US2529250A

US2529250A - Stenciling machine for applying luminous paint

Info

Publication number: US2529250A
Application number: US702557A
Authority: US
Inventors: Rufus G Fordyce
Original assignee: Luminous Processes Inc
Current assignee: Luminous Processes Inc
Priority date: 1946-10-10
Filing date: 1946-10-10
Publication date: 1950-11-07
Anticipated expiration: 1967-11-07

Description

Nov. 7, 1950 R. e. FORDYCE 2,529,250

STENCILING MACHINE FOR APPLYING LUMINOUS PAINT Filed Oct. 10, 1946 6 Sheets-Sheet 1 Nov. 7, 1950 R. e. FORDYCE 2,529,250

STENCILING MACHINE FOR APPLYING LUMINOUS PAINT Filed Oct. 10, 1946 6 Sheets-Sheet 2 Nov. 7, 1950 R. e. FORDYCE 2,529,250

STENCILING MACHINE FOR APPLYING LUMINOUS PAINT Filed Oct. 10, 1-946 6 Sheets-Sheet s Nov. 7, 1950 R. G. FORDYCE STENCILING MACHINE FOR APPLYING LUMINOUS PAINT 6 Sheets-Sheet 4 Filed Oct. 10, 1946 v, M M

Nov. 7, 1950 R. G. FORDYCE 2,529,250

STENCILING MACHINE FOR APPLYING LUMINOUS PAINT Filed Oct. 10, 1946 6 Sheets-Sheet 5 @2 26 azzw/ Ce Nov. 7, 1950 R. e. FORDYC'E 2,529,250

STENCILING MACHINE FOR APPLYING LUMI NOUS PAINT Filed 001;. 10, 1946 6 Sheets-Sheet 6 4770? we a d Patented Nov. 7, 19,50

ENT OFFICE STEN CILIN G MACHINE FOR APPLYING LUMINOUS PAINT Rufus G. Fordyce, Glencoe, 111.,

assignor to Luminous Processes, Inc., Chicago, 111., a corporation of Delaware Application October :10, 1946, Serial No. 702,557

15 Claims.

This invention relates to means for applying paint, and it is particularly concerned with the problem of applying luminous paint of the character used on the dials ofclocks and watchesand for some other purposes.

One object of the invention is to provide a new and improved mechanism by which such paint can be applied through a stencil of the silk screen type.

Another object of the invention is to provide a new and improved mechanism having adjustable pressure means forforcing thepaint through a silk screen stencil.

It is also an object of the invention to provide a paint applying machine including a silk screen stencil and a rotary squeegee device Operative to force the paintthrough such stencil and to make eficient use of the paintsupplied thereto.

An additional object of the invention is to-provide'a machine for applying luminous paint in which the paint is confined in a substantially closed chamber and is fed therefrom through a silk screen stencil onto the surface to be decorated.

More specifically, the invention provides a machine for applying luminous paint and including a stencil of the silk screen type and a squeegee mounted for rotation against the screen, togetherwith driving means forithe squeegee and control means adapted tolimit it to a single rotation when actuated, thereby insuring'uniformity'in the work produced.

v Other objects andadvantages of the invention will appearfrom'the following description considered in connection with drawings, in which:

Fig. 1 is a front elevation of a machine embodying this invention, lower portions of the frame being broken away to somewhat condense the view;

Fig. 2 is a side elevational view of the machine shown in Fig. .1, with parts broken away in the lower portion;

Fig. 3 is a vertical sectional view taken asindicated at line 3-3 on F'g. 2 and ma larger scale;

Fig. 4 is aplan sectional cated atline 4-4 on Fig. 3;

Fig. 5 is a detail section taken as indicated at line 55 on Fig. 3;

Fig. 6 is a fragmentary detail taken as a section at line 66 on Fig. 5;

Fig. 7 is a horizontal detail section takenas indicated at line T-l on Fig. 3;

view taken as indithe accompanying Fig. 8 is a fragmentary detail section taken as indicated at line 8-8 on Fig. 7;

Fig. 9 is a detail section taken as indicatedat line 9-9 on Fig. 7;

.Fig. 10 is a fragmentaryplan view of the work supporting carriage;

Fig. 11 is a side elevational view taken partly in section as indicatedat line I I-i I on Fig. 10.

