Bar a engages or rests at e, on a lug or projection on the link i, which fits in a recess provided in the side of the frame. This link i, extends up and has a bearing to receive the feed roller (f, Fig. 3160), whose driving gear is shown at o.
It is obvious therefore, that the amount of pressure on the feed roller f may be varied by moving the weight w along the bar a.
Similarly for the delivery pressure roller, the weight w′ is adjustable along the bar a′, which is pivoted to link n, and rests upon i at e′. The link i′ is guided in ways in the side frame of the machine, and at its upper end carries the delivery roller d, whose driving gear is shown at o′ (Fig. 3163).
It is obvious that there are bars a, a′, and links i, i′, on both sides of the machine, so as to adjust the feed rollers at both ends.
The work table and the two lower rollers are adjusted for different thicknesses of work as follows:
Between the two main side frames m and m′, Fig. 3164, are two frames having corresponding inclines or slideways, of which the upper carries the work table and the lower rolls.
The lower incline sits on ways k, k, Fig. 3164, cast on the side frame, and is capable of being moved endwise by means of the hand wheel r, Figs. 3163 and 3164, which operates a screw threaded into the lower incline. When the lower incline is moved endways, the upper one, which carries the work table, is moved vertically, and as the lower feed rolls are carried by the upper incline, and the upper rolls are guided to move vertically only, the lower rolls maintain their position beneath the upper ones, or in other words, the table and lower rolls move together in a vertical direction only, when the lower incline is operated.
The lower rollers run in bearings formed in the links q, q, Fig. 3160, which are pivoted at their other ends to the upper incline. On the sides of the incline are lugs through which pass adjustment screws z, which by operating beneath the outer ends of the links q, q, adjust the heights, bearings of the lower rollers so that the uppermost point on the circumference stands about 1⁄100 inch above the level of the work table surface.
The upper surface of the lower incline is shown by the dotted line f, f, f, in Fig. 3163.
We may now consider the means employed to drive the rolls, first remarking that the upper rolls f and d, are given a motion slightly quicker than the lower ones, so as to cause them to clean themselves (from particles of wood that might otherwise cling to them), by a sort of rubbing action which is due to their velocity being greater than the lower rolls and the work. This rubbing action is due to the fact that the work has the slower motion of the lower rollers, resisting the quicker motion of the upper ones, and as a result there is a certain amount of slip between the upper rollers and the work.
Another and important feature, is that the upper delivery roller (d, Fig. 3160), is placed from 1⁄4 to 1⁄2 inch nearer to the cutter head than the bottom delivery roll, which assists in keeping the work down upon the table.
The mechanism for driving the feed rolls is shown in Figs. 3163, 3164 and 3165, in which l, l are the pulleys which receive motion from a countershaft, and drive the cutter head, being fast upon its shaft, as is also the pulley s, which connects by belt and drives pulley t, on whose shaft is the stepped pulley u, which connects by a crossed belt to pulley v, which drives the feed gear through the medium of the pinion a. The two steps on pulleys u and v, obviously give two rates of feed.
The pinions o and o′, both receive motion from the gear wheel e, this part of the gearing consisting of gears a, b, c, d and e, and as both pinions receive motion from the same gear, their revolutions are equal. The lower feed roll is driven by the pinion p, which gears with and is driven by wheel d, whose face is broad enough to meet p, which sits nearer to the frame than pinion o does, so that the teeth of p may escape those of o.
Now the velocities of all the wheels o, o′, e, d and p, will be equal at the pitch circles, because they constitute a simple train of gearing. Thus if d moves through a part of a revolution equal to the pitch e, then o and o′ will move through the same distance, because the wheels are in continuous gear. Now as d drives p, therefore the velocity of p must at the pitch circle be the same as d, let the numbers of teeth in the respective wheels be what it may, and it follows that the velocities of o, e, d and p are at the pitch circles equal. But by making the diameter of the upper roll greater than the pitch circle of its gear o, and the diameter of the lower roll correspondingly less than the diameter of the pitch circle of its pinion p, the velocity of the circumference of the upper roll will be greater than that of the lower roll, and the rubbing action before referred to with reference to the upper roll will thus be induced.
