GB2320459A - Mitre saw - Google Patents

Abstract

In a mitre the rotary arm 20 is provided with a pair of rectangular blocks 23 perpendicular to the two ends, a pair of saw racks 30 each have a spring loaded positioning rod 231 selectively engageable with a plurality of positioning recesses 26 in the rectangular blocks. A pair of outer plates 33, each of which includes a semi-circular slot, are secured to the rectangular blocks with the saw racks rotatably disposed thereinbetween. Round flanges 32 are provided on the rack seats engageable with round notches 24 of the rectangular blocks and the outer plates. This effectively prevents sawdust from accumulating in the rotation mechanism of the mitre saw.

Description

2320459 A Mitre Saw Equiped with Sawdust Protection Device

BACKGROUND OF THE INVENTION

The present invention relates to the carpentry sawing apparatus, and wore particularly to an improved aitre saw which enables to prevent the sawdust from entering into the adjustable mechanism of the rotatable saw racks so as to ensure a precise displacement of the vertical angles at the vertical circle.

Typical mitre saw comprises generally a working table with a horizontal circle thereinbetween, a saw rack parallel and rotatably secured to each end of a rotatable arm which is pivoted to an axle hole at a center of the working table, a pair of vertical circles perpendicular to two ends of the rotatable arm adjacent the saw r thereinabout and saw can precisely vertical angle as characterizes in vertical angle for sawing 5,605,086 discloses a compound mitre sa plurality of longitudinal the working tabl working piece 0 inclinations. Ho neglected that th saw support rotatably retained within the concave of the rack which has the arcuate outer circumferential edge must be exactly the same curvature relative to the arcuate concave of the rack so ack which permits a backsaw vertically sliding tilt together with the rack. So that the mitre pinpoint both the horizontal angle and the well for a working piece.

No. 5. 392, 979 discloses a saw Fquipment whj eh readily positioning of the horizontal and a work piece. My U.S. Pat. No.

w which characterizes in a formed on the surface of slant disposition of the t o in a k e a v a r i a t y 0 f very important fact projections which facilitate the working table ever, there is a was arcuate concave in the top of the rack and the - 1 as to ensure the pinp piece deemly accurate it is unavoidable rack and enter into concave so that t support becomes concave and moves pinpointing of the longer accurate.

the aforediscussed disadvantages.

SUMMARY OF THE PRESENT INVENTION o i n t i n g the vertical ang[ps F. After the commencement of that the sawdust shall accumulat its rotation mechanism such he arcuate outer circumferentia wore and more disengageable wit upward relative to the conc r 111C working the mitre saw, over the saw s the arcuate edge of the h the arcuate ave, thus the tilting angle for the working piece would no To obviate this, the operation has to frequently cl ean that part by disassembling the support from with the saw rack. This is a very wearisome task for the operator to do so.

The present invention is arisen to militate and/or obviate The main object of the present invention is to provide a mitre saw equiped with sawdust protection device which prevent the sawdust from entering into the rotation mechanism of the saw r a c k.

Another o't.-,iect of the present invention is to P.-ovide mitre saw equiped with sawdust protection device in which the saw rack is structurally improved as to permit the support rotatably disposed within a circ le plate and the rack therebetween so as to protect the support from accumulating the sawdust to ensure a precise pinpointing of the vertical angles for the working piece.

Still another object of the present invention is to provide a mitre saw equiped with sawdust protection device in which the components are simplized for easier producing in order to save the cost to manufacture.

The present invention will become more fully understood by reference to the following detailed description thereof when read a - 2 in conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE D

R A W 1 N G 5 Figure 1 is an exploded p Preferred embodiment of the present Figure 2 is a sectional view i a support within a saw rac F igure 3 is Figure 4 t o s h o w a erspective view invention, llustrating an assemblage of k and a circle plate, a front elevation of Fig. 2, s a perspective view to show of the present invention, Figure 5 is an exploded perspective v embodiment of the present invention, Figure 6 is a sectional view of Fig. 5, and Figure 7 is an exploded perspective view to show a fourth embodiment of the present invention.

