US2385902A - Fixture for grinding threadcutting tools - Google Patents

Description

-Oct. 2, 1945. i H. c. WILSON 0 FIXTURE FOR GRINDING THREAD CUTTING TOOLS File d March 1, 1943 3 Sheets-She'et l W4, WM

Oct. 2, 1945, H. c. w l LsON 2,335,902

FiXTURE FOR GRINDING THREAD CUTTING TOOLS Filed March 1, 1943 s Sheets-Sheet z Oct. 2, 1945. H. q. WILSON 2,385,902

r FIXTURE FOR GRINDING THREAD CUTTING TOOLS z Filed March 1, 1943 I :s She'ets-Sheet s Patented Oct. 2, 1945 FIXTURELFQRi-GRINDING THREAD- GUTTING TOOES Harry G. Wilson, Huntington Park, Califl, assigno'r to Robert H.' Clark, Los. Angeles, Calif.

' Application March 1, 1943', SerialiNo. 477,59?

13 Claims.

Thisinvention relates to: fixtures: or holders for holding cutting tools and relatesm'ore. pare ti'cula-rly to grinding fixtures. for thread cutting tools. A general object of this: invention is to provide a simple; practical fixture for holding a threadcutting tool on a grinder so that it will lee-presentedtothegrinding-wheel t'o-heaccurately ground to the correct angles.

Thread cutting tools are usually" formed" from lengths of'ste'el provided at one end with pitchecl' side surfaces, a top surface, and sometimes a forward edge face, j'o'lningto form the cutting point. Holders or1 fixtures have been developed to hold the cutters so that they may be ground by a surface grinder. These prior fixtures are usually complicated and expensive ,annd are constructed so that the cutters must: be. manually adjusted. in order to grind". surfaces thereon for the cutting of threads'of different types;

Another object of. this invention is. to provide a fixture for thread cutting tools that is very. simple and inexpensive, comprising a one-piece body and a simple screw or the equivalent for securing thebits or tools inthe body.

Another object of this invention is to provide. a fixture. of the character referred to by meansof which. the bits or cutting tools may beacon: rately set or positioned. relative to the. grinding. wheel of a. grinder to. be. properly and accurately ground for. the. cutting of. either oneoii'two par-' ticular. kinds of. threads, withoutadjusting. or changing the positions of the. tools inthe fixturev and withoutlthe manipulation of any securing, adjusting or clamping parts. 'I'h-fixtureof; the. present invention" is. adapted. to support a cutting tool at-the-correct-'angles-wherebyit-may be. ground for the. cutting of either. one oftwo. selected: forms ortypes of. threads,. tor example, Acme threads or standard. V-threads, and the: simple positioning of the fixture: on the table of: thegrinder determines the manner which. the toolis to be ground; It is'unnecessary to. lic-osem the'too'l'lin the=fixture7 and shift or adjust. it, and it. is'unnecessary ta operate any mechanisms; for? shifting the: tool so: that: it may be: ground fort the; cutting of either type of: thread. This: is important as: it expedites: thev grinding operation and eliminates the possibility of: errors that may result from manual adjustments, etc.

Another object of thisinvention is to provide afixture of thecharactermentihned in w-hi'clrth'e tool" is supported so that its side surfaces are given the necessary clearance or rake when the fi'xtureis arranged or positioned for the" grinding of the tool in either of the. alternative manners above referred to.

Another object of the: invention is to provide a toolholder or fixture of the character men tioned that is operable-to support the toolitol have. its upper surf-ace ground: truly: parallel with the longitudinal axis of the tool' or: to" have this surface ground to slope downwardly and rearw-andiy relative to said. axis to give therpointvitscleararrce or rake. The fixture isishaped to permittthe: op:- tional grinding of the upper face-in either'of the two manners just referred to. without the necese ity of adjusting, shifting, or disturbing the't'col", the setting of the tool for grinding in eitheroi the two ways being accomplished by merely engaging the fixture on: the table of: thegriindersto have either oneof'two surfaces contact the face of the table.

Another object of the invention is taprovide a fixture of the class referred tothatmay embody blocks or holders to mount the tool, when it is to be ground for use in various classes oi tool holders, when it isto be used for grinding offset thread cutting tools, and when it is to be used fer grinding thread chasers.

A further obj ect" of this invention is to'provide a holder or fixture of the character referred to that embodies no delicate parts liable to be made inaccurate through use does not have calibrations or scales that are liable to get out 0t adjustment or to be misread.

