Fig. 1629Fig. 1629.
Fig. 1629.
Now endiis caused to rise or lower as follows:—The headdis adjusted by means of its gibs to be a sliding fit on the barginFig. 1629, which bar is rigidly fixed atpto the planer bed; hence as the planer table and the chuck traverse,dslides along barg. If this bar is fixed at an angle to the length of the planer head,dmust travel at that same angle, causing endiof the work-holding frame to rise or lower (fromo,o, as a centre of motion) as it traverses according to the direction of motion of the planer table.
Suppose that inFig. 1629, the planer table is moving on the back or non-cutting stroke, then headdwill be moving towards the point of suspensionpof the barg, and will therefore gradually lower as it proceeds, thus lowering endiof the work-holding frame and causing the curved link to pass beneath the tool with a curved motion or suppose the table to be on its cutting traverse, then headdwill be raised as the table moves and the cut proceeds, and the surface cut by the tool will be concave.
Now, suppose that the bargwere fixed at an angle, with its end, that is towards the back end of the planer, inclined towards the table instead of away from it as inFig. 1629, and then on the cutting traverse headdwould cause endi(Fig. 1628) of the work-holding vice or frame to lower as the cut proceeded, and the tool would therefore plane a convex surface.
Thus the direction of the angle in whichgis fixed governs whether the surface planed shall be a concave or a convex one, and it is plain that the amount of concavity or convexity will be governed and determined by the amount of angle to whichgis set to the planer table.
When the chuck is not required to plane curved surfaces the bargis altogether dispensed with, and the chuck becomes an ordinary one possessing extra facilities for planing taper work.
Thus for taper work the work-holding frame may be set out of parallel with the base of the chuck to an amount answering to the required amount of taper, being raised or lowered (as may be most convenient) at one end by means of the gearsm, of which there is one on each side meshing into the segmental rack shown, the work-holding frame being secured in its adjusted position by means of a set bolt.
To set the work-holding frame parallel for parallel planing, a steady pin is employed, the frame being parallel to the base when that pin is home in its place.
The construction of the chuck is solid, and the various adjustments may be quickly and readily made, giving to it a range of capacity and usefulness that are not possessed by the ordinary forms of planer chucks.
Planing Machine Beds.—In long castings such as lathe or planer beds, the greatest care is required in setting the work upon the planer table, because the work will twist and bend of its own weight, and may have considerable deflection and twist upon it notwithstanding that it appears to bed fair upon the table. To avoid this it is necessary to know that the casting is supported with equal pressure at each point of support. In all such work the surface that is to rest upon the foundation or legs should be planed first.
Thus supposing the casting inFig. 1630to represent a lathe shears, the surfacesfwhereon the lathe legs are to be bolted should be planed first, the method of chucking being asfollows:—
Fig. 1630Fig. 1630.
Fig. 1630.
The bed is balanced by two wedgesa, inFig. 1630, one being placed at each end of the bed, and the position of the wedges being adjusted so that it lies level. A line coincident with the face of the bed (as faced) is then drawn across the upper face of each wedge. Wedges (asb,c,) are then put in on each side of the bed until they each just meet the bed, and a line coincident with the bed surface is drawn across their upper surfaces. Wedgebis then driven in until it relievesaof the weight of the bed, and a second line is drawn across its upper face. It is then withdrawn to the first line, and the wedge on the opposite side of the bed is driven in untilais relieved of the weight, when a second line is drawn on this wedge’s face. The wedges at the other end (asc) are then similarly driven in and withdrawn, being also marked with two lines, and then the four wedges (b,c, and the two corresponding ones on the opposite side of the bed) are withdrawn, having upon their surfaces two lines each (asa,b, inFig. 1631). Midway between these two lines a third (asc) is drawn, and all four wedges are then driven in until linecis coincident with the bed surface, when it may be assumed that the bed is supported equally at all the fourpoints. When the bed is turned over, surfacesfmay lie on the table surface without any packing whatever, as they will be true.
Fig. 1631Fig. 1631.
Fig. 1631.
Another excellent method is to balance the bed on three points, two at one end and one at the other, and to then pack it up equally at all four corners.
To test if the surface of a piece of such work has been planed straight, the following plan may bepursued:—
Fig. 1632Fig. 1632.
Fig. 1632.
Suppose that surfacee,Fig. 1632, is to be tested, it having been planed in the position it occupies in the figure, and the casting may be turned over so that faceestands vertical, as inFig. 1632, and a tool may be put in the tool post of the planer, the bed being adjusted on the planer table so that the tool point will just touch the surface at each end of the bed. The planer table is then run so that the tool point may be tried with the middle of the bed length, when, if the faceeis true, it will just meet the tool point at the middle of its length as well as at the ends.
