Fig. 3136-3137Fig. 3136.Fig. 3137.
Fig. 3136.Fig. 3137.
The feed rolls are carried in slides which are operated in slidewaysby means of screws, and the two back rolls, or those nearest to the column are maintained vertical. The two front ones, however, are provided with means by which they may adjust themselves to bear along the full depth of the work, notwithstanding that it may be taper. The construction by means of which this is accomplished is shown inFigs. 3136and3137, in whichais front andba back feed roll. The bearings of feed rollaabut against rubber cushionsc,c, whose amount of compression is regulated by the set screwsd,d.
Fig. 3138Fig. 3138.
Fig. 3138.
The construction of the saw guides is shown inFig. 3138, which is a plan view partly in section.s sare hardened steel plates set up to the saw by means of studs whose nuts are shown atn n.wis a friction wheel which supports the saw against the thrust caused by the work feeding to the saw. The adjustment of the wheelwto the saw is obtained by means of the wheelh.
The hand wheelhoperates the screwr r, that adjusts the wheelwto the saw, the wheeljserving to lock the screw in its adjusted position.
Fig. 3139represents Worssam’s band saw machine, in which the standard may be set at any required angle for cutting bevels.
When the work is heavy and not easily handled it is preferable to set the standard and saw at the required angle, rather than to set the table at an angle and have the saw remain vertical. In Worssam’s machine this is accomplished as follows:
ais the main frame carrying the work tablet, and having circular guidewaysb,b′, which carry the standardchaving guidec′for working in the circular guidewaysb,b′.
The saw-driving wheeld, is carried in bearings provided inc, and, therefore moves when the standardcis moved.
At the upper end ofc, is the slidee, which carries the bearing for the upper wheelf, this slide being adjusted to regulate the saw tension by the hand wheelo, whose screw threads into a nut in the slidee.hcarries the front guideg, for the saw, the back guideg′being carried by a bracket bolted toc. The back guide is fixed in position, but the front one is adjustable to suit the height of the work by raising or lowering it.
The means for setting the saw at the required angle to the work table are as follows:
At the back of the standardcis a rackj, whose pitch line is an arc of a circle of which the axis of the guidewayc′is the centre.
Into the rackjfits the worm wheelk, at the bottom of the shaft of which is a pair of bevel gear wheelsl, which are operated by the hand wheelm.
A band saw machine constructed by Messrs. London, Berry & Orton, is shown byFigs. 3140,3141and3142, inplate XXIII. The saw-driving wheeld, has wrought iron arms turned true and screwed into the wheel hub. The wooden segments have their grain lengthways of the rim, and between them are placed pieces of soft wood with the grain across the rim. This acts to keep the joints tight, notwithstanding the expansion and contraction of the wood.
The upper wheel is adjusted for straining the saw, and for leading the saw true, by the following construction. It is carried in a U-shaped framef, which is pivoted atyto a slide that is gibbed to the main frame, and by operating the screw shown atx, the framefis set to the required level.
To regulate the tension of the saw, the hand wheelkis operated, which drives the pair of bevel gearsjandi, the latter of which operates the threaded shafth, whose upper endgconnects with the slide which carriesf. Withingis a spring to act as a cushion to the slide, and thus prevent saw breakage should a chip pass between the saw and its driving wheel.
The saw guide frame is secured to the main frame atm′,m′. Upon the face ofm, is a slideway for the saw guide armn, which may thus be adjusted as closely to the upper face of the work as possible.
The weight of armnis counterbalanced by a rope passing over the pulleyv, and supporting the counterbalance weightw. The feed motion is constructed as follows:
On the same shaft as the main fast and loose pulleysa,b, is the feed pulleyl, which by belt connection drives pulleym, which is on the shaftw, upon which is a friction discn, by means of which the rate of feed is regulated. The feed discndrives the wheelo; the degree of contact between these two (nando) is regulated by means of the weightt, on the leveru.
On the same shaft as the friction wheelo, is a pinion driving the gearx, which is on the same shaft as the piniony, which drives the two gearsy′andy′′.
Referring now toFig. 3142, geary′drives the pair of bevel gearszandz′, for the feed rolle, and the pair of bevel gears shown atz′′, the feed rollf. The geary′′drives similar gearing for the feed rollse′andf′, seen in the planFig. 3140.
Referring now to the planFig. 3140, and the side elevation,Fig. 3142, the feed rollfis carried in a frameg, which is fitted on the slidewayd,d, and receives a screwi, upon which is a hand wheelh; at the back of this wheel is the leverj, which is weighted as shown, so that the force with which feed rollfgrips the work is determined by the weighted leverj, and may be varied to suit the nature of the work by moving the weight alongj.