The various objects andfea-tures'of' my inven: tion' will be fully understood from the following detailed description of typical pref-erred forms and applications of my invention; throughout which description reference is made to the" accompanying drawings, in' which:

Fig. 1 is a side elevation of the fixture' provided by the invention arranged in position on the table of a grinder so that; a parallel or axial surface is formed onthe upper'sid'e of the tool. Fig. 2 is a View similar to Fig. 1 showing the fixture positioned so that a sloping surface is formed on the upper side of the tool. Fig; 3 is an end elevation of the fixture in position on the table positioned so that the grinder forms one side of the cutter for cutting a v-threadl Fig. 4 is an elevation of the other end of the fixture' with the fixture positioned on the table so that the other side of the cutter is ground-to cut a V-thread. Fig. 5 is a side view of the fixture positioned so that the point or forward edge of the cutter is ground to form the root of the thread. Fig. 61s a view'similar to-Fig. 4' showing the fixture positioned so that one sideof: the

cutter is ground to cut an Acme thread. Fig. 7 is a front elevation of the fixture. Fig. 8 is a perspective view illustrating the manner in which a tool and a block may be assembled in the fixture to grind the tool so as to be useful in an angularly disposed tool holder. Fig 9 is a perspective View of the fixture on the grinder table with the tool engaged in the block illustrated in Fig. 8. Fig. 10 is a perspective view of a tool and a block for supporting the tool in the fixture for righthand offsetting. Fig. 11 is a perspective a top than to the bottom of the body. The longitudinal axis of the opening I I and the upper and view similar to Fig. 10 showing the block and tool arranged for lefthand offsetting of the tool and in position for engagement in the fixture. Fig. 12 is a perspective view of the fixture arranged on the grinder table with the tool supported to be ground for lefthand offsetting. Fig. 13 is a perspective view of a holder for mounting a thread chaser in the fixture. Fig. 14 is a perspective View of the fixture on the grinder table showing the thread chaser supported by the holder of Fig. 13. Fig. 15 is a front elevation of another form of fixture of the invention. Fig. 16 is a side view of the fixture of Fig. 15 showing one side of the tool being ground. Fig. 17 is a side view of the fixture in position to grind the other side of the tool. Fig. 18 is a side view of the fixture positioned to grind the tool for cutting a different angle or type of thread. Fig. 19 is a side view of the fixture positioned to grind the other side of the tool and Fig. 20 is a side view of the fixture in position to grind the end of the tool.

The fixture of the present invention is primarily intended to hold a tool bit for presentation to the wheel of a grinder for the purpose of grinding thejbit for the cutting of threads. The fixture is suitable for use on a surface grinder having a magnetic table although the fixture may be used in a grinder having a non-magnetic table, in which case it is to be clamped or otherwise secured to the table. The fixture of the invention may be formed to receive or hold tool bits of different types and sizes and may be constructed to support the bits in the grinder to be ground for the cutting of different styles of threads. In the drawings -I have shown typical preferred'forms of the invention adapted to support tools in a grinder to be ground so that they are conditioned tocut either standard V-threads or Acme threads at the will oroption of the operator, it being understood that the fixtures may be formed to support tools to be ground so as to cut threads of other forms or styles and'the invention is not to be construed as limited or restricted to the specific embodiment of the invention herein disclosed. I

The fixture illustrated in Figs. 1 to 7 comprises a body 10 for carrying the bits or tools C and shaped to be arranged on the table T of a grinder to present the cutters to the'grinding wheel W. In accordance with the invention the fixture body I is a simple, integral block-like part. It is preferred to form the body ll) of steel or other suitable paramagnetic material. The fixture body I0 is provided with simple means for receiving and releasably holding the bits or tools. Thisfmeans includes an opening I! extending through the body II] from its front :2 to its rear surface l3. Theopening I! is preferably square in transverse cross section and is of substantial size to receive both round and square cutters or tools .0 varying greatly in size. The opening H is spaced midway between the opposite sides 'ofthe body l0 but is considerably closer to the surfaces to join the opening H.

the top surface 14 9f the body.

The tool holding means further includes clamp screws or set screws l screw-threaded in openings IS in the body and adapted to enter the opening II to cooperate with the cutting tool C. The upper corners of the body H! are preferably bevelled off and the openings l6 extend downwardly and inwardly from the bevelled corner The openings I6 carrying the clamp screws l5 extend in diagonal relation to the opening II and join the opening H at'its corner (see' Fig. 7). The active inner end of the screws l5 are adapted to engage upper corner edges of the tool C and the screws serve to hold the tool downwardly and inwardly against the lower wall of the opening II. Thus the sides of the tool C are perpendicular relative to the body surface M. The body surface l2 which forms the front of the fixture, when positioned as illustrated in Figs. 1 and 2, is plain and fiat and occupies a plane perpendicular to the surface M. The cutter or tool C projects from the surface l2 and its longitudinal axis extends at 90 to said surface.