In the planing of theV-guides and guideways of a bed for a machine tool, such as, for example, a planer bed and table, the greatest of care is necessary, the process being asfollows:—
Beginning with the bed it has been shown inFig. 1601that the sides of the guideways must all be of the same height as well as at the same angle, and an excellent method of testing this point is asfollows:—
Fig. 1633Fig. 1633.
Fig. 1633.
InFig. 1633is shown ataa male gauge for testing theV-guideways in the bed, and atba female gauge for testing those on the table. These two gauges are accurately made to the correct angle and width, and fitted together as true as they can be made, being corrected as long as any error can be found, either by testing one with the other or by the application of a surface plate to each separate face of the guides and guideways. The surfacescanddof the respective gauges are made parallel with theV-surfaces, a point that is of importance, as will be seen hereafter. It is obvious that the female gaugebis turned upside down when tried upon the table.
Fig. 1634Fig. 1634.
Fig. 1634.
Suppose it is required to test the sidese,f, of the bed guideways inFig. 1634, and the gauge must be pulled over in the direction of the arrow so that it touches those two sides only; a spirit-level laid upon the top of the gauge will then show whether the two facese,f, are of equal height. It is obvious that to test the other two faces the gauge must be pulled over in the opposite direction.
This test must be applied while fitting theVs to the gauge. Suppose, for example, that when the gauge is applied and allowed to seat itself in the ways, the two outside anglese,g, are found to bear while the two inside ones do not touch the gauge at all, then by this test it can be found whether the correction should be made by taking a cut offeor offg, for if the spirit-level stood level when the gauge was pulled in either direction, then both faces would require to be operated upon equally, but suppose that the gauge and spirit-level applied as shown proved endeto be high, then it would be the one to be operated on, or if when the gauge was pulled over in the opposite direction endgwas shown (by the spirit-level) to be high, then it would be the one to be operated upon.
By careful operation the table and bed may thus be made to fit more perfectly than is possible by any other method. To test the fit of the gauge to theVs it is a good plan to make a light chalk mark down eachVand to then apply the gauge, letting it seat itself and moving it back and forth endways, when if it is a proper fit it will rub the chalk mark entirely out. It may be noted, however, that a light touch of red marking is probably better than chalk for this purpose.
Fig. 1635Fig. 1635.
Fig. 1635.
It is of importance that theVs be planed as smooth as possible, and to enable this a stiff tool holder holding a short tool, as inFig. 1635should be used, the holder being held close up to the tool box as shown. It will be obvious that when the head is set over to an angle it should be moved along the cross slide to plane the corresponding angle on the other side of the bed.
Fig. 1636represents a planer chuck by Mr. Hugh Thomas. The angle pieceais made to stand at an angle, as shown, for cylindrical work, such as shafts, so that the work will be held firmly down upon the table. The base platebhas ratchet teeth at each endc, into which mesh the pawlsd, and has slotted holes for the bolts which hold it down to the table, so that it has a certain range of movement to or from the angle piecea, and may therefore be adjusted to suit the diameter or width of the work.
The movable jaweis set up by the set-screwfand is held down by the bolts shown. The pawlsdare constructed as shown inFig. 1637, the pin or stemsfitting the holes in the planer table and the tonguepbeing pivoted to the bodyrof the pawl. As the pawls can be moved into any of the holes in the table, the base platebmay be set at an angle, enabling the chuck to be used for taper as well as for parallel work, while the chuck has a wide range of capacity.
InFig. 1614is shown a supplementary table for increasing the capacity of planer tables, and which has already been referred to, andFig. 1638represents an application of the table as a chucking device.a,a, &c., are frames whose upper surfaces are to be planed. An angle plate is bolted to the planer table and the supplementarytable is bolted to the angle plate. The first frame is set against the vertical face of the supplementary table, and the remaining ones set as near as possible,b,b, &c., being small blocks placed between the frames which are bolted to the planer table as atc.
In many cases this method of chucking possesses great advantages. Thus in the figure there are six frames to be planed, and as they would be too long to be set down upon the planer table, only three or four could be done at a time, and a good deal of measuring and trying would be necessary in order to get the second lot like the first. This can all be avoided by chucking the whole six at once, as in figure.
Another application of the same tables as useful chucking devices is shown inFig. 1639, where two framese,f, are shown bolted to the machine table and supported by the supplementary tablest, which are bolted to the main table and supported by angle-piecesb,b. Work that stands high up from the planer table may be very effectively steadied in this way, enabling heavier cuts and coarser feeds while producing smoother work.
Fig. 1640Fig. 1640.
Fig. 1640.
