US3150068A

US3150068A - Electrolytic etching device

Info

Publication number: US3150068A
Application number: US69138A
Authority: US
Inventors: William J Montgomery
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-11-14
Filing date: 1960-11-14
Publication date: 1964-09-22
Anticipated expiration: 1981-09-22

Description

p 1964 w. J. MONTGOMERY ELECTROLYTIC ETCHING DEVICE 2 Sheets-Sheet 1 Filed Nov. 14, 1960 Maw INVENTOR 0 N f m w M? M w W L J p 22, 1964 w. J. MONTGOMERY 3,150,063

ELECTROLYTIC momma DEVICE Filed Nov. 14. 1960 2 Sheets-Sheet 2 I Will/I10 IN VEN TOR.

. y BY W/'///ZIm J Mo/nfqame/y A TTORNEYS' United States Patent 3,350,968 ELECTRGLYTIC ETCHHNG DEVECE William 3. Montgomery, IUD. 4, Benton, Pa. Filed Nov. 14, 1960, Ser. No, 69,138 13 Claims. (Ci. Mid-224) This invention relates generally to the art of etching and is directed particularly to improvements in apparatus for effecting the etching of metal by electrolytic action.

A presently employed procedure for applying letters, numbers, designs, code markings and the like to metallic surfaces by electrolytic action involves the use of stencil tapes which are moistened with a suitable electrolyte and are then placed upon an electric current conducting body beneath a frame which outlines the character to be etched and the metallic body is then placed over and upon the frame and a low amperage electric current is caused to pass through the supporting body through the moistened stencil and into and through the metal body so as to efiect the transfer of the character to the surface of the metal body. This procedure has many undesirable features associated with it, among which are that the operator is required to pick up the moistened stencil tape and place it in the correct position beneath the frame and upon the underlying current conducting support, which is in the form of a carbon block, holding the ends of the tape in his hands while moving it to the proper position under the frame.

The tape in the wet condition is awkward to pick up and will twist and become wrinkled so that the operator has difficulty in getting it in the proper position. In addition, having to handle the tape moistened or saturated with the electrolyte, the operators hands and fingers are at all times wet with the electrolyte.

It is a particular object of the present invention, in view of the foregoing, to provide a new and novel apparatus whereby metallic material may be etched by the use of conventional tapes, wherein the operator is able to position the stenciling tape properly upon the supporting carbon block and moisten the tape with the required electrolyte and carry out the etching operation, without having to handle the wet tape and without getting the elec' trolyte on his hands.

A further object of the invention is to provide apparatus for carrying out an etching operation by the employment of electrolyte moistened stencil tape wherein means is provided for maintaining the tape in a desired taut condition across the carbon supporting block and wherein means is also provided for effecting the longitudinal shifting of the taut tape so as to bring selected characters into proper position for transfer by electrolytic action to a metal body.

Still another object of the invention is to provide an apparatus for maintaining a stencil tape in a straightened out, taut condition across the top of the current conducting carbon body as above set forth, wherein the tape holding and supporting means may be adjusted to apply just the right amount of tension to the tape and wherein means is provided for supporting the adjustable tape tensioning means so that such means with the tape may be moved as a unit with respect to the current conducting block over which the tape lies.

A still further object of the invention is to provide a new and novel means for adjustably securing to a suitable support, the current conducting carbon block through which the current is passed to and through the tape and into the body to be etched, whereby the carbon body can be shifted as desired transversely of the tape supporting means so as to bring the supporting means for the tape and the supporting means for the carbon block into a proper cooperating relationship.

3,150,068 Patented Sept. 22, 1964 The invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawings forming a part of this specification with the understanding, however, that the invention is not confined to a strict conformity with the showing of the drawings but may be changed or modified so long as such changes or modifications mark no material departure from the salient features of the invention as defined by the appended claims.

