US2389296A

US2389296A - Tool support

Info

Publication number: US2389296A
Application number: US401350A
Authority: US
Inventors: Everett E Crane
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-07-07
Filing date: 1941-07-07
Publication date: 1945-11-20
Anticipated expiration: 1962-11-20

Description

E. E. CRANE TOOL SUPPORT 3 Sheets-Shet 1 Mm w m v C mw vm F.- m w o. m mb? \J 3 3H E. E. CRANE TOOL SUPBORT Nov. 20, 1945.

Filed July '7, 1941 3 Sheets-Sheet 2 v 3nventor Everei-l' E. Crane Gttomeg Nov. 20, 1945:. E. E. CRANE v- ;3

TOOL SUPPORT Filed July 7, 1941 3 Sheets-Sheet 3 I Arm A Depgrhke Angle a l0 0 Arm 8 Depar-l'ure Angle b-Degre s attorneg f m 45 .5 2 m .4 z g B: a 3 (D L 1 l t 0 I z a B 4 Arm Len H1 Ra'i'io AX 9 A Zinnentor .Evere'H' E Crane Patented Nov. 20, 1945.

* UNITED, "STATES PATENT OFFICE TooL SUPPORT v I Everett E. Crane, Seattle, Wash. Application July 7, 1941. Serial No. $101,350 (01.14346).

20 Claims;

The mechanism of myinventionflwill support a tool or the like for straight line mot on toward and away from a reference'point. ,Theftool or other reciprocating element is carried, by the free end of a dog-leg linkage supported 'in cantilever fashion by the other end, and the relative movement of the links is positively controlled to compel the tool to trace a linear locus.

Supports for lineally' reciprocating tools and similar elements heretofore have generally employed guideways extending parallel to and over the length of path travelled. The space occupied by the work being operated upon is usually obsoured to a greater or less degree by such guideways in every positionv of extension or retraction of the tool. With my mechanism the space over the work may be cleared entirely by retraction of the tool.

Mytool support consists primarily of a dog-leg type linkage, that is, one composed of two links which are pivotally connected end to end. The other end of the inner or supporting link is pivoted to a mounting bracket, while the opposite end of the supported link carries the tool, which-may be a trim saw, or any other desired, element. The pivoted end of the outer or supported arm is controlled from such mounting bracket so that its angular departure from a given reference direction, such as vertical, 'willbear a predetermined relationship to the departure of thelsupporting arm from thesame reference direction. To express this relationship in another way, movement of the arms is controlled and coordinated so that the angular velocity of the sup-,- pcrting arm bears a predetermined and substantially constant relationship to the angular velocity of the supported arm. I have found that linear movement of the free end of the supported arm may be maintained within very close limits for any given relative arm lengths, if the proper constant angular velocity ratio of thearms for such arm lengths is maintained. For a reasonable angular departure from the reference direction provided that thediflerence in arm lengths of the dog-leg linkage is not too great, linear motion of .the free end [of the supported 'arm may be maintained within the limitations of the mechanism employed, such-as the rigidity-of the arms under load, the accuracy of pivot pin lit, and the play and strain ofthe arm control mechanism.

Not only can the free end of the'supported link be restricted to linear motion, but the tool pivoted on such arm end may be controlled from the supporting am so that it will always remain ina predetermined attitudejsuch as vertical, with respect to the reference direction. This result is produced by regulating the angular velocities orrelative-angular departures from the reference direction of the supported arm and tool head, so that a. constant ratio again is present. Similarly, while maintenance of an exact attitude maynot quite be achieved theoretically, for all practical purposes the change of attitude is inconsequential. i .The controlling mechanis for they linkage which insures maintenance of thedesiredratio of angular-movement may. take various forms, but I. have found thatchain. and sprocket connections are simple and effective. Correct relative arm movementfor linear traverselof the linkage endmay be obtained by interconnecting asprocket fixed to the linkage support with a sprocket rigid'With the pivoted end of the supported ,arm. The attitude of the tool may be maintained constant by interconnection of. a sprocket-integral with it and a second sprocket rigid with the outer end of the inner or supporting. arm. In each case, of course, the sprocket ratio selected Will be determined by the relative lengths ofthe arms constituting the linkage. ,It willbe evident that my linkage mechanism may be; made in a wide variety of sizes andforms according tothe particular use for which it is intended. Thus it may support the pen .of a recording machine, inwhich case the structure will be very small and-light, or the same principle may be utilized in a lifeboat davit, for example, requiring heavy construction. In fact, my mechanism is applicable to any use in which pivotal orrotary motion is to be transformed into linear motion. A particularly useful application is fora bench trim saw support, which has been illustrated in .detail in the drawings, andis specifically described hereafter.

A primary purpose of my invention, therefore, is to support an element in cantilever fashion and guide it for linear reciprocation without work-obscuring guide mechanism, such as ways and the like. This operation I accomplish by the useof simple mechanical parts, various types of machine elements being available foraccomplishingthe desired controlled movement .of the link: age, those selected being dictated by the purpose for which the mechanism is to be used and the preference of the individual designer.

i Furthermore the accuracy of operation of my controlled linkage may be checked readily, and

if not proper, it may be adjusted quickly andwith little difficulty.

Especially when applied to a bench trim saw or the like, it is an object to aiiord universal movement for the saw, so that it may be swung bodily for reciprocation along any line of cut, with the saw blade either parallel to the plane of the supporting linkage, or making an angle relative thereto such as for chamfering or bevel cutting edges. For ripping purposes, whether the saw is vertical or inclined, the tool head may be swingable with respect to the free end of the supported arm'whic'h carries the Moreover the saw may'be vertically adjustable withrespect to the free end of the supported arm, or the entire linkage may be movable vertically, to enable the depth of cut made by the saw or other tool to be varied as desired.

