US 2664586 A
Description (OCR text may contain errors)
Jan. 1954 w. c. E. PRINS ET AL ROTARY SCRAPER, ABRADING, OR POLISHING TOOL 2 Sheets-Sheet 1 Filed April 3, 1951 Jan. 5, 1954 w. c. E. PRINS ET AL 2,664,586
ROTARY SCRAPER, ABRADING, OR POLISHING TOOL Filed April 5, 1951 2 Sheets-Sheet 2 Enventors Patented Jan. 5, 1954 ROTARY SCRAPER, ABRADING, OR POLISHING TOOL Winston C. E. Prins and Dougal W. S. Prins, Washington, D. 0.
Application April 3, 1951, Serial N 0. 219,082
This invention relates to a rotary scraper, abrading or polishing tool.
The tool as described herein and as depicted in the drawings attached hereto is adapted for many uses, viz., cleaning the hulls of ships or boats, large boilers and preparing surfaces for a ground coat of paint or the like and further by utilizing certain hereinafter described special type of blades. Rather than producing a scraping or cutting action such special blades are of the abrasive or polishing type and effect a polishing or finishing or buffing or planishing action on various surfaces and articles which may consist of or be fabricated from glass, metal, wood, plastic, or combinations of same.
The present tool is of the rotary type and includes generally an exterior stationary shell with a shell concentrically disposed therein and which latter shell is rotatable and carries thereon a plurality of cutting, scraping, abrasive or polishing blades, as the case may be, and which blades un-- der centrifugal force due to rotation of the inner shell will move outwardly and their outer end portions will emerge or project beyond the axial face portions of the inner and outer shells. The inner shell while so rotating relative to the outer shell will produce the scraping, cutting, abrading or polishing action on the article or device or other surface under controlled conditions of operation. These controlled conditions of operation are such that the blades will, as aforesaid, be ejected or moved outwardly beyond the face or axial face portion of the tool under centrifugal force and if the tool is pressed against the work naturally the blades will be retracted somewhat and as each blade operates independently of the other blades the blades will automatically adapt themselves to the work whether it be for cutting, scraping, abrading or polishing purposes in finishing work or otherwise removing some surface portions of the work.
Further, this rotary tool which embodies the aforementioned inner and outer shells, the former having the blades movably associated therewith, is connected with a flexible hose or the like which hose is in turn connected or associated with a vacuum or suction producing device so that the surface portions that have been removed from the work, whatever the work may be, are collected in the vacuum or suction producing device which may be a container or the like or under certain circumstances the said removed material may be ejected through the hose that is connected with the tool to any source of discharge and need not be confined in the vacuum or suction producing device as this last mentioned device may not be utilized or embodied with the tool.
Furthermore, in connection with the present rotary tool the inner shell is concentrically and specially anti-frictionally mounted within the outer shell so that ease of rotation of the inner shell relative to the outer shell is readily accomplished and this rotation may be effected by a simple electric motor drive that is gear or otherwise connected with the interior shell but, of course, other sources of driving the inner shell may be employed, such as a power take-off from any motor or other power driven source.
Additionally, the present rotary tool is comprised of a minimum number of very simple component and cooperative elements all of which may be assembled in final form by unskilled workmen and which parts can all be prefabricated and assembled rapidly and properly in a minimum of time. Moreover, the structural component cooperative elements comprising the present tool are relatively inexpensive to manufacture and assemble.
As shown and described herein the invention may take the form of a compact portable unitary device which comprises the aforesaid inner and outer shells, the former shell carrying the blades thereon, and which blades are centrifugally emerged partly from the inner shell when in use and the outer shell preferably having connected therewith a flexible hose and a relatively small horse-power motor such as utilized in connection with rotary drills which serve to drive and rotate the inner shell and the motor of this driving means being preferably trigger controlled to allow ease of operation on the part of the operator and the hose being connected with a vacuum or suction producing device in the form of a container whereby the material, whatever it may be, that is removed from the surface of the work that is being treated is collected in the inner shell and flows into the hose under suction or vacuum into the container and, of course, the container has means embodied therewith so that the said collected material can be removed from the container.
With these and other objects in view, the invention consists in the construction and novel combination and arrangement of parts hereinafter fully described, illustrated in the accompanying drawings and pointed out in the claims hereto appended, it being understood that Various changes in the form, proportions, and minor details of construction, Within the scope of the claims, may be resorted to Without departing from the spirit of or sacrificing any advantages of the invention.