In accordance with the invention the body I0 is shaped so that it may be set on the table T to present the tool C to the wheel W at either of two angles, one where the wheel W grinds a surface 20 on the top of the tool T that is parallel with the longitudinal axis of the tool, and the other where the wheel W grinds a surface 2| on the top of the tool which slopes downwardly and rearwardly relative to said axis. The end of the body In opposite the surface or end l4, that is, the lower end of the body as viewed in Figs. 1 and 2 of the drawings, has two angularly of Fig. 2.

related surfaces 22 and 23. The surfaces 22 and 23 are each flat and regular to evenly bear on the surface of the table T. Thesurface 22 is parallel with what I have termed the top surface M and is parallelwith the longitudinal axis of the opening H and the cutting tool T. Accordingly, when the surface 22 is'engaged' on the table T, as illustrated in Fig. 1 of the drawings, and the cutting tool is presented'to the wheel W, the wheel grinds a surface 20 on the top of the tool that is parallel with the longitudinal axis of the tool. This is clearly evident from an inspection of Fig. 1. V g

The surface 23 is pitched with respect to the surface 22. The direction of inclination of the surface 23 is such that when the surface is engaged on the face of the table T the cutting tool C slopes downwardly and forwardly with respect to the grinding wheel W. Accordingly, when the tool- C is presented to the wheel W the wheel grinds a surface 2| on the top of the tool which slopes downwardly and rearwardly from the point of the tool. This is apparent from an inspection The grinding of the top surface 20 or 2| may be the first grinding operation and is readily performed by engaging either the surface 22 or the surface 23 on the table T so that the cutting tool C is presented to the wheel W to be provided with either the surface 20 or the surface 2|, as selected. I 7

As pointed out above, the fixture may be arranged on the table T of the grinder so that the bit or tool T will be ground to cut V-threads or Acme threads. Each side of the fixture body I!) has two angularly related surfaces A and B. The corresponding surfaces A and B on the opposite sidesoijthejbody are-of equalwirlth and of 0.0!;- eShQnd-ing: inclinat o and: pitch. The: suI QS A and; B: are fla and smeqthz and" QXfiBnd? tram the beve ed? orners of; the-body o; the endiof thebodr formed by the; surfaces; 223 and; 23. The surfaces A; anal-1 B, occupyingthe. opposite sides of the: body: are conver n in: the; dir ction- .of thesurface I4 as;wi-1l:be evident-from} an inspee,

q ir l ar nqelza will be: more; fullyde scribed.

The, surfaces which; occupy the. sides of the odyb w n what I hav te med: th r ar surfiace ;3r nd the ,surfacesB, are empl edfwh n it: s des r d: t rin he ool If for; the c tin V'- hr ds- A h t z ustnated in; Fi oi he dr wi he n le et e n h se, corr sp nd;- ing; side; surfaces; A is 60. This. angle cornea pqn s Q he-desired:ans e between; the; munjd sidev u f e Q the bit: or t l. 0.: To rind: t s r ac th k s set on. the..- tab e,- tha n sur a e, b ns: 1.1 he tahleand the o Q ptese ted o; the wh el: W so that: th Wh el: rinds .1 .6; o the surf-at s: s; This Qperae tion i trat.edo t e: draw s: The bp dy II]: is then released; from the, table arrd'yis tum d ove s de forside an s: re-en a ed on the table; withits other surface A; bearing on the face o hegt h a. henrith too (3 is pn sent dto the-wheel: W the wheelg glii-ilds the other surace ,as;se.eni ,Fi @51-h I' nW 1' tbQ:aPDai I B h8$ th surfa 5 of he; bi r: opl; 0 o med; he; manner j stv d se bedbear he same re atian to one another, as; the surfaces A,; that i s-,;tl- 1e1;e is an angle; of 60 between them and they diverge downward-g or; toward theu nder side-1 of the tool-.3

'I he. sur ace B c upy the -s d s of he dy L0, between the surfaces A and the flo it I2- ot the q w h ur a es a e mp o ed w en it. is. deisred to. ind the bit rtool; (3 for'the; cutting of Acmethreads. The; a agle be weegi; the surf ce 13, s app ox a ely 29 s; i cle rlx o n m 3' Wh n thete lqis toe sha e to cut Acme threadsthe-lopgiy .IIr, arranged; on the table I sothat, onesurface B bears on the surface of the table -arid; thetool; C is; presentedto the wheelso that one sidesurf -acefli ground on-tl eltool; Thebotly- I this then released from, the table T andis turned/ over or turned:

sidefor side andis positioned spy-that its otl ierv sur e B bears 0.111 the tab .1 t eltoel G is. presented o thewheel W thewhe l g r-binds the other sidesurface 2fi. T lr 1e= two sidesurtf'aces 25 thus ground on the tool C bear the same ar gular relation as" the surfae esfi of. the body I 0 fiavmg ah angle of about 295 betweenthemand converging downwardly toward. thelower side of thetool. A

