US2548450A - Dental hammer - Google Patents

Description

April 10, 1951 M STAUNT 2,548,450

DENTAL HAMMER Filed Oct. 10, 1947 2 Sheets-Sheet l TTORNEY April 1o, 1951 M STAUNT 2,548,450

DENTAL HAMMER Filed Oct. 10, 1947 2 Sheets-Sheet 2 l/a 5 71H 5,.' /2523 ATTORNEY Patented Apr. 10, 1951 UNITED `STATES PATENT OFFICE DENTAL HAMMER Martin Staunt, Chicago, Ill. Application October 10, 1947, Serial No. :779,191

The present invention relates to dental hammers and is particularly concerned with dental hammers of a type peculiarly adapted to be used for compacting amalgam llings, but `is also of universal application and may be provided -with suitable tools for use on inlaysand for other purposes.

One of the objects of the invention is the provision of an improved dental hammer which may be employed with any of a multiplicity of different tools for compactng amalgam fillings, the tool being preferably selected to cover a maximum area of the lling and to conform as nearly as possible to the shape of the exposed area of the filling.

Another object of the invention is the provision 14 Claims. (Cl. 32-54) of an improved dental hammer which is provided with an improved tool holding device by parts of the dental hammer. A

Another object of the invention is the provision of an improved dental hammer including an angle head which may be turned and secured in any of a multiplicity of angular'positions so as to enable the user to adjust the tool into a position where the hammer can act directly on.

the amalgam lling in a direction which is normal to the surface of the filling. f

Another object of the invention is the provision of an improved dental hammer in which the driving teeth of the gears are so constructed that they will always take up the play and wear which is caused by continued use, so thatthe device may be used-for a long period of time without the necessity for replacement of its gears.

Another object of the invention is the provision of an improved Vdental'hammer adapted to press out substantially all of the mercury from the amalgam llings so that therfillings which are treated with this hammer will be hard and white and more .durable than thosev installed with the devices of the prior art.

Another object of the invention is the provision of an improved construction .of dental hammer in. which the. .impact collar has a. lclear-A ance except when a, dog hits it, so that. the pressure is exerted on the angle head bearing.

`Another object of the invention is the provision of an improved dental hammer which may be held lightly and which is adapted to make the work easier and to provide the operator with better controi and more eicient action in the compacting of amalgam fillings. y 1 Another object ofthe invention` is the pro'- vision of an improved dental hammer which is so constructed that saliva and amalgam is kept out o f the bearings of the device and whichzis durable, capable of economical manufacturaand adapted to be used for a long period of time without the necessity for repair or replacement.

-Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the two sheets of drawings accompanying this specification, Y

Fig. 1 is a fragmentary sectional view taken onv a plane passing through the axes of the spindles" of the handpiece and its dental hammer attache ment; Fig. 2 is a side fragmentary elevational viewk ofv the handpiece with the dental hammer attach.- ment secured to it;

Fig. 3 is an axial sectional view takenthrough the axis of the angle head for the dental hammer;

Fig. 4 is aI front elevational view ofthe angle.

head; Fig. 5 is a side elevational View of the plugger tube assembly shown withv the dental hammer; Fig. Bis an enlarged axial sectional view of the plugger tube shown in connection with a hammer tool to illustrate the mode of securement of the tool shank; L

Fig. 7 isa transverse sectional view taken onl theplane of the .line 'l-r'l of Fig. 6 looking in the K direction ofthe arrows;

Fig. 8 is an end elevational view of the plugger tube; v u v Fig. 9v is an inside elevational View of the cap with the shank position shown in dotted lines,"

Fig. l0 is a sectional view taken on the plane of the line lil-H3 of Fig. 6 looking in the direct--` tion of the arrows with the tool removed;

Fig. 11 is a fragmentary side elevational view or" the-hammer shaft showing the hammer or dog insideV elevation;

Fig. 12 is an end elevational view taken on the plane of the line |2-I2 of Fig. 1'1;

Fig. 13 is a side elevational view of one form of hammer tool;

Fig. 14 is an end elevational view of the tool of Fig. 13;

Fig. 15 is a side elevational view of the cap bearing for the plugger tube;

Fig. 16 is an end elevational View taken on the plane of the line |6-I6 of Fig. 15.