The construction of the gear for feed rollf′is similar, as may be seen in the planFig. 3140,f′being in a slideg′, which has a screwi′, and hand wheelh′, a weighted lever corresponding tojacting against wheelh′. In proportion asfandf′areopened out to admit thick stuff or work, the hand wheelshandh′, respectively are used to screw the screwsiandi′into their respective slidesgandg′, and thus maintain the weighted levers in their requisite horizontal positions. The feed rollseande′are carried in slidescandc′, and are adjusted to suit the thickness of the stuff or work by a hand gearing, which consists of the hand wheela, seen in the plan and in the front elevation,Fig. 3141, which drives the pinionsbandb′, which operate screws for the slidescandc′, the latter being a left hand screw. The front rollseande′are therefore held in a fixed position, whereas the back onesfandf′may open out under the pressure of the weighted leversj, and thus accommodate any variation in the thickness of the work.
The rate of feed is varied to suit the nature of the work by the following construction: The friction wheeloand the hand wheelrare connected by a yokeq,Fig. 3142, at the ends of which are the jointsp,q, seen in the plan,Fig. 3140. Hand wheelris threaded to receive the screws, and it follows that by revolvingr, the friction wheelomay be moved towards the centre of the friction discn, which would reduce the velocity with whichnwould driveo, and therefore reduce the rate of feed. If the friction wheelobe moved from the position it occupies in the planFig. 3140, to any point on the other side of the centre of the friction discn, the direction of feed motion would be reversed.
Fig. 3143Fig. 3143.
Fig. 3143.
A band saw machine for the conversion of logs into timber, and constructed by Messrs. London, Berry & Orton, is shown inFig. 3143. The logs are fixed to the carriage by dogs and the carriage traverses the log to the feed.
Reciprocating Cross Cutting Saw For Logs.—The machine shown inFigs. 3144and3145is designed for the purpose of cutting heavy and long logs into convenient lengths preparatory to cutting the logs up in other machines, and it is usually therefore placed at the entrance to the mill, where it is of immediate service as the lumber comes into the building.
The machine here shown is intended for logs up to 36 inches in diameter, is simple in construction, requires very little foundation, is easy to handle, and occupies but very little room.
The saw is here fed mechanically to its cut, whereas in some machines it is fed by its own weight, and therefore requires great care to be taken, when the saw is finishing its cut, in order to prevent it from falling after it has passed through the log.
Fig. 3145is a side elevation andFig. 3144a plan of the machine, in whichais the frame of the machine on which are the bearings for the shaftbcarrying the fast pulleyc, loose pulleydand fly-wheeleat one end, and at the other, a crank discf, whose pin is shown atg. This drives the sawkthrough the medium of the connecting rodh.
The saw is fast at the butt end to along slidej,j, which works in a long guide formed on the face of the swinging framel, which pivots at one end on the shaftband at the other is carried by a slidep, on the vertical slidewaym, and is fed down the same to give the saw its cut by the screw whose hand wheel is shown atn.
vis a second guide for the saw, and being connected to the slide feeds down with the saw until it meets the log.
A counterweightwbalances the weight of the slides and saw, so that there being a pit beneath the balance weight the saw and its guides may be raised so that the saw stands out of the way when not in use.yis a dog for holding the log, which is also blocked by the wedgesz z′.
Fig. 3146Fig. 3146.
Fig. 3146.
The construction of the main bearing is shown inFig. 3146, in which it is seen that the hub or boss of the loose pulley is much longer than that of the fast one, thus providing a large amount of bearing surface, which is advantageous because the belt will remain longer at the loose pulley than it will on the tight one. The sleeves or bushes in which the shaft runs afford a simple means of renewal to restore the fit when the shaft has worn loose in its bearings.
It is obvious that as the guide framelis pivoted to the shaftb, it carries the end of the saw (as it is fed down) in an arc of a circle of which the axis ofbis the centre, whereas the slidewaymis straight, and slideptherefore moves in a straight line instead of in the required arc. Provision however is made to accommodate these two motions as follows:
Fig. 3147Fig. 3147.
Fig. 3147.
Fig. 3147is a sectional view of the slides on the slidewaymandFig. 3148a plan of the same. The hand wheelncorresponds toninFig. 3145. Upon the vertical slideway (inFig. 3145) of the standard fits the slidep, which has a horizontal slideway for the slider, which is free to slide automatically, having no screw or other device to restrain it, save the guide framel, and therefore as this frame is lowered to feed the saw the slidermoves automatically to accommodate the arc of a circle in which the guide moves on account of being pivoted atb.
