US2034072A

US2034072A - Core drill

Info

Publication number: US2034072A
Application number: US689897A
Authority: US
Inventors: Jesse C Wright
Original assignee: Globe Oil Tools Co
Current assignee: Globe Oil Tools Co
Priority date: 1933-09-18
Filing date: 1933-09-18
Publication date: 1936-03-17
Anticipated expiration: 1953-03-17

Description

' March u, wop. rc, WRIGHT CORE DRILL Filed Sept. 18, 1933 2 Sheets-Sheet 1 Patented` ar. 517, 1936 .consumo Jesse C.Wrlght,'I`nsfAngcle`s,Calif., asslgnorto Globe Oil Tools Company, Nietos. Calif eornvrstionofClilvmi y This invention relates to swell and relates more particularly to a wellcoredrlll or core receivmg drilling tool. Itis aigeeral object o: the present -invention to provide-a simple.l practical tive in obtaining recovering-,maior hard, toulrearth formations. f

In drilling through certain earth i formations` with a core drill or corerecelving drilli'n'gtool.l

l0. the cores obtained are veryhardand'tough and' have great tensile strength. Thecore drills that-f,

'have been introduced are usually provided with a core catcher for gripping the core when the drill is raised to break theV core loose from the f la formation and thereafter retainithe core inthe drill as it is withdrawn from the well. When-a hard core is obtalned, the typical core catcher ls not capable of properly gripping the core and' lts core engaging parts are not suillciently strong.

to resist the great strains necessary to break thecore loose from the formation, and `as no other i@ Other objects and features of the invention will provision is made .to free the core from the formation, it remains in the well and the drill mustl be removed from the well without or I obtaining a core. It is an obie'ct of the inventionl to provide acore' drill or core receiving drilling Vtoolthat 'is oper-,L

able to automatically breakthecore free from the formation upon the core'obtalning a suitable length so that the core catcher is not required to perform the core breaking function.l

f n is another object of the. invention .to'provlce a core drill that is operable to break the core free from the formation when the'core has attained a suitablelength andto successively'break sec- Q,`

tions or lengths of core free from the formation f as the drill advances so that the drillis adapted to obtain or recover E' plurality of lengthsof core of suchlengthithat they may be Vconveniently and 40 safely removedy from the drill atthesurface of the ground.

small pieces or fragments.

a core drill having avsimple and eifective means for automatically breaking tlie'core loose from the `formation that 1 not, affect or i interfere with A the 4proper functibning ofthe otherparts of the It is another 'object of ,the invention to'provide a means foi-.breaking a core free'from the-earth formation that may beembodied in various forms ofgcore drills and corefreceivlng drilling tools with but slight inexpensive additions "or modificanung e l 5 core receiving welltoolthat is particularly eifec-j Itis a'furtherobiectiofitherinvention -topro- 6 -vldea `c :oredrlll that is operable to drill fa straight vertical bore andtha't is operable lto automatically break "a `core-v` of'sbstantial length free from the vv:fi'lrlation .by'imposing a lateral strain `on its upper vend. causing its lowerend to break loose lo lfrom theformation.4

- 'is a further biect of the invention-to provide La core drill orcore receiving drilling tool having ank internal `projection for engaging the upper end portion of a core to impose a lateral strain on `1'5 the-curato itsy lowerend vfree from the formation andfhaving external partsfor centering-the drill inthe'well bore and for guiding the drill to make a'straight vertical bore so that the engagement of the said internal projection with 20 the coredoes notl cause thedrill tomake an inbestand more fully understood from the following detailed vdescription of typical forms and 25 appllcationsoi the invention. throughout which description reference is made to the accompanyingdrawings, in which:` f

.-in operation in a well bore. Fig. 2 is an enlarged transverse detailed sectional view taken as yindilarged fragmentary 'elevation of a portion of the body luustraungone of. the bearing 'parte v'and as.

invention illustrating it in'operationin a.y

well bore, and Fig. 5 is a transverse detailed secl 1 itional yvlewtaken as indicated bylineH on 40 v r... .riig-,llg f l i It is another object of theinventlon to provide a core drill that is operable to automaticallybreak` f the core from the -formationas the drilling 'cone-r' 45 tinues to obtain a'plurality of sections voficore"y of suitable length without the core intor The features vof thepresent-inventionare fea? I pable of embodiment in coredrills and core ref celvlng drilling tools pf various types andchar-frv f Masters. Throughout the following'detailedfjdis-y all .closure I'wlll describe the inventlon 'embodled in v v l two single barreledcore drill'sorcore'reivingg.