Wheri the bitor toolt C, isground to cut Acme threadsiit is provided with a. front suriace 26- for fo'rfnirig theroots of the tl'ireads. T l-iegsurface 216\occurs between theconvergin-g sidesurfaees-g and extends between the top-surface; 2 0 or 11: and the lower face oi the; tooL, accordance with the invention thebody I1} is forme dv to sup: port the-tool Con thetable'll to present it to the wheel W for the grinding of the surface 26; T0 QQ QQthe to l 0. for he: hdinaof the, face 25 the body I0 is arranged; on the table li as illustrated in Fig. 5 toha-ye whatI havetermed its rear face I 3- rest on the table. The surface l3, isiflat and regular toevenly bear on the face of the tableT. The rear body surface I3 is pitched: with respect to the longitudinal; axis of the toole t y e open n IIs. Accor n ly, hen, the:

sur ace this; en a ed: on the'table-T the tool: is p tched: 011' inc ined w th-respect to th r ndin w e l: Asa result; thewsurface 26 ar und o the top of the 1200110 i itched; with respect to the longitudinal axis of thetool; to have therequ reducleerancen Fi '5 of; the drawings: i ust tates t e manner inzwh ch: the er dine wheel W forms: the surtace A6 and clearly illustrates the cleara r qe; .QI; downward: and rearward; inclinat-itn: 0i 1 t'svurfacei It 'bleil fevedithat-thej use or oh ra iqnof: the fixture. illustrated in Figs; 1; to;7',.in.c1usive; of the drawin s: will be; readily nder tood f m the toregoi g detailed. description; It is to be noted that. here .isn ne es i y a adj s or h f ithe tzqqllqdu eth rinding perations. The tool Grfirm y fixed: inithefbcdy IO- nd remains-in. its: ori in .pcsitimr n; t e edyr thr hout the series erindine opera ions- It is o e p r icr' ularlynotecl that it is unnecessary-t0 adjust or shift the tool C to make eithep of the tep'gninds 21 r 21 as may be: e ect m and; h h tool: C d: 11:11 th samepos t th imply II st east-cum o: cut: it er Y'al -fitted?) or Acme threads 'Fhfi use f'theholdenon fix? mass es the ccur e z nfi n ofthe bit on eek -l an beca-use hereisnq need fur-manual r r ulation: of: ny parts the: snindr the; p ra iQnsaem er l y xpeditedand=them is nel chance? for. error-z v In producing or machining the :fix-mreof-Figa; o 7:; inelu w rt. pre er 0 fi st: orm. th op n I 5 lasqbyrbroachingr Anarbor orother supr ti -then en e inhe op ni g: I I-l 0 1 1 1 01 the: eer III? or; he: ther machining perations: Asaaresuit-ofp edur he v al; surfaces 0i the bodg may be; readiIymach-inedto: bear thecerr eet relationshigto, the. longitudinal axis; of thewogening; I-=I= and-are therefgre, correctly:- relatedl toathe; longitudinahaxis Qf: thethread, euteting; toolsthat: aneg later?- engaged in the opening Ill; tor the; grii ding operations.

Figs; 3 and? 9 of the drawings illustrate the; manner in which the fixture of Figs. 1 to; '7,; in--*- qlusiuebeutihzedY to grind a; thread-cutting; tool that, is to be; carried: bya tool holder;- su h' a -a Arm-s rung. l er, in whichitl ie; ool is. atan; angle when: miesentedte the: Work. The; i-r ver -rtian prouides a blocle 53') adaptedteesuppert tce 'fiimthe penme I k of the fixture. The black; d n dta moun th tool in: the; ope ing; I I at: an n lerw t -l tesp nt to h o er-- udinalaxi o th reening, w h n le; c rr spends t h ang leatwhichtthe;tockmamb ueb The; block 5% i n; elongate part having a: fiat; bottom; surface and: flat a-rallel v sides: The b m su f ceof the; block 50.; and. 2/, sid surface of the block: are ada ed: Q: enga e; with the bottom wall: and a welt; respective y; o the opening -lt'... The b eak; 59 is substantially -r haped in: transverse; m sr t h, h ting aalQn i dina-l: encore; OIIBPI ssan ph ome Th lower wall. 5; Qt hi rec s i at:- aniia is: pitched;- with respect to; he? lcne xudiznal laxisi If the block. The inclinatiomq th Wall;- 51 corre ponds. to: the n e; whieh the; tool is. to: be; ,suppforte in the tool; holder A venticalsideywall 52;1%ises:fromzthe intclinedrwal 5;:I nd: naralletwitn thaextemal; side surfaces of the: block 50.: The, recess; 01:

Fig; 8; illustrates the: manner in; which the: tool G s set in the: block: 5M9 he engaged imthe fix,

WEfiZWfiQiFi-Ez. 9;- showathehlonk:strand thetoot C;

clamped in the opening IIby one or both of the clamp screws I5. It will be seen that a clamp screw I5 may engage against the tool C to tightly secure both'the tool and the block 50 in the opening I I where the tool is held against the Walls" 5Iv and 52 to project from the side face l2 of the fixture. The tool C mounted in the openin g' II by the block 53 slopes .upwardly and outwardly when the body ID of the fixture has its surface 22 engaged on the table T. Fig. 9 shows the fixture arranged in this position with the tool C presented to the wheel W'for the grinding of the top surface 53 of the tool. The tool C mounted in the opening II by the block 50 is ground by carrying on the above described series of grinding operations to be shaped or formed for the cutting of the selected or required type of thread, it being understood that the tool and the block 50 remain engaged in the opening H and remain clamped in position throughout the se-. ries of grinding operations.