All of the views except Fig. 2 are enlarged.

Referring to Figs. 1 and 2, the dental hammer attachment is indicated in its entirety by the numeral 20 and is shown in connection with a dental handpiece 2| to which it is attached. The handpiece 2| is provided with a sheath 22, which supports the front end bearing 23 for the rotating` spindle 24. The spindle 24 has a cylindrical bore 25 terminating in a frusto-conical bore'26 for receiving the collet 21.

The collet 21 comprises a sleeve split at each of its ends by slots 28 and having a bore 29 adapted to receive the shank of a driven shaft 33. The collet 21 is engaged at its left end by an actuating member 3|, which in turn is engaged by a thrust ro'd 32 having the usual threaded portion (not shown) by means of which the collet is forced to move axially. The front end bearing 23 is preferably tapered toward its end and has an outer frusto-conical surface 33 and itis provided With a threaded bore 34 for receiving a screw bolt 35.

A screw bolt 35, the head of which projects above the frusto-conical surface, is for engagement with the hammer attachment 23. The front bearing 23 of the handpiece has a cylindrical bore 36, which is in alignment with the bore 29 in the collet so that the shaft 33 of the attachment may enter the front bearing 23 and extended into and through the collet 21, which is adapted to grip the shaft.

The dental hammer attachment 20 is provided with a rear bearing member 31, comprising a substantially cylindrical metal member, which may be made of stainless steel, and all of the outer parts of the dental hammer attachment are preferably made of stainless steel. The rear bearing 31 has a relatively small cylindrical portion 38 at its right end which is provided with a cylindrical bore 39, serving as a bearing for the right end of the shaft 30.

The cylindrical portion 38 carriesY a reduced cylindrical portion 4D, which is lprovided with threads 4| for engagement with the internal threads 42 on the knee member 43. The rear bearing 31 also has an annular surface 44, which is engaged by the end 45 of the knee 43 when the knee is threaded home onthe rear bearing 31.

The left end of the rear bearing 31 is enlarged and provided with an outer cylindrical surface v 46 and it is provided with an inner frusto-conical bore 41, which is complementary i-n shape to the truste-conical outer surface 33 of the front bearing 23 on the handpiece 2|. The enlarged cylindrical portion 4B of the rear bearing 31 has a slot 4B extending into its end edge 49, and the slot 48 is large enough to receive the head of the screw bolt 35, thus the head of bolt 35 prevents rearbearing 31 from rotating on the front bearing 33 of the handpiece 2| While the collet 21 grips the shaft 30 and prevents the attachment 20 from moving axially off the handpiece 2 When the attachment 2B is secured in the handpiece 2|, as shown in Fig. l, the spindle 24 of the handpiece is adapted to drive the shaft 33 of the attachment.

The frusto-conical bore 41 in the rear bearing 31 terminates at an annular surface 5S and the shaft 3B is provided with a thrust collar 5| secured to it by means of a friction pin 52 for engaging the thrust surface 5U. At its other end shaft 3|) has a pinion 53 comprising a cylindrical member formed with a fiat thrust surface 54 on its left end for engaging the end 55 of the reduced portion 49. The pinion 53 is secured to shaft 3|! by means of a friction pin 5S and thus the pinion '53 and collar 5| prevent the shaft 30 from moving axially, but they permit it to rotate within the bearing bore 39.

Pinion 53 is provided with teeth 51, which are preferably relatively sharp and V-shaped. These teeth are complementary to the teeth 5S on the driven pinion 59, which is carried by shaft 63. The V-shaped teeth tend to take up wear and reduce backlash or looseness which might be due to wear between the teeth.

The knee 43 is provided with a bore 6| in alignment with the threaded bore 42 and the bores 6| and 42 are large enough to pass over the pinion 53, thus the knee 43 may be passed over the pinion 53 and threaded on the threaded portion 4| of the rear bearing. The knee 43 also has an angle bore 62 for receiving the pinion 58 and a reduced portion |58 on the bearing member 58.