It is another object of the'inventiontoprovide drilling tools, it being understood that the lnven forms or applicationsabout to be described; but is to be'` taken as including features or modif fications lthat may fall within the scope vof The form of the invention illustrated in Figs. 2 and 3 of the drawings includes, generally, a tubular body I0, a pilot cutter II operable to make an annular cut in the earth formation and form a central core C, a reaming or bore enlarging cutter I2 on the body I0, guiding parts or bearing parts I3 on the body for guiding the drill, and means I4 for breaking the core C free from the earth formation upon the core obtainlng a substantial length. i g

The body I is an elongate tubular structure connected with the lower end of a barrel I5. The barrel I5 is lower end of an operating string of drill pipe, or the like, and is provided to receive or hold the core C. In the particular construction illustrated, the body I0 includes two threaded connecting members or subs, an upper sub I8 threaded on to the lower endlof the barrel I5 and a lower sub I'I having a downwardly projecting screw threaded pin I8 on its lower end. A tubular or annular shoe I9 is threaded on the pin I8 and constitutes the body of the reaming cutter I2 as will be subsequently described. In the form of the invention being described, the body I0-in cludes an elongate lower section extending downwardly from the shoe I9. The lower section,20 is preferably of considerable length and its core receiving opening 2| is of substantially the same diameter as the opening through the subs I6 and I1. Thelower section 20 is of smaller external diameter than the subs I 6 and I1, and the shoe I9, so that it may freely pass into the comparatively narrow annular channel or cut A made by the pilot cutter I I. In accordance with the broader aspects of thek invention, the lower section 20 maybe connected with the shoe I9 in any suitable or practical manner. In the particular case illustrated in the drawings, the section 20 is welded to the shoe I9 as at 22.

The pilot cutter I I is provided on the lower end the lower body section 20 and is operableI to make the comparatively narrow annular cut A. The pilot cutter II operates far in advance of the reaming cutter I2 so that the comparatively narrow annular cut A is of considerable vertical extent. The pilot cutter II includes a tubular body orshoe 23 threadedly connected with the lower end portion of the section 2U. circumferentially spaced cutting blades 24 project downwardly and outwardly from the shoe 23. The cutting blades 24 operate to make the vannular cut A sufficiently wide to freely or safely receive the body section 20 and project inwardly at the lower end of the drill to cut the core C to pass into the opening 2| with suitable clearance. The reaming or boreenlargingcutter I2 includesthe shoe I9 at the upper end of the body section 20. A plurality of. circumferentially spaced cutting blades 25 is provided on the shoe I9. The blades 25 project outwardly and downwardly from the shoe I9 and are proportioned and formed to enlarge the well bore to a considerable extent so as to safelypass the body subs I6 and I'I andthe barrel I5. "I'he cutting blades 25 are of considerable vertical length to have engagement with the wall ofthe well bore for a considerable distance to effectively guide and stabilize the drill. The lower outer corners loi the blades 25 may be bevelled in the manner illustrated. The outer edges and the lower edges of the blades 25 maybe suitably sharpened. VIt will be apparent how the reaming cutter I2 is operable to materially enlarge the well bore and to effectively stabilize the drill.

adapted to be connected with the" `The upwardly flowing circulation fluid s cutter .I2 as yit passes from the In the rotary method of well drilling, rotary mud or circulation iluid isjpumped downwardly through the drilling string -to discharge from the drill into the lower end of the well. In the form of the invention being described, the circulation uid passes downwardly through the barrel I5 and through the body III to discharge from the pilot cutter II at the lower end of the comparatively narrow annularv cut A. This discharging circulation fluid effectively flushes the blades 24 of the pilot cutter and flows upwardly between the section 20 and the outer wall of the cut A to prevent the pilot cutter and section 20 from sticking or from becoming sanded in the bore. i

operates of the reaming cut A into the main bore of the well. The circulation fluid, in iiowing downwardly through the body I0, washes around the core C and prevents the core from being sanded in the drill. v

