Single pedestal drafting table

Abstract

A single pedestal drafting table incorporating a unique, rigid, one-piece frame including a base, a post rising at a forward incline from the rear thereof and a horizontal cross tube on top of said post in T formation and lying parallel to the front of said base. A drawing board is tiltably mounted on the frame's horizontal cross tube by cup-like members fitting concentrically over opposite ends of the cross tube in rotatable relation. The drawing board is normally held against tilting movement by a manually applied locking device that causes a braking action by said cups against the ends of said cross tube and when released is cushioned in its turning by a counterbalancing spring mechanism housed in said tube.

Description

The invention relates to improvements in a single pedestal drafting table, appertaining particularly to one having a novel, rigid, unitary, supporting frame comprising a base, a post rising therefrom and a horizontal cross tube arranged in T formation on its upper end with a drawing board carried in tiltable relation thereon.

PRIOR ART

Drafting tables employing a single pedestal stand or having a tilting drawing board with counterbalancing mechanism are known, as disclosed in Canadian patents 547,284, Lawes, (also British specification 659.207/53; 636,418, Knudson, (also Denmark specification 764,065/57); 695,671, Wenger; and 901,056, Sautereau (also French patent P.V. 102,323); or U.S. Pat. Nos. 3,140,559, Grow et al; 3,161,159, Kritske; 3,273,517, Amthor et al; and 3,638,584, Cisler et al.

In the known structures, the assemblies are relatively heavy, cumbersome, complicated and expensive.

SUMMARY OF THE INVENTION

An object of this invention is to provide an improved and simplified drafting table.

A further object of the invention is to provide an improved drafting table having a novel supporting frame with the base, post and drawing board-carrying cross piece formed as a rigid one-piece unit.

A further object of the invention is to provide a simple mechanism for allowing the tilt of the board to the desired angular position and for securely locking the same against unwanted movement.

A further object of the invention is to provide an improved spring counterbalancing mechanism assembly.

A still further object of the invention is to provide a drafting table of the nature described characterized by structural simplicity, compactness, operational efficiency and reasonable cost of production.

BRIEF DESCRIPTION OF THE DRAWINGS

To the accomplishment of these and related objects as shall become apparent as the description proceeds, the invention resides in the construction, combination and arrangement of parts as shall be hereinafter more fully described, illustrated in the accompanying drawings, and pointed out in the claims hereunto appended.

The invention will be best understood and can be more clearly described when reference is had to the drawings forming a part of this disclosure wherein like characters indicate like parts throughout the several views.

In the drawings:

FIG. 1 is a perspective view showing the rear side of single pedestal drafting table embodying the invention;

FIG. 2 is an enlarged detail elevation of the horizontal cross tube that forms the top portion of the unitary supporting frame;

FIG. 3 is a further enlarged vertical section showing the tube and drawing board brackets assembly;

FIG. 4 is a transverse section thereof as taken on line 4--4 of FIG. 3;

FIG. 5 is a further enlarged elevational detail of the drawing table pivot rod and cam locking lever;

FIG. 6 is a transverse section as taken on line 6--6 of FIG. 5; and

FIG. 7 is a sectional detail of an alternative assembly for the counterbalancing mechanism.

DETAILED DESCRIPTION OF THE INVENTION

In this drafting table the entire frame is a single rigid unit comprising a horizontal V-shaped base 1, having the spread of the arms of the V to the front, a post 2 rising from the apex of the V base at a forwardly inclined angle so that its top extends out over the open space between the free ends of the arms of the V and a horizontal cross tube 3 connected centrally to the top of the post 2 in a T formation, said tube paralleling a line between the free forward ends of the arms of the V base 1. Besides the cross member 3 being of hollow tubular form, the V base 1 and inclined post 2 appear herein as of rectangular cross-section profile and are both preferably hollow, as appear in a companion pending application, U.S. Ser. No. 383,347.