The bench trim saw shown in the iirawings represents a typical example of .a practical .embodiment of my invention, but the principles employed, by which linear movement of a 3300158111)- port, while maintained in a .constant attitude is obtained, maybe utilized in devices "of widely divergent nature. V

Figure 1 is a front elevation viewofmyinvem tion embodied in a bench trim saw, while Figure 2 is a "section through such trim saw along'line 2-2 of'Figure'3, showing'the supporting'lin'kage, and Figure 3 is a section through Figure 2 along line 3-13, 'showing'portions of the linkage in side elevation. Figure 4 is a section on line 4-1! of Figure3, of a portion of the tool unit itself.

Figure 5 is a diagrammatic view of'mechanism utilizing links of .difierent "lengths, and indicating in exaggerated fashion the deviation from linear movement occasioned "by a large angle of departure of the arms from vertical. Figure 6 is .a diagrammatic :view similar to Figure 5, in which-thearms offthe iinkage'are equal 'inlength.

Figure 7 *is a diagrammatic'p'lanvi'ew ofbench saw-mechanismshowing how bothsquare and inclined angle cuts may be made. FigLne 8 is a diagrammatic side elevation view of the table trim saw mechanism, set for a lengthwise or rip inclined cut. Figure'9 is a view similar-to Figure 8 with the saw positioned 'for a-vertical rip out.

Figure '10 is a diagrammatic plan view of my dog-leg linkage in general illustrating a preferred type of interconnection of the arms and control mechanism, and showing the linkage in fully expanded condition, so that thearms appear full length. 7

Figure .11 is a graph indicating the relative angular .departures of the "linkage .arms which must be maintained to produce substantially straighteline motion of the free .endof the supported arm when different arm lengths are employed. Figure 12 is another graph showing the inter-relationship between the arm length ratio and the relative diameters of the arm control sprockets, one curvedesignating the relationship whi h must bemaintained to secure substantially stnaight-line movement of the free end of the supported link, .and the other curve that necessary to preserve in all extended positions of the linkage a constant attitude of the tool mountms or equivalent element.

My tool support consists principally of anusleg linka e, hat issue composed oia supporting link 1, havingone end pivoted .to .a bracket H! by pins H, and its other end pivoted by a, pin l2 to one end of a supported link 2. Without the p ovis n r c ntrol mechanism thefreeend of the supported link .2 could be moved universally within .a circle having .a radius-equal to the combined length of arms I and 2 when extended in alignment, except as such movement might be prevented near the center of the circle by the relative lengths of arms I and 2, or by interference of the supporting base. The link I and 2 need not be of equal length, but if supported link 2 i longer than supporting link I the free end of the former could not be moved closer to the pivot ll than the difference in length of the two arms.

Universal movement of a tool or other element has been :permitted by using such a :dog-leg or two-arm linkage as a support. The problem which I have solved by the present invention was *to restrict movement of the free end of the linkage 'to substantially linear or straight-line movement. Moreover, such solution enables arms of different lengths to be employed, the supported armi usually being longer than the supporting arm 'I in such installations. No control mechanism has been proposed for such linkages heretofore which would restrict movement of .the .free end or the supported link to linear or substantially linearmotion.

"While 11 .have illustrated my invention as incorporated in a support for a bench trim saw, .it is .tobe understood that 'the same operating principles are applicable to similar mechanism used as 'a support for any tool or element which is to have straight-line motion.

"I have found that movement of such dog-leg linkage may be governed to afford substantially linear -reciprocation of its "free end even though the arms are of different lengths, as shown in Figure "5. The method of obtaining such motion is "to control relative angular departure of the two arms from a "given reference direction in the manner determined by the relative arm lengths. If the linkage is mounted for extension and collapse in a vertical plane, and horizontal traverse of its free end is desired, the reference direction will be vertical. 'In any case the reference direction, from which the relative angular departure of the arms is measured, will be perpendicular to the linear locus or path to be traveled by "the .free end of the linkage.

In Figure 5 a representative diagram'oi linkage having arms of unequal'length is shown, while in Figure Gthe "special case in which the arms are of equal length is illustrated. For purposes of general discussion 'the supporting arm is designated A and the arm supported thereby is indicated at .B. In order to obtain straight-line motion a predetermined, constant relationship between the angular movement of arms A and B must be maintained. As indicated in Figure 5, the angular departure of arm A from vertical is the angle a, whereas the corresponding angular departure from vertical of arm'B is the angle b; If the relationship of angle ajto angle 1) ismaintained a constant, properly selected according to the relative lengths of arms A and B, substantially straight-line movement of the free end of arm B will be maintained within reasonable limits of angles a and b.

In order to determine the conditions for linear movement of the free end of arm B the following equation must always be satisfied.

Bcosine 17-4 cosine am a constant The limiting position ofthe arms will, of course, be when they are in alignment, overlapping each other, such as both vertical, in which case the angles-a and 6 become zero. Since the above equation must be true in this special situation, o er t e difference in arm length, or B minus A, must be the equation constant for straight-line movement, both angles a and b in such case being zero, and their cosines equal to 1. We may thus write the equation-as follows;

B cos b-A cos a=B-A I r Transposing B cos b=A cos aA+B or cos A(cos aB-1)+B We now have an expression in which a function of the angular departure of arm A, a, is modified by the relative lengths of the arms,

2:15, :2, 2 3, and =4 respectively, of Figure 11. The broken lines drawn from degrees to 60 degrees departure of arm A, namely, angle a, alongside each of the curves B 1.5, 2 and 3 I and from 0 degrees to 50 degrees for the curve are straight lines, and the distances of these lines from the solid lines plotted from the above equation for the several arm length ratios is a measure of the deviation from linear motion of the free end of the linkage throughout an angular departure of 60 degrees for arm A when the angular velocities or relative angular displacements of arms A and B are in direct proportion, that is, when a/b is of constant value.