Referring now to the lower delivery roll, its pinion x receives motion through gear w, which is also driven by gear e, which has a broad face so as to gear with x, which is behind and below gear o′. In this case the circumstances are the same, as will be seen from the following.
An inch of motion of the pitch circle of e will produce an inch of motion at the pitch circles of o′ and of w and x, hence the velocities of the pitch circles will be equal, and if the diameters of the upper and lower rolls are equal, or the same as the pitch circles, the velocities of the circumferences of the respective rolls will be equal, but by making the diameter of the upper delivery roll greater than that of the pitch circle of its pinion, and that of the lower roll less, a rubbing action is induced between the roll and the work, and this rubbing action will keep the roll clear of any dust, etc., that might otherwise cling to it.
The cutter head is formed triangular, as in Fig. 3166, carrying three knives. The knives are set at an angle to the axis of the cutter bar or cutter head. When the knives are at an angle, they take their cut gradually, and the cutting action is more continuous, which diminishes the vibration of the machine, and causes the finished surface to be smoother. Furthermore, the knives take a shearing cut, and therefore cut more easily and freely.
In some practice the knives are made spiral, but spiral knives are difficult to bed properly to the cutter head, and also difficult to grind. The cutter head is made of a solid mild centre steel forging, and runs in phosphor bronze journals, in which it has about 1⁄8 inch end play, which tends to distribute the oil along the bearing. It is driven by a pulley at each end, the pulleys seating on a cone.
The amount of skew is about 3⁄4 inch for a cutter head carrying a knife 30 inches long, and about 3⁄8 inch for a cutter head whose knives are 10 or 12 inches long.
Figs. 3167 and 3168 represent a machine in which there are three feed rolls and one delivery roll, all being driven.
First there is the pair of feed rolls the bottom roll of which is set sufficiently above the surface of the table to relieve the work of friction upon the table.
The work next meets an upper feed roll that acts to force the work down to the table surface (there being in this case no lower feed roll).
After passing the knives, the work is carried out by a delivery roll that also acts to keep the work down to the table face.
All three upper rolls are provided with rubber springs in the casings h, h′.
p, p, are the pulleys for the cutter head and b, those for the feed works, which have two speeds. The feed is thrown in and out by the lever d, which moves the pinion d endways and engages or disengages it from its gear wheel.
Figs. 3169, 3170, 3171 and 3172 represent a pony planer, by P. Pryibil.
Referring to the sectional view Fig. 3170, the work table slides in vertical slideways s, in the side frames, the elevating screw being operated by the bevel gears at g, which receive motion from the hand wheel m in Figs. 3170 and 3171. There are four upper rolls, marked 1, 2, 3 and 4 respectively, and of these the first two are fluted in the usual way. There are two lower rolls, marked respectively 5 and 6. The fluted feed rolls 1 and 2 are weighted, the weight lever acting on the rod r, which at its upper end connects to the cap y, which covers the bearings of feed rolls 1 and 2. By this construction the two rolls are acted upon by the same weights and levers, the rolls being of course weighted at each end, or in other words on both sides of the machine.
The delivery rolls 3 and 4 receive their pressure by the construction shown in Fig. 3172, the bearings of the rolls being held down by rubber cushions receiving pressure from the cap e, screwed down by the bolt and nut.
The rolls 5 and 6 are idle rolls, and are set to just relieve the work from undue pressure on the work table.
By this construction of feed mechanism the following ends are attained. First, sufficient feed power for heavy cuts is obtained without driving the lower rolls. Second the work is held to the table on both sides of the cutter head, hence there will not be left on the end of the work the step that is left when but two upper and two lower rolls are used, and which occurs because the work falls after leaving the feed rolls, whereas, in this machine the work is held to the table by rolls 2 and 3.