- The drilling tool includes a core catcher to support and retain the core C in the drill when towash and flush the blades 25 l the tool is removed from the well. In accordance with the broader principles of the invention, any suitable form of corecatcher may be embodied in the tool.` Further, the core catcher may be arranged or carried in eitherthe shoe 23 of the pilot cutter orl in the lower section 20 of the body I0. In the particular structure illustrated in the drawings, the core catcher is carried by the shoe 23 of the pilot cutter. An annular re cess or groove 26 is provided in the internal wall of the shoe 23 to carrythe body' 21 of the core catcher. 'Ihe particular core catcher shown in the drawings includes a plurality of core `/engaging and supporting dogs 28 pivotally attached to the body 2l. The dogs-28 have sharpened inner ends for biting into the core and are yieldingly urged inwardly and downwardly by springs in the well known manner. As the core C advances into the shoe 23,the dogs 28 are retracted or pivoted upwardly and outwardly to the positions illustrated in Fig. l of the drawings where they do not interfere with the free passage of the core into the tool.

'I'he bearing parts or vided on the exterior guiding parts I3 are proof the lower body section 20 and are adapted to engage the lower wall of the annular out A to stabilize the drill' and to center the drill to make a straight. vertical bore. The bearing parts I3 are operablel to closely or accurately guide the lower body section 20 and thev pilot cutter II, and in accordance with the inventionare adapted to wear away as the cutting blades 24 become reduced in size through wear so that they have no tendency t'o jam or stick in the bore. In accordancev with the broader principles of` the invention, the bearing parts I3 maybe vvaried considerably in construction and their mode of connection with the section 20. In the drawings, I have shown one type `of bearing part'r'nounted on the exterior -of the body section 20, the-bearing parts and mountin'gs being fullyy described and claimed in my copending application filed on an even'date herewith andfentitled Well drill, Serial'No. 689',- 896, filed September 18, 1933.

There is preferably a plurality of circumferentially spaced bearing parts I3 provided on the exterior of the body section 20. parts I3 are preferably spaced a considerable distance above-the pilot cutter II and the location of the parts I3 is definitely related to the position of the core breaking part I4 as will herevings 35 in the inner Walls of the sockets 3 I Asockets3| extend into. the enlargements from their lower ends.V The sockets 3| have comparatively wide open outer sides and closed upper ends. The longitudinal or-fvertica1 side walls of the sockets 3| are under-cut or provided with longitudinal grooves '32. v

The guidingparts or bearing parts I3 are carried in the sockets 3| and project from the outer surfaces of the enlargements 30 to engage'the `outer wall of the annular cut A. A The parts I3 are in the nature of blocks of .piecesof relatively soft material removably-held in thesockets 3|. In practice. the bearing parts I3 may be formed -of bronze or a likerelatively soft material. The

bearing parts. I3 are shaped andproportioned so as to be slid or passed into the lower ends of the sockets '3|. Tongues 33 are provided on the longitudinal edges or sidesof the bearing parts .I3 to iit 'the' grooves 32.` When positioned in Vthe sockets 3 I, the upper-endsof the bearing parts AI3 bear upwardly against the upper. walls of -the sockets.' Screws34 are threaded through openings in the bearing parts I3 and extend into Vopen- The heads36 of the screws 34 are preferably countersunk in the outer `faces of the bearing parts I3. The screws 31%` react against the inner walls of the openings .35' to clamp the bearing'parts I3 outwardly so-that their tongues 33 are tightly forced against Vthe walls of the grooves 32 kand thus securely' clamp the bearing partsfin the sockets 3|. .It will -be apparent how the bearing parts I3, in engaging the outer wall of the cut A effectively center and guide the drill without in any way interfering with the free upward flow of the circulation fluid. l The. bearing parts I3; in being comparatively soft, wear away as the cutting blades 24 become reduced. in effective cutting diameter through wearso that they do not cause the drill to stick or bind in thewell and so that they are effective in guiding the drill after the blades have been materially reduced in size. 'I'he bearing parts I3 are inexpensive and are easily replaced. v