The reduced portion has an annular surface 63 at its left end for engaging the flat end B4 of the pinion 59. This pinion is also secured to shaft 5|) by means of a driven pin 35. The knee 43 has its right end (Fig. 1) provided with a multiplicity of axially extending teeth 56, which are also preferably V-shaped and relatively small in size. Teeth 66 are complementary to similar p teeth 61 on the end of the bearing member |38 for shaft 60.l

'I'he knee 43 also has a threaded cylindrical I portion 69 for receiving a threaded sleeve or ferrule 1|). The ferrule l'has an internal bore 1| with threads for engaging the threads 51 and it has a reduced cylindrical counterbore 12, which is large enough to receive the cylindrical portion 13 of the Vbearing E8.

The ferrule 10 has an internal annular shoulder 14 facing toward the left and shoulder 14, engages an annular shoulder 15 on the bearing member 68; thus the ferrule 10 may be threaded on the knee 43 and, it will draw the teeth E1 of the bearing member 68 into the teeth 66 on the end of the knee 43 until the bearing 68 is fixedly secured to the knee. Before tightening the ferrule 10 the pinion 53 and reduced portion |50 of bearing 53 must be inserted in the angle bore 32 of the knee 43. Y

The reduced threaded portion 63 of the knee 43 preferably extends od at an obtuse angle to the axis of the shaft 30, and thus the bearing 68 extends at an angle to the handpiece 2|.

It is also possible to rotate the bearing 68 and to bring different sets of teeth 5t, 61 into engagement with each other, so that the tool 16 may have any rotative position desired by means lof the adjustment that is. provided between the teeth 66, 61 secured by the ferrule 10. The head of the tool will thus have as many adjusted positions as there are teeth at 36, V|31, and the operator may use this adjustment so that the hammer tool 16 Will extend in the direction he desires, which is normal to the surface of the amalgam lling, when he holds the handpiece 2| in a position most convenient to him.

The bearing member 68 for shaft El) also has a reduced threaded portion 11 and an annular ascenso;

thrust surface; 18; and the angle headv 19 has a threaded bore 80 for eng-agement WitliitheY re'- duced threaded portion 1:1. Theiendci theangle head 19s engagesthe thrust surface 18iwl'1en the angle head is tightly threaded on the angle bearing' 68.

Shaft 00 is provided at its right end with. a cylindrical i-mpact col-lar 82; which forms an integral part of an eccentric dog 83. Bothoff these members have a bore for receiving the shaft' 5'0- to which they' arebothsecured by a fric-tion pin E4; The impact collarl 8'-2- has an outer cylin drical surface 85, and which eng-ages ther inner cylindrical bore 8.6 in the angle head 19;' thus any impact Which is transmitted by reaction` to the dog 8'3 is resisted by the collar' 82 engaging the cylindrical surface of the borek 86- in the angle head-19. 4

The reaction from the impacts is taken byf-the angle head' insteadv of the bearing bore 8'1 in the bearing member 68; thus7 the bearing will be maintained in aAv` good condition for a long period'l offtime;

The impact collar 82 also servesn as a thru-st' bearing: as itsv ilat lef-t side 88 engages the end 89:A of the` bearing memben E@ to prevent axial movement of thes-ha-ft'.

The dog 83 and thrust collar 82 are shownin Figsa l-l and 12 in connection with the shaft 69". Dog |33l comprises a partiall cylindrical portion 901 surrounding the shaft 90, but at one side the cylindrical portion 90 is enlarged to form a V-shaped point 9|, thev ridge of vvlrich-isA slightly-v rounded and the point 9| is Withinthefboundaries of thecylindrical surface 85 of the collar 92;- thus the bore 86 of the angle head 19L WillA pass overy bothY the dog 8f3 and the collar 82 when the angle head 19l is threaded on the bearing 68. y

The angle; head, 19- is shownV in Fig. 3- a-nd itcomprises agmetal member, preferably made of stainless steel, having the bore 86 previously described, and another threaded bore 92 at right angles to the borel 86. The threaded bore 9-2- is located in the tubularA portion 93 having a flat end surface 94'. Bore 92 is adapted tol receivethe threaded portion 95 of a cap 96, which had a radially extending cap flange 91' With a non-circular outer edge, suchV as,'ior example, an octagonal formation.. The head of the flange is adapted to be engaged by a Wrench so that it maybe threaded tightly into the bore 92.