The cutter head h, Fig. 3170, has in front of it the pressure bar p, whose lever is shown at l and the weight at w. On the delivery side of the cutter head is a pressure bar r, which is acted upon by a spiral spring in the box c. In the engraving to the right of Fig. 3170 the knife k is shown in action on a piece of work, and it is seen that the end of the pressure bar p coming close to the edge of the knife prevents the pressure of the cut from splitting or splintering off the end of the work at a, and therefore acts as what is termed a chip break. Furthermore, the sides of the cutter head between the knives being hollowed out gives the shavings s room to curl in and prevent the work from splintering at the end when the cut is terminating.
Balancing Cutter Heads and Knives.—Planer knives must be balanced as accurately as possible, in order that they may run steadily and smoothly, and therefore produce smooth work.
The first requisite for proper balancing is that the cutter head itself be properly balanced, and in order that this may be the case the faces forming the knife seats must be equidistant from the axis of the cutter head, and the journals must run true, being best tested on dead centres. The holes for the cutter bolts should all be drilled to the same depth, and tapped equally deep. The faces or seats for the knives should be parallel one to the other, and this may be tested by a pair of straight edges, one pressed to each face and the width between them measured at each end, or if a long surface plate is at hand, one face of the head may be rested on the surface plate, and the straight edge ruled on the other face, and its distance measured from the surface plate at each end, with a pair of inside callipers delicately adjusted.
A straight edge rested lengthways along the knife seat of the head and projecting over the journal will show whether each knife seat is equidistant from the journal as it should be, the measurement being taken with a pair of inside callipers adjusted to just sensibly touch the journal and the straight edge. This measurement should be taken at each end of the head.
In all tests made with straight edges, the straight edge should be turned end for end and each measurement repeated, because, if the straight edge is true, turning it end for end will make no difference to the measurement, while if the straight edge is not true the measurement will vary when the straight edge is reversed.
If the cutter head is square, the straight edge tests may be applied to all four of its faces, and they may then be tested with a square, and if the head shows no error under these tests, and the bolt holes or slots are of equal diameter and depths, the head will be correct as far as it can be tested without running it.
A cutter head may be roughly tested by placing it between the lathe centres, both centres being oiled and delicately adjusted so as to just prevent end motion of the head without perceptible friction when the head is revolved by hand.
The first thing to test is whether the journals run true, which may be tested by a pointer fastened in the slide seat, and moved up to just touch the journal. The pointer should be soft, and not a cutting tool, unless indeed it be set so high in the slide rest that it cannot cut.
If the journals do not run true, the next thing to test is whether the body of the head runs true to the centres, which may be done by first setting a pointer to just touch the extreme corners of the head at each end and in the middle of its length, and if there is an error in the same direction as the test at the journal shows, then the centres of the head are out of true, and must be corrected before a test of this kind can be proceeded with.
But the body of the head may show true at the corners while the journals do not run true, and if this is the case we may further test the body of the head as follows:
With the lathe slide rest at one end of the head we may set a pointer so that it will just pass on the flat of the cutter seat and make a mark when the slide rest is traversed along the lathe bed. We then move the slide rest so as to bring the pointer to the journal end of the head; give the head a half a revolution on the centres and try the pointer on the flat of the cutter seat, and if it makes a mark of equal strength, then two faces of the head are equidistant from the axis of the head.
The next thing to do is to make the same test at the other end of the head, and in order to do this without moving the pointer, and therefore without altering its adjustment, we must move the slide rest so as to bring the pointer opposite to the lathe centre, and out of the way of the body of the head, and take the cutter head out of the lathe and turn it end for end, and then repeat the test with the pointer, which will show whether both ends of those two flats are alike.
This test we repeat on the other two faces of the head, and if they show true, then the head is true, except the journal, which must be made true with the head.
This testing will clearly show any want of truth in either the head or the journals, and in what direction correction needs to be made.
