US2428964A

US2428964A - Pivoted-leg compass

Info

Publication number: US2428964A
Application number: US546614A
Authority: US
Inventors: Elmer E Fife
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-07-26
Filing date: 1944-07-26
Publication date: 1947-10-14
Anticipated expiration: 1964-10-14

Description

Oct. I4, 1947. E. E. FIFE PIVOTED-LEG CQIGPASSV Filed July 2,6, 1944 Patented Oct. 14, r1947 OFFICE fPIvoT-ED-LEG CoMrAss .Elmer in. FifaDetfoit, Mich.

lAppiaation only '26, 1944, 'Serial No. v5413,614

(c1. ss-m) SClaima The invention "relates to a two-'legged fscrilc'in-g or similar instrument ior use in orming -circles and arcs whether in inkl or"pencfl,-or'finthe lform .of .a merezscratch.

-|The r principal object-.of the linvenition iis ito `provide a novel :and eflectiveinstrument for--ac'cu- .l'ately scribing circles 'on steel, vparticularlysmall circles, say for .1/3 to vextremely small ones.

A further object is torprovideiafnovel constructhe -work .even if the instrumentisfnotfheld `truly ,perpendicularto the work.

vAnother y object of the .invention is .'-toprovide .1 a novel andi advantageous .construction `wvl'iereloythe v-pivot legof the instrument 'will-.loe Iheld against the work withfainuch-.greatery pressure component than the s'cribing leg, tofhold'saidpivot.leg-against A.slipping from the:proper centerl'pointabout--wl'iich -anV arc or circle' is .to be described.

Yet another object is to provide .fa "new .and iimproved Vconstruction for .bracing the :"scrioing leg against twisting and tfending 'tolag behind lduring operationof the instrument.

A fur-ther object is fto provide fagnovel "andsadvantageous quick-.acting.adjustingrmeans forati- .J' listingY thescribing legtowardaand :fror'nt-hepivot zleg.

.-A still v.further:object is tolprovidesa xzomparav.tivelysimpl-eand inexpensive Tinstrument, :gettone which will loe-easily.operable,-reliablezanddurahle.

With :the .foregoingin view, the invention fre- `.sides .in the .novel subject :mat-ter :hereinafter fdescribed and claimed, :description nein-g Saccomplished by reference to the accompamngfdraw'- Ling. y

Figure 1. is a -side .elevation of -t'he :instrument .the scribing leg being .ini-the slightly raised @osition which itoccupies yheiterefdownwa11d Lpressure Sisplaced upon the' operatingfknob.

Fig. 2 is -a vertical sectional viewgtnescriioing leg being lowered to operative position bynnwn- Ward pressure upon the knob.

Figs, 3, 4 and 5 are-:sectionalviewszasindicarted by the correspondingly vnumberedlines fof vl.

l.A preferred construction :has lbeenlillustrat'ed .and will be ratherfspecically;describedwithithe understanding, however, .that Within the scopehdf the inventionv as'.clairned,avariations;may 'loeimada A.The pivot yleg of .theinstrument ,.islin r-th'e .'f'orrn ofa vertical vshaft 6 .having :aipoint il at its '.lower i" fend, said point Abeing 'by 'preference adjustably :held inran appropriate -ichuck @8. Slidable upon the upper end of the '.shaft, .i'sran operating knob 9 which isrnormally .heldin faraised Vposition :by

:means .of a compression l:spring .10 .housedtwithin the bore Il, which bore also receives the upper Yend of .said/,shaft '-6. A slight distance below the vknob 9, the shaft l is formed with a diametrical Islot 'l2 fora purpose to appear, and said knob'is provided with a downwardly'projecting .bifurcated lug rI3 at one end of said slot, for aV purpose which will also later appear.