The means I4 for breaking the core C free or loose from the formation is operable to automatically break the lower end of the core C loose from the earthformation when the entering core has attained a considerable length and tothereafter successively break free portions of core of substantially equal.length as the drilling proceeds. It is a feature ofthe present invention that the means I4 is particularly simple and inexpensive and does not necessitate anycomplication ofthe drill structure. *The means I4 includesor provides a core engaging projection 38 lon .the interiorof the body I0. The projection` 38i`is provided to engage `the upper end `portion of the core C when the drill has penetrated` the formation for a certain distance to impose a lateral or substantially horizontal force on the core and .thus break its lower endfree from the earth formation. The core lengagingprojection 38 is preferably located onrthe interior ofthe body' III in the vicinity or .neighborhood of the bearing parts I3. `In the case illustrated in the drawings, the core engaging projection l38j is located'in the horizontal plane of the series'of `bearing parts I3 and is in substantially radial alignment vwith one of the bearinguparts. Due to this relation between the "projection 38 Yand the bearing parts I3, the engagement of the bearing part'y with 4the core C does not place .any vf Vundesirable strains; on .the drill andl doesnot cause'the drill to take any inclined course. .It will be obviousthat the bearing parts I3 brace the lbody section 20 vagainst the lateral thrusts caused by engagement of .the projection V.vvitlithe core C Vand transmit these forcesrdire'ctly to the-wall of ,the bore or cut A.A The core engaging.projection- 38 maybe integral with the 1body section. 20 as illustrated in the drawings.:4 In 'the preferred construction, the fprojection s38 has la gradually .rounded or convexedsurface so that .it does not score` orvcut linto the core C to an appreciable y sextent.' Furthenthe roundedexterior orsurface of the projection 38 allowstheprojection to slide-past-the freed sections or portions of the core C as thedrilling progresses without fracturing or destroying the-core. In accordance withftheinvention, the projection 38 is of substantial width or thickness to positively and actively engage. the` core'to force .the core horizontally away from it toward the other vside 4of 'the body and thus breakitslower end free vfrom theearth formation. -In practice, thethickness of the projection 38 is greater thanxone-h'alf `of the total yclearance between 'the core C and the Wall of the opening 2| but itsthickne'ssrdoes'not equal'thetotal clearancebetween the coreand thewall ofithe openingssoithatthecore may be" lthe earth-formation, without being crushed.

' It is believed that the operation vof thel em- I.

lbodiment 'of the invention illustratedin Figs. 1

to 3 inclusive of the drawings will be rgadily apparentfrom theforegoing detailed description.

- -During :operatiom` the drill -is rotated Ain :the usual manner yso that the 'pilot cutter II makes .the comparatively. narrow annular cut A inthe formation and provides the core C. The

reaming cutter I2 enlarges'the.boreto'provide .forV the safe passage of the barrel through the bore, and in being spaced a substantial distance abovethe pilot cutter II, stabilizes the drill 'during operation.` The-,core C is freely received in the opening 2| of the body andis washedfree of. sand etc., by the circulationk fluid passing downwardly throughthe body. After the drill has advanceda considerable'distance and the core Chas attained a'suflicientv 1ength,the projection 38 comes into engagement withthe upper endportion of the core. The rounded? or curved surface of the projectionI 38 lslides downwardly on the upper end portion" of the-core until the engagement of the projection-138.with the-core C puts .aheavy lateral pressure on the upper end portion of the core which,l c'ausesethelower end of the core .to break free fromme-formation somewhat# 'in the manner v.illustrated f in Fig. 1 of the drawings. The-freed portiony of the core C is supported on the stump. or remainingy stationary base of .thecore and is forced over against Vthe opposite walll of the opening 3| by the projection 38. As the drilling continues, the pro`1 jection 38 passes downwardly past the-broken or freed section of thecore C untilit comesinto ensections of core of a length that renders them safe and convenient to handle when being` re moved from the drill at the surface of the ground. The proportioning of the projection 38 issuchthat ythe projection does not mutilate or fracture the freed pieces Vof core as the drilling progresses and does not cause the pieces ofr core to` become jammed in .the drill. The bearing parts I3; in being located inthe vicinity of the projection 38 effectively center and guide the body section 20 so that the drill continues to bore a straight vertical hole. The. bearing parts I3. in being formed of a relatively soft'material, wear away as thecutting blades 24 become reduced in width through wear. sowthat rthey continue to function effectively without causing thedrill to stick or jam in the bor-e. The drill in being provided withfthe' two cutters II and I2 at vertically spaced pointsr and in having the bearing projections I3 spaced be- .tween the cutters is stabilized during operation,

and operates -to drill a straight vertical bore. When it is desired to remove the drill and core from the well, the drill is raised so that the dogs 28 of the core catcher come into engagement vwith the lower end of the lowermost freed section of core. The dogs 28 in engagingunder the lower end of the lowermost piece of core, operate to support the -plurality of stacked or super-imposed sections of Acore and retain them in the drill as the drill is lpulledfrom the well.A

The embodiment of the invention illustrated inFigs. 4 and 5 of the drawings includes, generally, a body 48, a Acutter head 4I on the lower end of the bodyformaking an annular cut in the earth formation, core catching means 42 on the body, bearing parts 43 on the body 48 for guiding the drill, and means 44'for automatically' breaking the core X free from the earth formation.