Now suppose the above tests do not disclose any error, either in the journals or in the head, and we may continue the tests by revolving the head by hand between the dead centres, and apply the pointer to the journals while the head is revolved as quickly as possible; as, however, the head cannot be revolved very fast in this way, we may adjust the lathe centres as before described, and revolve the head as rapidly as possible by hand, and letting it come to rest mark which side is at the bottom, and if on several tests the same side comes to the bottom of the plane of revolution at each test, that side is the heaviest and must be corrected. If it is found to be a flat side or cutter seat that comes to rest at the bottom, the correction can be made by deepening the bolt holes on that side, measuring to see which bolt hole is the shallowest, and making all as nearly as possible equally deep.
If the head has T slots instead of bolt holes, the slots may be cut or filed out to effect the balance, care being taken to make the slot equal in distance from the edges of the cutter seat face.
The next essential in order to have a properly balanced cutter head is that the bolts and nuts all weigh alike, and that the bolts be of the same length. The bolts should be turned to an equal diameter of equal length and threaded for an equal distance along the body of the bolt, and the nuts should be of equal depth and all fit accurately to the same wrench, and the weight of the bolts and nuts when put together may then be equalized by reducing the heads of the heavy ones.
We now come to the balancing of the knives, which must be made of equal thickness and width throughout, with the slots for the bolts of equal widths and depths.
The knives require to be as accurately balanced as it is possible to make them, for otherwise they will cause the head to jar and vibrate violently, thus producing rough work. The knives weighed individually may be of the same weight, and yet the head may run out of balance by reason of one end of a knife being heavier than the other end.
Fig. 3173 represents a machine constructed by J. A. Graham & Co., for balancing planer knives, moulding knives, cap screws, and knives in rotary cutter heads of all kinds.
Let it be supposed that the knives are the same specific weight, but that there is an excess of weight at one end; when revolving on the head, a violent jarring or throwing will be caused by reason of the excess. The knives could be reduced to the same specific weight by the aid of common grocers’ scales, but the ends could not be made the same proportional weight as on such balance.
In the cut s s is the base of the scale; l, m the standards for the support of the scale beams b b and k k.
d, d′ are two pivots of the scale beams.
d is the loop on which the pivot d works.
e is a joint in the loop.
d′, e′, and f show the loop and connection.
c is the sliding table which has the stop c′, and is adjustable for different lengths of knives.
a a is a knife in position for balancing endwise.
g is a slotted piece, and is held to the scale beam by the screw v. The slot in g is shown at g′, and limits the travel of the scale beams.
h is an angular piece fastened to the lower scale beam, and receives the screw j.
i is a small weight used for fine adjustment.
o, o are weights which slide along the scale beam k k, and are held in place by the thumb screws p, p.
n shows side view of weight, which is so constructed as to allow it to be easily removed. In using the machine the lightest cutter or knife of the set is first found and its two ends balanced, by turning it end for end on the scales, and reducing the weight of the heavier end. The other knife or knives are then balanced without disturbing the adjustment of the machine as made for the first knife.
ENDLESS BED OR “FARRAR” WOOD SURFACING MACHINE.
This class of machine has a bed composed of slats which are connected together and driven by a chain.
Fig. 3174 represents an endless bed double surfacer constructed by the Egan Company. The upper cylinder may be raised or lowered to suit the thickness of the work. The front feed roll is in two sections, enabling two boards of unequal thickness to be planed simultaneously to an equal thickness. These rolls are held to the work by a leaf spring, as shown in the cut, the tension on the spring being adjusted by the screw at d, d serving as a check-nut.
A longitudinal section through the centre of the machine is shown in Fig. 3175. The spring s bears at each end on a block t, which carries the bearings for the feed roll. Feed roll m is held down by the screws e, e, acting on a rubber cushion or spring, and is provided with a scraper to clean it from dirt, etc.
The travelling bed is composed of slats s connected together by the chain shown, and resting upon slides a, a, supported by the girts b, b.