Fig. 12 is a fragmentary detail view partly in section showing a modified arrangement for applying adjustable pressure to the squeegee blades; and

Fig. 13 is a detail sectional view taken substantially as indicated at line l.3-l3 on Fig. 12.

The drawings illustrate a machine which .is adapted to apply'luminous paint to a flat surface, either as a decoration or to serve a useful function, as in the case of a watch or clock dial. The frame of the machine includes upright leg members in supporting horizontal members l2 provided. with a cover plate M which may be used as a table surface for work pieces to be treated by the machine. Within an open middle portion of the table area there is mounted a carriage [5 which may be fitted with an suitable work-holding or positioning devices, such as clamps, jigs, lugs or pins. Fig. 1 indicates a work piece such as a clock dial in dotted outline at A, and also shows a locating and supporting fixtube B mounted on the carriage l5. Said carriage l5 surmounts a yoke I 6 which is guided by rods ll, l1 for vertical reciprocation and is arranged to be actuated by means of a treadle bar l8 carried by a pair of levers 19, which are fulcrumed on the frame at 20 and connected :by a link 2| to a lever 22. One end of the 1ever'22 is connected by a pivot 23 to a bifurcated coupling i611, extending from the yoke l6, and the opposite end of the lever may carry a counterweight 22a to insure easy action of the treadle.

Bracket

members

24, 24, extending upwardly from the level of the table l4, support the paint chamber 26. The bottom wall 28 of the chamber spans the space between'the

brackets

24, 24 and is reinforced by the vertical walls 39 and :32 which have triangular end portions 3s extending beyond the paint chamber proper. The side walls '36 of the paint chamber extend above the top wall 38 thereof to support a platform 45 :on which a driving motor 42 is mounted. To afford access to the interior of the paint chamber, the

walls

30 and 32 are provided respectively with

removable cover plates

44 and 45, and with gaskets therefor.

As shown in Fig. 3, the bottom wall 28 of the paint chamber 20 has an opening 46 below which there is mounted the silk screen stencil 48 through which the paint is to be applied to an object or workpiece supported on the carriage I5. The stencil layer 50 having cut-out portions corresponding t the design to be applied is secured to the under surface of the screen 52, and the stencil screen 48 thus formed has its marginal portions clamped to a frame 54 which, in turn, is secured by clips 56 to the underside of the bottom wall 28 in a position to cover the opening 46 therein.

Paint is supplied from a reservoir 58 which may be mounted on a suitable support 60 extending upwardly from one of the brackets 24, as seen in Fig. l. A stirring device 62 is provided with a crank handle 64 by which it may be manually actuated intermittently as required, and a feed pipe 66 leads from the bottom of the reservoir 58 into the paint chamber 26 to a point of discharge directly over the stencil screen 43. Paint of luminous character tends to produce some gaseous fumes such as Radon gas, and this is one reason for having the paint chamber substantially closed. To carry off these fumes, an exhaust pipe 68 is shown leading from the chamber 26, and this pipe may be connected by a flexible hose I to a suitable exhaust fan, not shown, for discharging the fumes outside the building in which the machine is located.

The consistency of the paint and the gage of the silk screen 52 .are such that the paint will not flow by gravity through the screen but must be forced through, preferably by means of a squeegee. For this purpose, the present invention provides a vertically disposed rotary shaft 12 which, as shown in Fig. '7, carries three radial arms 74 to each of which there is clamped a squeegee blade E6 of rubber or like material having a tapered lower edge I8 as seen in Fig. 9. A clamping block 80 and screws 82 serve to secure each squeegee blade 16 to its supporting arm I4, and preferably each of said arms I4 is bent to present a concave front face which gives the blade 16 a corresponding concave face at its forward side considered in relation to the direction of rotation of the shaft I2 and the arms I4. Thus, as the shaft rotates said arms with the squeegee blades I6 in contact with the stencil screen, said blades act to gather the paint and to force it through the screen along an annular path over which they sweep as they rotate. As hereinafter explained, the application of the paint to each object or workpiece is accomplished by a definitely limited rotation of thesqueegee blade I6.