This simple, rigid, unitary supporting frame is designed to support a drawing board 5 in rotatable relation on the T form, horizontal, cross tube member 3 to allow the tilting thereof to any desired angle from a substantially horizontal position to a substantially vertical position; means being provided to counterbalance the variable load of the tiltable drawing board and to releasably lock the board in any desired angular tilt within the limits above mentioned.

Referring now particularly to FIGS. 3 and 4, it will be seen that the unitary frame's cross tube member 3 has its ends closed by disks 10 welded on the tube, each with a central aperture 11. Additionally, spaced inwards from one end, there is another disk 12 welded inside the tube as a partition, which disk also has a central aperture 13 and is further provided with an off-center opening 14. Exteriorly on the tube 3 near each end there is a radially projecting, circumferentially extending abutment 15.

To mount the drawing board 5, with such equipment as may be carried by it, on the frame's tubular cross member 3 so that it may be readily tilted to any desired angular setting from approximately horizontal to approximately vertical position and there releasably secured in rigid, locked relation against accidental movement, a simple tilting connection mechanism is employed. A cut 16 is fitted concentrically over each end of the cross tube 3, the cup having an annular base 16a that has a close tolerance rotatable bearing-like fit about the end of the cross tube. It will be noted that the wall 16b is of such height as to reach inwards on the tube to approximately the inside limit of the adjacent abutment 15 on the cross tube except for the arc of the angle through which such arcuate abutment extends plus a further approximately 90.degree. where the upper edge of the cup wall is cut lower to accommodate the abutment and allow the cup freedom to rotate through an angle of approximately 90.degree. and be stopped by such abutment at each end of such permitted rotatable movement. These cups 16 are attached by fasteners such as bolts 17 to a spaced parallel pair of angle brackets 4 applied on the rear side of the drawing board 5, as clearly seen in FIG. 1 and so allow the drawing board to freely tilt on the tubular cross member 3 through an angle of approximately 90.degree.. The brackets are relatively stiff but enjoy a modicum of flexibility in their wide confronting cup-carrying sides.

Running through this tilting mechanism assembly is an elongated round rod 18 disposed axially of the tubular cross member 3 and the concentric drawing board bracket cups 16, passing loosely through the apertures 11 and 13 in the disks 10 and 12 respectively as well as through a close fitting bore 19 in one cup base 16a and the juxtaposed drawing board bracket and said rod having a rectangular-in-cross-section length 20 at the opposite end that passes in sliding but non-rotatable relation through a correspondingly rectangular shaped aperture 21 in the base 16a of the other cup and juxtaposed drawing board bracket. Where the round end of the rod 18 extends through the first end cup 16 it is terminally threaded and carries a nut 22 that captures a washer 23 against the outer side of the drawing board bracket 4. The remote, squared end 20 of the rod 18, after it projects through and beyond the other cup 16 and bracket 4, also carries a washer 24 and a manual locking lever 25 whose head is configurated as a cam 26, bifurcated to centrally accommodate the squared rod and pivoted thereon by a transverse pin 27. Thus it will be seen that when the lever 25 is swung to actuate the cam, the spaced pair of drawing board bracket cups 16 are firmly compressed against the end disks 10 of the frame's tubular cross member 3 thereby positively locking the drawing board in fixed and rigid position. The adjustable nut 22 on rod 18 allows of varying the braking force of the cam lock.

Besides acting as the tension bar for locking the drawing board in the desired tilted position, the axial rod 18 carries the torsion mechanism to counterbalance the tiltable drawing board 4, which it will be noted is pivoted to the tubular cross member 3 of the supporting frame on an axis adjacent the lower edge of the board. On the rod 18 near the squared end but located to lie well within the adjacent fixed end disk 10, there is a transversely apertured boss 30 and between this boss and aperture 14 in the fixed partition disk 12 a torsion spring 31 is coiled around the rod with its opposite ends hooked and captured in the respective openings in disk 12 and boss 30. The tension of the spring 31 can be varied as desired by twisting the pivot cup 16 on the squared end of rod 18 before bolting the same to the juxtaposed drawing board bracket 4. A cushion liner or silencing tube 32 of plastic or other suitable material encircles the rod within the convolutions of the torsion spring 31. It will be obvious that as the drawing board is tilted, when the cam lever is released, the rod 18 with its squared end 20 engaged by the correspondingly shaped aperture 21 in the cup 16 will be rotated with or against the action of the spring 31 biased against the fixed tubular member 3 of the frame.