In the drawings:
Fig. 1 is a perspective view of the complete assemblage of the rotary tool;
Fig. 2 is a sectional view substantially along the lines 2-2 of Fig. 1, looking in the direction of the arrows and showing certain parts in elevation;
Fig. 3 is an exploded view showing the inner shell partly in sectiton and the reduction gear for the inner shell in perspective and portions of the inner ball races in perspective;
Fig. 4 is an enlarged perspective view of the head portion of the rotary tool with certain parts broken away and shown in section;
Fig. 5 is an enlarged sectional View of one of the fins or ribs upon which the individual scraping or cutting blades or the like is carried; and
Fig. 6 is a perspective View of one of the scraping or cutting blades or the like, as the case may be.
Similar reference numerals or characters in the several figures of the drawings all denote the same component elements or parts.
The invention will be more readily understood by referring to the drawings in detail. In Fig. l of the drawings the overall tool or assemblage is disclosed. The overall assemblage comprises the outer stationary shell l, and the inner blade carrying rotatable shell 3 which, as will be noted, is concentrically disposed within the said outer shell. These shells and the integral parts thereof later referred to constitute the entire head of the tool generally indicated at 9. The outer shell 7 is substantially circular in outline and is hollow and includes the substantially cylindrical inner wall iii which is completely open at the front thereof l i and is closed by the rear wall i2. This rear wall i2 has a centrally disposed outwardly extending exteriorly screw threaded extension or neck is integral therewith. This extension i3 is hollow or provides an opening 54, and substantially in line with the rear wall !2 there is a circular convex seat or entrance l5 merging into the opening id for a purpose later described.
As will be noted from Fig. 2, there is a slight clearance is between the outer periphery of the inner shell 8 and the inner peripheral wall of the outer shell 1 which enables the insertion of the anti-friction means-the balls or spheres, ball races, and locking rings hereinafter described. Ihe inner shell 8 conforms generally with the inner contour of the outer shell '3 and it, like the outer shell, has a rear wall portion if and there is a centrally outwardly extending exterior screw threaded extension or neck 58 and the extreme exterior end portion 555 of the extension 5'8 is circularly concave and substantially conforms in shape to the convex interior portion l5 of the extension E3 on the outer shell. This concave formation is terminates at 2d and forms an outlet for the inner shell 8 and is slightly inside of the opening it in the extension it of the outer shell H. As a matter of fact the circular concave portion 2! of the extension 58 preferably slightly contacts and bears against the corresponding convex portion at the entrance of the opening it in the extension 53 of the outer shell 1 and this serves as a partial closure or retricted juncture of the two shells, with the space between shells exhausted by virtue of the suction hereinafter described,
The exteriorly screw threaded extension E8 of the inner shell 3 has mounted thereon the inte-- riorly screw threaded reduction gear 22. The screw threads E8 are left hand screw threads so that when the inner shell is rotated clockwise, as hereinafter more fully described, the gear will have a tendency to constantly tighten itself on these screw threads. Of course, if desired, the gear could be integral with the shell or keyed thereto rather than being screw threadedly mounted thereon or it can be secured or carried thereon in any desired manner.
Substantially the entire peripheral portion 2% of the inner rotatable shell 8 is in the form of relatively coarse screw threads and corresponding screw threads 25 are likewise on the inner peripheral surface of the outer stationary shell I.
These corresponding screw threads serve as a means for associating a pair of inner and outer ball races and a ring of balls corresponding with these races with the inner and outer shells. The pair of inner ball races is denoted at 25 and 2'? while the pair of outer ball races is denoted at 28 and 29. The inner ball races each has similar interior screw threads 38 thereon and these scre v threads correspond to the screw threads 2 on the periphery of the inner shell 8. The pairof outer ball races 23 and 29 each has similarly formed exterior screw threads 3! thereon and these screw threads correspond to the interior screw threads 25 of the outer shell There are also provided interior and exterior locking rings 32 and 33 for the pairs of ball races 26-2l and 2t29 respectively. These locking rings 32 and 33 are respectively provided with interior and exterior screw threads 32 and respectively and these screw threads correspond with the screw threads 2 and 25 respectively.
We may utilize a flat seal rin 33, which seal ring is brazed or otherwise permanently ciated with the outer face portion of the outer locking ring 33. This seal ring 33, it will be noted, closes the passage between the spaced apart pairs of ball races 2t2'i and 28 253 and their associated locking rings 32 and 33.