In the drawings:

FIG. 1 is a View in side elevation of apparatus constructed in accordance with the preferred embodiment of the present invention showing the apparatus mounted upon and secured to a supporting table or the like.

FIG. 2 is a view in top plan of the apparatus.

FIG. 3 is a longitudinal section taken substantially on the line 33 of FIG. 2.

FIG. 4 is a sectional view taken substantially on the line 4-4 of FIG. 3.

FIG. 5 is a top plan view on an enlarged scale of the central portion of the apparatus.

FIG. 6 is a sectional view taken substantially on the line 6-6 of FIG. 5.

FIG. 7 is a perspective view illustrating a modified mounting for the carbon block for facilitating vertical adjustment of the same.

FIG. 8 is a detail view illustrating another mounting for the carbon block by which the latter may be vertically adjusted.

The invention broadly contemplates the provision of at least one pair and possibly several pairs of spaced clamps which are positioned on opposite sides of a carbon block or other suitable supporting means through which an electric current may be passed and over and upon the top of which the stencil tape is supported. The stencil tape is secured at its two ends in these clamps and the clamps are in turn supported upon a slide or carrier suitably guided whereby it can be given rectilinear movement so as to shift the supported clamps and efiiect the longitudinal movement of the stencil tape across the current conducting carbon supporting block.

Means is also provided whereby the clamps are adjustably held upon the carrier slide, to be moved or adjusted longitudinally of the slide so as to apply desired tension to the stencil tape.

The tape clamps are of novel construction whereby the ends of the tape can be easily and quickly placed in position and secured and in addition a novel means is provided for clamping the carbon block base in such a way that it can be readily shifted or adjusted transversely of the line of movement of the clamp supporting slide and the stencil tape.

The drawings illustrate a preferred embodiment of the apparatus wherein there is provided an elongate slide box which is generally designated 10 and which is here illustrated as supported upon and secured to a suitable sup porting structure generally designated 12, such as a work table or the like.

The slide box is here illustrated as providing guide ways for two slide members and accordingly a two slide member structure will be described, although it is to be understood that the invention is not limited by reason of such description since an apparatus may be employed having only a single slide member and slide box or guide means or a slide box or guide means may be provided for carrying any desired number of slides.

The slide box illustrated is of substantial length as shown and comprises the bottom 14, upstanding longi- 0 tudinal side walls 16 and end walls 18.

For maintaining the box in position the bottom 14 is provided adjacent to its ends with suitable apertures for c.) the extension therethrough of securing screws 2t for engagement into the underlying table 12. This, of course, is only one of any number of ways that the box may be secured in working position and, of course, is not intended to be in any way limiting.

The slide box is here shown as having two spaced parallel guides 22 which are formed by providing the thin longitudinally extending division wall 24 spaced centrally between the side walls 16 and engaged at its ends in the vertical slots 26 formed in the inner faces of the end walls as best seen in FIG. 2.

Each of the guides 22 has positioned therein for longitudinal movement the elongate slide bar 28. This slide bar, while of substantial length, is materially shorter than the guide 22 and is located so that it may have a substantial degree of longitudinal movement therein.

To facilitate the smooth longitudinal movement of the slide bar, each end thereof is recessed as at 30 and in each recess is mounted on a transverse pivot pin 31, a roller member 32.

The slide bar 28 supports a pair of tape clamps, each of which is generally designated 33. The support for the clamps on their respective slide bars is such that the clamps may be readily shifted longitudinally of the slide bar while maintaining a proper central position thereon.

A preferred method of supporting the clamps 33 upon their respective slide bars so that they can be adjusted and maintained in proper alignment therewith comprises a rib or tongue '34 which engages in a slot in the clamp in the manner about to be described.

The clamps 33 are mounted upon the slide bar in pairs and each clamp comprises the body 35 of approximately the same Width or thickness as the slide bar upon which it rests and each of the bodies includes a rearwardly extending portion or tail piece 36 and a forwardly projectir'ig portion 37. The body 35 of each clamp has a tongue receiving groove 38 in the bottom edge thereof which groove extends into the tail piece 36. The forwardly extending portion 37 of the clamp lies above the tongue of the supporting slide bar as is clearly shown in FIG. 3.