The chain is operated by the spur or sprocket wheel w, and is therefore pulled and not pushed, which tends to keep it under tension, and therefore rigid upon the top side.
The ends of the slide a, a are depressed so that the slats shall not tilt up at one corner above the level of the slide when in the positions denoted by s′.
The lower cutter head is carried in a sliding head or frame j, adjusted for height by the gears at h, which operate screw h, while the bed above it is adjusted by the gears at f. It is obvious that the bottom surface of this bed is set at the same height as the lowest point in the path of revolution of the cutting edges of the knives of the front cutter head or cylinder. The upper delivery roll n is provided with a scraper.
PLANING AND MATCHING MACHINE.
Planing and matching machines that are made narrow to suit the planing and matching of boards for flooring are sometimes called flooring machines, the distinctive feature of a flooring machine being that it is (unless in the case of a double machine) made narrow (because flooring boards are narrow), and this makes the machine very stiff and capable therefore of a high rate of feed and speed.
Fig. 3176 is a general view, and 3177 a longitudinal section through a standard planing and matching machine of recent design, constructed by Messrs. J. S. Graham & Company. The plank passes through two pairs of rollers before meeting the front cutter head. The side heads then come into operation cutting (in the case of flooring) the tongue on one side of the plank and the groove on the other, the under side of the plank being dressed last.
The machine is built in three widths viz., 8′′, 14′′ and 26′′, each planing to 6′′ thick and matching as wide as it planes.
In place of matching heads, heads for beading, rabbeting, or fancy siding may then be used.
The board r (Fig. 3177) is fed in over the grate m′ until it reaches the rolls e and f′, which are held in place by the boxes fitted to the roll stand n′, and brought to bear on the lumber by means of the screw a′, equalizing bar m and nuts p, p, together with the lever y y and the weight x.
After the lumber leaves the second pair of rolls, it runs over the bed plate w (Fig. 3178) and under the shoe l, the duty of which is to hold the board firmly against the bed plate, and also to break the chips on a heavy cut. After leaving the shoe it is operated on by the upper cutter head h, then it passes beneath the pressure bar g, which holds the lumber firmly while it is acted on by the matcher c.
It then passes beneath the cleaner e′′ (Fig. 3177) and under the delivering roll, which is held down by the weight u in connection with the lever v and screw a′, the top which is shown at c (Fig. 3179). The board then passes underneath the pressure bar q (Figs. 3177, 3180) and over the under cutter s, from which it passes finished.
The pressure bar q is moved up and down by turning the shaft a′′, the motion of which is given to the screw h′ by means of a pair of bevel gears. k′ is also a scraper that cleans the board before it passes under the pressure bar q. The under cutter is adjusted for depth of cut by turning hand wheel a′, which moves the screw u′. The rolls are raised and lowered by turning the shaft at p (Fig. 3176).
In feeding two boards through the machine, one thicker than the other, that end of the roll that passes over the thick board can raise up without taking the pressure off the thin one at the other end of the roll. This raising mechanism is shown in Fig. 3179. The bevel gear c works over a ball joint q′. The shoulder b′ on the screw a′ works on the under side of the ball q′. The shaft a passes through the tubular shell b to the opposite end of the roll. The cross tie j is bolted to the roll box k′′.
c, Fig. 3178, shows matcher hanger in position. It is gibbed to the bed plate z by the gib f, which is so constructed as to be free from dirt. The sliding gib f is adjustable for wear. One matcher hanger is moved by the screw e, the other by e′. The left hand matcher hanger is moved by the shaft l′ (Fig. 3177), which passes along the side of the machine until it reaches the shaft e, where its motion is imparted to the screw by means of a pair of spiral gears. An index at the rear of the machine enables the operator to set the matcher heads to any desired width. The right hand matcher hanger, together with the guide, can be moved across the machine by turning the screw e′ at the side of the machine (Fig. 3176).