When the interior shell 8 is positioned concentrically within the outer shell l the said pairs of ball races are screw threaded-1y associated with the interior and exterior shells as shown particularly in Figs. 2 and 4 and the locking rings 32 33 serve to maintain or hold these ball races in their proper positions. With the inner race and the outer race 23, firmly run up to the termination of screw threads 2 of th inner race and 25 of the outer shell respectively, the balls or spheres B may be placed on the surfaces 38 and 33, respectively. Then the complementary races of the pairs 27 and 2% ma be run up so that their surfaces 3'? and 39, respectively also bear upon the balls or spheres B. The portions denoted S and S of the inner and outer races respectively are in fact the ends of the internal screw threads on the outer race and serve as abutments or stops to position and align the inner and outer races. In other words these portions S and S are the ends of the threads of the inner and outer races.
The inner shell 8 is provided with a plurality of preferably similarly formed spaced ribs or fins 48. A description of one of these fins will sufice for all of them. Each rib or fin 4%}, as will be clearly seen from Fig. 3, is cast integral with the inner rotatable shell 8 and is provided with an outer free end ii and a free side edge &2, while the remainder thereof is, as aforesaid, inte ral with the shell itself. Each of these ribs has a cutter or scraper, abrasive or polishing means carried by and supported on the forward face :13 thereof. This supporting face or surface at of each of the fins or ribs id is preferably at a angle relative to the rear wall portion ll of the inner shell 8 and tangent to the outlet 2% of inner shell 8, and the opposite face M of the rib may be slightly inclined from the perpendicular to the rear wall ii. In cross section the aforesaid ribs or fins ts are substantially triangular in shape. The angulated supporting surface 63 of each of i 1 I 1 e a :ansaarrr a s ieleinaiter described, are movably mounted on this support-- ing surface. The means to maintain the blades or a blade on each fin till may consist of the exterlorly headed and threaded bolt 55 which can be cast in each fin or rib 40 as clearly shown in Fig. 5 and this threaded bolt extends outwardly from the supporting surface 43 preferably normal thereto, there being two such bolts for each fln or rib 40, see Fig. 3. The blades D are substantially rectangular in outline and are preferably relatively flat on their opposite surfaces. Each blade is provided with a pair of elongated similarly formed enclosed aligned spaced slots 46 which slots are at a 45 angle with respect to the rear edge ll of the blade. These slots 46 are so positioned on each blade D that they register with the two threaded bolts 45 carried by each rib or fin 4i]. Substantially rectangularly shaped spacers it, which spacers ar provided with openings therein of substantially the same diameter as the bolts 45, are superimposed on the rear pore tions of each of the blades and, of course, the bolts extend through spaced openings 49 in each of these spacers The spacers 48 and the movable blade D are maintained on the supporting surface 43 by the bolts 45 and the castellated interiorly screw threaded nuts N and these nuts N are maintained in their proper position on the bolts 45 by means of a cotter key 5!) which passes through a transverse opening 5| in each of the bolts.
It will be understood that the bolts are not tightened against the spacers 48 so as to produce a binding action, there being enough tolerance between the bottom of the spacers and the outer face portion D' of each blade D so as to allow a sliding movement of each of the blades on the supporting surface 53 when the inner shell 8 is rotated and this sliding movement being induced or caused by centrifugal action upon the blades. The outer edges M of each of the fins or ribs 40 is such that when the blades are in inoperative position, as shown in the dotted lines in Fig. 5, the extreme outer edges E of the blades are slightly behind the extreme outer edge 41 of each of the ribs. Whereas when the blades are under centrifugal action the extreme outer end portion thereof as seen in Fig. 5 will project beyond the extreme outer end portions 4| of each of the ribs. Since the blades project from the shell during use of the device and are held in the extended position by forwardly deflected centrifugal force, outer ends of the blades Will be yieldably held in position for contact with a surface to be operated upon and may yield sufiiciently to follow irregularities in the surface.
It will be noted from Fig. 6 that the lower left corner 41' of the blade D is square. The square corner portion of the blade is adapted to be guided by and in spaced recesses or grooves G in the inner wall of the inner shell 8. Obviously, there is one of these grooves G adjacent the base of each of the fins that are integral with the interior of the inner shell.