The bore 92 communicates with ar smaller counterbore 93 in the angle head 19 and the counterbore 98 is adapted to receive the` bottom bearing 99, Bottom bearing 99` comprisesa cylindrical sleeve with an inner cylindrical bore m0 and the sleeve 9'9 is adapted to t in the counterbore 98. Sleeve 99 has a cylindrical enlargement |01, which litsY in the` unthreaded portion of they bore92 and the cylindrical enlargement I-0| is provided with a ilat side |02 on the side. adjacentA to bore 86.

The plugger tube |03 is adapted to slide inthe bore 99, of the bottom' bearing 99, and plussertube. |03 has an outer cylindrical surface |04. In order to hold the plugger sleeve |93 againstl rotating, the bottom bearing enlargement |0| has an axial extension |05. This extension has an outer cylindrical surface |06, but has a frat Surface |01 on its inner side. The nat surface |01 is adapted to engage a flat surface H35V on the plugger tube |03., so that the plugger tube may slide axially but it may not rotate. because of the two flatengaging surfaces |01, |08.

Plugger tube I`03 is provided with a radial-lyy extending flange |509,l

6 which has a iiat annular surface lA lili on itslef-t side (Fig. 6,). The flat'sur-i face liisformed byI cutting off the flange |09; at the top side ofthe plugger tube in Fig. 6. The, annular surface H0'. is located-'to be engaged by. the point 9| ofthe .dog 83, but the plugger tubel i023 has` aV sufficient` range of movement so that it may slide tov/ard= the rightv far enough so that the surface Hll is not' engaged. by the dog 8:3?.

Engagement between the dog 83. and the plug-J ger tube is brought. about only by pressing the tool 1:6 against the Work, Which pushes-the flange H0- backward-ly into. thev angle head' 1'92v until ity is struck by the dog 33. Thus the amount of impact may be controlledY by the pressure which the operator places: upon. the toolV and the impact ceases-.When the operator ceases to. press` the tool against the work.

The plugger tube |03: has a cylindrical outer surface I H on the lright side of the impact flange- If09 in Fig. 6. Cylindrical portion IH. is rotatively mounted in the bore H2. in the cap member 9i and the cap member is provided with an end' surface H3' that actsas a stop surface for engaging the right side H4V of the impact flange |09, thus determining the range of movement ofV the plugger tube |03.

Plugger tube |93 is long enough to extend out AWardly beyond the cap 9.9-, Where it is provided With a reduced cylindrical portion H51. YThis reduced cylindrical portion supports` a cam H6', which is pinned to it by a friction pin H1, and theY cam HG engages anannular shoulder H9. Cam H6 hasV an outer cylindrical surface H9 for rotatively supporting alock cap |29. The cylindrical surface H9 of cam Hilis located eccentricallyy with respect tothe axis oi the plug* ger tube |93, and this is accomplished by making the Wall of the cam IB thicker in a radial direction on one side.

The lock cap comprises a cylindrical cupshaped member having an inner cylindrical bore |2| with a rotating t on the surface l I9' on the cam H6. The outer cylindrical surface 22 of the lock cap |20 is knurled for engagement With the fingers. TheV lock cap |20 comprises a tubular portion |23 and a fiat end Wall |24, the tubular portion |23 being ro-tativel-y mounted on the cam H5. Tubular portion |23 is provided with a pair of axially extending lingers |25 which may be bent inward as shown in Fig. 6 in engagement with the frusto-conical surface |26- on the cam H6.

Thus the fingers |25 will retain the lock cap- |29 on the cam H5. In order to limit the rotative movement of the lock cap |20, the cam- |I6 is provided With a radially extending lug |21, Fig. 10, which engages fingers |25 and limits the rotation `of the lcck'cap to about onehalf rotation. rThe plugger tube |93 is preferably closed at its left end by means of end wall |29, but it is; provided with a cylindrical bore |29 having a sliding t with the shank |39 of any of a multiplicity of tools 16.

