US2051199A - Plaster cutter - Google Patents

Description

Aug. 18, 1936.

G. M. cHRlsfnANsoN PLASTER CUTTER 2 sheets-sheet 1 Filed Janl. 18, 1935 Aug. 18, 1936. G. M. cHRlsTlANsoN 5 2,051,199

PLASTER CUTTER l Filed Jan. 18, 1935 2 sheets-sheet 2 Fb'g. 1%

C KYENTOR AORNEY Patented Aug. 18, 1936 UNITED STATES PATENT OFFICE PLASTER CUTTER George M. Christianson, Union City, N. J. Application January 18, 1935, Serial No. 2,3775

13,Clams. (Cl. 'i2-138) This invention relates to plaster cutters, such as may be used by plasterers and painters when repairing defective plastered ceiling or side walls by cutting out and removing portions thereof, or by opening existing cracks in the plaster sufliciently so that fresh plaster may be applied and levelled oi to produce a continuous smooth surface.

An object of the invention is to provide a tool which is especially adapted for the purpose stated, and which will perform its work expeditiously and economically.

Another object of the invention is to provide a tool Whose cutting blade may be maintained in proper Working condition without the use of a grinder or the like.

A further object of the invention will be found in the improved organization of the blade and its handle so that the tool, as a Whole, may be folded to be carried in aY pocket, or the blade may be opened angularly to the handle or into extended alignment therewith, the blade and handle becoming securely locked relatively to each other, in either of the conditions named.

Another object of the invention is the provision o f a blade whose length is divided by grooves into a series of connected sections. which may be consecutively brokenoif with a pair of pliers or the like, to present a new cutting edge or point when required.

Other objects and advantages of the invention will hereinafter appear. g

In general practice, when repairs in plaster are to be made, requiring either the removal of patches of plaster, or else the opening or enlargement of existing cracks, the Workmen are apt to use what is generally called the broad knife for breaking through the plaster, this process, however, rendering the broad knife unfit for the use for which it was orginally intended, and therefore it needed resharpening to bring it back into usable condition.

'I'he tool of the present invention has, therefore, been designed for its particular purpose and for its ready and easy reconditioning Whenever the cutting edge or the point of the blade becomes dull or uni-lt for further use.

In the accompanying drawings- Figure 1 shows my improved cutter, with its blade extending substantially atV a vright angle to the holder or handle.

Fig. 2 is a top edge View thereof.

Fig. 3 is a side view of the cutter` shown in Fig. 1. i f

Fig. 4 is an enlarged section taken on line 4-4 of Fig. 1.

Fig. 5 is a similar view, taken on line 5 5 of Fig. 1.

Figs. 6, 7 and 8 illustrate the front views of 5 the handle, blade holder and the blade respectively. Y

Fig. 9 is an obverse perspective view of the blade, per se.

Fig. 10 illustrates the tool as it appears when 10 folded to b e carried in a pocket.

Figs. 11 through 18 show a modication in the construction of the tool, which, in these figures, is represented as a power-driven device instead of a hand-tool as shown in the preceding figures. l5 Here, Fig. 11 shows the face view of a multiblade cutter; Fig. 12 is a central vertical section thereof; Fig. 13 represents an edge view of the cutter shown in Fig. 11; Fig. 1li is a cross-section of the blade holder and the blade locked therein, on 20 line M-M'of Fig. 11. Figs. 15a, 15b are sections on line |5| 5 of Fig. 11-Fig. 15a showing the blade free to slide, while in Fig. 15b Vthe blade is clamped in place.

Fig. 16 is a perspective Vview of the blade, per se. 25

Fig. 17 shows a fraction Vof the disk, bladeholder and the clamping-plate ready to be placed thereinto, and Y Y Fig. 18 represents the clamping plate in operative position.