Even for this large departure angle of 60 degrees it will be seen that the deviation from q/b being constant is extremely small, and considering possible deflection of the arms under load, looseness of the pin joints, and play and; strain in the arm interconnecting mechanism, for practical purposes the motion of the free end of the linkage is linear. The deviation will, of course, be substantially decreased for smaller angles of departure of arm A, and cannot be noticed at all by a graphic comparison for values of a up to 20 degrees. Beyond this point the amount of deviation gradually increases, but it wouldseldom be necessary in most installations to use an angular deflection of arm A greater than 60 degrees, represented by broken lines in Figure 5,although with arms of equal length precisely straight-lin movement is preserved for any angle of deflection, asshown by the broken line posi-, tion which the equal arm linkage of Figure 6 may assume.

Having now proven that substantially linear movement may be obtained with such a dogleg linkage whether the arms are of equal length or not, and throughout reasonable angles of arm departure from'mutual registry, merely by efiecting proportionate relative angular movement of the arms, it merely remains to devise mechanism to produce relative movement of this type, and to determine what angular ratio of arm swing is necessary to obtain such linear motion with linkages of various arm length ratios. Such control of thetwo arms maybe attained by reaction on arm B 'from the linkage support to which arm A is pivoted. Suitable mechanism is diagrammatically represented in Figure 10, in which a sprocket, for example, designated "AX, is 'held' rigid with thesupport S, so thatitsfe -i fective rotation'rela tive to arm A will be angle a. To this sprocket is connected, by a chain or the like, a second sprocket BX, which is fixed to arm B in registry withits pivot ment with sprocket AX.

Because arm B is supported from arm A, when arm A swings about its pivot through angle a arm B must swing about its pivot, and relative to arm A, through angle a+b to attain a departure from the reference direction, such as vertical, of angle b. To effect such relative arm' movements the working Or root diameters of sprockets AX and BX must be inversely proportional to the actual pivotal motions of arms A and B through angles a' and a+b, respectively. The diameter ratio of sprockets AX and BX would therefor be,

, I: the-arm pivot or sprocket ratio,

1 g v w is .50; for t for for

B BX 71% Zr 59 for B BX 71 IX 64 for B BX =4, me?

and in; align:v

From these 'values we may determine that the equation for this arm swing curve of the catenary to -obtain linear movement of the free end of the linkage for any selected sprocket diameter ratio I an may'thus be determined either'by solution of this equation or from the arm swing curve of Figure Conversely, any desired arm length ratio V V A may be selected, and-the aboveequation solved to therequired sprocket diameter ratio TX 7 for .such. reciprocation, or such ratio may be determined graphically from the arm swing curve of Figure 12.

Extending the problem somewhat farther, the tool or equivalent element may not only be reciprocated lineally, but may be retained in a constantattitude during such reciprocation. It will be evident that such element, if fixed to arm B, would be deflected with it through the angle 17 from the reference direction. Constant attitude control may be exercised, however, if the tool holder issswung through the angle b with respect to arm 3 for a departure of the latter through angle 1) from the referencedirection, such as'ver- 'tical, or fora deflection of such arm through angle a+b with respect to arm A. Controlled swinging of the tool, designated T in Figure 10, may be accomplished from arm A by means of a sprocket BY rigid with the tool carrier, and a second sprocket LAY aligned'therewith and fixed upon the end of arm A to which arm B is pivoted, coinciding with such pivot axis. As before, the relative diameters of these sprockets would be inversely proportional to the actual pivot movement of the tool and arm A with respect to arm B. Thus for a pivotal tool movement of b the sprocket diameter ratio a AY would be a+b T I Again for Various arm length ratios of I the value of may 'be determined from the several curves of Figure 11 at 60 degree'sdepa-rture of arm A. These values plotted against arm length ratio give the tool trim curve oiFigure 1 2, by which thearm length ratios,

A and the tool trim sprocket ratios,

AY V o are coordinated. Selecting values from this curve we find that for an arm length ratio of The equation which may be derived for this curve, also of the catenary type, is

1og.( +1=ae l0g; ere) B 3.3 (are? Therefore Transposing From either this equation or the tool trim curve of Fig. 12 either the proper arm length ratio, or tool trim sprocket ratio, may be determined when the other has been established.

For further convenience the two final equations givenabove may be combined in the form B BY 3.3 B 1042(735) If)? 2 182 +'3=* 10 at 2): AX A Y.

and

. A u the other two values required to obtain straightline motion and, constant tool attitude. are thereby established.

While, as suggested, a chain and sprocket type mechanism is quite suitable for controlling the relative movements of the twoarms A andB, the linkage base or support S and the tool I,

it will be understood that any mechanismwhich will positivelyinterconnect these various elements to control their movement/in the manner described may beemployed. For instance, a bevel gear may be substituted for each of the sprockets AX, BX, AY, and BY, such gears of each pair having the same eflective relative diameters as the sprockets, determined as described above. Movement of the gears BX and AX maybe coordinated-by a'shaft carried by arm A, having on each end a bevel pinion, one meshing with bevel gear AX and the other with bevel gear BX, which pinions are of equal size. Such interconnected bevel gears, BX and AX, mustbe on opposite sides of the shaft so that they will turn in the same direction. Similarly a shaft would be carried by armB and provided with a pinion on each end, of the same size, and meshing, respectively, with bevel gears AY, and BY, also located on opposite sides of the pinionshaft.