The shank |39 has a fiat end portion |3| for enga-ging the end- WallV |28 of the plugger tube, so that the impact between the tool shank and the plugger tubeisI taken by the Wall i253. Theshank |30- of any tool to be used also has inter mediate itsends an annu-lar groove |322' which may be rectangular in cross section, as showny Fig. 13.

This leaves two annular surfaces |33y and and a reduced cylindrical portion |35, which de` fine the groove |132; `Beyondthegroove [32 to-Li ward the right, the working end |36 of the tool may take any of a multiplicity of different shapes. The end surface |31 is shown as being flat and provided with a circular edge |38, and the work end |36 of the tool is joined to the shank of hammer tool 16 by reduced curved portion |39.

I desire it to be understood that a multiplicity of different tools may be used, and the tools may be round, rectangular, concave, convex, depending upon the shape of the surface and the area of the surface of the exposed amalgam of the filling. A tool should be selected which will impact against most of the area of the filling and in sharp corners additional tools of complementary shape will be used to get into those corners and compact the amalgam.

The lock cap |20 has its end wall |24 thinner.

than the width of the groove |32 in the shank thus the inner side |40 of the lock cap wall |24 may engage the annular surface |33 in the groove |32, but the outer surface |4| of the lock cap is free of the annular surface |34 on the tool. This means that the tool does not transmit impact to the lock cap, but the impact is taken by the end |3| of the tool and the end |28 of the plugger tube |03.

The lock cap |20 rotates eccentrically on the tube |03 and on the cam ||6, but the aperture |42 in the lock cap |20 is eccentrically located, so that when the tool shank is in place, as shown in Fig. 6, the lock cap may be rotated until a portion |43 of its wall |24 is locked in the groove |32. The eccentricity of the aperture |42 in the lock cap with respect to its tubular portion |23 is the same in amount as the eccentricity of the cam ||6 with respect to the axis of the plugger tube |03. This means that, at a certain point in the rotation of the cap, the aperture |42can be brought into registry with the bore |29.

The lock cap 20 may thus be rotated to such a position that the aperture |42 is in registry with the bore |29. This is necessary in order that the shank |30 may be inserted in the plugger tube |03. The eccentricity of the aperture |42 in the lock cap |20 is such that the edge of the aperture |02 may be brought into wedging engagement with the reduced cylindrical portion |35 in the groove |32.

When this is done, the wedged condition between the inside of the bore |42 on cap |20 and the tool shank causes the tool shank to be held against rotation. This is desirable, when the working end |36 of the tool has a pointed or angular surface, to get into a corner of the lling cavity. Under such conditions it is not desirable for the tool to turn as the point must be held in the corner of the cavity while the amalgam is made compact.

It is not necessary however to turn the cap |20 until the tool shank is held against rotation. A slight turn of the cap without exerting much force will result in the securement of the Vtool While permitting it to rotate in the plugger tube |03.

Thus the operator may secure the tool for axial movement with the plugger tube while permitting it to rotate in the plugger tube or he may secure it in the plugger tube so that the tool cannot rotate and as the plugger tube is held against rotation, the tool can only reciprocate.

The operation of the dental hammer is as follows:

The dental hammer attachment has its shaft placed in the collet of the chuck of a dental handpiece 2|, where it is secured while the rear bearing 31 is engaged on the front bearing 23 of the handpiece. The bearing member .68 of the hammer attachment may be rotated as desired and adjusted by loosening the ferrule 10 and bringingthe teeth 66, 61 into engagement with each other with the bearing 68 in the desired position, where it 'is secured by threading the ferrule 10 home.

A suitable dental tool is selected and its shank may be inserted in the plugger tube |03 by rotating the cap |20 until its aperture |42 registers with the plugger tube bore |29. The dental tool is then secured by rotating the cap |20 in the opposite direction until the edge of the wall |24 at the bore |42 moves into the groove |32 of the tool shank.

When the spindle 24 of the handpiece is rotated by a suitablemotor the collet 21 will drive the shaft 30, which in turn drives its pinion 53. Pinion 53 drives pinion 59, which rotates shaft 60. Shaft 60 rotates collar 82 and dog 83, and the dog 83 is in position to engage the impact ilange |09 once for each rotation of the shaft 60, provided the flange |09 is pushed inward far enough to engage the dog.