A sleeve I4 is slidalole vertically'on the shaft and is by preference provided withbushings. I5. At itsupper end,the sleeve l 4 is formed vwith two -laterallyvprojecting,parallel lugs |16 between which the .upper-end of the scribing leg Il is pivoted by means of ascrew or the like I8. The lower end of this leg is provided `with a `suitable clamp .I3 for holding a scribing `point la, a pen or a piece oflead. Two parallelarms 20 are formed ori-the inner edge of the leg ll, said arms straddling the sleeve I4 to b-race said leg and prevent it from twistingfandvlagging during operation of the instrument. YIn the present disclosure, the sleeve I5 is formed with a ho-llow lug 2! projecting to yward the leg Il, said lug being of rectangular form and having its vertical sides disposed against the .arms 2E) of said leg I'l. .The sleeve I4, with its lugs .mand 2| may well bero-rmed from a single. metal blank lwhich mayhave its meeting edges welded or otherwise joined after being bent to forml said sleeve. It is also preferable to form the leg |"l and its arms 2B from a single metal blank which is of such form as to give said leg a channel shape 'in crosssection with its channel disposed toward the leg or shaft 6, said arrnsZ being integral with the side flanges 22 of said leg l?.

The inner side of the leg il is formed with.a curved seat '23, and 'said leg is also formed with an opening 24 from this seat to the side of 'said leg remote from the sleeve lil. A block 25, `constitutinga nut, isirockably"engaged'with the seat 23, being preferably of cylindrical form. Ascrew 2S, shown as having a left-hand thread, is threaded through the nut 25, the outer end of said'screw having an operating knob 2l. This screw is of 'tubular form 'and its interior is providedwith'a right-hand screw Ythread engaging a right-'hand screw 28. vThis screw'extends into the hollow boss ft and is pivoted'thereto by a. suitable pin or rivet 21.21.

An Lelongated yoke formed "from spring wire, straddles the screw 26 A"between the'fsidenasnges'z ofthe scribing leg Il Afand bearsagainstithe 'blockfor'nut 25 to hold the latter rockablyrengagedwith the seat 23, the vends fof sai-:lyoko 'i3d beingsecure'd Ato said leg I1 "by '-suitablelmeansi such asbolts and washers.

*Byturning-'the knob 27,113 one directionfor 'the 30 which is preferablyv other, it will be seen that the scribing leg I1 will be quickly adjusted inwardly or outwardly as desired, the speed of adjustment being much greater i than if only a single screw were provided.

A short lever 32 projects laterally from the leg or shaft 6 .and is disposed between the lugs I6 of the sleeve 4, said lever having a rounded inner end 33 received in the slot I2 of said leg or shaft 6. A slot 34 is formed in the outer end of the lever 32 and the Screw or the like I8 extends through this slot, to pivotally connect the lever 32 with the sleeve I4. Between its ends, the lever 32 is straddled by the bifurcated lug I3, to which it is pivoted by a pin 35. This pin is relatively close to the inner end 33 of the lever 32 and is relatively distant from the outer end of said lever. This lever, by having its end 33 in the slot I2, is fulcrumed upon the shaft or leg 6, and the parts are so proportioned that the upward thrust on the knob 9, caused by the spring I0, causes the lug I3 to swing said lever upwardly as shown in dotted lines in Fig. l. The outer end of this lever, being connected with the sleeve I4 by means of a screw or the like I8, vthus normally holds said sleeve and the scribing leg Il in a raised position as seen in Fig. 1. When the instrument is to be used, however, and a downward force is exerted on the knob I9, as indicated by the arrow in Fig. 2, said knob slides downwardly upon the leg or shaft 6, causing the pin 35 to swing the lever 32 downwardly as seen in full lines in said Fig. 2. This downward swing of lever 32 slides the sleeve I4 downwardly upon the leg or shaft 6, and the scribing leg I'I of course moves downwardly with said sleeve until its scribing point or the like 'Ia contacts with the surface to be marked. Then, while the instrument is being rotated to mark the work, the downward pressure on the knob 9 s of course continued. This downward force will be split into two components, one acting downwardly on the pivot leg 6 and the other acting downwardly on the scribing leg Il, and due to the location or the pivot 35 near the inner end 33 of the lever 32, the component acting on said pivot leg 6 will be much greater than `for carrying out the objects of the invention. At-

tention is again invited to the possibility of making variations Iwithin the scope of the invention as claimed.

I claim:

l. A scribing or similar instrument comprising two legs, an operating knob slidably mounted on one of said legs, and connecting means between said knob and legs including a one-piece lever movable relative t said legs by downward pressure on said knob, said lever being connected at one end to one of said legs, connected at its other end with the other of said legs and connected near said one end with said knob, whereby downward pressure on said knob will result in a relatively strong downward component on said one of said legs and a relatively weak downward component on the other of said legs, said one Qisaid legs having a point at its 1ower end constituting a pivot for the instrument, said other of said legs having a scribing point.

