US2536142A - Drafting machine - Google Patents

Description

Patented Jan. 2, 1951 DRAFTING MACHINE Morris Sanders and Joseph L. Sanders, Rochelle Park, N. J

Application January 24, 1950, Serial No. 140,212

2 Claims.

This invention relates generally to parallel motion drafting devices of the kind in which the several tools which the draftsman handles most frequently are embodied, in principle, in one unit to obviate the necessity of a draftsman reaching about for a required tool and thereby enabling the draftsman to keep his attention concentrated directly upon th drawing.

Drafting devices of this character are common in which adjacent ends of two arms are pivoted together, the free end of one arm being secured to the remote side of a drafting board while the free end of the other arm is provided with a head comprising a protractor and straight edges which are in fixed angular relation and move about the center of the protractor as an axis.

Hitherto the arrangement of drafting machines of the endless band and pulley type, to which this invention particularly relates, has been such that the protractor is situated under the arms containing the endless band, making it difficult to observe the markings on the protractor when the machine is to be set at certain angles; or in machines having the protractor above the arms, the mechanical arrangement for setting these machines automatically to certain prescribed angles must be actuated from a single particular point.

One object of this invention is to provide an arrangement whereby the protractor is visible in all positions of the arm, and yet having means for the automatic setting of the machine to certain prescribed angles arranged so that it may be actuated without the necessity for the operator to move his hand or to change the position of his hand.

Another object of this invention is to provide means for disengaging the automatic indexing mechanism, so as to enable the operator to set the arms in any position and lock the arms in that position.

Another object of this invention is to provide means so that the operator need not observe the protractor while setting the machine to certain prescribed angles, but may arrive at a desired angle through audible means.

Another object of this invention is to provide means for compensating for the deflection of the arms at the elbow by boring the bearin seat in the arm of the anchor at the necessary angle from the vertical, so that the deflection automatically is compensated for equally in all positions of the arms.

Another important object of this invention is to provide means for parking the machine when not in use, so that the entire surface of the drawing board is free and clear, and yet retaining the parallel positions of the arms, even on an inclined board.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel details of construction and combinations of parts hereinafter more fully described and pointed out in the claims, it being understood that changes may be made in the construction and arrangement of parts without departing from the spirit of the invention as claimed.

In the accompanying drawing a preferred form of the invention has been shown.

In said drawing:

Figure 1 is a top plan view of the entire machine in parking position;

Figure 2 is an enlarged, fractional top view and sectional view on the line 2-2 of Figure 3 of the head assembly;

Figure 3 is a sectional view of the head assembly on the line 3-3 of Figure 2;

Figure 4 is an enlarged fractional view of the head assembly;

Figur 5 is an enlarged fractional sectional view, as the sectional portion of Figure 2, but showing some of the parts in positions which differ from their positions shown in Figure 2; and,

Figure 6 is a fractional sectional view on the line 66 of Figure 2.

Similar reference characters refer to'similar parts throughout the several views.

Referring first to Figure 1, the drafting machine includes four housings I held apart by the tubes 2 through which the endless bands 3 pass. such housing is mounted pivotally at the anchor which consists of a bracket l affixed to the drawing board 5 by any suitable, well known means.

Referring to Figures 2 to 5, the head consists of a housing I into which a needle bearing 1 (Figure 3) has been pressed. A tubular shaft 29 rotates freely in the bearing 1 and is affixed securely to a casting 30, which preferably is made as a unit with a combination protractor head 31 and a pulley portion 32. A belt or an endless band 3 passes round the pulley portion 32. Rotating freely inside the tubular shaft 29 is a shaft 33, the upper portion of which is securely afiixed in the hub of a Vernier plate 34. This vernier plate. 34 fits into the annular bore of the protractor head 3| and is rotatable therein. To the lower portion of the shaft 33 is affixed a rule holder plate 42, which preferably is formed as a unit with a parking tongue section 59.

One.

tion of said rocker arm to which said cross-slide is pivoted and being adapted for engaging the notches in the periphery of said notched disk, a pawl adapted for engaging the peripheral notches of said ring-shaped plate and being pivotally connected to said cross-slide, as well as to said protractor head, a bolt rotatably extended through said protractor head, a thumb lock lever having a cam portion adapted for engaging said pawl and being secured to one end of said bolt, a clamp plate secured to the other end of said bolt having a reduced portion which is interposed between said ring-shaped plate and said vernier plate, resilient means interposed between said protractor head and said rocker arm being adapted for forcing the latter against said notched disk, and a pin secured to said anchor bracket being adapted for extending through the perforation in the parking tongue section of said rule holder plate for the purpose of retaining the device in its parking position.

2. In a drafting machine head, in combination, a housing having a needle bearing in its center, a tubular member encompassed by said needle bearing and being rotatable thereon, a protractor head having a hub portion which is secured to said tubular member, an upright shaft rotatably extended through said tubular member, a perforated vernier plate secured to the upper end of said shaft and being rotatable in said protractor head, a ring-shaped plate having a notched outer periphery and being secured to the lower side of said vernier plate, a peripherically notched disk through whose center said shaft is extended being interposed between said protractor head and said vernier plate, a knurled ring coaxial with the vernier plate being located upon the outer side of said vernier plate, upright pins secured to said knurled ring and extended loosely through the perforations of said vernier plate into said notched disk, a rocker arm having one of its ends pivoted to said protractor head, a cross-slide radially movable in said protractor head being pivoted to said rocker arm intermediate its ends, a roller secured to that portion of said rocker arm to which said cross-slide is pivoted, a pawl being adapted for engaging the peripheral notches of said ring-shaped plate and being pivotally connected to said cross-slide as well as to said protractor head, a bolt rotatably extended through said protractor head, a thumb lock lever having a cam portion adapted for engaging said pawl and being secured to one end of said bolt, a clamp plate secured to the other end of said bolt having a reduced portion which is interposed between said ring-shaped plate and said vernier plate, and a spring interposed between said protractor head and said rocker arm being adapted for forcing the latter against said notched disk.

- MORRIS SANDERS.

JOSEPH L. SANDERS.

No references cited.

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