When the tool 16 is brought into engagement with the work, such as an amalgam lling, this tends to push the tool backward into the angle head, which causes the plugger tube to move inward into the angle head. Then the impact flange |09 brings its surface |10 into the range of movement of the dog 83 and the dog 83 strikes the surface I0 once for each rotation of its shaft, thus producing an impact on the plugger shaft |03 and the tool 16. Y

The amount of force of the impact depends upon the force or pressure which is exerted by the operator on the work with the tool surface. The ferrule 10 and the reduced portion 38 of the rear bearing 31 and the enlarged portion 46 of the rear bearing 31 are all preferably provided with a plurality of annular grooves |44. These grooves are partially circular in cross section so that there are no sharp corners in which dirt may gather. The grooves are separated by lands |45, the cylindrical outer surfaces of which are preferably knurled, as shown in Fig. 2.

These knurledsurfaces and the grooves permit the operator to graspthe hammer attachment more firmly and surely so that it will neither rotate in his hand nor will it slip axially.

The knee member 43 is also preferably provided with a pair of grooves |46 oppositely located so as to provide flat surfaces |41 on the knee 43, by means of which it can be grasped with a wrench or other tool.

It will thus be observed that I have invented an improved dental hammer having an angle adjustment by means of which the Working end of the tool may be pointed in any direction, While the dental handpiece itself may extend at an angle to the bearings of the hammer attachment. The present hammer attachment has a simple but positive and secure structure for holding the tool shank, and impact on the tool is not brought to bear upon the tool holding arrangements but is transmitted to a plugger tube which is sturdily constructed to receive it.

The plugger tube is adapted to be engaged by a hammer dog, which, in turn, reacts against a collar that has a wide bearing surface in the angle head, so that the reaction of the impact is not borne by the bearings. The present dental hammer is capable of many different uses, but it is particularly effective in compacting amalgam fillings, because it is provided with suitable Y g, tools for engaging most ofthe exposed area simultaneously. Thus it presses out substantially all of the mercury and makes theV amalgam fillings harder and whiter and more permanent than those which are made by using the devices of the prior art. f yWhile most of the outer parts are preferably made of stainless steel, vthe angle head is preferably made of brass', which is chromium plated and provided with a stainless Ysteel bearing.

The gears are vpreferably made of YVcar'rbon steel and the structure of the device .is Vsuch that the amalgam and saliva and other foreign matters are kept out of the bearings by the lock cap. Thus the present device may be used for a long period of time without the necessity of repair or replacement' of its parts. The device is also easy to take apart so that it may bel cleaned and oiled and re-assembled with a minimum amount of labor. Y

While I have illustrated a preferred yembodiment of my invention, many modifications may be made without departing vfrom the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus-described` my i-vention, what I claim as new and desire to secure by Letters Patent of the United States, is:

1. A dental hammer attachment comprising an angle head havin-g a slidably mounted member for supporting a tool shank, a tool shank in said member, the said shank having anannular groove said member being provided with a cylindrical bore, and said shank being substantially cylindrical, and a rotatable member on said head having an eccentrically mounted portion for movement into said groove on said shank whereby the shank is Secured against axial movement with respect to said slidable member the Walls of said groove acting as stops for engaging said rotatable member.

2. A dental hammer attachment comprising an angle head having a slidably mounted member for supporting a tool shank, atool shank in said member, said member being provided with a cylindrical bore, and said shank! being substantially cylindrical, and a rotatable member on said head having an eccentrically mounted portion for movement into a groove on said shank whereby the shank is secured against axial movementwith respect to said slidable member, said rotatable member comprising a cap eccentrically mounted on said head and having an eccentrically located aperture for receiving the tool shank.