Figs. 10, ll and'12 illustrate the manner in which an offset thread-cutting tool C may be ground in the fixture." The invention includes a" block 60 for mounting the tool C in the fixture'opening II to be disposed at the required offset angle to the longitudinal axis of the opening II and the vertical plane of the fixture body I0, assuming the body to be in the position shown in Figs. 11 and 12'. The block 60 is like the above described block 50, having a fiat bottom surface for bearing on the bottom wall of the opening I I andhaving flat. parallel sides. One upper corner portion of the block 60 is cut away by a recess so that the block is substantially L-shaped in transverse cross section. This recess has a fiat bottom wall BI parallel with the bottom surface of the'block 60 and a side wall 62 that lies in a vertical plane but which is pitched with respect to the longitudinal axis of the block. The tool C is adapted to be engaged in the block 63 to have its lower side bear on the face 6| and to V cutter for righthand offsetting or lefthand offsetting, or grinding. The block 69 and the tool C are engaged in the opening I I in the relation il lustrated in Fig. 11 of the drawings and are clamped therein by one or' both of the screws I5 so that the tool projects from the forward face 12 of the body H1 at an angle to the longitudinal axis of the opening I I. in this manner the above-described series of grinding operations may be carried on to provide the tool with theoffset thread-cutting part.

Figs. 13 and 14 illustrate the manner in which a thread chaser III may be ground in the fixture of the invention. 'The invention provides a holder II for the thread chaser III. The holder II is an elongate block'proportioned to be readily entered into the opening II of the fixture. The holder H is sufiiciently long to project a substantial distance from the forward face I2 of the body I 0 and to rather accurately fit the opening II. The holder 'Il may be securely clamped in the opening II by the screws I5. Theforward por- With the tool C secured screw 14 is operable to actuate the jaws tion of the holder II is provided with' jaws I2; Thejaws I2 are formed by providing a longitudinal slot I3 in the forward portion of the holder. The forward part of the slot 13 is increased in width to receive the thread chaser stock. A clamp screw 14 passes through a transverse opening in one of the jaws I2 and is threaded into a similar opening in the other jaw. The I2 to tightly retain the thread chaser I0.

Fig. 14 illustrates the manner in which the thread chaser 10 may be secured in the holder II and carried by the fixture for the grinding operations. It will be observed that the holder II is secured in the opening I I so that the longiis then ground on the forward edge of. the'thread chaser'lfl; The body In is released from the table T and is turned side for side so that its other surface A is engaged on the table. The other active surface 15 is then ground on the thread chaser. It is believed that it will be apparent how the thread chaser 10 may be ground for use with either Acme or standard V-threads by successively engaging either the surfaces .A or the surfaces '3 of the body In with the table for the successive grinding operations.

The embodiment of the invention illustrated in Figs. 15 to 20 of the drawings includes a body 30. The'body 30 isa block-like member preferably formed of steel or other paramagnetic material so that it may be held on the magnetic table T of the grinder. The body 30 is an integral or one-piece member and is shaped to support the bits or threadcutting tools in various angular positions with respect to the grinding wheel W for the grinding operations. 1

An opening 3I extends through the body 30 from what I will term the front face 32 of the body to the rear face 33. The opening 3| is preferably square in transverse cross section and is sufficiently large to receive round or square bits.

or tools 0 ranging greatly in size. The means 'for securing the bits or tools C in the opening 3I comprises a set screw threaded in an opening 35 in the body 39. The opening'35 joins the opening 3I and the inner end of the screw 34 is engageable with the tool C to lock or clamp the same in the opening CH. The opening 35' is in diagonal relation to the polygonal opening 3| and joins the opening 3! at the line of joinder of two of its walls so that the screw 34 is adapted to cooperate with a corner of the cutter or tool C. Accordingly, the screw 34 is adapted to clamp the tool C against two walls of the body opening 3I. The bit or tool C is fixed in the opening 3| to project from the forward face 32 of the body 30 so that it may be engaged with the wheel W. The tool clamping screw 34 is inset or received entirely within theopening 35 so that it does not interfere with the engagement of the body 30 with the table T.