In the alternative assembly for the counterbalancing mechanism shown in FIG. 7, the drawing board bracket bearing cup 16' has a large central aperture 21' in which a coaxial sleeve 33 is welded that extends inwards to pass freely through the accommodating aligned apertures 11 and 13 in the end disk 10 and partition 12 respectively. Here, there is an apertured boss 30' on the sleeve 33 near its outer end instead of on the axial rod, and a similar concentric coil spring has its opposite ends hooked in apertured boss 30' and aperture 14 in partition 12. The rod 18' is rectangular in cross-section with its outer end passing through a correspondingly shaped rectangular slot 34 in the drawing board bracket 4' in longitudinally slidable, non-rotatable relation and since this bracket 4' is releasably bolted to the sleeve carrying bearing cup 16', the counterbalancing torsion spring in this assembly is biased between the integral frame and the tiltable drawing board to operate in the same way as the spring mechanism of FIG. 4.

In use, the hereindisclosed unitary rigid frame provides a very stable supporting base for the drawing board. When the cam actuated braking mechanism is released, the simple and adjustable counterbalancing spring allows the board to be tilted into the desired angular setting with the minimum of effort and when the cam lock is applied the steadiness of the drawing board is assured.

Various changes in the size, shape and arrangement of parts may be made to the form of invention herein shown and described, without departing from the spirit of the invention or scope of the claims.

Claims

What is claimed as new is:

1. A drafting table comprising

i. an integral one-piece frame including a base, a single inclined post rising therefrom and an elongated horizontal cross tube member mounted centrally on said post in T formation

ii. an inwardly facing cup disposed concentrically over each end of said cross tube member in rotatable bearing-like fit about the end of the tube and

iii. a drawing board carried by the cross tube member of said integral one-piece frame in tiltable relation having a spaced pair of parallel brackets on the rear thereof that lie beyond the ends of said cross tube member and are removably secured against the base of said rotatable cups.

2. A drafting table according to claim 1, having a rod disposed axially in said cross tube member with its opposite ends projecting through said end bearing cups and means on said rod to force said bearing cups against the respective engaged ends of said cross tube member in braking relation.

3. A drafting table according to claim 2, wherein the ends of said cross tube member are closed by centrally apertured rod-passing disks, and the means of said rod is a lever operated cam that forces said bearing cups against said respective disks.

4. A drafting table according to claim 3, wherein said rod is rotatable in one end cup, non-rotatably engaged by the other end cup and longitudinally slidable through both, an adjustment nut being threaded on the rotatable end of the rod exteriorly of engaged cup and the cam being pivoted on the other end of the rod exteriorly of the non-rotatably engaged cup.

5. A drafting table according to claim 1 having a radially projecting circumferentially extending abutment on said cross tube member near an end thereof engageable by one of said bearing cups, said cup having the upper edge of its wall recessed to accommodate said abutment and limiting the tilting movement of said board to a rotation of approximately 90.degree..

6. A drafting table according to claim 1, having a counter-balancing torsion spring coiled within said cross tube member and biased between said fixed integral one-piece frame and an end cup fitted over the end of said tube member in rotatable relation and secured to a bracket on said tiltable drawing board.

7. A drafting table according to claim 2, wherein said axially disposed rod has at least one end thereof non-rotatably related to the drawing board supporting cup whereby the rod is caused to turn as the drawing board is tilted, a counterbalancing torsion spring coiled concentrically about said rod within said cross tube member and biased between said frame and said drawing board, and a silencer tube encircled by the convolutions of said spring.