3. In a dental hammer an angle head comprising a metal member having' a pair of threaded portions extending transversely to each other and communicating with each other, a bearing member threaded inone of said b ores and having a shaft, said shaft carrying an eccentrically mounted impact dog and said shaft carrying an impact resisting collar engaging a complementary bore in said head, and a plugger tube slidably mounted in the other of said bores and lhaving means for supporting a tool,l said tube being provided with a radially extending ange for engagement with said dog whereby the rotation of said shaft produces an impact on the plugger tube to move it axiallyonoe for each rotation of the shaft, said angle head being provided with a threaded member forming a bearing for one endl of the plugger tube and with a cylindrical member housedin the head and forming a bearing 10" f vfor the other end of theV plugger tube, said latter bearing having an axially extending portion pro'e vided with` a hat surface, engaging a flat, surface on the plugger tube to prevent rotation v'of the pluggerv tube.

4. In 'a dental hammer an angle head compris'- ing a metal member having a pair' off threaded portions extending transversely to each` other and communicating with each other, a bearing member threaded in fone of said bores 'and having a shaft, said shaft 'carrying an eccentrically mounted. .impact dog and said. shaft carrying an impact resisting collar engaging a complementary bore inr said head, a plugger tube slidably mounted in the other of said bores and having means for supporting a tool, said tube being providedf with a radially extending flange for engagement with said dog whereby the rotation of said shaft produces an impact on the plugger Vtube tomove it axially once for each rotation of the shaft, and a knee member comprising a tubular metal member having communicating bores extending'at an obtuse angle to each other, the end of said knee member being provided with a toothed edgev and said head having a bearing member provided with ant end having a toothed edge and means for securing. the knee member to the bearing carried: by the ang-le head wheres by the plugger tube maybe extended in any of a multiplicity of diierent angles with respect to the knee member.y

5. In a dental hammer an angle head provided with a pair of threaded bores extending transversely to each other, one of said bores communi'- cating with a cylindrical unthreaded bore, a driving shaft having an enlarged collar for engagement in said unthreaded bore, said collar being integrally secured to an eccentric dog projecting into the other bore, a plugger tube slottedly mounted in said other bore and having 'a radially extending flange adapted to be engaged by said dog, the reaction from theV action of said dog on said flange being transmitted by said collar to said unthreaded bore, said plugger tube being provided with a flat surface on one side and a bearing member mounted in said other bore and provided with a complementary part having a flat surface for engaging the plugger tube and preventing its rotation.

6. In a dental hammer an angle head provided with a pair of threaded'bores extending transversely to each other, oneof said bores communicating with a cylindrical unthreaded bore,` a driving shaft having an enlarged collar for engagement in said unthreaded bore, sai-d collar being integrally secured to an eccentric dog. projecting. into the other bore, a plugger tube slottedly mounted in said other bore and having a radially extending'flange adapted to be engaged o by said dog, the reaction from the action of said dog on said flange being transmitted by said collar to said unthreaded bore, said plugger tube having a cylindrical borefor receiving the shank of a tool, a tool having a cylindrical shank located in said bore, said tool having a groove in its shank and an eccentrically mounted member Von said plugger tube adapted to rotate into wedging engagement in said groove for securing the tool shank in the plugger tube.

'7. A dental hammer assembly comprising a plugger tube adapted to: be reciprocably mounted, said plugger tube being provided with an axial bore for receiving the complementary shank of a tool, and a rotatable capV on the end of said tube, said cap having an aperture adapted to register with said bore in one position whereby a shank may be inserted in the bore, said shank having a groove, said cap being also eccentrically mounted so that it may be rotated until a portion of the cap adjacent to the aperture passes into said groove, whereby the tool shank is held in the plugger tube.

' 8. A dental hammer assembly comprising a plugger tube adapted to be reciprocably mounted, said plugger tube being provided with an axial 'bore for receiving the complementary shank of aftool, and a rotatable cap on the end of said tube, said cap having an aperture adapted to register with said bore in one position whereby a shank may be inserted in the bore, Said shank having a groove, said cap being also eccentrically mounted so that it may be rotated until a portion of the cap adjacent to the aperture passes into said groove, whereby the tool shank is heid in the plugger tube, said cap having a stop member for engaging a stop member on the plugger tube, whereby the cap may be rotated into engagement with the stop member to determine the position of registry of the cap aperture with the bore for easy insertion of the tool shank.