Fig. 3148Fig. 3148.
Fig. 3148.
Horizontal Saw Frame.—This machine is designed for the more expensive woods, such as mahogany, and is finding much favor because it will cut at a very high speed, the saw travelling about 150 feet per minute.
The roughest shaped trunk may be easily fixed on the travelling table, and a thin saw may be used as it may be very tightly strained. This machine is used either for breaking down timber, or for converting it from the log to any desired thickness, the thickness of the boards being very readily and easily varied.
The machine consists essentially of a framework carrying either one or two very thin and tightly strained saws operating horizontally and cutting on both strokes, so that the feed is continuous, the construction being as follows:
Referring toFigs. 3149and3150,ais a base plate or bed carrying two uprights or standardsb,b, having guidewaysc,c, for the cross-headd, which has slidewayse,e′, for carrying the framef,f, which carries the sawg, which is guided on each side of the work by the guidesh,h′.
Fig. 3150Fig. 3150.
Fig. 3150.
The framef,fis connected to the slidesj,j′, and has the rodk, to which the connecting rod pinlis attached, and the rodm, which acts as a stretcher. A connecting rodp, connects the pinlto the crank pinq, on the crankq′, which is driven by belt from the pulleyt, a fly-wheel being provided ats.
It is obvious that as the crank revolves the saw reciprocates, its line of motion being determined by the guidewayse,e′.
Fig. 3151Fig. 3151.
Fig. 3151.
The construction of the saw is shown inFig. 3151, and it is seen that for half its length, the teeth are formed to cut when the saw moves in one direction, while for the other half the teeth slope in the opposite direction, and are therefore arranged to cut when the saw is on the opposite or return stroke, and the construction whereby the saw is enabled to cut on both strokes is obtained as follows:
Referring toFig. 3149, the two slidese,e′, on which the saw-carrying framef fslides, are not in line or parallel one with the other, but each slide is at an angle of about 85 degrees to the line of feed, so that as framefis reciprocated at each stroke,one end of the saw advances towards the cut, and the other recedes from it, thus causing the saw to cut first on one half and then on the other of its length, one half cutting on the forward, and the other on the return stroke.
The studs or saw-buckles for attaching the saw to the frame are shown inFig. 3151, in place on the ends of the saw, the parti, that fits in the framef,Fig. 3149, being squared so that the saw cannot be twisted in tightening up the nuts of the saw-buckle.
The belt works for driving the saw are arranged as follows: attare the fast and loose pulleys for driving pulleyr, the belt passing fromtover two pulleys (shown dotted in,Fig. 3149),u,u′, whence it stretches to the crank driving pulleyr, whose bearing is provided on the cross-head, so that the two move together when the cross-head is altered in height from the work-table or carriage, to accommodate different thicknesses or diameters of logs.
It is obvious that in proportion as the cross-head is set nearer to the carriage, the belt fromttou,u′would become slack; provision is made however, to prevent this as follows:
Pulleyu, is carried on a frame or swing leverx, to which is attached by ropevthe weightw, which therefore regulates the tension of the belt.
The cross-headdmay be raised or lowered by belt power or by hand, as occasion may require, the usual course being to move it to nearly the required position by belt power, and then complete the adjustment by hand, a graduated scale being provided as shown, whereby the rack can be set to cut the required thickness of plank without measuring the timber.
The belt motion for raising or lowering the cross-head is obtained by the pulleys aty, the wheel for the hand adjustment being shown aty′. In either case the bevel gear wheelsz,z′operate, respectively, a vertical screw engaging a nut on the cross-head.
The log feed is obtained by a motion separate from the return motion, there being three rates of feed and a quick return motion, the construction being as follows:
Referring toFigs. 3149and3150, a is a belt pulley fast on the crank shaft, and driving pulleyb, which is also shown dotted in. Pulleybdrives the vertical shaftc, on which is the cone pulleyd, having three steps, and which drives (by means of beltd′) cone pulleye, on which is a wormf, driving the worm wheelg, which runs idle on its shaft unless engaged therewith by means of the clutchh. The shaft of worm wheelgis omitted inFig. 3149, so as to leave the belt-shifting mechanism for pulleysq,q′exposed to view. On this shaft however is a pinion driving the gear wheelk, on whose shaft is a pinionl, driving the gearm, which engages the rackn, on the under side of the carriage.
The clutchhis engaged by the leveri, to the upper arm of which is attached the rodj,j, from the leverp, hence operatingp(which is done by hand), back and forth, throws clutchhinto and out of gear with the worm wheelg, and puts the carriage feed on or throws it out, according to the direction in whichpis moved.