The shaft I2 is mounted with its axis substantially perpendicular to the plane of the stencil screen 48 and said screen is normally so mounted as to remain substantially flat; but to compensate for any possible irregularity in the screen or in its position, and also for any slight inequalities in the squeegee blades 16, the squeegee head, consisting of the arms 14 and the central hub 84, is mounted on the end of the shaft I2 in a manner which permits limited universal movement of the head. The lower end of the shaft is formed With a spherical surface 86 which engages the end wall 83 of the hub 84, and a spring 90 secured within the hub by a gland member 92 reacts against a shoulder 94 on the shaft 72 to maintain contact between the spherical surface 86 and the flat surface 88. A loose driving connection is provided by a side of the platform 40.

cross pin 96 in the shaft 12 engaging notches 98 in the gland member 92 of the hub. This arrangement permits the squeegee assembly to accommodate itself to the stencil screen so that all three blades I6 will bear evenly upon the screen as the shaft I2 is rotated. A steady bearing I5 for the shaft I2 is mounted in a cross bar '11 extending between the side walls 36.

As seen in Fig. 3, the motor 42 is shown associated with a housing I00 which may be understood as containing any suitable speed-reducing gearing and from which there extends a driving shaft I02 which is axially aligned with the shaft 12. Said shaft I02 carries the upper member I04 of a toothed clutch which is shown in elevation in Fig. 6, and the lower member I06 of such clutch is secured to a hollow shaft or sleeve I08 journaled in ball bearings IIO which are supported in a bracket H2 depending from the platform 40 on which the motor 42 is mounted. A spring Il4"coiled about the sleeve I08 tends to urge the clutch member I06 into engagement with the clutch member I04 but such engagement is normally prevented by a latch II6 which is pivoted at H8 on the under A roller I20 projecting radially from the clutch member I06 engages under the cam surface I22 of the latch II6, as seen in Fig. 6, to hold the member I06 out of clutching position. By means of a link I24 connected to a bell crank I26 and actuating rod I28, the latch II6 may be withdrawn laterally out of engagement with'the roller I20,

thus permitting the spring II4 to lift the clutch member I06 into connection with the'clutch member I04 which is rotated continuously by the motor 42. The rod I28 is connected to a rock shaft I2'I having an operating handle I29 (see Fig. 2). As the handle I29 is released, the spring I30 will return the parts to their initial positions, shifting the latch H6 into place so that its cam face I22 will engage the roller I20 at the end of the first revolution of the clutch member I06, thus withdrawing said member I06 from the clutch member I04; and

' as seen in Fig. 6, the shoulder I23 of the latch H6 will engage the roller I20 to positively arrest the clutch member I06 and the sleeve I08 to which it is keyed. 1

The sleeve I08 is splined to the upper end of the shaft I2 at I32 so that whenever the clutch I04, I06 is connected as just described, the shaft I2 will make a single revolution, causing the squeegee blades 15 to sweep over the stencil screen 48 through a single turn, and thiswill be suffi-' cient to apply a measured quantity of the paint through the stencil to the surface to be decorated. During this operation of the squeegee blades, said blades are held yieldingly against the upper sur face of the stencil screen 48 by a' spring 134' coiled about the shaft I2 and reacting between a collar I36 on said shaft, and a block I38 secured to the under surface of the top wall 38 of the paint chamber through which the'shaft. I2 extends upwardly. It is preferable, however, that when the squeegee blades'IIi are at rest, they shall remain out of contact with the stencil screen, thus permitting the paint to flow evenly over it between operations. Therefore, a collar I40 is secured to the upper end portion of the shaft I2 and carries a radially extending stud I42 with a roller I44 thereon for engagement with an annular cam track I46 which encircles the shaft I2 and which is formed on the upper isseenin sectionin'Fig. .-3,and;a plan view thereof is presented in Fig. 4, the high portion of the:

track being indicated at Mfia andthe lower'portion at 14617. As the roller I25 of the clutch member I95 encounters the cam surface I22 of. will be relatively so I6 from the surface of the stencil screen. The

splined connection between the shaft I2 and the.