, Spur gears, on the other hand, might replace the several'sprockets, such spur gears being of proportional size as in the case of the sprockets.

Such gears AXand BX might be interconnected by 'a train of intermeshing idler gearscarried by arm A, provided "that an odd number of idler gears is used tojestablish relative rotation of the control gears in the same sense. Similarly gears AY and BY could be interconnected by a row of intermeshing idler gears, again an odd number of such gears being'required. Instead of interconnecting such spur gears by idler gears reciprocating racks might be mounted one on each arm A and B', which would mesh'with the gears AX, BX, and AY, BY, respectively, to transmit motion from one gear to the other in each case. Such gears might alternatively be in terconnected by a silent chain instead of using idler gear or rack connections.

A combination of such interconnecting mechanisms might be employed. Two pairs of gears, one to control arm swing and the other'to control tool trim, the gears of each pair being of the proper relative diameters and meshing directly, may be mounted with one gear-of each pair aligned with a pivot axis. The motion of; the other gear of each pair, not in registry with a pivot, may be transmitted to the pivot axis at the more remote end of the arm by unit movement ratio mechanism, such as" a chain and sprocket arrangement employing sprockets of equal size, a bevel gear'and pinion train employing pinions of equal size and gears of equal size, or a rack and pinion connectionhaving pinions of equal size. Still other typesof connection may be preferable for certain installations;

For purposes of illustrating furtherthe capabilities of my linear motion mechanism, in Figures 1 to 4, inclusive, I have shown it used as a bench trim saw support. Other devicesin which linkage of this type is useful, however, have been mentioned above. a

The supporting link of the trim sawlinkage is composed of two arms in spaced, parallel relationship, one being pivoted to each bifurcation of a yoke 10 by a pin l I. In operation these two arms act in unison. This yoke, 'in" turn, is mounted to swivel on a fixed base'3. Index marks 30, cooperating between" the yoke 10 and clamped in any desired angular position by means oi the clamping screw and lever arrangement 3|, including a set screw which may be screwed inwardly to engage an extension l3 of yoke l0 projecting into base 3. Any other clamping mechanism of suitable type may be used instead oi such a set'screw device. a The supported end of link 2 is received between the arms I,: and, as previously described, these supported and supporting links, respective- 13;; are interconnected by a pivot pin I2 extending "through a long bearing 20 integral with the supported; endof link 2. The immediate sawsupp'ortingbracket' 4' preferably is bifurcated Lo form'fingers 4i] straddling the free end of arm 2 and'connected to it by a pivot pin 2|. All of the

arms

1, 2,an'd4 should be ribbed, such as of T beam or'cruciform section, so thatthey will have greatstiffness for their weight, to reduce, as'ra 'as possible, bendingwhich would induce departure of the pivot pin 2i from linear'motion during extension movement of the'linkage. a

control orthe relative angular departures r the arms is obtained in the manner previously described." The specific saw mechanism'linkage illustrated has arms I and 2 of equal length, and hencesprocket M has an effective diameter twice as gr'eat'as sprocket 22. Sprocket l4 corresponds to member AX shown in the diagramof Figure 10, and is'integral with pivot pin H, which in turn is secured in yoke lfl against rotation. Each arm |',"'there'for'e, moves upon its pivot pin II and relative"to both sprocket l4 and yoke I0. Sprocket 22 corresponds to element BX intlie diagram of Figure 10, and is'secured rigidly 'to the bearing sleeve 20 of arm 2. Sprocket'l5 is securedrigidly to arm "I, and corresponds to lement AY shown diagrammaticallyin Figure '10. 'Its effective'idiameter is one-half that of spr0cke't4l,which is rigid'with a bifurcation of bracket 4, and corresponds to'element BYof Figurelosm a A "A' chain H5interconnects sprocketsil-ll and 22, and asecond chain 23 interconnects sprockets l5 and 41, 'so'that the cooperating sprockets will be positively interconnected to control accurately therel'ativle" angular velocities of the arms I and 2;"a11'd' "of' the "saw head.' In" order" to'mainta'in maximum accuracy; while enabling the control mechanism" to i be 7 assembled easily, a 'tightener I1 is pivoted on arm l forholding chain l6 tight, and.Ta'SimiIantightenerf'Z-A,pivoted on arm 2, keeps chain 23 tight. These tighteners'are urged toward'armsil and '2 by springs [Band 25, respectively, which". extend between each tightener and its'ar'm; 'I'n'ord'erto enable the parts to be adjusted-for establishing the proper initial relationship :of' the arms, the angular position of sprocket l4 'with'respect to yoke I0 may be varied by'slackening off the'clamping nut of pivot pin ll "to which it is'screwed, and then retightening it, .to secure it again against movement with respect toyoke Jllljwhen' the proper p'osition of the sprocket has been established. Similarly a set screw 42 enables sprocket M to beset in its proper angular position with respect to yoke 40 of bracket 4', and then s'ecuredin such position.

The saw mechanism 'and. arms will have cohsiderable weight, and hence counterbalances 1 may be secured to'the lower ends of arms I which willtend to equalize the turning'mom'ents'of the various parts of the arrangementab ou t pivot H.