The tail portion or tail piece 36 of each clamp has a longitudinal slot 39 therein which slot opens through the top and bottom portion of the tail piece and this slot receives or has extended therethrough a clamping bolt 4-0 which is threaded into a bore 41 in the underlying slide bar 28. The slot 39 is of a width greater than the diameter of the bolt so that when the bolt is loosened by being threaded outwardly in the bore 41 the head of the bolt will rise from the top of the tail piece and the clamp may then be shifted longitudinally on the slide bar within the limits of the longitudinally extending slot 39.

Each clamp body 35 has formed therein from the top the drilled and tapped hole or bore 42 in which is threaded a pin 43 which functions as a handle for facilitating the sliding adjustment of the clamp. This pin may be of metal or of any other suitable material which will serve the desired function.

The forwardly extending or inwardly extending portion 37 of each clamp body has cut therein and transversely thereof the angulated slot '44, the inner end of which opens into a transverse drill hole 45 for the purpose hereinafter described. As shown this angulated slot 44 comprises an inner end portion a and the forward angularly extending entrance portion 12. The slot 44 is formed of gradually increasing width, being narrowest in its outer end b, which end opens through the inner face of the clamp body portion 37 close to the top of such portion and gradually increasing in width toward the transverse bore or hole 45. Also as is shown, the portion b of the slot slopes downwardly from the top of the body portion 37 of the clamp, for a desired distance and then continues into the portion a which is substantially horizontal. Thus there is provided by the slot 44 a flexible tongue portion 46 which is adapted to be drawn down into clamping engagement with an end of a stencil tape inserted into the open end of the slot portion 12 in the manner about to be described.

The tongue 4-6 of the clamp is drawn down by a headed bolt 47, the shank portion of which is extended downwardly through the oversize bore 48 for threaded engagement in the drilled and tapped bore 49 in the part of the clamp body 37 below the tongue.

In referring hereinabove to the Width of the angulated slot 44, reference is had to the spacing between the top and bottom surfaces of the slot and not to the distance of the slot from one side of the clamp body portion 37 to the other. It will, of course, be understood that the clamps 33 may be formed of any material suitable for functioning as desired in this apparatus, preference being had for the plastic Lucite as this is not only uneffected by moisture of any kind and particularly by the electrolyte used with the apparatus, but it also gives a pleasing appearance in the structure. Lucite is also of a character which will provide necessary flexibility for the small bending or flexing movement of the tongue 46 when the head of the bolt 47 is drawn down to clamp an end of a stencil tape in the portion 1) of the clamping slot.

The bore or passage 45 is formed transversely through the clamp body to reduce the possibility of the plastic material breaking or cracking when the tongue is flexed.

It is also preferred that the slide bar 28 be formed of the same type of plastic above referred to. However, it is to be understood that while this type of plastic is preferred, it is not intended that by specifying plastic generally or the specific type named, there is any intention to limit the invention to the use of these materials, since it will be apparent that there are other mateials which would function efliciently.

The numeral 54) generally designates the stencil tape which carries a number of characters of any desired form or type which may be desired to apply to a metal body. Such characters are here illustrated as being in the form of letters of the alphabet, designated 51 but it is to be understood that such characters may be numbers, code characters or special designs. This type of stencil tape used in electrolytic etching is of standard and well known character. Accordingly, no detailed description of the same is believed to be necessary to an understanding of the operation of the present invention.

The tape 50 when put into use is connected between a pair of clamps 33 which are mounted upon a slide 28 and the ends of the tape are secured to the clamps by being extended into the open ends of the clamp slots 44 and then secured down by the flexible clamping tongues 46.

interposed between the inner portions 37 of the pair of clamps between which the stencil tape is held is the electrode unit and supporting base, which electrode unit is generally designated 52 and the supporting base is generally designated 53.