The body Ellis provided with two sets of external surfaces 3%: and 31 for engagement on the table T, one set of surfaces being employed when it is desired to grind the bit or tool C to cut one form of thread, say a standard V-thread, and

the other set of surfaces being employed when it is desired to grind the tool to 'cutanother form of thread, say an Acme thread; The surfaces 36 which are used :when'the tool '0 is to'b'e ground to cut standard, -V-threads constitute opposite side surfaces of the body 30. The surfaces 35 may occupy the entire sides of the body. The surfaces (ii-tare flat and smooth to evenly bear on the-face 'of the table T. best illustrated in :Fig. -16 of the drawings the angle "occurring between the two surfaces :36 is '60', .e'ach surface -35 being at 30 to the longitudinal axis of the opening 3L In "addition t0 the"60 angular relation just described the surfaces 36 are in convergent-relation to give theside surfaces X of the tool "0 the required downward convergence or clearance. Thus, assuming theb'ody -30 to be :in-thepositionillustiatdih Fig. 17 or the drawings; the surfaces 35 diverge sea-merrily or toward the'backgroun'd. I

To'g'rind the bit or-there "to cutv-tnreads the bit first provided with a hat upper surface. This surface --niay be ground-manually or in any other manner. The tool is then inserted i'n-the openin'ge l and clamped in place by the screw 34. The for war'd face 3'2 of-the body 30 is provided with-the notation br mark te and a line 38 extends to the "opening 3'] The ground upper face of the bit-or tool T is arranged'to face the mark or notation 60 and to'be nor'malto the line ea The r001 e is clampedih the body w e in thisr'elejtion'ship'and when projecting a suita'ble distance from the forward -face "32 of the body. The body "-30 is then arranged on the table T with one of its shffaces 3 6 bearing on the table T anathema 'ispresent'ed'tO the wheel W to have one e'f-the surfaces ground thereon; This -i'sill1istrated iii -Fig. 16 of-the fdi awings. When this-operationhas been completed the b0dy'30'is released 'frorn thetablegan'd is turned side for -'sid e so that the other surface .36 rests on the table With the magnetic tab le energizedthe tool '0 is presented to the grinding wheel W so that the other surface 'XiSQlQlllld 'on thecutter. 'eoiirletes the ,i'giin'ding of the cutter for the cutting of standard V-thre'ads.

Thesu r-facesfil are employed when the fixture is utilized-to grindthe 'too1 C for the cutting of heme threads. The surfaces31 areo'n opposite {sides of thebo'r ly tffl and may completely occupy two sides of the body; {The surfaces 31 are fiat and re'gjdla'rftojevenly bear on the face of the were TL The surfacjesjl arepitched with respect to thelongit'udinal axis r the opening 3| so that surfaces Ybea'riiig thcorrect angular 'rlas t'ion for the cutting of Acihe threads will be groundjoii'the opposite sides of the tool C. The surfaces?! arefdisposed 56 that thereis, an angle of about 29 between them and arevconvergent towardon'e of the sides 36 of the body 3'0." The zaianigular relation andthe cor'ivergence ofthe surfaces'vfl provide ioi the grindingof the surfaces Y on the tb'ol-C at.29 to one another with the required d'ovi n'wafd convergence or clear- .ahp'e- U ,When the toblCis to-be ground to out home threads it i's first provided with a ground. surface Z at its upperside adjacent its ;,active end. This initial grinding action may be manually pertermed, The tool C; is;arrangedin the opening 3'! to project frornthe Iorwardiace 32 of the body- 30 and is positioned so that its ground upper surface Z;f;aces;- a"notation or mark 929 formed on the forward ;f;ace;-:3;2 ofp-the body and so that the upper face is normal :to-a lin'e;39: extending --inwai'dly to the opening3-l WhenthetoolC has been positioned in this manner it is :secured (in place by the screw 34. The body 30 isthen ars d for de 9 ha ot e s rf c 5 1mm b a h able het l is th p e ente 2 the wheel'W so that its; other. surfaceY-is ground thereon;

l Y 32 S ape ottm d q n he to ol C pn -the table T for the grinding Of a 91.-

ward face v l llvon the ;too1 sothat the tool ,will b e operable to giyethe threads the desiredroot configuration, 'Thesrearfsurface 3 30f thebody 30 is pitched with resp'ectto the longitudinal axisof the opening BI and is adap ted to be ernpl qyed :to positionfthe body when theend surface 40 is to be ground more ItoolC. Impraetietne rear surface; 33' qr-the body 3b ni'ay,bepitched-at about 10 to the l ng itudinfilf xis of the opening 3l w en the forward face 40 isto befgroun'd 'Onthe tjo'olCthe rear surface 313 of the body isllenfglage d 0h th'effac 0f thetabl Taiidtheltool C i'sip'i'esente'd to the whee so that the surface In groan-g thereon. This is clearlyjillustrated in Fig. 20 o'f the drawings.