Referring first to the embodiment of the invention shown in Figs. 1 to 10 inclusive, my improved cutter comprises a handle 20 consisting preferably of a sheet-metal plate 2| which is stiffened by a Wood hand gripr22 riveted thereto, as 35 at 23. At its upper end the plate 2| has attached to it one end of a blade holder 24, the connection being established by a bolt 25 (see Fig. 4) which is provided with a square shoulder 26 adapted to fit square perforations 21, 28 provided therefor in v4.0 the handle plate 2| and the blade holder 24, respectively. Hence it will be seen that the blade holder'24 may assume four different positions relative to the handle 20, viz. as shown in Fig. 1 (extending to the right at a right angle therefrom) or vextending to the left therefrom, or beyond the handle V(in a straight line therewith) or in line with and covering the body of the handle, as shown in Fig. 10. It willY also be understood that, when the handle and blade holder are in any of the positions named, and a nut 25 is tightened, the handle and blade holder become immovably locked together in those positions, therefore making the device a stiff and strong structure. f Y" VVExperience has demonstrated that the working-end of the cutter blade is best adapted for its work when'it is shaped kas illustrated in Figs. l, 8 and 9 in which the blade 29 is shown made'o-f thin Vsheet steel adapted to be slid into desiredY posi-V tion'in the holderr24, the latter being also made of sheet metal, having its longitudinal edges bent tojormV channels 24a (see Fig. 5) whose margins overlap'the edges ofthe blade and are sufficiently spaced from the mainplate ofthe holder to also overlap'thefopposite upper and lower) edges of a'clampngV plate 30.

It should be understood that both the blade Y.zey

as well 'as the clamping plate V3l) are normally freely and independently slidable in the -channels* 24a of the holderthe blade 29 preferably having Y at its inner enda'bent-up tabl3| which projects outwardly Yenough to serve as .afin'ger hold, while the clamping plate30'has Va binder-.screw ,32,`

which projects beyond the holder and serves as a ngerfpiece `forY moving the clamping plate into Vthe desired position. When, now, the screw 321s being turned in ,theV plate k30 until its end Aabuts against the face of the blade, the clamping plate 30 will ,perforce be 'pulled outwardly until its upper and lower edges bringup against the inside Vfaces of the channel lips 2412 (see Fig. 5) andthe screw 32 therefore serves for Vholding both the blade2a as well as the clamp-plate 3| Vin xed positions in the holder 24,.k Y

. As above stated one featureof the present invention is the improved form of thecutter blade which is so'constructed that When either the cut- Y blade and the clamping plate may 1550 ting edge or the point becomes dull orrbroken, the

VYdamaged portion of the blade may be broken off,

blade a'thin and leaving on the main body of the be used .roughly ,ragged cutting edge which may on the plaster or the like withoutlosjng its` eilici-v 'ency as a cutter.

YIn order to accomplish'this result, my improved blade is diagonally-grooved,across its face, as at 35, either by milling or indentne; and thus dividingthe'blade-length into a series of similar con- Y nected sections 36, which may be broken off or` 4severed from each `other at the grooves :ii-leaving a sharpragged edge 31 and an acutely angular 'and correspondingly-sharp point 3B, asleft by the Vdiagonal break--it being understood that the `be relocated in any desired position inthe holderto again form a, ,rigidY structure.

When not in use,'andtoadapt the tooltorbe carriedv :in a pocket,

. Y thelblademsy be slipped not project vbeyond the holder and the latter may be alenedgwiththe handle,

' `as above described, thus'leafving no sharp edges i Vorprojections which mighttear the pocket.

The tool thus .far described answers the purpose of a hand tool `adapted for use on smaller jobs, `and, where minorrepairs are to be made, ForV larger jobs. which require cutting out larger areas of plaster, I Dreier tousea power drivencutting device, suchas is incidentally Vshown in Flgsfll to 19, inclusive.V

Inthat case, I deem,.it expedient to provide a; plurality of cutters,v theV blades 40 of Y' which are held for indivdualfadiustment and Y treatmentv `in holdersllI'-'eigl1tV being shownriveted, individually orin a multiple unit Aon a disk 42. the central portionof-vvhich has ajhub'42a which may besecured to the driving spindle 43 jbya set screwy .4.4.