The electrode unit 5.2 comprises a body of electrically conductive material which is conventionally in the form of a carbon block body 54.

The electrode base 53 is preferably in the form of a rectangular body or plate 55 formed of Lucite or other suitable plastic or other noncorrosive material upon the top of which the electrode 54 is secured in the manner about to be described.

The electrode base extends across the guide or guides 22 above and spaced from the top or tops of the underlying slide bar or slide bars depending upon whether there are one or more, in the following manner. Means is provided for the support of the base 53, which means in the present instance consists of the side walls 16 of the slide box 15). Each side wall is formed or provided with a long recess 56 in the top edge thereof in which the electrode base positions and one end of each of the two recesses 56 in which the base is supported, is undercut as designated at 57 while the opposite end of the recess preferably is vertical as indicated at 58.

The body 55 of the electrode base has its opposite longitudinal or side edges beveled as indicated at 59 and one of these bevels corresponds in its angular disposition with the angle of the undercut end 57 of the recesses 56 so as to form the conventional dovetail connection between the walls of the box and the base. The opposite longitudinal beveled edge of the electrode base body 55 may be of the same slope or angle as that engaging the undercut end 57 of the slot and this other beveled side of the base is engaged by a pair of clamp bars 60, each of which is adapted to position in the recess 56 between the straight or vertical end 58 and the adjacent beveled side of the base body 55. Each of these clamp bars has its inner end beveled or sloped as indicated at 61 and the bars 60 are of a length slightly greater than the length of the open space between the vertical end 58 of the recess and the adjacent side of the base body and the clamping bars are secured in clamping position against the base body 55 by screws 62 which extend downwardly therethrough through oversize holes or bores for threaded engagement in the bottom of the recess 56. Since the clamping bars 60 are of such length that they cannot be drawn down flat onto the bottom of the recess 56, it will be seen that they will apply a camming action against the base body 55 to force the opposite side thereof into engagement with the undercut face 57 and the base body will thus be held against shifting movement transversely of the box walls as Well as against movement out of the recesses.

The carbon electrode block 54 is of rectangular form and is disposed upon the top of the base body 55 with its long sides parallel with the beveled longitudinal sides 59 of the base body as is clearly shown in FIG. 5. This carbon electrode block is positioned upon a copper terminal plate 62 which rests upon the base body 55 as shown in FIG. 6 and a portion of this plate is extended beyond one end of the electrode block forming the terminal tongue 63 which carries a binding screw 64.

The carbon electrode block 54 is provided with suitable vertical bores 65 for extension therethrough of securing bolts 66 which pass through aligned openings in the terminal plate 62 and into tapped and threaded openings 67 in the base body 55 as shown in FIG. 6.

At the opposite end of the electrode block 54 from the terminal tongue 63, the base body 55 has secured thereto the lower end portion 63 of a spring terminal which is generally designated 67. This spring terminal is of substantially C shape and stands vertically with the rounded top portion 69 thereof normally at a substantial elevation above the top of the terminal block 54. The bottom portion 66 of this terminal is secured to the base body 55 by the headed bolt 7%) which is threaded into the drilled and tapped opening 71 in the base body as shown in FIG. 6.

The carbon electrode block 54 has the top surface thereof transversely curved or arced as indicated at 72, the arc of curvature extending from one long side of the block to the other as shown in FIG. 3 and this arcuate or curved top surface had secured thereon a pad '73 of a suitable absorbent material to retain a suitable amount of electrolyte for establishing the necessary electrolytic action and conduction of current from the carbon electrode block to a metal body placed upon the top of the pad.