T e aw e cha ni tsel u pered u on a;

vertioal spinc ille 5, whieh is. snuglyi eeeive'd in a cdna'riis formed by the outer end of bracket. Ah annulai recess .44 is out in the top 01 this e to s me deei es'ed s ould 45.- o hi h s eatsa oi oss bat-.50., serving as a suppo t for spin-.-

die 5 and. xtendingthroughfsjlots 51 in opposite Shes e m l h cent -vi s; .ber' 'e loored; and threaded to receive. a screw 52, ro-

tatable for vertical'aii i pigeneprthespnigies y h d W e .3. nieerei w th. h me imi t o WTQW 5. or secu ed n. s i able f t hiem e eett ee hushies which isveneeee n ath. ee -te ate. .5. n eetel; wi h s incue A set ce l r ma be ie uhdeiupwe d thtust .Q a si in m k n mi. @153!- this se npi ee exreeeeme t the pindle .mayero ete ebo t a vert al axis to di pose the sew e tion, or king a v etice u along any li e an the heed. Wh el 53; m b

to receiyethe. circular head EQi-nteeralwith. t e

. .c e d to th wee? 9. .bii hine t9 re e t i e of the ini d o e seo llow saw: bearing s1eeve.-&,which rleeeivee aiyloolr 6!; of

saw 62. Aperture. 51: is fiangedat one end to.pr. e-. vent. endwise-movement of head. 60. out ofr such apertuxe, angi. a thnust rin-e 5.8, projecting. inward beyond its periphery, restricts theopposite end of-. the ape ture tov engagethe other end of head 86.. Thesammay be mtated; by a. motor, another suitable; dnive, conneotedtoend.- 63. ofspindleji by aflexible connection.

Aperture 5! may be formed as a split .ringjand a. elaimh 59. nmyige i to. constriot the. ring. for ampin head -61}. in. any rotative position. with r pect. -to.the..ring-, A l g. 59! maybe carried by thQlQdwQf this; clamp, adapted toseat in. anyone 01%. hetnotshesjkextendihg radiailyinward-from the. Peni he y. of? head. 61}. These. notches are preferably haced: de rees, apart, so. that the heed. ,eybe locat dreadiln n a y'such position, and qnrespomi severallx to. vertical: disposition of win and; &1 degrees. downswing. .Ihelbar or 111g 5.8; mayhe out of the apertureil and liglkqfilz QGQh 5.4:- n. Qrder to. allow. the'headifl t9 be.-1;ota, tedgfrom onesueh position to another. lenythermore, this. ban may be left insuch outw lfiltksw n pqsition, in, which case head so inexbe. set in any angular position intermediate 21 .9 9QQF iQ PQI GiQ tQ-Smh notCh and clamp 25% ti hiqehfidf.tqeseeurelthe head in such intermedie e eulanpo i.oh. Ring 58. ancthead so nax b gegged tq aciiitateisuch.settings. A cut wi h; slwde ree oi: hamfer or. inclinationmay h ete lie-mach. i

-- figures 7;, 3; and a, aswell as Fligure 6, indicate diagrammatically. various types about which may fifi properly; adjusting the. mechanism d eei'ihedi Eieureifi; thesaw. isxpar -l l' t th plane which, the dogrleg. linkage moves, and plane is pemendieular. to; the work table'.

The saw is thus set. for. aoshallova straight orbssm F ure'i,

out; e hdiqe d; b one dPtted line.h sitie i we as indicated by the'other dotted line position, t

. eied. t sw ne he saw-down. thiz u h d em and the. Y ke H1 is wuh in the op o te d reci e hr an ngl o d .rees.,. m c nte or jna e ih mi r o be l cut a neenqns slte ob i ue ine Eith r bevel, o evert l p t my: e se made he e bein o t ed. hown in gu es 8 nd t ze ee fi ve m, he. s is setat t e desi ed am .erqm he bee 3" e m the umb rm eqee fi t zie di e t qe ne oeeeieoiar W t e e em f h iekeee- The iste ee te m e cut fiqthe ewe may e. ar ed. n w enthe eme i an e been es abl shed; he -eels: .9 ma e; e ie ed; secu a m; I a ainst m tel moyementneiatiye to yoke in, by-lateral contact, and hem turthe elet we o ement. o ll; e ee ie, ot eete e n an r t act on s or ventedv mtilafter he? h s eeno meletedz- Whilel h we s ibed.- in de i nly; ine t;- time! mbod men ep l eet ohs o the B ibep s in ol d: n. my il-t e41, lin a e 0. 2 us n the hani m t q lmee movement u h. as- Suggested e q e ma a il b d vised:- when l im my inv nt on. s

