser comprising a multiplicity of body sections, a clamping bar having a spring pressed lock bolt at one extremity and a vlook groove at its other extremity, of a two clamping bars against said body secsecond clamping bar having projecting partions. 10 allel arms, one ofsad arms having` a head In testimony whereof I aflx my signature adapted to be nterloeked with the lock slot n presence of two Witnesses.

of said first clamping bar, by endwvse and HOIVARD W. MITCHELL. rotary movement, and the other of said arms Witnesses:

having a perforation through which said A. L. KUSSKE,

look bolt sadapted to be passed to lock the CHAs. B. SACKRUTER.

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