I-I Vi'h'g described only I typical preferred forms and applications of nvention, Ifdb no sh to be liinited "or restricted to the 's'p'ecificdetails herein set forth, but wish to l s' lfv .td "myself my variations. or modifications 'that ihay appear to thosfe skilled the art bi fall Within thetlscope of the following claims. I I v Having described i'ny invention, I claim:

1. A flxture forts1 11: 1; ort'in,g atool on the table of a grinder-having} wheel, the fixture dinga unitary body having an opening ,for re 'ceiving the tool so it projects ffrorn the'forwar'd end of the body, and means carried by the body to engage and clamp the tool the opening, the body having two afijomingbmtom urf ces on its undersi'daohe bottom surface occupying a pla iie parallel with the longitudinal axis of the tool engaged in said opening so that it may be engaged err-the table to'have the wheeljgrind asuiface on thet'op of'the tool which-lies ina plane parallel with said aziis of the tool; the other bottom surface of the body occupying a plane inclined with respect mosaic axis of the tool to extend upward and forward from the first mentioned surface so that it may be enaged on the table to have-the wheel grind a surfaceon the=t0p of thetool which team a plane pitched rearwardly and downwardly relative to saidaxis of the tool;

42. A fixture for supporting a tool on theta'ble of "a grinder having i. awheel, the fixture including albodyhaving a forward end and an openirig extending into it .from its forward end for holdingthe'tool so it -projects from the-forward end of the body, andmeans forrsecuring-the tool in said opening sothatthe longitudinal axis of tht'ool is parallel with the longitudinal axisof the opening, two oppos'itetsides of--the:body each being-provided with two surfaces ;for vsupporting the b'ody whilelia tool is" being ground at the end projecting fro'm the forward end of the-body, one. surface of each of said sides :being pitched withlrespect to said axis of the opening so that itim'ay belenga'ged on the table to have said wheel grind a surface on a side of the tool hav ing a given pitch, the other surface of each of said sides of the body being pitched with re- "spect to said axis of the opening to have said wheel grind a surface on aside of the tool having a pitch different from said given pitch.

3. A fixture for supporting a tool on the table of a grinder having a wheel, the fixture includforward end of the body, two opposite sides of the'bo'dy each being provided with two surfaces each for supporting the body with the tool projecting from its forwardend presented to the wheel, said'surfaces being in directly opposite sets, one set of surfaces having an angle of about 60 between them, the other set of surfaces having an angle of about 29 between them.

4; A fixture for supporting a tool on the table of a grinder having a wheel, the fixture including a body having a forward end and an opening for receiving the tool, and means for securing the tool in said opening so that the tool projects from the forward end of the body and so that the longitudinal axis of the tool is parallel with the longitudinal axis of the opening, the under side of the body having a surface adapted to be engaged on 'the' table and disposed in parallel relation to said axis of the opening so that the wheel may grind a top surface on the tool parallel with its longitudinal axis, the under side of the body further having a surface adapted to be engaged on the table and pitched downwardly and rearwardly relative to said axis on the end of the tool projecting from the forcorrespondingly pitched surface on the top of the tool, the opposite sides of the body each having two surfaces 'angularly related to said axis of the opening and adapted. to be successively engaged with the table so that said wheel may grind forwardly convergent side surfaces on'the .end of the 'tool projecting from the forward end of the body, the rear side of the body having a surface disposed at a non-normal angle to said axis of the opening and adapted to be engaged with the table so that said wheel may grind a correspondingly disposed surface on the forward edge of the tool. 7

5. A fixture for supporting a tool on the table of agrinder having a wheel, the fixture including a body having a forward end and an opening for receiving the tool, and means for securing the tool in said opening so it projects from 'the forward end of the body and so that-the longitudinal axis of the tool is parallel with the longitudinal axis of the opening, two opposite sides of the body bearing an angular relation to said axis of the opening and adapted to be successively ,engagedon the table so that said wheel may grind forwardly convergent side surfaces on the end of the tool projecting from said forward end of the body, said sides being disposed at an angle of 60 to one another, and two other opposite sides of the body substantially equal in area to those first'mentioned and bearing an angular relation to saidaxis of the opening and adapted to be successively engaged on the table'so that said wheel may grind forwardly convergent side surfaces on the tool, the

last named sides being disposed'at an angle of 29 to one another.

' 6. A fixture for supporting a tool on the table of agrinder having a wheel, the fixture including a body having an openingv for receiving the tool, means supporting the tool and insertable in the openingfor mounting the tool in thefopening so thatthe longitudinal axis of the tool'is vertically pitched with respect to the longitudinal axis of the opening, and means for releasably securing the 'tool in the opening and on'the first mentioned means, two opposite sides of the body each being symmetrical relative to the opening and each provided with two surfaces, one surface of each side being pitched with respect to said axis of the opening so it may be engaged on the table to have said wheelgrind a surface, on a side of the tool having a given pitch, the other surface of each of said sides of the body being pitched with respect to said axis of the opening to have said wheel grind a surface on a side of the tool havin a pitch difierent from said given pitch.

7. A fixture for supporting a tool on the table of a grinder having a wheel, the fixture including a body having an opening for receiving the tool, means supporting the tool and insertable in the opening for mounting the tool in the opening so that the longitudinal axis of the tool is pitched laterally withrespect to the longitudinal axis of the opening, and means for releasably clamping the tool on the first mentioned means in the opening, two opposite sides of the body each being provided with two surfaces, one surface of each side being pitched with respect to said axis of the opening so it may be engaged on the table to have said wheel grind a surface on a side of the tool having a given pitch, the other surface of each of said sides of the body being pitched with respect to said axis of the opening to have said'wheel grinda surface on a side of the tool having a pitch different from said given pitch.