s uhh r e meehenism: fo ateolp the like, ee hri pe. e. base... d e es inka e. ne udi ee seee rt e lime pi e ly cqee c edr s ii base eesla s -e et ecip inh e teliy cqm e tee to. s i sspeee he it. a looeti n emo e teem: he. ee-Piv t fic on. nka e c nt o means o QQQ Z in the heu a rmq ei ehta z aiq sewe -ted: -ist e d; b se ie e i to. eid sup. Porting .li e1 tool .carren ei e supported :90. 2 he. we. o said:.s i e r ea in1e.end tool trim C xten in losely ontrol; aloeeeis e. sa steepered: 1 n a l. eeeules' os itan he reaoti eso e y fipmzseidsupeoxte t 1 ee sned; by relative mov ment f .1. q oqx na eth n ular movement i: said oo enie: m! sa d supportin nle lae ive. to..- e e ueno zted ink o i-h ain ne. said too i su t h i l yie h t nt a titud rela ive o..- sa d; ba e fo e hcled po itions. saiddosee. linka e i in.- t not ai wohkm aneei unpp ti e meeh nismi ee a. ool: r. the like, comprising a h oe-leeihkaee; mo d: me e; sup o ctine nk; h v ng n end iv 15; connected to ai ase; andga. so ooo ed; ink: my,- otally-conneet etothe ot r end of saisi s p.- porting linle; linkaeenoont olimeans for coordin te ine the angiulaomovement.of-saidisueoq cted. 91; said; base. re a ive o; said sueeort he n e & .01 cai rierpiilotallyzsu e med." 9.91 he: e s? end: of; said suppo ted l nk; amt to l: tr m eerie trol" means .eonneeted. betwe n. s d; otheneedz f said s pporting link: nd sai tQQ fi ifi 'alffis acting solely from said sup oortingdink an g gay erned'byrelat vfi movemen f ei 1. c ordinate. thev ine-111a: mo em nt 1 3 2 9 carrier. andsaidsup or ine ink e e i eto i ssepfl ported: link, for. maihtainingsaid tool oai'fieg; slihstantially constant an ular a itu e letite to. said base for. all. extend o--.posi io s; f: said respective rotations 3, Supporting mechanism for a lineally reciprocable tool, comprising a base, dog-leg link age,including a supporting link pivotally connected to said base, and a supported link pivotally connected to said supporting link at a location remote from the base pivotal connec tion, linkage control means interengaged between said base and said linkage, and operable to guide movement of said supported link for substantial- 1y linear reciprocation of its free end, a tool carrier pivotallysupported upon the free end of said supported link, and tool trim control means interengaged between said linkage and said tool carrier, reacting solely from said supporting link, and governed by relative movement of said links to control angular movement of said tool carrier relative to said supported link, for maintaining said tool carrier in substantially constant angular attitude relative to said base for all'extended positions of said dog-leg linkage Within its normal working range.

'4. Supporting mechanism for a lineally reciprocable tool, comprising a base, dog-leg linkage, including a supporting link pivotally connected to said base, and a supported link pivotally to said supporting link at a location remote from the base pivotal connection, linkage control means for restricting movement of said linkage relative to said base and of said links relative to each other, to guide said supported link for substantially linear reciprocation of its free end, a tool carrier pivotally supported upon the free end of said supported link, and tool trim control means to control movement of said tool carrier relative to said supported link, for main- 3:)

taining said tool carrier in substantially constant angular attitude relative to said base -for all extended positions of said dog-leg linkage within its normal working range, including a circular control element supported nonrotatively withrespect to said tool carrier, a second circular control element supported uponand ;nonrotatively with respect to said supporting link, and means interconnecting said control elements and operable to coordinate the respective rotations thereof relative to said supported link.

5. Supporting mechanism for a lineally reciprocable tool, comprising a base, dog-leg linkage,jincluding a supporting link pivotally connected to said base, an d a supportedlink pivoted to said-supporting link at a locationremote from the base pivotal connection, linkage control means for restricting movement of said linkage relative to said base and of said links relative to each other, to guide said supported link for substantially linear reciprocation of its free end, a tool carrier pivotally supported upon the free end'of said supported link, and tool trim control means, including a circular control element supported nonrotatively with respect to said tool carrier, a second circular control element supported .upon and nonrotatively with respect to said supporting link and means interconnecting said control elements and operable to coordinate the thereof relative to said supported link for maintainin said tool carrierin substantially constant angular attitude relative to said base for all extended positions of said dogleg linkage within its normal working range, said tool trim control means conforming substantially to the equation in which 7 is the ratio of the efiective length of the supported arm to that of the supporting arm, and

is the ratio of the effective radius of said first control element to that of said second control element.

6. Supporting mechanism for a lineally 'reciprocable tool, comprising a base, dog-leg linkage, including a supporting link pivotally con nected to said base, and a supported link of equal length pivotally connected to said supporting link at a location remote from the base pivotal connection, linkage control means for restricting movement of said linkage relative to said base'and of said links relative to each other, to guide said supported link for substantially linear reciprocation of its free end, atool carrier pivotally supported on the free end of said supported link, and tool trim control means to restrict movement of said tool carrier relativ'e'to said supported link, for maintaining said tool carrier in constant angular attitude relative to said base for all extended positions of said do leg linkage, including a circular control element supported nonrotatively with respect to said tool carrier, a second circular, control element of onehalf the effective radius of said first control element, supported upon and nonrotatively with respect to said supporting link, and mean interconnecting said control elements and operable to coordinate the respective rotations thereof relative to said supported link.

I '7. Supporting mechanism for a tool or the like, comprising a base, dog-leg linkage, including a supporting link pivotally connected to said base,

and a supported link pivotally connected to said supportin link at a location remote from the base pivotal connection, linkage control means for coordinating the angular movement of said supported link and said base relative to said supporting link for effecting substantially linear movement of the free end of said supported link, including a circular control element supported nonrotatively with respect to said base, and a second circular control element. supported non,- rotatively with respect to said supported'link,

and connected to said first control element toeffect rotation of said second circular'control element relative to said supporting link in the rotative sense opposite that in which said support;- ing link swings relative to said base, a tool carrier pivotally supported upon the free end of said supported link, and tool trim control means for coordinating the angular movement of said tool carrier and said supporting link relative to said supported link, for maintaining said tool carrier in substantially constant angular attitude relative to said base for all extended positionsof said dog-leg linkage within its normal working range, including a circular control elementsupported nonrotatively with respect to said tool carrier, a second circular control element supported upon and nonrotatively with respect to said supporting link, and means interconnecting said last two circular control elements and operable to efiect rotation of said tool carrier circular control element relative to said supported link in the opposite sense and proportional in degree to the swinging of said supported link relative to said supporting link.

