Tape measure

Abstract

A crank operated long tape measure includes a reel member and a casing side member having an internal center post with a conical free end. The reel member has a central shaft extending toward the center post for engagement therewith, the central shaft being axially segmented to define a plurality of leg portions. The free ends of the segmented leg portions bear against the conical end of the center post to assure centering of the reel within the casing while simultaneously providing constant frictional engagement between the reel member and the casing for resisting rotary movement of the reel member with respect to the casing. A long tape blade is secured to the reel for storage within the casing. The blade is provided with a laterally weakened break area adjacent its butt end and a replacement tape attaching aperture intermediate the break area and the butt end. Both the break area and the attaching aperture are spaced from the butt end by a distance sufficient to permit full exposure thereof outside the casing without disengagement of the butt end from the reel.

Description

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates generally to measuring tapes and is more particularly concerned with a crank operated tape measure having a relatively long rule blade.

It is an object of the present invention to provide a new and improved crank operated long tape of economical construction that resists unintentional unwinding or rewinding of the blade. Included in this object is the provision for a reel that coacts directly with the casing to provide the dual function of automatically centering the reel within the casing and of providing constant frictional engagement to prevent free-wheeling of the reel and facilitate the application of a smooth torque force when rewinding the tape blade.

Another object of the present invention is to provide a new and improved measuring tape of the type described including a tape blade construction that permits replacement of the blade without opening the casing. Included in this object is the provision for an exposable attachment means adjacent the innermost or butt end of the blade that permits removal of a damaged or worn blade and replacement with a new blade without disassembly of the casing.

Still another object of the present invention is to provide a new and improved tape measure of the type described that is particularly well suited for long tapes having a length of about 50 feet, 100 feet or more wherein the casing is provided with snap-fit interlocking elements capable of rapid initial assembly and of holding the casing in its assembled condition until it is permanently secured. Included in this object is the provision for a tape measure having fixedly secured mating casing parts and a tape blade with an integral "leader" portion that permits replacement of the blade in a simple and facile manner without disrupting the securely assembled casing.

A still further object of the present invention is to provide a manually operated long tape measure of economical yet rugged and durable construction that is well suited to rapid assembly.

Other objects will be in part obvious and in part pointed out in more detail hereinafter.

These and related objects are accomplished in accordance with the present invention by providing a tape measure comprising a casing, a reel member mounted on the casing for rotary motion relative thereto, and a relatively long tape wound within the casing and having one end extending outwardly therefrom. The casing is provided with a short center post and the reel member includes a central shaft extending toward the center post for engagement therewith. The central shaft is segmented to define a plurality of leg portions having free ends bearing against the center post to thereby assure centering of the reel within the casing while simultaneously providing constant frictional engagement between the reel member and the casing for resisting rotary motion of the reel member with respect to the reel casing.

A better understanding of the invention will be obtained from the following detailed description and the accompanying drawing which set forth an illustrative embodiment indicative of the way in which the principles of the invention are employed.

A BRIEF DESCRIPTION OF THE DRAWING

In the drawing:

FIG. 1 is an elevational view, partially broken away, of a tape measure embodying the features of the present invention, the tape blade being illustrated in a fully extended position;

FIG. 2 is an enlarged bottom view, partially broken away and partially in section, of the tape measure of FIG. 1 detailing portions of the reel member;

FIG. 3 is a further enlarged end view of the central shaft of the reel member of FIG. 2; and,

FIG. 4 is a top view of the exposed terminal portion of the blade of FIG. 1 .

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to the drawing in greater detail wherein like reference numerals indicate like parts throughout the several figures, the tape measure 10 of the present invention is illustrated as being comprised of a casing consisting of a pair of mating casing side members 12, 14 which, in their assembled condition, define an enclosed tape storage cavity 16. An opening 18 in one end wall of the casing provides communication with the storage cavity 16 and permits withdrawal and retraction of a long tape blade 20 such as a metal blade of about 50 or 100 feet in length. The mating side members 12, 14 are provided with side walls 22, 24 respectively having slightly concave exterior surfaces at the central portions thereof. The side member 14 is free of openings except to provide for passage of the blade 20 into and out of cavity 16 while side member 12 has an enlarged circular central aperture 28 in its side wall 22 with a radially extending lip 30 defining its periphery. The interior surface of side wall 24 is provided with a center post 32 projecting for a short distance into the interior of the casing and terminating in a conically shaped nose 34 on the free end thereof. The casing side members 12, 14 are constructed of a suitably durable material. In the preferred embodiment, high impact polystyrene has been found to give excellent results and similar tough molded plastics may be used.