2. A scribing or similar instrument comprising a vertical shaft having a point at its lower end constituting a pivot for the instrument, a knob slidable vertically on the upper end of said shaft, a sleeve slidable vertically on said shaft under said knob, a leg at one side of said sleeve and having a scribing point at its lower end, means for connecting said leg with said sleeve, a vertically swingable lever extending laterally from said shaft and fulcrumed at its inner end on said shaft, the outer end of said lever being connected with said sleeve to downwardly slide the latter on said shaft when said lever is swung downwardly, and means between the ends of said lever and connecting said lever with said knob for downwardly swinging said lever when said knob is downwardly slid, said means being relatively close to said inner end of said lever and relatively distant from said outer end of said lever to cause said lever to exert a greater downward component on said shaft than on said leg.

3. A scribing or similar instrument comprising a, leg having a point at its lower end constituting a pivot for the instrument, a second leg having a scribing point at its lower end, a slidable member on one of said legs, a knob adjacent the upper ends of said legs and slidably mounted on the first mentioned leg, and connecting means between said knob, said slidable member and the upper ends of both of said legs, said connecting means includingY a one-piece lever pivoted between its ends to said knob and extending transversely with respect to said slidable member and said legs, said lever being movable relative to said legs by downward pressure on said knob.

4. A scribing or similar instrument comprising a vertical shaft having a point at its lower end constituting a pivot for the instrument, a knob slidable vertically on the upper end of said shaft, a sleeve.. slidable vertically on said shaft under said knob, a leg at one side of said sleeve and having a scribing point at its lower end, means for connecting said leg with said sleeve, a vertically swingable lever extending laterally from said shaft. and fulcrumed at its inner end on said shaft, the outer end of said lever being connected with said sleeve to downwardly slide the latter on said shaft when said lever is swung downwardly, and means between the ends of said lever and connecting said lever with said knob for downwardly swinging said lever when said knob is downwardly slid.

5. A structure as specified in claim 2; said means for connecting said leg with said sleeve including a pivot for said leg and a lateral lug on said sleeve through which said leg pivot extends, said leg pivot and lug constituting the means for connecting the outer end of said lever with said sleeve.

6. A scribing or similar instrument comprising two legs, a slidable member on one of said legs, a pivoted connection between the other of said legs and said slidable member, a one-piece lever extending transversely to the longitudinal axes of said legs and having one end fulcrumed to said one of said legs and its other end pivotally connected to said slidable member, and a knob slidably mounted on one of said legs and pivotally connected to the intermediate portion of said lever at a point closer to said one of said legs, whereby downward pressure on said knob will result ina relatively strong downward component on said .one of said legs and a relatively weak downward component on the other of said legs, said one of said legs having a point at its lower end constituting a pivot for the instrument, said other of said legs having a scribing point.

7. In a scribing or similar instrument, a leg h'aving a curved seat in its inner side and an opening from said seat to its outer side, leg-adjusting means including a nut having a curved surface rockably engaging said curved seat and a screw threaded through said nut and extending through said opening, an elongated yoke straddling said screw and extending longitudinally at the inner side of said leg, said yoke bearing between its ends against said nut to hold the latter engaged with said seat, and means securing the ends of said yoke to said leg, said leg being of channel shaped cross section, said nut and yoke being disposed in the channel of said leg.

8. A scribing or similar instrument comprising a leg having a point at its lower end constituting a pivot for the instrument, a. knob having a downwardly opening socket to slidably receive the upper end of said leg, a coil spring in said socket above the top of said leg, a sleeve slidable on said leg beneath said knob, a transverse lever fulcrumed at o ne of itsends to said leg and havl 6 ing its other end pivotallyconnected to said sleeve, the intermediate portion of said lever being pivotally connected to said knob, a second leg having a scribing point at its lower end and its upper end pivotally connected to said sleeve, and a screw-threaded adjusting means between said sleeve and the intermediate portion of Said second mentioned leg.

ELMER E. FIFE.

REFERENCES CITED The following references are of record in the le -of this patent:

UNITED STATES PATENTS n