a second embodiment iew to show a third DETAILED DESCRIPTION OF

With reference to 1; c a; itre saw of a working table 10, a into which a backsaw The working table includes a horizontal c rectangular flat portion 1 each having an upright wa has a cant inner end s indentation 14 therebetwee center of the circle 11 b walls 13, graduations circle 11 abutting front THE PREFERRED EMBODIMENT the drawings and initiating from Figs. 1 the present invention comprises genei-.cLiiy rotary arm 20 and a pair of saw racks 30 is slidable thereabout.

is of conventional in ircle 11 at a middle portion form and a p a i r o f 2 extended laterally from the circle 11 1 13 at a backside and each of which as to define a roughly V-shaped a first axle hole 15 formed in the tween the cant ends of the upright 16 engraved on the upper surface of circumference thereof t h e and a predetermined number of Positioning recesses 17 formed spaced apart in an underside of the circle 11.

The rotary arm 20 comprises an elongate rectangular body 21, a second axle hole 22 vertically formed proximal the rear end made in registry with the first axle hole 15 and rotatably engaged by a screw 18, a pair of rectangular blocks 23 each having a lower inner surface perpendicularly integrated with two ends of the body 21 respectively, a first round notch 24 at the tip, an arcuate guide slot 25 centrally formed in the block 23 with a plurality of positioning recesses 26 formed spaced apart along and beneath the slot 25 and a screw hole 27 abutting each of the four corners.

The body 21 further includes a thru hole 28 in an appropriate position for slidably receiving a tubular retaining means 281 which has a retaining hole 282 in a peripheral wall, a lever means 29 including a tip end engageable within the retaining hole 282, a thru hole 291 laterally fermed through the center and pivotally engaging the lever means 29 on an under side of the arm 20 with a tug 294 by a retaining pin 293 which has a free end riveted into a corresponding lug 294 at opposite side, a c,,i. ooved end 23Z -!n-r facilitating finger operation and a lateral projection 295 extended from an inner surfal-e adjacent the grooved end 292 and biasing with a first spring 296 thereon which provides resilient for ce to force the lever 29 back to normal position after a upward rotation, a positioning rod 231 including a threaded end engageable with a second spring 235. a radial thru hole 231 engageable within a retaining pin 233 and a taper end 237 selectively engageable with the positioning recesses 26.

The pair of saw racks 30 each includes a rack seat of a generally pentagon shaped, a second round notch 31 made in registry with the first round notches 24, a pair of first and second round flanges 32 extended outward from two ends of the s c c ond r o tin d no I c h 3 1, an ax 1 e t u b c 30 1 c e n t ra 11 y extended' outward through the lower center of the pentagon shaped r a c k seat, a slit 302 formed in an upper pt,ipheral wa 1 1 abutting the free end of the axle tube 301, a tiireaded screw hole 303 through an appropriate portion of the rack seat for engaging with a butterfly bolt 305 therein. The rack seat further has an axle rod 304 centrally extended from an inner surface above the axle tube 301 and slidably engageable within the guide slot 25 of the blocks 23. A pair of uprights 39 parailel extended spaced apart from the top of the rack seat and secured by appropriate fastening weans through respective lateral screw holes thereof.

The uprights 39 are provided in corporation with other conventional elements for slidably supporting a backsaw as set forth in the prior art saw racks. A pair of outer plates 33 are engageable with the rectangular blocks 23 with the rack seats disposing therebetween. The outer plates 33 each has a rectangular flat body equal to the rectangular blocks 23, a third round notch 34 at tip equal to the first round notch 24, a semi-circular recess 35 which has a radius equal to that of the arc uate s lot 25 and cent ra 11 y f ormed i n an uppe r por t ion abu t t 1 ng the third round notch 13 4. The recess 35 includes graduat i o n s formed around the outward circumference. A plurality of internally threaded tubes 36 project transversely from the inner ends of a plurality of screw holes 37 adjacent four corners o f the outer plate 33 and engageable with a plurality of screws 38.

The tubes 36 are made in registry blocks 23.