A circular reel or hub member 38 is positioned within the large central aperture 28 and is provided with a peripheral flange 40 that cooperates with the lip 30 of the casing to prevent withdrawal of the reel from the casing. The reel projects outwardly from the side wall 22 and is provided with a transverse slot 42 well suited for storing a crank arm 44. The reel 38 is further provided with a generally cylindrical integrally depending skirt-like drum 46 that integrally extends across the interior of the casing and is received within a circular groove 48 within the side member 14, the groove 48 circumscribing center post 32 and being spaced therefrom by a radial distance less than the radius of aperture 28. The drum 46 defines an interior wall of storage cavity 16 and is provided with an appropriate key-hole slot 50 to permit secured attachment thereto of the T-shaped interior or butt end 52 of the tape blade 20. The crank arm 44 of reel 38 is provided with a projecting handle 54 adjacent one end and its opposite end is pivotably mounted within slot 42 through a snap fit connection on pin 56 for movement between the closed or stored position illustrated in FIG. 1 and the open operating position illustrated in FIG. 2. Thus as will be appreciated, the reel 38 can be manually rotated by crank 44 to wind the tape blade 20 onto drum 46 for storage within compartment 16.

In accordance with the present invention the reel member 38 is also provided with an axially slotted or segmented reel hub or central shaft 60 that extends toward the conical center post 32. As shown in FIGS. 2 and 3, the shaft 60 is comprised of three equally spaced leg portions 62 having arcuately tapered free end surfaces 64 for contacting the conical nose 34 of center post 32. The legs 62 are of a slightly greater length than the distance required to assure contact with the center post so that forced engagement of the surfaces 64 with the conical nose 34 tends to spread the legs 62 outwardly. Simultaneously this causes an axial force on the reel member 38 urging the peripheral flange 40 into intimate frictional engagement with the radially projecting lip 30 of the casing. This constant frictional engaging force between the central shaft of the reel member and the center post of the casing prevents free-wheeling of the reel member 38 and permits the application of a smooth torque force to the reel as the blade is retracted into the storage compartment of the casing.

The reel 38 may be constructed of suitably sturdy yet flexible material capable of providing the desired frictional properties, strength, memory and durability, particularly in the leg portions 62 of the reel shaft. In this connection it has been found that acetal resins, such as the material sold under the name "Delrin" by E. I. du Pont & Co., provide the desired properties.

The side members 12, 14 are each provided with a plurality of snap-fit connections that facilitate initial assembly of the casing members 12, 14 and assure application of an axial force on the reel member 38. As shown in FIG. 2, these snap-fit connections can take the form of segmented plastic snaps 68 and clasps 70 located in alignment adjacent the periphery of the casing at spaced locations and capable of holding the side members together until they are permanently fastened by ultrasonic welding, threaded fasteners or the like. In the particular embodiment illustrated, three such snap-fit connections cooperatively interengage to provide the desired retention of the side members in their aligned mated position.

As mentioned, it is also a feature of the present invention that the casing need not be reopened or disassembled in order to replace a worn or damaged rule blade. This is achieved by utilizing a rule blade 20 having a suitable replacement blade attaching means adjacent the interior or butt end thereof but spaced therefrom sufficiently to permit exposure outside the blade casing when the blade is fully extended. In the particular embodiment illustrated in FIGS. 1 and 4, the replacement blade attaching means takes the form of a triangular aperture 72 located centrally across the face of blade 20.

The blade 20 is also provided with a laterally weakened break away area to permit complete removal of the printed portion of the original blade prior to replacement. As will be appreciated most blade damage and wear occurs on that portion of the blade capable of being exposed and primarily upon the forwardmost end thereof. Thus a break away area can be incorporated in front of aperture 72 by providing a pair of laterally aligned edge notches 74. The exposed printed portion of the original blade 20 then can be easily and rapidly detached from its integral trailing leader portion at the weakened area and a replacement blade can be quickly attached at the replacement blade attaching aperture 72.