The blades D, if utilized for scraping or cutting purposes, are preferably formed of metal and are rigid. When the inner shell 8 is rotated clockwise as viewed in Fig. 1 the edge portion E effects the cutting or scraping action. However, it is to be distinctly understood that in lieu of the blades D, we may utilize blades which may be formed of Carborundum or other abrasive type blades. Then too, instead of being either abrasive, scraping or cutting blades the blades may be formed of materials which would produce a polishing action on the work and further it is conceivable that somewhat resilient or flexible blades both metallic and non-metallic may equally well be utilized as manifestly no matter what function the 6. blades perform the centrifugal action'to emerge the outer edges of these blades is inherent in the tool.
The flexible hose which may be fabricated from any suitable material such as rubber or plastic materials is denoted at H. One end of this hose or flexible'conduit h is slipped over a reduced coned extension l3 of the exteriorly screw threaded extension 13 and this end portion h of the hose or the like is flared to the tool by means of a hollow interiorly screw threaded cap nut C which has a coned opening therein 0 that surrounds the hose. The interior screw threads of this cap nut correspond with the screw threads I3 on the central extension of the stationary shell i at the rear wall thereof and when these screw threads are interengaged obviously the cap nut will serve to retain the end h of the hose on the tool. The other end of the hose 52 is attached to the vacuum container V by means of a cap nut 53 which is similar to the cap nut C, or any other connection with the vacuum container may be utilized. This container V can either have its top or bottom removable for access thereto or it may be provided with an exteriorly screw threaded substantially circular removable closure 54 in its top. Contained within the vacuum or suction chamber V there is a conventional rotary gear type pump or other such pump or fan that is motor driven for producing the suction or vacuum through the hose H and in the interior of the rotatable shell 8. As the pump or fan, as the case may be, is conventional the same is not shown. An electrical conductor 55 extends into the interior of the chamber or container V and is connected with the pump or motor therein and the end of this conductor is provided with a three or four pronged quick detachable connector 56 that may be plugged into any suitable source providing electric current for the operation of the suction producing pump or fan within the chamber or container V.
The inner rotatable shell 8 is rotated by a conventional electric drill type motor M that is provided with a hand grip 51 and a trigger electric switch 58 adapted for ready control by the operator. Thismotor M has connected therewith an electric conductor 59 which also has the quick detachable three or four pronged connector 66 therein which is adapted to be plugged in any suitable source of electric current.
The motor M has a rotatable shaft Bl projecting outwardly therefrom and the extreme end of this shaft 62 is preferably in the form of gear teeth which correspond with the exteriorly extending gear teeth on the gear ring 22 that is mounted on the inner rotatable shell 8. The mounting for the motor shaft 6| is preferably an anti-frictional one denoted at 53. This anti-friction bearing 63 is substantially identical in structure with the inner and outer bearing recesses 26-27 and 28 89 respectively as hereinbefore described and the same is screw threaded similarly to the races 26-2l and 28-29, with the outer races screwed within a hollow circular cast or inserted boss 64, which boss extends outwardly from the rear wall i2 of the outer shell I and to one side of the extension l3. The inner races, it will be noted, are screw threaded on the shaft 6|. The shaft Si is thus secured relative to the outer shell I for proper association in driving the ring gear 22 andto effect rotation of that gear and consequently rotation of the inner shell 8 relative to the outer shell.
The operation of the tool is indeed simple.
Having selected the particular type of blades whether they be cutting, scraping, polishing, planishing or other type blades and whether such blades be metallic or non-metallic and rigid or possessing flexible 'or resilient characteristics and mounting these blades on the studs or bolts it, as aforesaid, all that is required of the operator is to plug in the connectors 56 and '60 and then by gripping the driving motor M on the portion thereof and depressing and pressing the trigger 53 the inner shell will immediately rotate and the blades under centrifugal action will simultaneously emerge and the ends of the blades under centrifugal action will emerge beyond the axial face of the tool and the tool applied to the work' to perform its function. The material, whatever may be, that is removed from the work enters the inner shell and exits through the central extension in the shell into the opening id of the outer shell and hence through the hose or other flexible conduit H into the container V. In operation the blades being individually mounted for movement relative to the inner shell will adapt themselves, each one of them, to the contour of the particular work. If the surface that is worked on is flat then, of course, each blade will project or emerge outwardly substantially the same distance from the axial face of the tool, but if the surface is irregular then each blade will automatically either be emerged or retracted and follow the surface across which it moves during the rotation of the head 3.