Inasmuch as the cuttingdevice as ai whole isY inthe present instance arpower driven device,

hand, Iprovide a handle 45 which is preferably v made of wood but has a metallic bushing 46 serving as a bearing for the spindle 43. At its other end the spindle may be connected to a motor, either directly or through the intervention of a ilexible shaft (not shown) the latter construction being preferable on account'ofits lightness inv Weight and ease ofV hand-manipulation. The disk and its cutters partake of the nature of a'circular saw, whose teeth (cutters)V are ad-V justable radially, the individual blades V4l) being grooved or lscoredin Vthe same manner as the blades 3l previously describedj but, inasmuch as ,the present device is power driven at a high speed,

' I deem it expedient to provide means whereby the Vblades will be locked against outward radial slip movement which might be caused by centrifugal force due to the high velocity of the disk. I pro- 'vide these means ina very simple manner, pref-` erably by forming at the inner end of each bladeV a projection or bent-up tab 46 whose sides 4l (see Figs. 1,4 and 17) are tapered'and of .such size that the tab-width at its bottom or lroot 48 isless than the width of the space between the holderVV Y lips 49'; Therefore, when the tab 46 gis grasped by the fingers and raised until the edges ofthe longitudinally in its holder without hindrance. On the other handwhen the tab 46 is in a position of alignmentwith any-one setof notches 50 (see Fig. 18) provided'in the holder lips 49, vand then released, the Vtapered sides 41 of the tab will enterthose notches until theyibecome interlocked and wedged in place therein, Vthe tightness of this wedging eiect depending, ofcourse, upon the action of the clamp plate 5l and binder screw 52 (see Fig. 15b) whose functions and construction are identical with those previously-designated by 3U and 32, respectively,.the interlock between blade and holder being effective in both directions longitudinallyof the holder.

Inasmuch as it isessential to maintainthe radial distances ofthe points of al1 bladesfrom the axial center of the disk'the samein order that the points may all be equally eliectiveduring the operation of the tool, several features are'incorporated in my improved device, viz., all holders lare notched alike, the distances between thesevveral grooves of Vthe blades, so that the several connected sections of the latter are'also allalike,

' and,When the pointed end-sectionof anyone blade of the series is removed or Vbroken off, it is only necessary to move that, particular blade4 radially outward in its holder *until the tab 46Y enters the next outward set of notches 50 in the the rst Vand nearest grooveV 35 of each blade notches, and the distance between the tab 46 and'V being also the same in all cases; (3) While I pre'- fer to spacethe eight holders illustrated at equal angles (45) on the disk, such Vequal distribution is not essential, provided, howeven'thatthe opposite pairs should be in diametral alignment in order to facilitate the balancing of the device to minimize its vibration under high speed.

Y upper face of the blade engage theunderside of K 'Y the holder lips'49, the blade can 'be slid alongV VFrom the foregoing description, it will be 75,

derstood that a power driven tool constructed in accordance with the present invention is capable of doing its work rapidly and cleanly, and that it may be guided to cut along definite lines, leaving the edges clean-cut so that new plaster may be matched in place evenly and smoothly. In order to guide the cutter properly, it is, of course, essential that the cutting operation of the tool be performed Without undue or excessive vibration, such as may be caused, for instance, when blades of different lengths are used and will naturally throw the disk out of balance. However, this fault may be remedied by the fact that the clamping plates With their binder-screw may be adjusted longitudinally in the holders to counterbalanoe each other at opposite sides of the disk center, and therefore minimize, if not entirely eliminate, the vibration, thus providing a smoothrunning and non-trembling device.

Variations and modications may be made within the scope of this invention and portions of the improvements may be used Without others.

Having thus described the invention, what is claimed as new and for which it is desired to obtain Letters Patent, is:-

1. A cutting tool comprising a blade having grooves in its surface extended across the blade to form a series of connected sections adapted to be broken 01T along the groove lines, substantially as and for the purpose described.