The upright d which carries the pulley which drives the top cutter head, or cylinder as it is sometimes termed, is set at an angle so that the cylinder belt will always be of the same tension.
The top cylinder is raised by the shaft d (Fig. 3176) and screw b. It is held in place by the nut m (Fig. 3177). The bar i ties the cylinder boxes together. k is held down by the weight i, and yields with the pressure bar l.
The spindle of the matcher c′ (Fig. 3177) is driven by a belt which comes from the pulley h and passes over the guide pulley k, and then to the pulley b′.
The lower end of the matcher is held in place by being gibbed to the cross tie p′, Fig. 3177, which is adjusted and kept in position by the screw o′.
s′ sustains the matcher spindle by means of an adjustable step.
y′, Fig. 3176, is the feed shaft which drives the gearing that operates the rolls. The pulley that drives the feed shaft is shown at l′ (Fig. 3176). The belt passes over this pulley and under and over the tightener pulleys w′, w′, then to the pulley u′ which is on the feed shaft y′.
The apron m′ in front of the under cutter s (Fig. 3180) is easily dropped to m′′ by loosening the nut r′ and releasing the bolt t′ so as to allow the apron m′ to drop.
This enables the operator to have free access to the under cutter for sharpening knives, etc. z′ is the bed plate over which the lumber passes before it reaches the under cutter.
A planing and matching machine designed and constructed by Messrs. London, Berry and Orton is represented in Fig. 3181. In this machine the upper surface of the board is surfaced first, and the matching second, the under surface being operated upon the last. The method of suspending the upper feed rolls of this machine is shown in Fig. 3182, in which a is an upper and b a lower feed roll. The upper roll a is suspended by the link c, which is supported by the link d, and also by link e, these three links forming a parallel motion which guides a in a vertical line.
At f (which is fast to e) is a bearing for the screw g, and the pair of bevel gears g that drives it. This screw threads into the nut h on the rod i, which receives the pressure of the bar j and weight k.
The lower feed rolls being larger in diameter gives them increased grip on the work, and gives it a better base, and also makes it enter and leave the rolls easier.
Each matcher bracket is fitted with a screw by which it can be moved at will across the machine, and by turning one other screw with the same wrench that moves the others, both brackets are firmly set to the slide and all screws held firmly. There are three changes of feed. The top cutter head is provided with improved pressure bars, which are set to or from the head by means of a double eccentric, which, while they can be set at any desired distance from the knives, limits their movement when moved towards them, rendering it impossible to get them into the cutters.
TIMBER PLANER.
The term timber planer implies that plain knives only are used in the machine, which is therefore intended for producing plane surfaces. It also implies that the machine is designed for heavy or large work, such as is found in ship yards, bridge construction or car works, etc., etc.
In such work the cuts taken by the machine are sometimes very heavy, and as a result the feed works of the machine require to be very powerful and positive.
Fig. 3183 represents a timber planer designed and constructed by J. S. Graham & Co., to plane all four sides of the timber at one passage through the machine.
The timber passes through three pairs of feed rolls before reaching the first cutter head, which planes the bottom surface.
It then passes to the side heads, which dress both sides simultaneously, and then passes beneath the cutter head that finishes the upper surface, and is finally delivered from the machine by a pair of delivery rolls.
The work is passed over roller b, the fence or gauge being shown at b′. 1 and 2 are the first pair of feed rollers, a and b being merely adjustable intermediate wheels, which by means of the pieces c′, b′, may be set so as to connect rollers 1 and 2 together, whatever their distance apart may be, or in other words whatever the thickness of the work may be.
From 1 and 2 the work passes to the second pair of feed rolls 3 and 4, c and d being the intermediates.
Similarly 5, 6, 7 and 8 are feed rolls, and e, f, g, h intermediates. The first head is shown at k′, the side heads at h, and the last head at i′, the latter being carried on a sliding head j, which is secured in its adjusted position by nuts i. On the side of the frame d on which j slides is a graduated index to denote the adjustment of the head i′.