8. Supporting mechanism for a tool or the like, comprising a base, dog-leg linkage, including a supporting link pivotally connected to said base, and a supported link pivotally connected to said supporting link at a. location remote from the base pivotal connection, linkage control means for coordinating the angular movement of said supported link and said base relative to said supporting link, including-a circular control element supported nonrotatively with respect to said-base, and a second circular control element supported nonrotatively with respect to said supported link, and connected to said first control element, a tool carrier pivotally supported upon the free end-of said supported link, and tool trim control means for coordinating the angular movement ofgsaid tool carrier and said supporting link relative to saidsupported link, for maintaining said tool carrier in substantially constant angular attitude relative to said base fOrall extended positions of said dog-leg linkage within its normal working range, including a circular control element supported nonrotatively with respect to said tool carrier, and a second circular control element supported nonrotatively with respect to said supporting link and connected to said tool carrier control element, said linkage control means and said tool trim control means conformin substantially to the equation B B 13.3 B 10 is the ratio of the effective radius of -said supported link control element to that of said base control element, and i is the ratio of the eflective radius of said .tool

carrier control element to that of said supporting link control element.

9. Supporting mechanism for a tool orthe-like lineally reciprocable ina constant attitude, comprising a base, dog-leg linkageincluding, a supporting link pivotally connected to saidbase, and a supported link pivotally'connected; to said supporting link at a location remote'from the base pivotal connection, linkage control means for restricting movement of said linkage relative to said base, and of'said links relative to-each other, toiguide said supported link for substantially linear reciprocation of its free end including a circular control element supported nonrotatively with respect to said base, and a second circular control elementsupported nonrotatively withrespect to said supported link andconnected to said first control element, a tool carrierpivotally su, ported on the free end of said supported link, and tool trim control means for restricting movement of said tool carrierwithrespect to saidlinkage, to maintain said -.tool carrier in substantially constant, angular attituderelative to said base ior all extended positioilsLof said dogleg linkage within its normal working range, in-

cluding a, circular control element supported nonrotatively with respect to said tool carrier, a second circular control element supported upon and nonrotatively with respect to said supporting link, andmeans interconnecting said control elements and operable to coordinate the respective rotations thereof relative to said supported link. i

10. Supporting mechanism for a tool or the like lineally reciprocable in a constant attitude, comprising a base, dog-leg linkage, including a supporting link pivotally connected to said base, and a supported link of equal length pivoted to said supporting link at a, location remote from the base pivotal connection, linkage control means for coordinating the angular movement of said supported link and of said base relative to said supporting link, to guide said supported link for linear reciprocation of its free end, including a, circular control element supported nonrotatively with respect to said base, and a second circular control element, of one-half the effective radius of said first control element, nonrotatively supported with respect to said supported link, and connected-to said first control element, a tool carrier pivotally supported upon the 'free end of said supported link, and tool trim control means for coordinating the angular movement of said tool carrier and of said supporting link relative to said supported link, for maintaining said tool carrier in substantially constant angular attitude relative to said base for all extended positions of said dog-leg linkage, including a circular control element supported nonrotatively with respect to said tool carrier, a second circularcontrol element of 'onehalf the effective radius of said tool carrier control element, supported upon and nonrotatively with respect to said supporting link, and means interconnecting said control elements and operable to coordinate the respective rotations thereof relative to said supported link.

11. Supporting mechanism for a, bench saw or the 'like lineally reciprocable in a constant attitude, comprising a base, dog-like linkage, including a supporting link pivotally connected to said base, and a supported link pivotallyconnected to said supporting link at a location remote 'from the base pivotal connection, linkage control means interengaged between said base and said linkage, and Operable to guide movement of said supported link for substantially linear reciprocation of its free end, a saw carrier pivotally supported upon the free end of said supported link, saw carrier trim control means interengaged between said linkage and said saw carrier, reacting solely from said supporting link, and governed by relative movement of said links to control angular'movement of said saw carrier relative to said supported'link, for maintaining said saw carrier insubstantially constant angular attitude relative to said base for all extended positions of said dog-le linkage within its-nonmal working range, a saw, an arborrcarrying said saw, and means supportingsaid saw arbor from said saw carrier foradjustment of said saw relative to said carrier abouta horizontal axis.

12. Mechanism of the character described comprising a base, a supporting arm pivoted at one end to said base and swin able'to either side of its pivotal connection therewith, a supported arm pivoted at one end to the other end of said supporting arm and having its other end free, said supported arm being' swingable across said supporting arm to either side of the latter and wheels to constrain said arms also to either side of the pivotal connection between said supporting arm and :said base, and

gearing positively supported zarm towtraverse 'a zstraightgiline, said connecting gearing being disposed substantially parallel "to and being :confined substantially within theflength ofsaid'supportingrarm.

1.3. Mechanism :of the character described comprising a :base, a supporting arm pivoted at one :end to :said base, a supported arm pivoted at one end to :the other end of said supporting arm and having its other end .free, a sprocket wheel fixed to said base in axial alinement 'with the pivot between the latter and :said supporting arm, :a sprocket wheel fixed to :saidsupported arm in axial alinement with the pivotal connection between said arms, and :a sprocket chain connecting and cooperating with :said sprocket to :'SWl.1lgiSimll1ta-- neously and to cause the free end of 'said supported arm to traverseastraight line.