While we have shown the vacuum or suction producing chamber V, under certain circumstances it may be desirable to eliminate this container and substitute therefor a conventional Venturi means in the hose H or utilize a steam or hydraulic jet to produce the suction or vacuum in this hose for removing the material from the interior of the rotatable shell 8. In such event the end 52 of the hose could be unattached and the detritus or removed material from within the hose could be discharged into a container or into a stream or any other'suitable discharge. Where the removed material is flaky or dust-like it is preferable, however, to utilize the container or chamber V and collect this mateial for later discharge.
The head of the tool 9 may be madeof various diameters and, of course, this head includes the inner and outer shells and the speed of rotation of the inner shell may vary depending-upon the work that the blades or the like are to perform. Likewise, the type of motoras regards horsepower may be varied depending upon the type of work that the tool is to perform. Other driving means in lieu of an electric motor may be used employing similar simplicity of controls. vVhile manual support, operation of the controls, and manipulation of the tool head depicted are intended, it may also be envisioned that the basic principles of the tool head herein described are equally applicable to :a mechanically supported and/or manipulated tool head and/or with-auto matic or semi-automatic control devices which embodies the unique characteristics of said tool head.
As to the anti-friction means which consists of pairs of inner and outer ball races 26- 21 and 28-29 respectively and the ring of balls 3, the inclined opposed bearing surfaces or race paths 3B and 3? of the inner ball races are ofl5 while the opposed bearing surfaces or race paths of the outer races and are 52 with the transverse 8 plane perpendicular to the inner shell axis passthrough the centers of the balls or spheres B. This particular disposition of the opposed race paths of the inner and outer races avoids friction and the extent of rotation of the balls on the inner races is equal to the rotation of the balls on the outer races.
Six ribs or fins 40 and likewise six blades 1) are disclosed in the drawings. It is to be understood that any number of such ribs and blades may, however, be utilized. For instance, it is conceivable that one rib and one blade might suffice under certain conditions while two or more of such ribs and blades would be required under other conditions. In other words, the number of ribs and blades that may be utilized is optional.
In addition to serving as a supporting means for the blades the ribs or fins as also considerably reinforce and strengthen the inner rotatable shell 8.
1. A rotary tool of the character described comprising a rotary shell rotatable about a'longitudinal axis and open at one end, operating members shiftable through the open end of the shell from a retracted position to an extended position for use, said operating members having radial movements imparted'to'them by centrifugal force exerted during rotation of the shell, and guide means engaged by said operating members and constituting cams shifting the operating members outwardly through the open end of the shell to an extended position for use durin their movement by the centrifugal force.
2. The structure of claim 1 wherein the guide means for each operating member consists of pins passing through diagonally extending slots formed through thesaid operating member, said pins limiting movement of the operating members through the open end of the casing as well as imparting longitudinal movement to the operating members.
3. The structure of claim 1 wherein the operating members have side-by-side engagement with webs in the shell, the guide means for shifting the operating members longitudinally consisting of pins projecting laterally from the webs and passing through diagonally extending slots formed through the operating members, nuts screwed upon'said pins, spacer means about said pins between the operating members and said nuts, and fasteners releasably holding the nuts in adjusted position upon the pins.
4. A rotary tool of the character-described'comprising a rotatable carrier rotatable about a longitudinal axis and having front and rear ends,
operating members slidably carried by said carrier and shiftable radially and forwardly thereof, the radial movement being in response to centrifugal force created during rotation of the carrier, and guide means for limiting movement of the operating members relative'to the carrier and directing the operating members forwardly to an extended operative position simultaneously with their radial movement by the centrifugal force.
5. The structure'of claim' i wherein the means for directing the operating members forwardly also serves to limit sliding movement of the'operating members.
6. A rotary tool of the character described comprising a rotatable carrier having an edge portion and serving to create centrifugal force when rotating, spaced-apart operating members slidably mounted for limited movement on said carrier, each member being adapted for inde pendent movement relative to each other and to the carrier from a retracted position forwardly to an extended operative position partially beyond the said edge portion of the carrier in response to centrifugal force created by rotation of the carrier, and cooperative means on the said members and said carrier for permanently maintaining each operating member in sliding engagement with the carrier and to allow for the independent movement of the members relative to each other and to the carrier when the carrier is rotated.