9. In a dental hammer assembly the combination of a rear bearing adapted to receive the front bearing of a handpiece and to be secured thereon with a shaft carried by said rear bearing and adapted t be inserted in the collet of the handpiece and secured therein, said rear bearing having a reduced threadedportion and said shaft being provided with a pinion, and a knee member threaded on said reduced portion and having a bore for receiving said pinion, said knee member having another bore at an obtuse angle to said first-mentioned bore and a second shaft adapted to be moved into said latter bore, said latter shaft being provided with a pinion, both of said pinions being provided with tapered teeth whereby the teeth are adapted to be brought into closer engagement with each other to take up wear and prevent backlash.

10. In a dental hammer assembly the combination of a rear bearing adapted to receive the front bearing of a handpiece and to be secured thereon with a shaft carried by said rear bearing and adapted to be inserted in the collet of the handpiece and secured therein, said rear bearing having a reduced threaded portion and said shaft being provided with a pinion, and a knee member threaded on said reduced portion and having a bore for receiving said pinion, said knee member having another bore at an obtuse angle to said first-mentioned bore and asecond shaft adapted to be moved into said latter bore, said latter shaft being provided with a pinion, both of said pinions being provided with tapered teeth whereby the teeth are adapted to be brought into closer engagement with each other to take up wear and prevent backlash, said latter shaft being carried by a bearing member, the end of said latter bearing member and said knee being provided with complementary teeth and a ferrule mounted on said latter bearing member and engaging a shoulder thereon, said ferrule having threads for engaging said knee, whereby the latter bearing member may be secured in any of a multiplicity of rotative positions on said knee.

11. In a dental tool assembly, the combination of a movable shaft. mounted for axial sliding movement, said shaft having a cylindrical bore,

atooljmember having a cylindrical shank with a sliding nt in said bore, and a rotatable cap eccentrically mounted on said tubular shaft and having an aperture `for passing said shank, said shank being formed with an` annular shoulder engaged by said cap when the cap is rotated into an eccentric position to retain the tool shank in the shaft. i

l2. In a dental tool assembly, the combination of a movable shaft mounted for axial sliding movement, said shaft havinga cylindrical bore, a tool member having a cylindrical shankwith a sliding nt in said bore, and a rotatable cap eccentrically mounted on said tubular shaft and having an aperture for passing said shank, said shank being formed with an annular shoulder engaged by said cap when the cap is rotated into an eccentric position to retain the tool shank in the shaft, saidshank'also having a Yreduced cylindrical portion, and said cap` being rotatable until its aperture wedges against said kreduced cylindrical portion to prevent rotation ofthe tool shank in saidshaft.

13. 'In a dental tool assembly, the combination of a hand piece attachment adapted to iit on the end of a hand piece housing having a collet, said attachment having an axial bearing bore, a shaft inl said bore, and projecting backwardly to be engaged by the collet of the dental hand piece, said shaft having a pinion with axially extending angular teeth, an obtuse angle knee member carried by said attachment, and having a cylindrical bore at each end, said knee member terminating in a threaded tubular part having teeth at the end of said tubular part, a right 'angle tool supporting head having a pair of cylindrical bores at right angles to each other, one of which supports a tool, and the other of which has a bearing member which supports a shaft for driving said tool, said latter bearing also supporting a threaded bearing, and said bearing having teeth at its rear end for engaging the teeth on the knee member, said threaded bearing drawing said teeth together for fixedly supporting the angle tool supporting head, with the tool extending in any direction relative to the knee member.

14. A dental plugging tool comprising a metal member provided with a head at its working end, and having a cylindrical shank, said cylindrical shank being provided with a plane end for engaging the end of a supporting tube, and the said cylindrical shank having an annular groove that is rectangular in cross section, the said groove being located adjacent the working end of the tool in the cylindrical shank thereof.

MARTIN S'IAUNT.

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

UNITED STATES PATENTS Number Name Date Re. 11,956 Seeger et al Dec. 17, 1901 347,828 Register Aug. 24, 1886 628,524 Case et a1. July 11, 1899 656,124 Kinnison Aug. 14, 1900 '112,813 Korb Nov. 4, 1902 733,784 Whitney July 14, 1903 1,821,079 Schultze Sept. 1, 1931 2,135,933 Blair Nov. 8, 1938 2,344,605 Droegkamp Mar. 2l, 1944

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