It is assuming that the with the lug 294 and the tubular the rotary arm 20 is rotatably as with thescrew holes 27 of the lever means 29 is already engaged etaining means 281, and that e m b 1 e d to the first axle hole of the working table 10. The process to assemble the saw racks 30 with the rotary arm 20 is described as such that first sleeve t 11 e s p r i n g 235 onto the positioning rod 2 3 1 and i n s e r t t h e threaded end 232 of the rod 231 into the axle tube 301 making the radial thru hole 234 aligned with the slit 302 so as to allow the retaining pin 233 to insert into thru hole 234, then fasten the positioning rod 231 by nut 236. This time, the positioning rod 231 is biasing by the spring 235 and its taper end 237 is slidably disposed in or out of the inward end of the axle tube 301. Secondly, insert the outward end of the axle tube 301 through the semi-circular recess 35 of the outer plate 33 with the f irst round f lange 32 of the second round notch 31 engaged on the third round notch 34 and the second round flange 32 of the second round notch 31 against the first round notch 24 of block 2 3. So that the internally threaded tubes 36 shal 1 be facing the screw holes 27 of the block 23. Finally, fasten the outer plate 33 onto t.he block 23 with the screws 38 through the tubes 36, and then secure the rack seats by the but terf ly bolt 305 (as shwon in Fig. 2). Normally, the tubular positioning means 281 is toward upward by the lever means 29 and engaged into any one of the positioning recesses 17.

In operation, f i r s t t u r n upward t h e 1 e v e r m e a n s 29 to disengage pesitioning means 281 with the p,-s.J tioning recess!7 w h e r e it is engaged to set the rotary a r in 20 free to rotate transversely on the axle hole 15 pinpointing a desired horizontal angle for the arm 20, then release the lever means 29 so as to permit the positioning means 281 engaged into a respective recess 17, so that t h e a r m 20 is stationary a t t h e selected a n g 1 e r e 1 a t i v e to t he longitudinal axis of the working table 10 ( t h i s manner for deciding horizontal angles is done as it has in a conventional mitre saw). Secondly is to decide vertical angle by u n 1 R s t e n i in g the butterfly bolts 305 and drawing the outward end of the positioning rods 231 outward so as to set the saw racks 30 at two ends of the rotary arm 20 free to rotate c 1 o c k w i s e o r - 6 counterclockwise to pinpoint a desired vertical an to the graduations on the outer decided, release the positioning which will automatically inser recesses 26 under the resilience of the spring 235. the butterfly bolt 305, so that the saw racks relative to the plane of the rotary arm 20 and sta in Figs. 2 and3).

Referring to Fig. 4, which shows a second embodiment of the present invention, in which the basic structure and function are mostly similar to the first embo the discussions are applicable i The only differences are the rack seat, the round notch 31 is denoted as numeral 31b, howeve remains unchanged. The axle rod 30 an outward axle rod formed facing as 34b. An inward arcuate groove surface of for slidably 1 he . 1 p a i r c c n gle according plates 33. Once the angle is rod 231, the taper end 237 of t into one of the Positioning Then fasten became tilt le (as shown the outer plate 33 unde receiving the axle rod f rectangular blocks each of which a rectangular notch first round.notch 24 and the screw ho and redenoted as 27b so as to permit through blocks 23b and fastened by the iment as shown in Figs. 1-3 and most instances.

ccurred in the saw becomes a rectangu the first roun is omitted and he outer p 2 5 b the semi-circular r 34b. Further changes a 3 which are racks 30. On ar notch and f I ange 32 nstead of is late 33 and denoted is formed in the inner cess 35 e made re-denoted as 23lu 24b is formed instead of the es 27 are slightly widened the screws nuts 271b.

Referring to Fig. 5, a third embodiment of invention is provided. In this embodiment, the bas and function are mostly similar to the above e illustrated in Figs. 1-4 and the aforediscussion in most instance either.

The changes are occurred first in the lever means 29 in which an upright projection 295b engaged with a spring 296b are 38 threaded the present ic structure mbodiment as are applicable 295 and the first spring 2 9 6 The screw holes 27 are also widened and re- denoted as 276. The rack seats become a semi -c i rcu lar shape including a pair of uprights 39, a second round notch 39 with an inward round flange engageable with the first round notch 24 of the blocks 23, graduations 33 abutting a plurality of spaced positioning recesses 34 formed around adjacent the lower peripheral edge and a large screw hole 40 formed adjacent the round notch 32 which is engageable with a bolt 401.