8. A fixture for supporting a tool on the table of a grinder having a wheel, the fixture including a body having an opening for receiving the tool, a supporting block for mounting the tool in the opening so that the longitudinal axis of the tool is vertically pitched with respect to the longitudinal axis of the opening including a block for engagement in said opening having a pitched surface against which the tool bears, and a set screw carried by the body to engage the tool to clamp it on the block in the opening, two opposite sides of the body each being provided with two surfaces, one surface of each side being pitched with respect to said axis .ofthe opening so it may be engaged on the table to have said wheel grind a surface on a side of the tool having a given pitch, the. other surface of each of said sides of the body bein pitched with respect to said axis of the opening to have said wheel grind a surface on a side of the tool having a pitch different from said given pitch.

9. A fixture for supporting a tool on the table of a grinder having a wheel, the fixture including a body having an opening for receiving the tool, means supporting thetool and insertable in the opening for mounting the tool in the opening so that the longitudinal axis of the tool is vertically pitched with respect to the longitudinal axis of the opening including a block adapted to be arranged in said opening and having avertically pitched surface against which the tool bears, and a set screw carried by the'body for clamping against the tool to hold it on the block in the opening, two opposite sides of the body each being provided with two surfaces, one surface of each being pitched with respect to said axis of the opening so it may be engaged on the table to have said wheel grind a surface on a side of the tool having a given pitch, the other surface of each of said sides of the body being pitched with respect to said axis of the opening to have said wheel grind a surface on a side of the tool having a pitch different from said given pitch.

10. A fixture for supporting a tool on the table of a grinder having a wheel, the fixture including carried by the body to directly engage the tool and clamp it between adjacent sides of the opening, the under side of the body having a surface adapted to be engaged on the table and disposed in parallel relation to said axis of the opening so that the wheel may grind a top surface on the tool parallel with its longitudinal axis, the

projecting from said forward end of the body,

the rear side of the body having a surface dispcsedat a non-normal angle to said axis of the openin and adapted to be engaged with the table so that said wheel may grind a correspondingly disposed surface on the forward edge of the tool.

11. A fixture for supporting a tool on the table of a grinder having a wheel, the fixture including 1 a unitary body having a forward end and an opening with angularly related surfaces for receiving the tool, and means for securing the tool in said opening in direct bearing engagement with said surfaces so that the longitudinal axis of the tool is parallel with the longitudinal axis of the opening and so the tool projects from the forward end of the body, two opposite sides of the body each having a surface to be engaged on the table to support the body with the tool projecting from its forward end presented to the wheel, said surfaces being disposed at substantially 60 to one another so that upon being successively engaged with the table the sides of the tool may be ground by said wheel to have surfaces separated by about 60, each of said sides of the body having a second disposed about 29 to one another so that upon being successively engaged with the table the sides of the tool may be ground by said wheel to have side surfaces separated by about 29.

12. A fixture for supporting a tool on the table of a grinder having a wheel, the fixture including a body in the form of a unitary block of magnetic material having a forward end and an opening substantially square in cross section for receiving the tool, and a set screw carried by the body to directly engage the tool for securing the tool in said opening so that the tool bears against two adjacent sides of the opening and projects from the forward end of the body and so that the longitudinal axis of the tool is parallel with the longitudinal axis of the opening, the under side of the body having a surface bearing a given angular relation to said axis of said opening and adapted to be engaged on the table so that said wheel grinds a surface on the top of the tool bearing the same angular relation to its longitudinal axis, the opposite sides of the body each having two surfaces angularly related to said axis of,

the opening and adapted to be successively engaged with the table so that said wheel may grind forwardly convergent side surfaces on the end of the tool projecting from the forward end of the body, the rear side of the body having a surface disposed at a non-normal angle to said axis of the opening and adapted to be engaged with the table so that said wheel may grind a correspondingly disposed surface on the forward edge of the tool.

- 13. A fixture for supporting a tool on the table of a grinder having a wheel, the fixture including a unitary body in the form of a block of magnetic material having a forward end and an opening with adjacent sides disposed in a definite relation to other parts of the body and for receiving the tool, and means for securing the tool in said opening in bearing engagement with said sides of the opening so that the tool projects from the forward end of the body and so that the longitudinal axis of the tool is parallel with the longitudinal axis of the opening, the opposite sides of the body having surfaces angularly related to said axis of the opening and adapted to be successively engaged with the table so that said wheel may grind forwardlyconvergent side surfaces on the end of the tool projecting from the forward end of the body, each of said sides of the body having two of said surfaces bearin different angular relations to said axis of said opening so that the angular relation of said convergent side surfaces of the tool may bear different angular relations, the rear side of the body having a surface disposed at a non-normal angle to said axis of the opening and adapted to be engaged with the table so that said wheel may grind a correspondingly disposed surface on the forward edge of the tool.

HARRY 0. WILSON.

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