sleeve-IIl8 permits this endwise movement of the shaft. The collar I49 may beadjustable vertically on the shaft l2 along a threaded portion 72a thereof, but will be locked at adjusted position by means of a set screw I50 engaging in a..key slot 121) in the shaft I2, as seenin Fig. 3.

.It is of course important that when the squeegee blades I6 are lowered onto the stencil screen, they shall exert the required pressureto perform their function without unduly straining the screen or excessively flexing the blades themselves. The lower limit of movement of the shaft I2 is therefore rendered delicately adjustable by means of the slidable wedge block I52 disposed under the wedge block I48 to cooperate therewith in vertically adjusting the cam track I46. Said block I52 carries a threaded plate I54 secured to one edge of the block and engaging an adjusting screw I56 which is side wall 36 with stop collars I58 preventing endwise movement of the screw and with a hand wheel I65 by which it may be turned forshifting the wedge block I52. The pressure applied by the spring I34 may be varied by adjusting the collarl36 along the threaded portion of the shaft on which it is secured.

In view of the fact that the stencil 50 is mounted in a fixed position, it is important that the workpiece such as that indicated at A in Fig. 1 shall be accurately positioned on the work support or carriage I5. Therefore, after a suitable jig or holding device, indicated in Fig. l at B, has been affixed to the upper surface of the carriage I5, it may be necessary to adjust this portion of the carriage to register the workpiece A properly with the design of the stencil 50. To permit such adjustment, the table I10 of the carriage I5 is supported rotatably upon a post or spindle III with roller bearings I12 and I73 interposed. The post III is extended rigidly from a cross slide I'M having an adjusting screw I15 and handwheel I16 for shifting it on a main slide I TI. The slide IT! is similarly provided with an adjusting screw I18 and hand wheel I79 for shifting it in a transverse direction on its base I 89. Rotative adjustment of the table I70 about the axis of the post I TI is efiected by a handwheel I8I which operates a worm I82 engaging a worm gear I83 affixed to the underside of the table I19 as seen in Figs. 1 and 10. The base I89 on which the adjustable parts are carried is anchored to a pad I34 which is formed integrally with the yoke I5. With this arrangement, after the work holding fixture B has been secured in place on the table III), the table may be adjusted by any desiredamount either forward or backward or to the right or to the left, or it may be turned about the axis of the post I1I through any required angle sothat a workpiecesupported on the fixture B will come into proper relation with the stencil 55 when the carriageis elevated.

,Figs. l2.and 13 illustrate a modified arrangement for providing any desired pressure-between V journaled in the.v

the squeegee blades I5 and thestencil'screenfl.

Fig. 12-shows a fragment of what maybe (3011-. sidered one of the Side walls 36 of the paint chamber 26 and shows a rock shaft I which may be journaled in said side walls so as to ex-,

tend through the paint chamber. Outside the chamber said rock shaft carries a lever arm I9I, and there is secured to the wall 36 an angle bracket I92 in which the upright rod I93 is anchored, being threaded into the bracket at I94 and provided with a lock nut I95 to secure it. The lever I9I has a clearance opening. I96, through which the rod I93 extends freely. A spring I9! is interposed between the bracket I92 and the underside of the lever I9I, and a second spring I98 is interposed between the upper side of the lever I 9! and an adjustable nut I99 on the threaded upper end of the rod I93.