The upper end of shaftcis carried in a bearing on the cross-head, and is provided with a featherway or spline, so that as the cross-head is raised or lowered the upper end ofcpasses through its upper bearing, and the pulleybtravels with the cross-head. The three rates of carriage feed are obviously obtained by means of the three steps on the cone pulleysdande.
We have now to explain the construction of the mechanism for traversing the table back, and giving it a quick return motion, or in other words a quicker motion on the back than on the feed traverse, and this is arranged as follows:
q, is a fast andq′,q′′, are loose pulleys, one driven by an open beltr,Fig. 3150, and the other by a crossed beltr′, from a countershaft. The belt-shifting forks are operated by levers, whose upper end engages with the rodt, which is operated by the leveru.
The loose pulleysq′andq′′are twice as wide as the fast pulleyq.
Now suppose that leveruis moved to the right, and the belt would be moved from the loose pulleyq′′to the fast pulleyq, while the other belt would merely be moved or shifted from one to the other side of loose pulleyq′.
Similarly if leveru, be moved to the left, the belt on the loose pulleyq′will be moved on to the fast pulleyq, and the belt on pulleyq′′would simply be moved across the face of the pulley, and as the countershaft pulleys for the two pulleys are of different diameters, therefore two rates of motion are obtained.
The shaftv, on which pulleyqis fast, drives the pinionl, which drivesm, the latter gearing with the rack beneath the carriage.
The carriage is guided by the wheelsz, which are secured to it, and run on the iron guidewaysz′, the flanges of the wheels preventing side play, and causing the carriage traverse to be in a straight line.
The simplest form of planing machine for wood work, is the hand planer or buzz planer, as it is termed, an example of this classof machine being shown inFig. 3152, which has been designed and constructed by George Richards, for the use of pattern-makers.
Fig. 3152Fig. 3152.
Fig. 3152.
It consists of a frame carrying a revolving shaft, which is by some called thecutter head, and by others the cutter bar, and to which the cutters or knives are attached.
The work is rested upon the work table, or else pressed against a guide orfence, and fed by hand over the revolving knives, whose cutting edges protrude above the surface of the table, to the amount of the depth of cut it is intended to take.
Fig. 3153Fig. 3153.
Fig. 3153.
In this example, however, the table is made in two sections, the front one of which is below the cutter edges to an amount equal to the depth of the cut, and the back one level with the cutter edge, when the latter is at its highest point in its path of revolution, the construction being shown inFig. 3153, in whichj,j, represents the top part of the main frame of the machine,cthe cutter head,bthe front or feed table,athe back or delivery table, andwa piece of work being fed in the direction of the arrow.
Upon the upper surface of the framej,j, and on the feed side of the cutter head is the carriageg, to which are pivoted two linksl,l, which support the feed tableb. Atdis a hand wheel whose screw has journal bearing in a lug from the table, while the screw threads into a nut provided in the carriage. Obviously then by operating the hand wheeld, carriagegis moved along the top of the framej, and the height of tablebis adjusted. Thus if the carriagegis traversed to the left, the linklwould fall more nearly to a horizontal position, and tablebwould lower. Or ifgwere moved to the right, linkslwould stand more nearly vertical, and tablebwould be raised, it being understood that tablebis not permitted to move endways. Similarly by means of hand wheelc, carriagehmay be moved to adjust the height of tablea.
By this construction, the work can bed fairly on the delivery side, as well as on the feeding side of the cutter head, which is not the case when a single table is used.
It is obvious that the work must be fed in opposition to the pressure of the cut, which endeavors to push the work back from the cutter, and this limits the size of work that the machine can operate upon.
Fig. 3154Fig. 3154.
Fig. 3154.
The work can be fed easier however, with a cutter skewed or set out of line with the axis of the cutter head. Thus inFig. 3154, is the common form of cutter head, carrying two knives placed diametrally opposite, so that the weight of one counterbalances that of the other, and the head will therefore run steadily and smoothly. The knivesk,k′are here set parallel with the axis of the cutter head, hence the whole length of the cutting edge meets the work at the same instant, and a certain amount of time must pass after one cutting edge has left the work before the other cutter edge meets it.
Fig. 3155Fig. 3155.
Fig. 3155.
This is remedied by the construction of cutter head shown inFig. 3155, in which three cutters are used, and each cutter is set askew, or out of parallel with the axis of cutter head, so that the knife begins to cut at one end, and the cutting action gradually extends to the other, hence the cutting action is more continuous and uniform, and better work is produced, while less power is required to drive and feed the machine.
Fig. 3156Fig. 3156.
Fig. 3156.
Fig. 3156shows a cutter head with two skew cutters.
