US1590410A - Plumb bob - Google Patents

Description

June 29 1926. 1,590,4l 0

` F. J. BERNARD PLUMB BOB Filed April 2, 1925 Patented June 29, 1926.

UNITED STATES FRANK J. BERNARD, OF POETLAND, OREGON.

PLUMB BOB.

Application filed Aprl 2, 19535. Serial No. 20,079.

My invention relates to plumb bobs in which the suspending cord enters the head axially, issues through a hole in the side of the neclnand is then wound around the neck screw-fashion in one or more coils.

The objects of'my invention are to 'furish a plumb bob which will accurately center, which can be adjusted very precisely tor height by the simple tuning 01 the coils around the neck, and which will retain its osition on the cord without slippng.

'Other objects and advantages are to be found in the Construction and arrangement of parts, as will be described in the specification, and particularly pointed out in the appended claims. i

I attain these objects with the mechanism illustrated in the accompanying drawing, in whichr Fig. I is an elevation of my plumb bo-b, the hole in the neck being shown in front.

Fig. II is a side view of Fig. I, the upper portion thereof being shown in section.

Fig. III is a rear View of the neck shown in Fig. I.

%imilar numerals refer to similar throughout the several views.

This plumb bob may be used for ordinary purposes but is especially valuable for high class precision work, and has a tapering body portion l terminating downwardly in a removable steel point 2 to facilitate repair or exchange in case of accidental damage. The transverse hole 3 in the steel point makes provisions tor unscrewing the latter by means of a pin. The neck 4: of the plumb bob is comparatively long, cylindrical, and provided with a rela'tively large axial bore 5, which latter extends below a hole 6 entering the side of the neck 4- radially. The bushing 7 which is firmly inserted in the hole 6 should be ot' a length to extend a short distance to the outside of the neck and reach within one-half of the thickness of the cord S toward the center line of the axial bore The head 9 of the plumb bob in the drawing is shown to consist of a plug which is screwed into the bore of the neck, but a screw cap could be equally well employed providing the hole 10 in the head 9 is accurately proportioned to the diameter of the cord S.

The plumb bob is now ready for the reception of the cord 8, the winding of which latter is accomplished in the following manner: The lower of loose end of the cord 8 is parts pressed against the neck e of the plumb bob with one hand. The upper part. ot the cord is then wound in one or more coils around the necl: downwa *dly toward the body portion l, as indicated by the numeral ll in Fig. III, thereby clamping, the loose end tightly between necl and coils in order to prevent the uncoiling of said loose end. Thereupon said upper part ot the cord 8 is carried over the initial coils ll, as indicated by the numeral 12, and given several ;more turns upwardly toward the bushing 7. T he upper terminal of the cord is then caried through the bushing 7 and finally through the axial hole 10` in the head 9,' the latter for this purpose being preferably unscrewed. The upper terminal' of the cord can now be attached to the surve n in- 3 e strument or any other support in the usual manner.

To lengthen the cord of the Suspended plumb bob, the coils around the neck are turned in a direction which will feed the coils ot the cord into the bushing. The shortening ot the cord is accomplished 'by turning the coils in the opposite direction; in the latter case, however, the plumb bob should be slightly lifted in order to reduce the friction of the cord at both terminals of the bushing.

It is truly surprising to experience the ease with which the length of the cord can thus be changed, how even small adjustments can efi ectively be accomplished, and how firmly the plumb bob will retain its position without slipping, also the range ot adjustment is considerable, as one or two coils of the cord around the neck suflce to retain the plumb bob in place, while the neck is long enough to accommodate quite a number of coils.

The bore. 5 in the neck is large enough to give easy access to the end of the cord as it protrudes from the inner end of the bushing during the insertion of the cord. The projection of the outer end of the bushing beyond the circumference of the neck has the purpose, partly to prevent the coils from encroaching upon the cord as it enters or emerges from the bushing, and partly to form a guide whereby each newly forned coil is added in orderly array to the previously formed coils. Although the coils glide quite readily over the smooth surface of the neck, it should, of course, be understood that the plumb bob itself must be prevented from rotation When the cord is adjusted for length.

Having thus described my invention, it Will be seen that my objects have been acconplished and, though I have shown the preterred form ot' Construction, I reserve to myself the right to make minor changes, providing I do not contravene the spirit and principle of my invention.

l claim:

1. As an article ot nianufacture, a plumb bob having a tapering body portion, there being' a renovable Steer point at the lower end ot the body portion, a oylindrical neck at the top of the body portion, said neek having a sereW-threaded axial bore, a head sorewably engaging said th'eaded bore, said head having an axial hole communicating with the axial bore in the neck, there being a hole inthe Wall of the neck, and a bushing rinly niounted in the hole in the Wall ot the neck, said bushing projecting into the axial bore of the neck and beyond the outer circumterence of said neck.

2. A plumb bob having a tapering` body portion, there being a cylindrical neck at the top of the body portion, said neck having a screW-threaded axial bore, a head screwably engaging said threaded bore, said head having an axial hole, there being a hole in the Wall ot the neck and a bushing traversing said hole in the Wall of the neck in `radial direction, With a oord coiled around the neck, the upper end of said cord entering the bushing and energing through the head.

3. A plumb bob having a tapering body portion, there beinga cylindrieal neek integrally With the body portion, a relatively large aXial bore in the neck, a hole in the Wall of the necl, a head screwably engaging the neck, said head having an aXial hole,

a bushing traversing the hole in the Wall' of the neck in radial direction, With a cord coiled around the Wall of the neck below the bushing, the upper part of the oord entering the head and energing at the side ot the eck through the bushing, the inwardly projecting end of the bushing approaching` the center line of the bore to within one-half the. diameter of the cord.

t. A plumb bob, having` a tapering body portion, there being` a cylindrical neck, an aXial bore in the neck, a hole in the Wall of the neck, a head serewably engaging the neck, said head having' an aXial hole, a bushing traversng the hole in the Wall of the neck in radial direction, said bushing communicating With the axial bore. in the neck, With a eord coiled screw-fashion around the neck, the lower end ot the cord retaining its relative position to the coils by superimposing a part of said coils over said lower end ot the cord.

Signed by me at Portland, Oregon, this 27th day of March, 1925.

FRANK J. BEBNARD.

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