A pair of alternative outer plate 26 are provided in which the four internally threaded tubes 36, screw holes 37 and the screws 38 remain unchanged. However, a semi-circular notch 262 is and the round notch outward from the for engaging the structurally and end 237 is 34 of the n o t c h 2 6 2.

formed ins 34 in the lower out positioning functionally now selectiv rack seats 3 Fig. 6 shows Referr.

tead of the semi-circular recess 35 rack seat and centrally projected ward surface of the plate 26 rod 231 which remains unchange The only difference is that the taper ely engaged into 1 and a pointer 26 the assemblage of to F ig 7, a f which the structure and functio embodiment as shown in Figs. 5 and both the graduations 33 and the 1 from the rack seats and added to contrarily. the pointers 261 and added to the rack seats the round notc the positioning recess 1 is added abutting the the saw racks 30.

ourth embodiment. is provided n n are mostly similar to the third 6, the only changes are that arge screw holes 40 are removed the pair of the outer p 1 a t e s 2 6, is removed from the outer p 1 a t e s 2 6 31 in which the round flange at inward end of h 24 now is formed with splines 236 on under peripheral wall so as to provide a smooth rotation o f the flange on the round notch 24.

Accordingly, the aforediscussed embodiments provide greater advantages and features which have not seen in the prior art references. The present invention is particularly C11;1racterized in the round flanges at two ends of the round notches which provide unexpected result because they rotatably engage on the round notches of the blocks and the outer plates that would completely prevent the sawdust from accumulating rotation mechanism precisely pinpointing In comparison with lessen the contact mechanism which is ready to assemble.

Note that the specification relating to the above embodiment should be construed as exemplary rather than as limitative of the present invention, with many variations and modifications being readily attainable by a person of average skill in the art without departing from thereof as defined by the appended claims equivalents.

i n t o t h e of the mitre saw. This ensures a mitre saw the vertical angles for the working piece. the prior art reference, the round flanges area betweeen the elements in the rotation otherwise lessening the friction area and

9 the spirit or scope and their legal [ CL AI M:

1 a t e r a 11 y back side to define ax 1 e ho 1 e ends o f surface of p 1 u r a 1 i,t y side of th he upright walls, graduations A mitre saw with a working table portion, a pair of rectangular flat portion extending from the circle and each having an upright wall at a each of the upright walls has a cant inner end so as a roughly V-shaped indentation therebetween, a first formed in the center of the circle between the cant engraved on an upper the circle abutting front circumference thereof and a of positioning r e c i r cl e -, a rotary arm rotatably from the underside of the circl elongate rectangular body, a seco proximal a rear end and engageable means oil a screw, a pair of general their inner surfaces perpendicularl the body respectively, said rectang r.und ncteb at tip, an arcuate gu. flat portion, a plurality of posit apart and around out positioned abutting body. a thru hole slidably receiving a rotary arm horizontal receivable peripheral p i vo ta 11 y projected sawdust protection device comprising:

including a horizontal circle at a ecesses formed spaced apart in an under secured to the first axle hole e, said rotary arm comprising an nd axle hole vertically formed with the first axle hole by ly rectangular blocks having y integra u 1 a r b 1 o c k de slot cent i o n i n g r e c er periphery of the guide each of the four corners in an appropriate position of the body for tubular retaining means for retaining s a i d into one of the positioning recesses under the circle, said retaining means having a peripheral hole with a lever means which a tip end inserting into the ho I e, a 1 a t e r a 1 t h r u h o 1 e in a m i dd 1 e po r i o n f o r securing the lever means within a pair of lugs downward from two lateral edges of the body by an axle - to - ted with two ends of each including a a 1 l Y f o r m e d t n a sses formed spaced slot, a screw hole of the rectangular eral projection Lriner surface to which a first spring means the under side of the body and the lever means; engageable with said rectangular including a flat rectangular body, equal to the first round notch, a o u t e r 1 edge formed in an upper portion beneath the third a plurality of internally threaded tubes projected from inner ends of a plurality of screw four corners thereof for securing said plates into of screw holes of said blocks by means of screws; r of saw racks rotatably engageable within a pair of outer plate blocks, said outer plates each a third round semi-circular circumferentia round notch, transversely holes adjacent the plurality a pai a pair of receiving sp,aced defined by said outer plates and said b 1 o c k s thereinbetween, said saw racks each including a rack seat, a second notch at tip having a first and a projected outward from two ends for engaging third round notches respectively, an axle tu through a lower center of the rack seat recesses of the outer plates and having peripherall wall abutting free end thereof, a through a lower portion adjacent a lateral extended from an s biasing between notch in the tip recess including graduations around second round flange with the first and e extended outward nd the semi-circular a slit in an upper threaded screw hole ide for engaging a with butterfly bolt which is to fix the rack seat against said blocks and prevents the rack seats from rotation, an axle rod centrally extended from an inner surface of the rack seat for siidably engaging the rack seat said rectangular blocks, and a engaging a h into the arcuate guide pair of uprights for acksaw parallel extended upward from top of seat and secured by a pair of threaded pins respectivel a pair of position-ing rod slidably engaging axle tubes of said outer plates, said positioning including a taper inner end selectively engageable - 1 1 S 1 ots o f s 1 i d a b 1 y the rack i n t o t h e rods each w i t h t h e positioning recesses o F 1 lie 1) 1 o c k s, a threaded o u t e r e n d inserting into the axle tubes of said outer plates with a second spring means wrapped on an the axle tubes and a radi position of the positioni from the slit thereof.