Inside the paint chamber 25 the rock shaft I99 has a pair of arms 2E9 sides of the vertical shaft I2 which carries the squeegee head at its lower end. The shaft is provided with a thrust collar 252 with a ball bearing 2B4 interposed between said collar and the shaft I2 and anchored to the shaft between a flange 12a formed thereon and a securing nut 296. The collar 252 is connected to the lever arms 200 by pivots 201 and links 255, so that pressure or movement affecting the arm I9I is transmitted through the rock shaft I99, arms 2053, links 258 and collar 252 to the shaft "I2. The springs I9! and I98 thus operate in place of the spring I35 to provide the desired yielding pressure which holds the squeegee blades 76 against the stencil screen 38 during the rotation of the shaft ?2. effective pressure on the shaft l2 may be richcately adjusted by means of the nut I 95 which incidentally is accessible outside the paint chameber and is therefore more convenient than the collar I38 shown in Fig. 3 for adjusting the tension of the spring I55.

The ball bearing 285 which is mounted on the shaft I2 inside the paint chamber 25 is protected against any possible deposit of paint by means ing outer surface of the member 2H3 tends to' shed the paint by gravity if any of it lodges thereon, and also tends to throw it off by centrifugal force when the shaft 72 is rotated.

While there is shown and described herein a combination of certain devices and mechanisms embodying the invention and illustrative thereof, it will be understood that the invention is not limited thereto or thereby but includes all modifications, variations and equivalents which may come within the scope of the appended claims.

I claim:

1. In a stenciling machine, means forming a substantially closed chamber including a stencil screen which serves as a wall of said chamber, ashaft journaled for rotation about an axis substantially perpendicular to the plane of the screen, a squeegee carried at the end of said shaft for rotation about the squeegee for automatically compensating for deviation of the shaft or screen from. planes andmeans to rotate the shaftand squeegee.

extending at opposite.

With this arrangement, the Iv axis thereof and in contact I with said screen, means providing a loose uni- Y versal connection between said shaft and-Jthe.

T2. Ina stenciling machine, a horizontally dis' posed stencil screen, a shaft journaled for rotation about an axis perpendicular to the planeof the screen, a squeegee carried at the end of said shaft for rotation thereby against the screen,

said shaft axially as it rotates and formed to permit movement of the squeegee into contact with the screen during a portion of each rotation and to separate it from said screen during the remainder of the rotation. I

3. In a stenciling machine, means forming a substantially closed chamber including a stencil screen which serves as a Wall of said chamber, a shaft journaled for rotation about an axis substantially perpendicular to the plane of the screen, a squeegee carried at the end of said shaft in contact with said screen, a thrust collar journaled on said shaft, a rock shaft extending transversely of the first shaft in said chamber with one end of said rock shaft extending through a wall of said chamber, an arm on said rock shaft connected to said thrust collar, and

adjustable spring means outside the chamber arranged to produce a torque in said rock shaft in a direction to urge the thrust collar and the other shaft toward the screen for pressing the squeegee into operative contact therewith.

4. In the combination defined in claim 3, said rock shaft having an arm outside the chamber and said spring means comprising a pair of springs engaging opposite sides of said arm, and abutment means for said springs, at least one of said abutments being adjustable to vary the torque transmitted to the rock shaft.

5. In a stenciling machine, a horizontally disposed stencil screen, a shaft journaled for rotation about an axis perpendicular to the plane of the screen, a squeegee carried at the end of said shaft for rotation thereby against the screen, a driving member for rotating the shaft, said shaft being axially movable and being normally positioned to hold the squeegee out of contact with the screen, control means including a clutch axially aligned with said shaft and driving member and yieldingly engageable with the latter to connect the same with said shaft, latch means operative to disconnect the clutch and arrest movement of the shaft, and shifting means including a cooperating cam and follower means on the shaft and machine for raising the shaft as it is arrested and thus separating the squeegee from the screen.