Any suitable means may be employed for securing the absorbent pad to the top of the carbon block 54, such means here being illustrated as comprising an elastic band 76 or the like extending around the top of the block and across end portions of the pad which are extended downwardly along the ends of the block as shown in FIG. 6. Overlying the absorbent pad 73 is a sheet of waterproof or non-absorbent material which is generally designated '74 and which has one or more openings or cutout portions therein forming a window or windows 75 beneath which the character carrying tape passes as shown in FIG. 5. These windows are of sufiicient size to disclose the entire character which is to be etched on the metal base.

Since the electrolyte liquid is applied to the absorbent pad to facilitate carrying out the etching process, there is a possibility of an excess of the electrolyte running down onto the surface of the carbon electrode base body 55 and in order to prevent this excess material from flowing into the box or onto the surface to which the apparatus is secured, the top of the body 55 is provided along each longitudinal side with a gutter slot 77 to carry off beyond the outer sides of the box any of the liquid entering therein.

Any suitable means may be employed for securing the waterproof shield sheet 74 in place upon the top of the absorbent pad but the means here illustrated comprises carrying the ends of the sheet down along the ends of the carbon block in the same manner as the ends of the absorbent strip 73 are placed and securing the ends of both of these pieces of material by the hereinbefore referred to elastic band 76 as illustrated.

In the operation of the apparatus it is conventional to use a suitable power pack for transforming AC. to D.C., where an AC. source of electricity is employed for supplying the electric current, so as to obtain the necessary low amperage. Since the electrical system in which the apparatus is used forms no part of the invention no illustration of the same has been given or is believed to be necessary.

The

terminals

63 and 67 have merely been illustrated with portions of electric

current conductors

63a and 67a attached thereto through which current is supplied on one side to the carbon electrode body 54 and in the performance of the etching operation the circuit is completed by the application of the metal body to be etched upon the top of the windowed absorbent pad cover 74 and in contact with the resilient terminal 67. FIGS. 5 and 6 show in broken outline a body which is designated M, which is representative of any metal body such as a metal tool or the like which is to have a character etched into the surface thereof. When the pad 73 is suitably saturated with the electrolyte by having a few drops thereof deposited thereon through the window opening or openings and the metal body M is placed over the window openings to contact the wet pad and the resilient terminal 67, then the direct current charge will flow through the terminal box 54 to the metal body through the circuit completing electrolyte to effect the transfer to the metal body of the symbol exposed in the tape through the window opening '75.

It will, of course, be obvious that if any single letter, number or other symbol is to be applied to the metal body, only one tape need be used, but if a pair of letters, numbers or other characters are to be applied to the body, then two or more tapes may be used and, of course, the number of window openings will be increased to correspond with the number of tapes and the number of symbols to be etched in side-by-side relation in the metal body.

FIGS. 7 and 8 illustrate two modifications of the supporting means for the carbon electrode block, which permit the block to be vertically adjusted. With these vertical adjustments in association with the means for moving the carbon block supporting base transversely of the tapes it will be seen that the flexibility of the apparatus is greatly increased since the height of the carbon block can be adjusted as may be desired to obtain the best results in the operation of the apparatus.

In FIG. 7 the carbon block is generally designated 78 while the underlying supporting base is generally designated 79. The block is supported upon the base 79 by a U-braclret which is generally designated 8% and which comprises the bottom plate portion 81 and the upstanding parallel arms 82. These arms 82 are provided with vertical slots 83. The plate portion 81 of the bracket is secured to the base 79 by bolts 84. The carbon block is positioned between the upstanding arms 82 of the bracket and it is provided with a suitable longitudinal bore 85 to have extended therethrough the shank portion of a headed bolt as which also extends through the slots as shown so that the head of the bolt engages the outer side of the one upstanding arm $2 While the the opposite end of the bolt which is screw threaded extends through the slot in the opposite arm to receive a wing nut 87 which, when threaded onto the bolt, bears against the adjacent arm and effects the tightening of the arms against the block. With this arrangement it will be seen that by loosening the wing nut the carbon block may be raised or lowered as desired.