2. A mitre has a rectangular outward end of the rectangular facing said outer plates and d fastened by a nut outside free end of al thru hole through an appropriate n g rod and secured by a retaining p i n saw as recited in claim 1 wherei notch on the tip including a ro said saw rack und flange at notch, an outward axle rod formed under the axle tube.

3. A mitre saw as recited in claim 1 wherein said outer plates each includes an arcuate groove formed in an inner surface under the semicircular slot for slidably receiving the outward axle rods of said rack seats.

4. A mitre saw as recited in claim 1 wherein said rectangular blocks each includes a rectangular notch at tip engageable with the rectangular notches of said rack seats, a plurality of positioning recesses arcuately arranged spaced apart in an outer surface and a widened thru hole adjacent each of four corners for passing through the screws from said outer plates and,u-.ch fastened on inner side by a nut.

cited in claim 1 wherein said lever a grooved end, a lateral hole in a ht projection extended from an upper end having a spring means biasing 5. A mitre saw as r means includes a tip end middle portion and an upri edge proximal the groove thereon.

6. A mitre saw as recited in rectangular blocks each includes a round guide slot in an upper portion beneath widened thru hole adjacent ea through the screws from said oute nut on an inside surface thereof.

claim 1 wherein said notch at tip, an arcuate the round notch and a S for passing h fastened by a eh of four cornp r plates and eac 7. A mitre saw as seats are of semi-circu projection from two late a round flange at inward end of the notch engageable with the round notches of said r plurality of spaced adjacent lower circumfe round notch engageable projected inward from an i slot of said rectangular 8. A mitre saw as plates each including circumferential pointer slit centrally extended beneath the semi-circular rod and four internally thr from the inner ends of the engageable with the four scr 9. A mitre saw as re seats are of semi-circular p.,;,jjection from two lateral round flange at inward end said rectangular blocks, arranged spaced apart with circumference and an axle r i n n e r b 1 o c k s.

r e c 1 t c d in c la im 1 where in said rack lar shape and each includes an upright ral ends, a round notch at tip including ectangular blocks, graduation abutting a positioning recesses arcuately arranged r e n c e a large s c r e w hole adjacent t h e with a bolt and an axle rod centrally nner surface engageable with the guide b 1 o c k s.

r e c i t e d a se in upper outward notch fo eaded f o u r n claiE 1 wherein said outer i-circular notch with portion, an axle tube with from an outward surface and en-eaging with the positioning ubes spacedly extended inward c revA h o 1 e s respectively and a surface engageable ews. cited in claim 1 wherein said rack shape and each includes an upright e n d' s, a r -- u n d n o t c h at t i p w i t h a engageable with a plurality of a pointer thereabo od centrally proie with the guide slot the round notch of recesses arcuately ve adjacent lower cted inward from an of said rectangular 10. A mitre saw as recited plates each includes a semi-circular therearound in an upper portion, an axl extended outward from in claim 1 wherein said outer n 0 '1 c h w i t h graduations t u b e w i t. h s 1 i t cpnti.ally an outward surface under the graduations for engaging with the positioning rod and a larger s c r e w h o 1 e 0 engageable with fastener means which has an i nner e, n (1 s 1 o p p i n g against on outer surface of said rack seats.

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