6. In a stenciling machine, a horizontally disposed stencil screen, a shaft journaled for rotation about an axis perpendicular to the plane of the screen, a squeegee carried at the end of said shaft for rotation thereby against the screen, spring means adapted automatically to urge the shaft axially toward the screen, means for shifting the shaft to hold said squeegee out of contact with the screen when the shaft is at rest including a cam and a follower therefor, one of said parts being fixed and the other being rotatable with said shaft, a driving member for the shaft, clutch means to connect said shaft to the driving member, and means to disconnect said clutch automatically at a predetermined position in the rotation of the shaft, said cam being formed to separate the squeegee from the screen as the shaft approaches said position" in its rota tion.

'7. In a stenciling machine, a horizontally disposed stencil screen, tion about an axis perpendicular to the plane'of the screen, a squeegee carried at the end of said shaft for rotation thereby against the screen, spring means adapted automatically to urge the shaft axially toward the screen, means for shifting the shaft to hold said squeegee out of contact with the screen when the shaft is at rest including a cam and a follower therefor, one of said parts being fixed and the other being rotatable with said shaft, a driving member for the shaft, clutch means to connect said shaft to the driving member, and latch means operative to disconnect said clutch and to arrest the shaft at a predetermined point in the rotation of said shaft, said cam being formed to shift the shaft for separating the squeegee from the screen at said point in the operation of said shaft.

8. A stenciling machine including in combination a horizontally disposed stencil screen, a shaft journaled for rotation about an axis normal to the plane of the screen, means for intermittently rotating said shaft, a squeegee carried by said shaft for rotation against the screen, yieldable means for biasing the shaft and squeegee for axial movement toward said screen, means for movingsaid shaft axially in opposition to said yieldable means to separate the squeegee and screen when the shaft comes to rest and to free the shaft for movement toward the screen when said shaft starts rotating including stationary cam means and cooperating cam means rotated by said shaft, and means accurately to adjust the limits to which said shaft and squeegee move axially relative to the screen including wedge blocks to support said stationary cam means having reversely inclined faces disposed in superposed relation, said blocks being adjustable to bring more or less of the inclined faces into superposed relation, tionary cam and the limits to which the shaft moves axially relative to the screen.

9. In a stenciling machine, a stencil screen, a

shaft journaled for rotation about an axis normal to the screen, a squeegee carried on one end of said shaft for rotation thereby against the screen, driving means to rotate said shaft and squeegee; means to arrest rotation of said shaft and render said driving means inoperative to rotate said shaft each time the squeegee has been rotated far enough to complete a stenciling operation, a spring to bias the shaft in a direction to move the squeegee into stenciling relationship with the screen, cam means to move the shaft axially in opposition to the spring including a fixed part and a part engaged thereby and rotatable by' said shaft, said parts cooperating to move the shaft axially in a direction to separate the squeegee from the screen when the squeegee completes a stenciling operation and to free the shaft for movement of the squeegee into stenciling relationship with the screen under the influenceof said spring when the shaft starts rotating, andv means to adjust the cam means axially ofthe shaft to vary the limits to which the shaft and squeegee move axially relative to the screen.

10. In a stenciling machine, a horizontally disposed stencil screen, a shaft journaled for rotation about an axis normal to the screen, a squeegee carried on one end of said shaft for rotation thereby against the screen,

rotate said shaft and squeegee, means to arrest a shaft journaled for rota thereby to raise or lower the sta driving means to rotation of said shaft and render said driving means inoperative to rotate said shaft each time the squeegee has been rotated far enough to complete a stenciling operation, a spring to bias the shaft and squeegee toward the screen, means to adjust said spring to increase or decrease the biasing force exerted thereby, and cam means to move the shaft axially in opposition to said spring including a fixed part and a part engaged thereby and rotatable by said shaft, said parts cooperating to move the shaft axially in a direction to separate the squeegee from the screen when the squeegee completes a stenciling operation and to free the shaft for movement of the squeegee into stenciling relationship with the screen under the influence of said spring when the shaft starts rotating.

