Title:
Drafting instrument
United States Patent 2303676


Abstract:
My, invention relates to drafting instruments and comprises an instrument with which a draftsman can automatically draw a series of parallel broken lines or single broken lines as desired. Various devices have been used in connection with pens in order to make it possible to draw broken lines...



Inventors:
Lewis, Bixby John
Application Number:
US39091741A
Publication Date:
12/01/1942
Filing Date:
04/29/1941
Assignee:
Robert, Dexter G.
Primary Class:
Other Classes:
33/494, 33/563
International Classes:
B43L13/24
View Patent Images:



Description:

My, invention relates to drafting instruments and comprises an instrument with which a draftsman can automatically draw a series of parallel broken lines or single broken lines as desired.

Various devices have been used in connection with pens in order to make it possible to draw broken lines automatically, but I know of no such device or instrument capable of use with a pencil. In the face of the present urge to save time in making drawings and blueprints, draftsmen are omitting the step of inking in drawings before the blueprints are made. Therefore it is important to promote the more accurate use of the pencil. Briefly speaking, my invention comprises a transparent block having a longitudinal slot, and a strip of flexible material secured to the block and provided with a series of spaced slots disposed beneath the slot in the block. The slot in the block guides the pencil and keeps it moving in a straight line while the slots in the strip provide the pattern for the broken line.

The advantages and details of my invention will be best understood and appreciated from the following description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawing, in which, Fig. 1 is a plan view of a drafting instrument constructed according to my invention, s0 Fig. 2 is a view in cross-section along the line 2-2 of Fig. 1, Fig. 3 is a view in cross-section along the line 3-3 of Fig. 1.

As shown in the drawing, the instrument comprises a long rectangular block 10 of transparent material such as cellulose acetate or other transparent plastic. The block 10 should be thick enough to be fairly stiff and rigid but still capable of being bowed somewhat. Cut into the block 10 is a longitudinal slot 14 having straight sides and bounded at the upper surface of the block by a dished portion 12.

In both ends of the block 10 the edges are transversely slit as shown at 16, the slits entering farther into the block at one side than the other. The lower edges of the ends of the block 10 are undercut.

A thin strip 20 of transparent material is provided with a centrally located row of short, spaced slots 22. The ends of the strip 20 are bent over and fit into the slits 16 in the edges of the block 10. The block is bowed downwardly, allowing the strip 20 to be snapped in place. The tapering of the slits 16 serves to wedge the strip 20 tightly in place.

It will be seen that the series of spaced slots 22 of the strip 20 lies directly beneath the slot 14 of the block 10. If the instrument is placed with the strip 20 against a sheet of paper, a pencil can be drawn along the slot 14 of the block 10, the pencil reaching the paper only in the areas of the slots 22. Thus a broken line will be produced on the paper in one stroke of the pencil.

If the pencil is canted so that it meets one of the upper edges of the slot 14 and so that its point reaches the paper at the opposite lower edge of the slot 14, the instrument will make it possible to draw a series of parallel broken lines. After one line has been drawn, the pencil is moved to vertical position and the instrument is moved until the point of the pencil is struck by the advancing edge of the slot 14. The other edge of the slot 14 has then moved a distance almost equal to the width of the slot 14. Then the pencil is used to draw another broken line, resting against the same edge of the slot 14 as before.

The advantages of the instrument of my invention will be apparent, to those skilled in the art, from the foregoing description of a preferred embodiment thereof. It will be understood that different effects can be obtained by changing the dimensions of the slots in the block and the strip. Also the strip may be fastened to the block by means other than that specifically described herein.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is: 1. A drafting instrument which comprises an elongated transparent block provided with a narrow longitudinal slot, the end edges of the transparent block being provided with slits, a flexible strip of transparent material having folded ends adapted to be fitted into the end slits in said block and having a series of spaced slots extending longitudinally therein and disposed beneath the slot in said block.

2. A drafting instrument which comprises a transparent block having a longitudinal slot and slits in the edges of the ends thereof, a thin strip of flexible material having its ends bent over to fit into the end slits of the block and a series of spaced slots formed in said strip and arranged to underlie the slot in the block.

3. A drafting instrument which comprises a relatively stiff elongated block having a long slot, a relatively thin, flexible strip having a series of spaced slots, fastening means formed in the ends of the strip, and cooperating means disposed in the end edges of the block, whereby the strip may be detachably secured to the block so that the slots in the strip underlie the long slot in the block.

JOHN LEWIS BIXBY,