In FIG. 8 the means for vertically adjusting the carbon block consists in providing the base body 83 upon which the carbon block 39 is mounted, with four drilled and tapped bores 90 extending vertically therethrough, two at each end of the body es and directed toward the bottom of the recess 91 of the underlying box side wall 92. Adjusting bolts 93 are threaded downwardly through the bores 99 for engagement with the underlying bottom of the channel.

While FIG. 8 illustrates only two of the adjusting bolts 93 positioned for engagement with the bottom of the recess 91 with one side wall 92 of the box, it will be understood that the opposite side wall carries a corresponding recess which has the bottom thereof engaged by a similar pair of adjusting bolts at the other end of the body 88. Each of the recesses 91 also has placed therein a clamping bar 94- corresponding with the previously described clamping bars 69, the inner end of which bar 94 rests against the beveled side of the adjacent carbon block supporting body 88 in the manner shown and the bar being secured in place by screws 95 passing downwardly therethrough into the bottom of the recess 91.

As will be readily apparent, when the clamp bars 94 carried by the side walls of the box in the recesses thereof are loosened so that their inner or beveled ends can be raised, then by properly turning the four adjustment bolts 93, two only of which are shown as above explained, the carbon supporting base 38 may be elevated to the desired extent and the clamping bar then resecured by screwing down the holding screws 95. Lowering of the carbon block supporting base would, of course, involve the reversal of this operation by turning the bolts 93 in the proper direction and then following up the base by the clamping bars, by screwing or turning down the securing screws 95.

It will be obvious from the foregoing that in setting up the tapes for operation of the apparatus one end of the tape is secured in one clamp 33 and the other end is then threaded between the absorbent pad 73 and the overlying windowed sheet 74 and then carried on to the other clamp where it is secured in the manner hereinbefore described. Any slack in the tape may be taken up by loosening one of the clamp bolts 4% and shifting that clamp away from the other clamps so as to draw the tape taut after which the bolt 4% is tightened down to hold the clamp in adjusted position on the slide bar 28.

The tape after being placed in position as described may then be shifted lengthwise across the carbon electrode by moving the entire slide bar 28 and the clamps thereon so as to progressively bring the letters or other characters into position for exposure through the window opening 75 beneath which the tape lies.

In. setting forth the present invention reference has been made to the use of a stencil tape and electrolyte eases for carrying out the desired etching operation. No spev cific type of electrolyte is herein set forth, however, first for the reason that the electrolyte itself forms no part of the invention and secondly for the reason that in this 3 type of etching diiferent electrolyte formulas must be used according to the type of metal to be etched.

In addition to the foregoing the stencil tape has only been generally referred to. Here again, the tape forms no part of the invention since such tapes are of well known character. These tapes or stencils are made ac cording to special processes and are of high dielectric value through which the electrolyte fluid contacts the part to be marked. In carrying out the process a low amperage, low voltage current passes through the electrolyte to electrically dissolve out the metal in the shape of the characters in the stencil to the desired depth in a mater of seconds. The mark is made without stress, strain or deformation of the most precise metallic surface. The process is similar in many respects to electroplating, except that polarity is reversed so that metal is removed from the part being marked, rather than depositing metal as in plating.

While in the illustration and description of the invention reference has been made to the rollers 32 for supporting the slide bar or bars and this construction is preferred, nevertheless it is to be uncerstood that the invention will function satisfactorily by having the bars 28 rest fiat upon the bottom 14 of the box to slide thereon and therefore it is to be understood that the invention is not limited to the use of the rollers in question.

It will be seen from the foregoing that the present invention provides a relatively simple but highly effective means whereby the stencil tape can be easily and efficiently handled or manipulated without requiring that the operator handle the tape to the extent that is necessary at the present time in following out the presently employed procedure and also without requiring that the operator get the electrolyte on his hands. By maintaining the tape in the proper degree or" tightness across the top of the carbon electrode block the tape can be readily shifted as required to accurately bring the desired symbol or character into position for exposure through the masking window.