11. In a stenciling machine a horizontally disposed stencil screen, a shaft journaled for rotation upon an axis normal to the screen, a squeegee carried on one end of said shaft for rotation thereby against the screen, drivin means to rotate said shaft and squeegee, means to arrest rotation of said shaft and render said driving means inoperative to rotate the shaft each time the squeegee has been rotated far enough to complete one stenciling operation, yieldable means to bias said shaft and squeegee toward said screen, means to adjust the biasing force exerted by said yieldable means, and means rendered effective by rotation of said shaft as the squeegee completes a stencilin operation to move the shaft axially in a direction to separate the squeegee and screen and to free the shaft for movement of the squeegee into stenciling relationship with the screen under the influence of said spring when the shaft starts'rotating.

12. In a stenciling machine a stencil screen, a shaft journaled for rotation about an axis normal to the plane of the screen, a squeegee carried at the end of said shaft for rotation thereby against the screen, means to rotate said shaft intermittently, a coil spring surrounding said shaft and reacting between a stationary part of said machine and said shaft to bias the latter and said squeegee toward the screen, means to adjust said spring to increase or decrease the axial thrust on said shaft, cam means to move the shaft axially in opposition to said spring including a part on said machine surrounding said shaft and a part rotatable with said shaft to move the shaft axially in a direction to separate the squeegee from the screen at a predetermined point in the rotation of said shaft and to free the shaft for movement into screen under the influence of said spring at another predetermined point in the rotation of said shaft.

13. A stenciling machine comprising means forming a substantially fluidtight gas collecting chamber including a stencil screen forming at least a portion of one wall of said chamber, a shaft journaled for rotation about an axis perpendicular to the plane of the screen and having at least a portion thereof extending into said chamber, a squeegee in the chamber secured to the shaft for rotation thereby against the screen, a driving member for rotating said shaft, said shaft being axially movable and being normally positioned to hold the squeegee out of contact with the screen, clutch means yieldingly engageable with the driving member to connect the same with said shaft, latch means operative to discontact with the r connect the clutch and arrest movement of said shaft, means to shift the shaft axially, including cooperating cam and follower means on the shaft and machine for moving the shaft axially as it is arrested in a direction to separate the squeegee from the screen, and means for holding work to be stenciled in contact with the stencil screen on the outside of said chamber.

14. A stenciling machine including in combination mean forming a substantially fluidtight gas collecting chamber including a stencil screen forming at least a portion of one wall of said chamber, a shaft journaled for rotation about an axis perpendicular to the plane of the screen and including a part extending into said chamber, a squeegee carried at the end of said shaft in the chamber for rotation thereby against the screen, driving means to rotate said shaft and squeegee, means to arrest rotation of said shaft and render said driving means inoperative to rotate the shaft each time the squeegee has been rotated far enough to complete one stenciling operation, yieldable means to bias said shaft and squeegee toward said screen, means to adjust the biasing force exerted by said yieldable means, means rendered effective by rotation of said shaft as the squeegee completes a stenciling operation to move the shaft axially in a direction to separate the squeegee and screen and to free the shaft for movement of 'the squeegee into stenciling relationship with the screen under the influence of said spring when the shaft starts rotating, and means for holding work to be stenciled in contact with the'stencil screen on the outside of said chamber.

15. In a stenciling machine, a stencil screen, a shaft journaled for rotation upon an axis normal to the plane of the screen, a squeegee as-- sembly on said shaft including a central hub, a .plurality of rigid generally radially extending arms fixed to said hub and a flexible squeegee blade fixed to each arm for wiping contact with the screen when the shaft is rotated, the ends of said blades being turned forward with respect to the direction of rotation of the shaft, yieldable means to bias said shaft and squeegee toward said screen, driving means to rotate the shaft,

means conditioned manually to connect said shaft and driving means and automatically to disconnect the same at a predetermined point in the cycle of rotation of said shaft, and means operable automatically to move said shaft axially in a direction to separate the squeegee and screen at said predetermined point in the rotation of the shaft Y RUFUS G. FORDYCE.

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

UNITED STATES PATENTS