'I'he'body 40 is an elongate sectional structure connected with or forming avv part of the core receiving barrel 45. 'I'he barrel 45 is adapted to be connected with the lower end of an operating string in the usual manner. The body 40 inthe earth formation. Inl accordance with they broader principles of the invention, any form of cutting'parts may be provided on the cutter head 4I. The particular cutter head 4I illustrated in the drawings includes a body or shoe 48 attached to .theA lower end of the sub 41, and circumferventially spaced cutting blades 49 on the shoe.

The blades 49 project downwardly andA outwardly from the shoe 48 and are operable to' make the annular cut-Y which passes the body*v 48 with suitable clearance. The blades 43 .project inwardly at the lower end of the tubular shoe 48 to cut a core X which is received in the body 4I) with substantial clearance. 1

The'core catching means 42 is provided to support or retain the sections of core in the drill when the .drill is removed from lthe well. In practice, any suitable type of core catching vdevice may be embodied in theA drill structure. In the particular case illustrated in the drawings, the core catching or retaining means 42 includes -circun'lferentially 'spaced pairs of pivoted core supporting dogs 58. vertically-elongatedy blocks 5I are heldin slots 52 'in the vwallof the sub 41 to carry the dogs 50; vThe dogs 501 are pivoted in recesses 53 in the inner sides of the blocks 5I and are adapted'tozproject into the core receiving opening of Ithe body. The dogs 501'are spaced one Labove the other, and are yieldingly urged to :pivot downwardly and inwardly into the body opening by springs in the-usual manner. The lower dog 50 ofeach pair is preferably coml paratively long so as to eiectively engage undersized cores or cores of reduced diameter while A 'I'he guiding partsor bearing parts 43 are provided on the exterior'of the body 48 to engage the wall ofthe bore Y to -center` the drill and t0 stabilize. the drill; Further, thebearingpartsl 43 operate to preventthe engagement of the core breaking projection with the .core-fromy deflecting the drill fromits'vertical course. The bearing parts 43 may be similar to the'bearing'parts I3 J Projecting bosses or enlarge- -ments 54 are provided .on the exterionof the coupling member 46 andfhave vertical sockets described' above.

55 for'carryingA the bearingparts 43.v The sockets 55 have comparatively wide open outer sides and extend. upwardly into the. enlargement 54 `from Atheir lower ends to allow for the easy. insertion lof the parts y43. Longitudinal grooves 56 are provided inthe side walls of the sockets 55 to re ceive tongues 51 on the vparts 43. Screws. 58 are v threaded through openings in the parts 43 to react fagainst the inner ends'of openings 59 in the inner walls of the sockets to clamp the tongues4 circumferentially spacedbearing `parts 43. In

the particular case illustrated in the drawings there are three equally spaced bearing parts 43.

The means 44 for breaking the core X free from the formation is operable. through engagement with the upper end of a comparatively long piece of'core to impose a heavy lateral strain on it. and thus break its lower end free from the earthformation. 'I'he means 4.4 includes or provides an internal projection 68 on the coupling member 45.. Theprojection 6I! is provided on the wall of thelcore passing opening 6I ofthe coupling member 46 andis preferably located `In the vicinity of the bearingparts 43..; In the preferred arrangement illustratedv in. the vdrawings the projection is locatedin the plane ofthe plurality of bearing parts 43 and is radially inward of-oneoftheparts43. j i

In being located on thecoupling member 44 .the core engaging projection 60 is spaced a considerable distance above the cutter head 4I so that it is operable to break free sections of -core of substantial lengths.` 'I'he core engagingsurface ofthe projection 50 is smooth and gradually rounded so-thatthe projection does not bite-into or destroy the core. In accordance. with thev in' 4the upper ldogs 50 are.. comparatively short to vengage under and support'large or full sized cores. #When the core 'X enters the drill the dogs 56 arepivoted upwardly andoutwardly to retracted positions where they do not interfere. with the reception-of ythe core by the body.

toy

vention, the projection 60 is proportioned so as to positively engage the upper end portion of a core with considerable force to break it away from the formation, but is not'sufliciently thick to cause the freed piece of core to become lodged or wedged between it and the opposite wall of the opening E l The core engaging projection 60 may be integral with the coupling member 46 as illustrated in the drawings.