I claim:

1. In apparatus for electrolytically etching metal by use of an electrolyte moistened stencil character carrying tape lying across the top of a carbon electrode from which electric current is caused to pass through the stencil tape to a metal body lying thereon, spaced clamping means each formed to provide cooperating jaws for gripping an end of a flexible stencil tape lying on and across the electrode, said means being relatively adjustable for drawing the tape to a taut condition, means for moistening the tape in the part thereof lying on the electrode, and means for reciprocably rectilinearly moving said clamping means and tape relative to the electrode for selectively positioning stencil characters on the tape relative to the top of the electrode, whereby an operators hands may be kept free for positioning a metal body upon the tape and electrode for stenciling and also kept free of contact with the electrolyte.

2. Apparatus according to claim 1 for electrolytically etching metal by use of an electrolyte moistened stencil character carrying tape lying across the top of a carbon electrode from which electric current is caused to pass through the stencil tape to a metal body lying thereon, wherein the said means for moistening the tape consists of an electrolyte absorbent body supported upon the top of the electrode.

3. Apparatus for selectively etching metal through an electrolyte moistened stencil tape, said apparatus comprising in combination with an electrode body upon which a moistened stencil tape is placed for the passage of electric current therethrough from the body into a metal element placed on the top thereof, a supporting base for said electrode body, a pair of spaced clamptmembers having said electrode body spaced therefrom and interposed therebetween, said clamp members being adapted to grip the ends of and hold taut a stencil tape extending across and engaging the electrode body, and means for moving the clamp members and a tape connected therebetween as a unit relative to the electrode body, the said means comprising a slide member beneath and supporting said clamps.

4. Apparatus for selectively etching metal through an electrolyte moistened stencil tape, said apparatus comprising in combination with an electrode body upon which a stencil tape is placed to be moistened with an electrolyte for the passage of electric current therethrough from the body into a metal element placed on the top thereof, an elongate supporting base having said electrode body mounted thereon, a pair of bodies, means supporting the bodies on the base in spaced relation one with the other and having said electrode body positioned therebetween and in spaced relation therewith, means for securing to said spaced pair of bodies the ends of a stencil tape and for supporting the tape at an elevation to lie on and across the top of the electrode body, means for relatively adjusting said pair of bodies on the supporting means therefor to draw into a taut conditon a tape connected therebetween, and means connecting the said supporting means for the pair of bodies for shifting the bodies as a unit together with a tape connected therebetween relative to the electrode.

5. In apparatus for carrying out an electrolytic etching operation on metal wherein use is made of a stencil tape through which electrolyte fluid contacts a part to be etched, a carbon electrode, a supporting base for the same, means for connecting said electrode with one side of an electric circuit, an electric terminal supported on the base adjacent to the electrode for connection with the other side of such circuit, an electrolyte absorbent body supported by said electrode, a pair of members disposed in spaced relation and having said electrode located therebetween, means forming a part of each of said members for securing to each member an end of a stencil character carrying tape, said members being adapted to support a tape connected therebetween at an elevation to pass over and in contact with said absorbent body, an elongate member disposed beneath and supporting said spaced members, means for moving said elongate member rectilinearly, and means for adjusting the positions of said pair of members relative to one another and with respect to the elongate supporting member whereby a stencil carrying tape may be drawn into a relatively taut condition across and in contact with the absorbent body.

6. The invention according to claim with a guide means for said elongate member for maintaining the latter against lateral movement during its rectilinear movement.

7. The invention according to claim 5 with means for adjustably shifting said carbon electrode supporting base transversely of the said pair of spaced members.