The forewardmost end of the tape blade 20 is also provided with a hook unit 76 that facilitates its withdrawal from the case. The hook unit 76 illustrated in FIG. 1 is of the folding type so that it can be conveniently and neatly received within a casing recess 78 located adjacent the aperture 18.

As can be seen from the foregoing detailed description the present invention provides a simplified and economical crank operated long tape that avoids free-wheeling of the reel member. This is accomplished by providing a segmented reel shaft that constantly bears against a conical center post on the interior of the casing to provide both centering of the reel and stabilized frictional engagement between the reel and the casing. Additionally the structure of the present invention need not be disassembled for replacement of a broken or damaged blade since the original blade can be snapped off at a weakened area near its butt end leaving a leader to which a replacement blade can be easily secured. Additionally the assembly of the unit is facilitated by a plurality of spaced snap-fit interlocking elements that can be molded into each of the casing side members to hold the assembly together until more permanent securing means are installed.

As will be appreciated by persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

Claims

I claim:

1. In a tape measure, the combination comprising a casing, having a lip portion a reel member mounted on the casing for rotary motion relative thereto, a relatively long tape wound within the casing and having one end extending from said casing, a center post within the casing, said reel member having a central shaft extending coaxially toward the center post for engagement therewith and a rim radially spaced from the shaft for engagement with the lip portion of the casing, one of said central shaft and said center post being segmented to define a plurality of leg portions having free ends and the other of said shaft and post having a cam surface, said free ends bearing against said cam surface to urge said leg portions apart and thus provide an axial thrust to the reel within the casing and simultaneously provide constant frictional engagement between the rim of the reel member and the lip of the casing for resisting said axial thrust and rotary movement of the reel member with respect to the casing.

2. The tape measure of claim 1 wherein said central shaft is axially segmented and the center post is tapered to bias the free ends of the leg portions outwardly during assembly.

3. The tape measure of claim 1 wherein the casing comprises a pair of mating casing members having opposed side walls and an opening for a tape to pass through, said center post extending integrally from one of said opposed side walls and having a conical free end engaging said leg portions.

4. The tape measure of claim 1 wherein said casing has a side wall with an enlarged central aperture defined by said lip portion, said reel member being mounted within said central aperture and including a wind-up drum and a peripheral flange provided with said rim for engaging said lip to prevent removal of the reel member from the casing, said long tape being wound on said wind-up drum and having one end secured thereto.

5. The tape measure of claim 1 wherein said long tape has a butt end secured to the reel and is provided with a laterally weakened break area adjacent said butt end and a replacement tape attaching means intermediate said break area and said butt end, both said break area and said attaching means being spaced from said butt end by a distance sufficient to permit full exposure thereof outside the casing without disengagement from the reel.

6. The tape measure of claim 5 wherein the laterally weakened area includes side notches in the tape blade and the attaching means includes an aperture in the tape blade.

7. The tape measure of claim 1 wherein said segmented shaft is constructed of acetal resin.

8. The tape measure of claim 1 including a crank arm mounted on the reel through a snap fit pivot connection.

9. In a tape measure, the combination comprising a pair of mating casing members having opposed side walls and an opening for a tape to pass through, one of said opposed side walls having an inwardly projecting center post and the other of said side walls having an enlarged central aperture defined by a peripheral circular lip, said center post having a tapered cam surface, a reel member mounted within the casing and projecting through said central aperture, said reel member including a wind-up drum and a peripheral flange having a rim engaging said circular lip to prevent removal of the reel member from the casing, a relatively long tape wound on said drum and having one end secured to said drum and its opposite end extending from said casing opening, crank means mounted on said reel member for winding an extended portion of the tape into said casing and onto said drum, said reel member having a central shaft extending toward the center post for engagement therewith, said central shaft being axially segmented to define a plurality of leg portions having free ends bearing against the tapered cam surface of said center post to provide axial thrust to the reel within the casing and simultaneously provide constant frictional engagement between the rim of the reel member and the lip of the casing for resisting said axial thrust and rotary movement of the reel member with respect to the casing.

10. The tape measure of claim 9 wherein said center post has a tapered end engaged by the leg portions of the central shaft, said leg portions being equally spaced.

11. The tape measure of claim 9 wherein the drum is provided with a key-hole slot and the end of the tape secured to the drum is provided with a T-shaped end portion.