The operation of the form of the invention lllustrated in Figs. 4 and 5 of the drawings is substantially the same as the operation of the previously described embodiment. During the drilling operation, the blades 49 make the annular cut Y to pass the body 40 with the suitable clearance and cut the core X which is received by the body. The rotary mud or circulation fluid is passed downwardly through the body 40 under pressure, and washes sand or loose material from the core and then discharges from the lower end of the cutter head 4l to Wash the blades 49 and provide a turbulence in the lower end of the well bore. As the bearing parts 43 are spaced considerable distances apart, they do not interfere with the upward flow of circulation fluid around the body 40. When the core X attains a considerable length, the projection 60 comes into engagement with its upper end portion. The projection 60, in having a gradually aring or rounded exterior, slides downwardly over the upper edge of the core X so that its inner side or top comes into pressural engagement with the periphery of the core to put a heavy lateral strain on the upper end of the core. This strain or pressure breaks the lower end of the core free from the earth formation. The freed piece of core is supported on the xed stub or base of the core and is received in the barrel 40 as the drilling con.- tinues. 'Ihe projection 60 functions to automatically break the sections of core free from the formation when they attain a suitable length as the drilling continues so that the drill may receive a plurality of pieces of core of substantially uniform length. These pieces of core may be safely and conveniently handled when they are removed from the drill at the surface of the ground. The bearing parts 43 effectively centralizje the body 40 in the bore and prevent the engagement of the projection 60 with the core X from causing the drill to take an inclined course. parts 43 and the projection 60 are provided on the sub or coupling member 46, their embodiment or inclusion in the tool does not in any way complicate or involve the construction.

Having described only typical forms and applications of my invention, I do not wish to be limited or restricted to the specific forms or applications herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art or fall within the scope of the following claims.

Having described my invention, I claim:

1. In a core receiving well drilling tool, a body As the bearing having a longitudinal opening, cutting parts at the lower end of the body for making an annular cut in the formation and leaving a core for reception by the body opening, a core catcher in the body opening, a projection on the wall of the body opening spaced above the core catcher to engage the upper portion of the core and impose a lateral strain on the core to break its lower portion from the formation, and an external projection on the body directly backing up the first named projection by engaging the wall of the well to support the body against lateral pressures.

2. In a core receiving well drilling tool a body having a longitudinal opening, cutting parts at the lower end of the body for making an annular cut in the formation and leaving a core for reception by the body opening, a blunt projection on the wall of the body opening spaced between the opposite ends of the opening and operable to engage the upper portion of the core to put a lateral pressure on the core and break its lower portion from the formation, an external projection on the body operable to engage the wall of the well to directly back up the first named projection and hold the body against lateral displacement, and a core catcher on the wall of the opening below the projections to retain the freed portion of the core and other such portions of the core that may be stacked in the opening.

3. A core drill including a barrel, cutting means on the lower end of the barrel operable to make an annular cut and leave a core for reception in the barrel, a projection on the .interior of the barrel above said means for engaging the ccre to break it free from the formation, and a projection on the exterior of the barrel directly backing up the rst named projection by bearing on the wall of said cut to support the barrel against lateral forces.

4. A core drill including a barrel, cutting means on the lower end of the barrel operable to make an annular cut and leave a core for reception in the barrel, cutting parts on the barrel spaced above said means for enlarging said cut, a projection on the interior of the barrel above said means for engaging the core to break it free from the formation, and a projection on the exterior of the barrel directly backing up the rst named projection by bearing on the wall of said cut to support the barrel against lateral forces.

5. A core drill including a barrel, cutting means on the lower end of the barrel operable to make an annular cut and leave a core for reception in the barrel, a projection on the interior of the barrel above said means for engaging the core to break it free from the formation, core catching means in the barrel for retaining the core, cutting parts on the barrel above its lower end for er1- larging said cut, and a projection on the exterior of the barrel directly backing up the rst named projection by bearing on the wall of said cut to support the barrel against lateral forces.

JESSE C. WRIGHT.