8. The invention according to claim 5 with means for effecting the vertical adjustment of said carbon electrode.

9. In apparatus for carrying out an electrolytic etching operation on metal wherein use is made of a stencil tape through which electrolyte fluid contacts a part to be etched, a carbon electrode, a supporting base for the same, means for connecting said electrode with one side of an electric circuit, an electric terminal supported on iii the base adjacent to the electrode for connection with the other side of such circuit, an electrolyte absorbent body supported by said electrode, a slide bar, a pair of relatively flat bodies disposed on edge and in spaced rela tion longitudinally of and upon said bar, means forming a guide channel lying below said electrode supporting base and having said bar positioned therein for longitudinal movement, means whereby at least one of said bodies may be adjusted on and longitudinally of the slide bar relative to the other body, means for securing said one body in adjusted position on the slide bar, means supporting said base between and in spaced relation to said bodies above the slide bar, and means whereby an end portion of a stencil tape may be releasably secured to each of said bodies at an elevation to extend across the top of the carbon electrode block, said last means comprising a slot formed in each of said bodies from an end thereof adjacent to the carbon electrode body whereby a portion of the body above the slot forms a flexible gripping tongue and means for efliecting the flexing of the gripping tongue relative to the lower part of the slot whereby to secure in the slot an end of the stencil tape.

10. The invention according to claim 9, wherein the said means for supporting the electrode base comprises a pair of upstanding spaced and parallel wall members in the top edge of each of which a recess is formed, said base resting in said recesses and spanning the space between said wall members and a clamping element in each recess interposed between a side edge of the base member and an end of the recess and securing the base member in the recess by forcing the opposite edge of the base member against the other end of the recess.

11. The invention according to claim 10, wherein the said opposite end of the recess is undercut and the adjacent edge of the base is beveled to engage in the undercut and wherein the said one edge of the base member is beveled and the clamp member adjacent thereto has a beveled end engaging against the adjacent beveled edge of the base.

12. The invention according to claim 9, wherein said electrode supporting base has a top surface provided with electrolyte drainage gutters lying on opposite sides of the carbon body electrode.

13. The invention according to claim 9, wherein said spaced bodies and the slide bar upon which the bodies are supported have a tongue and groove coupling one with the other whereby to facilitate movement of at least one of the pair of bodies in a straight path along the slide bar.

References Cited in the file of this patent UNITED STATES PATENTS 312,384 Richter Feb. 17, 1885 1,324,044 Harris Dec. 9, 1919 2,884,853 Cantoni May 5, 1959 2,943,562 Phillips July 5, 1960 OTHER REFERENCES Marking Precision Parts, Bulletin of the Lectroetch Company, 1727 Doan Ave., Cleveland 12, Ohio (1943) (two sides).

Claims

1. IN APPARATUS FOR ELECTROLYTICALLY ETCHING METAL BY USE OF AN ELECTROLYTE MOISTENED STENCIL CHARACTER CARRYING TAPE LYING ACROSS THE TOP OF A CARBON ELECTRODE FROM WHICH ELECTRIC CURRENT IS CAUSED TO PASS THROUGH THE STENCIL TAPE TO A METAL BODY LYING THEREON, SPACED CLAMPING MEANS EACH FORMED TO PROVIDE COOPERATING JAWS FOR GRIPPING AN END OF A FLEXIBLE STENCIL TAPE LYING ON AND ACROSS THE ELECTRODE, SAID MEANS BEING RELATIVELY ADJUSTABLE FOR DRAWING THE TAPE TO A TAUT CONDITION, MEANS FOR MOISTENING THE TAPE IN THE PART THEREOF LYING ON THE ELECTRODE, AND MEANS FOR RECIPROCABLY RECTILINEARLY MOVEING SAID CLAMPING MEANS AND TAPE RELATIVE TO THE ELECTRODE FOR SELECTIVELY POSITIONING STENCIL CHARACTERS ON THE TAPE RELATIVE TO THE TOP OF THE ELECTRODE, WHEREBY AN OPERATOR''S HANDS MAY BE KEPT FREE FOR POSITIONING A METAL BODY UPON THE TAPE AND ELECTRODE FOR STENCILING AND ALSO KEPT FREE OF CONTACT WITH THE ELECTROLYTE.