2. A cutting tool comprising a blade having diagonal grooves across its face forming a series of connected sections adapted to be severed from each other at the groove lines and leaving at its severing line a diagonal cutting edge, and an acute-angle cutting-point on one of the sections.

3. A cutting tool comprising a holder having channels at its opposite edges, a blade slidably supported in the channels of said holder, a clamping plate also slidably held in said channels, and a binder screw carried by said plate and extending outside of said channels for I'lrst sliding said plate into proper position in the channels and subsequently clamping said plate, blade and the holder together and in xed positions therein.v

4. A cutting tool comprising a blade, a holder slidably receiving said blade, said blade being shiftable in said holder in a direction at an angle to the direction of sliding of the blade, means carried by said blade and engaging said holder for locking said blade against sliding movement in the holder, and means for then locking said blade in the holder against such shifting.

5. A cutting tool comprising a holder having spaced notches and a blade having a projection adapted to enter any of said notches to lock the same against movement relative to each other, said blade having grooves similarly spaced in its surface and forming connected sections adapted to be severed at the groove lines to present a new cutting edge and point. 4

6. A cutting tool comprising a holder having its longitudinal edges bent to form a pair of opposite channels, one of the channel-walls having a series of equally spaced notches, a cutter-blade adapted to be moved longitudinally in said channels and having a tab adapted to enter any one of said notches and to be locked therein, and a device for holding said tab in said notch.

7. A cutting tool comprising a holder having its longitudinal edges bent to form a pair of opposite channels, one of the channel-Walls having a series of equally spaced notches, a cutter-blade adapted to be moved longitudinally in said channels and having a tab adapted to enter any one of said notches and to be locked therein, said blade also having equally-spaced grooves in its surface to form a series of equal sections, the central distances of said grooves being equal to the central distances of said notches, and a device for holding said tab in said notch.

8. A cutting tool comprising a handle, a bladeholder attachable thereto, means for positioning and locking said blade-holder on the handle, a blade slidable in said holder, and a device for locking said blade in position in the holder.

9. A cutting tool comprising a blade having V- shaped diagonal grooves across its face forming a series of connected sections the terminal one of which is adapted to be severed from an adjoining section at the line between these two sections to remove the terminal section by splitting the blade material along said line opposite the apex of the V thereby to leave said adjoining Section with a cutting edge having a bevel established by a leg of the V, said edge terminating in an acute angle cutting point.

10. A cutting tool comprising a blade having V-shaped grooves in its surfaceV to form connected sections the terminal one of which is adapted to be broken oi along one of the groove lines, to leave at the breaking-off line a cutting edge following substantially said groove line and being rough and irregular because established by the breaking of the blade material opposite the point of the V of said line, said edge having a bevel established by a leg of the V.

l1. A cutting tool comprising an elongated iiat blade having diagonal grooves across its face forming a series of connected sections adapted to be severed from each other at the grooves, and leaving at its severing line a diagonal cutting edge and an acute angle cutting point on one of the sections; a holder for the blade having its longitudinal edges bent toform a pair of opposite channels in which said blade is slidably mounted and having its edge diagonal so as to be parallel with the diagonal grooves of said blade; and means for securing the blade in the holder against casual movement.

12. A cutting tool comprising an elongated iiat blade having a iinger-piece at one end; a holder for the blade having its longitudinal edges bent to form a pair of opposite channels in which said blade is slidably mounted with the finger-piece in the blade projected through the space between said longitudinal edges for manual engagement to adjust the blade relative to the holder; and means for securing the blade in the holder against casual movement.

13. A cutting tool comprising an elongated flat blade having a finger-piece at one end; a holder for the blade having its longitudinal edges bent to form a pair of opposite channels in which said blade is slidably mounted with the finger-piece in the blade projecting through the space between said longitudinal edges for manual engagement to adjust the blade relative to the holder; a clamping plate having its lateral edges located in said opposite channels and slidable therein relative to the blade and holder; and means on the clamping plate for securing the blade in the holder against casual movement.

GEORGE M. CHRISTIAN SON.

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