The cutter head is provided with a cover or guard, which is arranged as follows: In the table is cut a groove or slideway, in which a slide fits, and to this is attached a thin sheet-iron guard. To the slide is attached a weight, which draws the guard back to the fence after the work has passed over the cutter head. By this means the guard covers all the knife edge that protrudes beyond the work, no matter what the width or thickness of the work may be; the guard can however be fixed in position when a number of pieces of the same size are to be planed.
The fence provides a guide surface for the work, and its face may be set at any required angle to the surface of the work table. Suppose, for example, that the sides or edges of a piece of work require to be at an angle of 100 degrees to the top and bottom surfaces, then the top surface may be planed first, and the fence being set at an angle of too degrees to the table surface, the top of the work may be pressed to the surface of the fence while fed across the cutter, and as a result, the side or edge will be planed at 100 degrees to the top.
Fig. 3157represents a roll feed wood planing machine, designed and constructed by George Richards & Co., of Broadheath, near Manchester, England, the construction being more fully shown in the detailed figures following. The machine consists essentially of a framework, carrying a cutter head with two knives, and having a pair of feed rolls, in front and a pair behind it. The front pair feed the timber to the cutter head and the back pair deliver it from the cutter head.
Fig. 3157Fig. 3157.
Fig. 3157.
Each pair of rolls is geared together, so that both the top and bottom rolls act to give a positive feed. Immediately in front of the cutter head and between it and the feed rolls (i. e.the front pair of rolls), is a pressure bar extending across the full width of the machine, and having at its lower extremity a steel spring which presses the work down to the table, and thus causes it to be planed of an equal thickness throughout its length. Immediately behind the cutter head and between it and the delivery rolls (i. e.the back pair of rolls), is a pressure bar that also extends across the machine and prevents the timber from rising up from the table after it has passed the cutters, all timber being found to have a tendency to rise after having been acted upon by the cutters. The arrangement of the feed rolls, delivery rolls and pressure bars is shown inFig. 3158, in whicht,t,t, represents three sections of the work table andw,w, a piece of work passing through the machine in the direction of the arrow. Feed rollerfis fluted to increase its grip upon the work and insure a positive feed. The lower feed rollerf′, and the lower delivery rollerd′, are fixed in position, their upper surface projecting above the work table to about1⁄100inch. This is necessary to take the thrust of the upper rolls (f,d) and prevent them from forcing the work down upon the surface of the table with an undue amount of pressure, which would induce friction and consume an unnecessary amount of power in driving the rolls. The method of adjusting the lower rolls will be explained presently.
Fig. 3158-3159Figs. 3158, 3159.
Figs. 3158, 3159.
Between the cutter headcand the feed rollfis the pressure barp, and behind the cutter head is the pressure barb, both these bars being more clearly seen inFig. 3159, in which the workwis shown entering the machine, and the lower rolls and work table are removed.
Fig. 3160Fig. 3160.
Fig. 3160.
Pressure barphas at its lower end a steel springj,Fig. 3159, and is supported at each end by circular linksy, projecting into grooves provided in the main frame of the machine, as shown inFigs. 3160and3161, in whichcis the cutter spindle,ythe circular link at the end of pressure barp, andythe circular link at the end of pressure barb, the two fitting into the one stepped groove.
Fig. 3161Fig. 3161.
Fig. 3161.
This groove is concentric with the cutter spindlec, so that the pressure bars keep at a positive or equal distance from the edges of the cutter, no matter what the thickness of the work or the depth of the cut may be.
Fig. 3162Fig. 3162.
Fig. 3162.
InFig. 3162, the work is shown passing beneath the two upper rollers, and the springj(which extends the whole length of the pressure bar), is depressed from the weight of the bar. By this construction, the work is pressed to the table at a point as close as possible to the cutters. The pressure barpcannot drop beyond a certain point, because of its tail piecey′,Fig. 3160, which rests on the top of the frame aty′′when the barphas fallen to its required limit.
The feed pressure barpis bolted to its circular links, as shown inFig. 3162, in whichyis a part of the circular link which is bolted to the pressure barp.
The delivery pressure barb(Fig. 3160) is riveted to and forms part of its linksy. It acts through the medium of spiral springss, which are carried in cases or boxess′, which overhang the end of the barb. A set screws′′regulates the pressure of the spring, and a screwa(Fig. 3162) regulates the height of the pressure bar.
The adjustments of the feed and delivery rollers are made as follows:
The feed pressure is obtained through the medium of weights, shown atw,w′, inFig. 3163, upon the barsa,a′, whose ends are pivoted to the lower ends of linksm,n, the upper ends of which are pivoted to the side frame of the machine.