14. Mechanism of the character described comprising a base, a supporting arm pivoted at one end to said base, a supported arm pivoted at one end to the other end of said supporting arm and having its other end free, a gear wheel fixed to said base in axial alinement with the pivot between the latter and said supporting arm, a gear wheel fixed to said supported arm in axial alinement with the pivotal connection between said arms, means connecting and cooperating with said gear wheels to constrain said arms to swing simultaneously and to cause the free end of said supported arm to traverse a straight line, a tool support pivoted to the free end of said supported arm, a gear wheel fixed to said supporting arm in axial alinement with the pivotal connection between said arms, a gear wheel fixed to said tool support in axial alinement with the pivotal connection between the latter and the free end of said supported arm, and means connecting and cooperating with said two gear wheels last mentioned to cause said tool support to maintain a constant angular attitude relative to said base during its straight line movement with the free end of said supporting arm.

15. Mechanism of the character described comprising a base, a supporting arm pivoted at one end to said base, a supported arm pivoted at one end to the other end of said supporting arm and having its other end free, a sprocket wheel fixed to said base in axial alinement with the pivot between the latter and said supporting arm, a sprocket wheel fixed to said supported arm in axial alinement with the pivotal connection between said arms, a sprocket chain connecting and cooperating with said sprocket wheels to constrain said arms to swing simultaneously and to cause the free end of said supported arm to traverse a straight line, a tool support pivoted to the free end of said supported arm, a wheel fixed to said supporting arm in axial alines ment with the pivotal connection between said arms, a wheel fixed to said tool support in axial alinement with the pivotal connection between the latter and the free end of said supported arm, and means positively connecting said two wheels last mentioned and acting precisely tangentially of both thereof in all swung positions of said arms to cause said tool support to maintain a constant angular attitude relative to said base 7 connecting said base withsaid, supported arm and constraining said arms to swing simultaneously and the free ,end of saidduring its straight line movement with the free end of said supported arm.

:16. Mechanism of "the character described comprising a base,-.a supporting arm pivoted at one end to said base, a supported arm pivoted at one end to the other end of said supporting arm and having its other end free, a gear wheel fixed to said base in axial alinement with the pivot between the latter and said supporting arm, a gear fixed -to said supported arm in. axial alinement with the pivotal connection :between said arms, means connecting :and cooperatingwith sai gear wheels :to c.onstrain said arms to wing simultaneously and to cause :the free end of said supported arm to traversea straight'line,-a tool support pivoted to-thefree zend'oi :said sup orted arm, a sprocket wheel fixed to said supporting arm "in. axial alinement with the pivotal iconnection between said arms, a sprocket wheel fixed to said toolsupport in axial alinementwith the pivotal iconnection :between the latter and the free end :ofsaid supp tl farm and 2a sprocketchain connecting and cooperating with said two sprocket wheels las mentioned to cause said toolsupport toimaintain a constant :ansular attitude relative to said base during its straight line movement with the free end of said supported arm.

l7. Mechanism of the character described comprising a base, a supporting arm pivoted at one end to said base, a supported arm pivoted at one end to the other end of said supporting arm and having its other end free, a sprocket wheel fixed to said base in axial alinement with the pivot between the latter and said supporting arm, a sprocket wheel fixed to said supported arm in axial alinement with the pivotal connection between said arms, a sprocket chain connecting and cooperating with said sprocket wheels to constrain said arms to swing simultaneously and to cause the free end of said supported arm to traverse a straight line, a tool support pivoted to the free end of said supported arm, a sprocket wheel fixed to said supporting arm in axial alinement with the pivotal connection between said arms, a sprocket wheel fixed to said tool support in axial alinement with the pivotal connection free end of said supported arm, and a sprocket chain connecting and cooperating with said two sprocket wheels last mentioned to cause said tool support to maintain a constant angular attitude relative to said base during its straight line movement with the free end of said supported arm.

18. Mechanism of the character described comprising a base, a supporting arm pivoted at one end to said base and swingable to either side of its pivotal connection therewith, a supported arm pivoted at one end to the other end of said supporting arm and having its other end free, said supported arm being swingable across said supporting arm to either side of the latter and also to either side of the pivotal connection between said supporting arm and said base, gearing positively connecting said base with said supported arm and constraining said arms to swing simultaneously and the free end of said supported arm to traverse a straight line, said connecting gearing being disposed substantially parallel to and being confined substantially within the length of said supporting arm, a tool support pivoted to the free end of said supported arm, and gearing positively connecting said supporting arm with said tool support and conbetween the latter and the straining thelatter to gular attitude relative r straight line movementwith thefree end of said maintain a constant an supported arm, said last mentioned gearing being disposed substantially parallelto and being confined substantially within the length of said between said arms, and means positively connecting corresponding sides of said two circular members and acting on parallel lines precisely tangentially of 'both'thereof in all swung positions a of said arms to constrain said arms to swing simultaneously through corresponding angles, thus'to'cause' the free end of'said supported arm to traverse a straight line;

20. Mechanism of the character described to said base during its comprising a base, a supporting arm pivotedat one end to said base, a. supported arm pivoted at one end to the other end of said supporting:

arm and having its other end free, a circular member fixed to said base concentrically with the pivot between the latter and said supporting arm, a second circular member fixed to said supported arm concentrically with the pivotal con nection between said arms, and means positively connecting said two circular members, operable to effect rotation of said second circular member relative to said supporting arm in the rotative sense opposite to that in which said supporting arm swings relative to said base, and acting precisely tangentially of both'of said circular members in all swung positions of said arms to preserve a constant ratio between the rotation of "said second circular member relative to said supporting arm onthe one hand, and the rotation of said supporting arm relative to said base on the other hand, thus to cause the free end of such supported arm to traverse a straight line within its normal working range.

EVERETT E. CRANE.