referring now to the drawings , reference numeral 1 indicates one illustrative embodiment of tattooing tool embodying the present invention . the tool 1 includes a motor - driven dental handpiece 3 and a needle / cone assembly 4 . the handpiece 3 includes a motor 5 , a gear drive 7 , and a modified reciprocating head 9 . the motor 5 may be of any standard type , such as air - powered or electrical , and is preferably an electric motor operating at a nominal speed of about 15 , 000 revolutions per minute . the gear drive 7 may be a standard dental handpiece drive , typically having a gear ratio of 1 : 1 . the modified head 9 may be similar to the head shown in u . s . pat . no . 3 , 552 , 022 to axelsson , and will be described in greater detail hereinafter . the motor 5 , drive 7 and head 9 are contained in separate housings all of which are connected to each other by standard fittings to form a handpiece having a housing indicated generally at 11 . the head 9 includes a generally cylindrical housing 13 having at one end a standard connector 15 for connecting the head 9 to the drive 7 . at its free end , the cylindrical housing 13 communicates with a perpendicular oscillator housing 17 . an oscillator mechanism 19 is threaded into the free end of the head housing 13 as shown in fig1 . the oscillator mechanism 19 includes an oscillator bearing 21 , a shaft 23 in the bearing 21 , a connector 25 on the shaft 23 for drivingly connecting the shaft 23 to the drive 7 , and a cam 27 on the free end of the shaft 23 . the cam 27 includes an eccentric lug 29 extending into the oscillator housing 17 . the oscillator housing 17 includes a cylindrical bore 31 having a step 33 at its rearward end and internal threads 35 at its forward end . a bearing 37 is tightly fitted in the bore 31 , against the step 33 . the bearing 37 includes a depending tail 39 . a retaining tube 41 is slidably mounted in the bearing 37 . as shown in greater detail in fig5 and 6 , the retaining tube 41 is in the form of a tube having a forward annular rib 45 and a rearward annular rib 47 , spaced apart sufficiently to receive the lug 29 between them . the rearward rib 47 is cut away to form a flat 49 which cooperates with the tail 39 on the bearing 37 , thereby preventing rotation of the retaining tube 41 in the bearing 37 . the retaining tube 41 is preferably formed of stainless steel . as thus far described , the device 1 is a dental handpiece of a type sold by young dental manufacturing company as its dawn eva handpiece . the retaining tube 41 , as shown in fig5 and 6 , is modified by four longitudinal cuts extending from the rearward end of the retaining tube 41 to the forward rib 45 to form a pair of fingers 51 . the fingers 51 are bent inwardly at their free ends . an adapter 53 is threaded into the forward end of the oscillator housing 17 . the rearward end of the adapter 53 includes an internal bearing 55 for the retaining tube 41 . the forward end of the adapter 53 includes internal threads 57 . the adapter 53 is made of stainless steel . the needle / cone assembly 4 includes a needle assembly 61 and a cone structure 63 . the needle assembly 61 includes a needle carrier 65 and three needles 67 carried by the carrier 65 . the carrier 65 has a thin tubular forward part 69 , an annular shoulder 71 , a rearwardly - facing abutment 73 , a body part 75 , a thin frangible neck 77 , and a cap part 79 having a rim 81 . a blind axial bore 83 extends through the forward end of the carrier 65 into the body part 75 . the three needles 67 are accurately aligned with each other in the form of an equilateral triangle , are fitted snugly into the bore 83 , and are glued into the bore 83 . the needle carrier 65 is machined from aluminum . the needles are nickel - plated carbon steel . the cone structure 63 includes a frustoconical part 85 at its forward end , a collar part 87 , a threaded plug part 89 , and a rearward cylinder 91 . the frustoconical part 85 is turned inwardly somewhat at its forward , free , end to form an ink reservoir . breather holes 93 are provided at the rear of the frustoconical part 85 . the cone structure 63 is formed of aluminum . the needle assembly 61 is assembled to the cone structure 63 , with the shoulder 71 in the cylinder 91 of the cone structure 63 and with the needles in the frustoconical part 85 . the entire free rearward edge of the cylinder part wall is swaged inwardly as shown at 92 , to trap the needle assembly shoulder 71 in the cylinder 91 . the shoulder 71 is somewhat smaller than the inside diameter of the cylinder 91 , to permit free reciprocation of the needle assembly in the cone structure . an installation tube 95 is inserted into the frustoconical part 85 of the cone structure 63 and abuts the forward end of the needle carrier 65 . the tube is pinched slightly out of round , as shown at 96 , to hold it snugly in the frustoconical part , with its end pushing needle assembly to its rearward - most position in the cone structure . the tube 95 performs the dual function of protecting the needles 67 and aiding in the installation of the needle / cone assembly as described hereinafter . the installation tube 95 is made of stainless steel . the needle / cone assembly 4 , including the installation tube 95 , is assembled , sterilized , and packaged in a sterile container . in use , the needle / cone assembly 4 is removed from its packaging and inserted into the adapter 53 and oscillator housing 17 . the threads 89 on the cone structure 63 are threaded into the threads 57 until the collar part 87 abuts the forward end of the adapter 53 . as the cone structure 63 is threaded onto the head 9 , the cap 79 on the needle carrier 61 is forced between the fingers 51 of the needle retaining tube 41 . to ensure complete insertion of the needle assembly 61 into the retaining tube 41 , the installation tube 95 is pushed rearwardly into the oscillator housing 17 before the tube 95 is removed . when the needle assembly 61 is completely inserted into the retaining tube 41 , the abutment 73 on the needle assembly 61 engages the forward end of the retaining tube 41 , and the fingers 51 tightly engage the cap 79 , on the forward side of the rim 81 . the body 75 of the needle carrier 65 fits snugly in the retaining tube 41 . the fingers 51 perform the dual functions of locking the needle assembly axially with respect to the retainer tube 41 and of locking the needle assembly 61 against rotation . upon application of a rotational force on the needle assembly 61 , the stainless steel fingers 51 tend to dig into the softer aluminum to provide positive locking . the tattooing device 1 is used in a conventional manner . rotation of the motor 5 is transmitted through the drive 7 and connector 25 to the cam 27 . the cam lug 29 reciprocates the retaining tube 41 at approximately 15 , 000 cycles per minute , thereby causing the needles 67 to be driven into and out of the frustoconical part 85 . the frustoconical part 85 is dipped in ink in a conventional manner , and the ink is held in the frustoconical part and carried on the tips of the needles 67 . the breather holes 93 prevent the ink from being drawn into the cylinder 91 . at the maximum forward stroke , the needles 67 extend about 1 . 5 millimeters from the end of the frustoconical part 85 . when a particular tattooing job has been completed , the needle / cone assembly 4 is unscrewed from the adapter 53 . when the needle / cone assembly is backed out partially , the turned edge 92 of the cylinder 91 engages the shoulder 71 . continued unscrewing of the needle / cone assembly 4 causes the neck 77 to be snapped . the cap 79 is then able to fall out of the rearward opening of the oscillator housing 17 , when it is pushed by a new needle / cone assembly &# 39 ; s being inserted into the device 3 . it will be seen that the position of the needles is accurately controlled by the bearings 37 and 55 , the fit of the needle carrier 65 in the retaining tube 41 , and the secure permanent bonding of the needles in the bore 83 of the needle carrier 65 . in use , the needle assembly does not touch the cone structure . because the needle / cone assembly may be pre - sterilized and requires no handling of the needles during assembly , sterility is easily maintained . automatic breakage of the frangible neck 77 ensures that needles , once removed , will not be reused . the accidental use of dull or unsanitary needles is thus prevented . the neck may easily be made strong enough for ordinary use , yet readily breakable upon removal of the needle / cone assembly . should the neck break in use , the needles would no longer be driven , but would not fall out of the device . numerous variations in the tool and needle assembly of the present invention , within the scope of the appended claims , will occur to those skilled in the art in light of the foregoing disclosure . for example , other single use tools could be substituted for the needle assembly . other drive devices could be used . other materials may be employed . these variations are merely illustrative .
a reciprocating tool in the nature of a dental handpiece is modified to carry a needle / cone assembly for use as a tattooing device . the needle / cone assembly includes a needle assembly trapped in a cone structure . the needle assembly includes a cap portion which is held by fingers in the handpiece to prevent rotation of the needle assembly , and a frangible neck which is broken on removal of the needle / cone assembly from the handpiece to prevent reuse of the needle assembly . a removable protective tube around the needles acts also as an insertion tool for the needle assembly .