US139507A - Improvement in drawing-boards - Google Patents

Description

A. HITCHCOCK, Drawing-Boards.

"0.139507. Patente djune3,l873.-

[222/622 afar .when in place, revolves.

UNITED STATES ALONZO HITGHCOCK,

OF NEW YORK, N. Y.

IMPROVEMENT IN DRAWING-BOARDS.

Specification forming part of Letters Patent No. 139,507, dated June 3, 1873 application filed September 27, 11:71.

To all whom it may concern:

Be it known that I, ALONZO Hrronooox, of the city, county, and State of New York,

Y have invented a new and useful Improvement in Revolving Drawing-Boards, of which the following is a specification, reference being had to the accompanying drawings, forming p..rt of the same.

Figure 1, Sheet I, is a top face view of a revolving board embodying my improvements; Fig. 2, same sheet, is an elevation of the same; Fig. 3 of the same sheet is a face of the under side of the drawing-board; Fig 4, Sheet II, is a top view of the frame, with its attachments, on which the drawing-board is mounted; Fig. 5, same sheet, is a central vertical sectiona'l view of my drawing-board mounted on its frame; Fig. 6, same sheet, is an end view of the same.

M yinvention relates to a revolving drawingboard, constructed as hereinafter particularly described, the same consisting of a table pivoted in the center upon a portable frame and having combined with it a fixed graduated rest, and the mechanism described for stopping and holding the revolving board in certain fixed positions, and on its face a graduated circle located off from the pivotal center of the board.

A is a drawing-board, which may be of any suitable dimensions and form; B is a frame, preferably made of irons, on which the board is mounted; U is a fixed rest and graduated scale, mounted upon the ends of the arms a, extending out from one side of the frame. Upon the under side of the board A is fixed the graduated and indented disk or circle I), made of metal, in the center of which is the pivotal post or pin I), upon which the board, In the center of the cross-bar c of the frame B is a socket, d, fitted to receive the post I), and upon which the board may revolve, resting on the base 0. The board is held in place by a pin through the lower end of the post b. The socket may be on the circle D and the pin on the frame. E is a lever pivoted in post f, connected with the frame. Upon the inner end of this lever is a bevel-edged pin, 03, and the spring 9 presses the end of the lever upward against the board when in place, thus forcing the pin against the indented circle D. The opposite end of this lever is furnished with a catch, h, that is pressed up to the lever by the spring k. When the board is in place on' its frame it is evident that it may be rotated at, pleasure, and adjusted to any required position,

by lifting the opposite end so that it is held by the catch it. When thus adjusted the lever may be liberated from .the catch, when the pin 2' will be pressed upward by the spring 9 against the board, or rather the circle I), thus fixing it in position. The circle may have in its face any number of indentations or creases, graduated to mark given angles, into which the pin 6 may enter, whereby the board may, without measurement at the moment, he set to any angle on the said circle. F Fare graduated circles drawn upon or affixed to the face of the board, off from the. center, not concentric to it nor embracing the center within it. Placing these graduated circles thus away from the center gives the opportunity of fixing the paper upon which the N drawing is to be done upon the board, Without covering them up. From these graduated circles, by means of the fixed rest U and a T-square, any required angle for drawing may be taken.

The operation is as follows: Adjust the board, .having the drawing-paper properly attached, with one end parallel to the fixed rest. After the first or base line of thedrawing is made at right angles to the fixed rest, and any given angle to that line is required to be drawn, turn the board until the radial line on the circle F, vhich indicates such angle, is parallel with the T-square when adjusted to the fixed rest, and in that position the T-square held to the fixed rest will give the requisite angle in the drawing. It is evident thatthe use of'these noncon centric circles, and the mechanism l have described for holding the board in position, will obviate the necessity for a great -deal of measurement with dividers and scales in drawing, and save much time What I claim as my invention, and desire to secure by Letters Patent, is-

A revolving drawing-table, composed of the board A, the portable frame B, the fixed rest G, the catch h, and the graduated circle F F, one or both, all constructed, combined,-

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