7. A rotary tool'of the character described comprising a rotatable carrier having front and rear portions and being rotatable about a longitudinal axis and serving to create centrifugal force when rotating, spaced-apart operating members slidably carried by said carrier and mounted for independent movement relative to each other and to the carrier from a retracted position forwardly to an extended operative position partially beyond the carrier in response to centrifugal force created during rotation of the carrier, the carrier and the operating member being provided with cooperating means for permanently maintaining the members in limited slidable engagement with the carrier and to allow the independent movement of the said members relative to each other and to the carrier to occur when the carrier is rotating.
8. A rotary tool for performing cutting, scraping, finishing or polishing functions comprising a rotatable shell having an open outer end, blades Within said shell slidably mounted for limited movement radially and axially of the shell, means for rotating the shell and creating centrifugal force to move the blades radially, and means within the shell engageable by the blades as they are moved radially to simultaneously impart the axial movement to the blades to cause them to partially emerge axially through the open end of the shell.
9. A tool as defined in and by claim 8 wherein the said shell is concentrically disposed within an outer shell also having an open outer end, bearing means between the inner and outer shells rotatably mounting the inner shell, and the emergence of the blades axially from open ends of the shells being induced by outwardly deflected centrifugal action thereon created while the inner shell is rotating.
10. The tool as defined in and by claim 9 where in the bearing means consists of inner and outer ball races, the ball races having opposed race paths thereon and a ring of balls contacting the said paths during the rotation of the inner shell relative to the outer shell, and means for maintaining the ball races in position relative to the inner and outer shells.
11. A rotary tool of the character described comprising inner and outer shells concentrically disposed one within the other and in spaced relation to each other, both shells having open front ends, the inner shell being rotatable relative to the outer shell, blade supporting ribs disposed within and integral with the inner shell and extending substantially radially thereof, a blade movably supported on each of the ribs and shiftable thereon radially of the inner shell and outwardly axially of the inner shell through the front end thereof, anti-friction bearing means between the two shells, means for rotating the inner shell relative to the outer shell and creating centrifugal force to move the blades radially, and guides carried by said ribs and engaging diag- 1d onally extending portions of the blades and individually moving the blades forwardly through open ends of the shells as the blades are moved radially of the inner shells under centrifugal influence.
12. A tool of the character described comprising inner and outer shells disposed one within the other in spaced concentric relation to each other, each of the shells being open at its front end and having a rear wall portion carrying a rearwardly projecting centrally located hollow extension, the said extensions being aligned with each other and providing a throat extending rearwardly from the inner shell and outwardly from the outer shell, said inner shell being mounted for rotation in the outer shell, driving means for rotating said inner shell and creating centrifugal force, blade mounting means carried by the inner shell, a blade movably carried on the blade mounting means and shiftable radially of the inner shell and forwardly from a retracted position within the inner shell to an extended position through the open front end thereof, guide means carried by said mounting means and engaging said blade and shifting the blade forwardly as the blade moves radially, a hollow conduit connected at one end with the exten ion on the outer shell and communicating with the throat formed by the said extensions, the conduit at its other end having suction producing means connected therewith, driving means exteriorly of the outer shell and including a shaft extending through the outer shell and connected with the inner shell to rotate the same and thereby create the centrifugal force exerted on the blades during rotation of the inner shell and effect movement of the outer end portion of the blade from the open front ends of both shells to perform their functions of removing surface portions from work, the removed surface portions passing into the said throat and through the hollow conduit into the suction producing means.
13. A tool as defined in and by claim 12 wherein there are integral ribs in the inner shell eX- tending radially thereof and blades are movable radially and forwardly of the said ribs, a gear ring carried by and extending about a portion of the inner shell, the driving shaft being provided with a gear meshing with the said gear ring for rotating the inner shell relative to the outer shell and creating the centrifugal force which is exerted on the blades and causes outer end portions of the blades to emerge from the open ends of the inner and outer shells during use of the tool.
14. A tool as defined in and by claim 13 wherein the blades engage supporting surfaces on the ribs and such surfaces are angularly disposed with respect to a rear wall of the inner shell.
15. A tool as defined in and by claim 14 Wherein the angulated supporting surfaces are at substantially a 75 angle relative to a rear wall of the inner shell.
WINSTON C. E. PRINS. DOUGAL W. S. PRINS.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 409,743 Gail Aug. 27, 1889 1,641,103 Small Aug. 30, 1927 2,168,692 Vidal Aug. 8, 1939 2,504,643 Burgoon Apr. 18, 1950