As horizontal surfaces can be planed very much quicker than vertical ones, it frequently occurs that it will pay to take extra trouble in order to chuck the work so as to plane it horizontally, an excellent example being the planing of the faces of the two halves of a large pulley, the chucking of which is illustrated inFig. 1640.
Four pieces, as ata, are made to engage the rims of the two halves of the pulley and hold them true, one with the other. The two platest′andt′are set under the pulley halves to level the upper faces, and wooden clampsc,c, are bolted up to hold the pulleys together at the top,wrepresenting wedges between the hubs.srepresents supports to block up the pulley near its upper face, and atpare clamps to hold the two halves to the table. It is found that by this method of chucking more than half the time is saved, and the work is made truer than it is possible to get it by planing each half separately and laying them down on the table.
Fig. 1641Fig. 1641.
Fig. 1641.
Supplemental tables may also be made in two parts, the upper one being capable of swiveling as inFig. 1641, the swiveling device corresponding to that shown for the Thomas shaper chuck inFig. 1530. This enables the work to be operated upon on several different faces without being released from the chuck. Thus in figure the segment could be planed on one edge and the upper table swiveled to bring the other edge in true with the table, which would be a great advantage, especially if the face it is chucked by has not been trued.
Fig. 1642Fig. 1642.
Fig. 1642.
Fig. 1643Fig. 1643.
Fig. 1643.
Figs. 1642and1643show other applications of the same swiveling device.
Fig. 1644Fig. 1644.
Fig. 1644.
Fig. 1645Fig. 1645.
Fig. 1645.
It is obvious that the chuck shown inFig. 1636can be mounted on a supplemental and swiveling table as shown inFig. 1644, thus greatly facilitating the chucking of the work and facilitating the means of presenting different surfaces or parts of the work to the tool without requiring to unchuck it. The pawls, also, may in heavy work have two pins to enter the work-table holes and be connected by a strap as inFig. 1645.
Fig. 1646Fig. 1646.
Fig. 1646.
In the exigencies of the general machine shop it sometimes happens that it is required to plane a piece that is too wide to pass between the uprights of the planing machine, in which case one standard or upright may be taken down and the cross slide bolted to the other, as inFig. 1646, the blocksa,a, being necessary on account of the arched form of the back of the cross slide. In the example given the plates to be planed were nearly twice as wide as the planer table and were chucked as shown, the beamdresting on blockse,f, and forming a pathway for the piecec, which was provided with rollers at each end so as to move easily upond. The outer end of the plate was clamped betweenbandc, and the work was found to be easily and rapidly done. In this chucking, however, it is of importance that beamdbe carefully levelled to stand parallel with the planer table face, while its height must be so adjusted that it does not act to cant or tilt the table sideways as that would cause oneVof the planer ways to carry all or most of the weight, and be liable to cause it to cut and abrade the slide surfaces.
Cutting Tools for Shaping and Planing Machines.—All the cutting tools forged to finished shape from rectangular bar steel, and described in connection with lathe work, are used in the planer and in the shaper, and the principles governing the rake of the top face remain the same. But in the matter of the clearancethere is the difference that in a planing tool it may be made constant, because the tool feeds to its cut after having left the work surface at the end of the back stroke, hence the clearance remains the same whatever the amount or rate of feed may be.
Fig. 1647Fig. 1647.
Fig. 1647.
On this account it is desirable to use a gauge as a guide to grind the tool by, the application of such a gauge being shown inFig. 1647. It consists of a disk turned to the requisite taper and laid upon a plate, whereon the tool also may be laid to test it. The tool should not be given more than 10° of clearance, unless in the case of broad flat-nosed tools for finishing, for which 5° are sufficient.
The principle of pulling rather than pushing the tool to its cut, can, however, be more readily and advantageously carried out in planer than in lathe tools, because the spring of the tool and of the head carrying it only need be considered, the position of the tool with relation to the work being otherwise immaterial. As a consequence it is not unusual to forge the tools to the end of pulling, rather than of pushing the cutting edge.
Fig. 1648Fig. 1649Fig. 1648.Fig. 1649.
Fig. 1648.Fig. 1649.
InFigs. 1648and1649, for example, are two tools,wrepresenting the work, andathe points off which the respective tools will spring in consequence of the pressure; hence the respective arrows denote the direction of the tool spring. As a result of this spring it is obvious the tool inFig. 1648will dip deeper into the work when the pressure of the cut increases, as it will from any increase of the depth of the cut in roughing out the work, or from any seams or hard places in the metal during the finishing cut. On the other hand, however, this deflection or spring will have the effect of releasing the cutting edge of the tool from contact with the work surface during the back stroke, thus rendering it unnecessary to lift the tool to prevent the abrasion, on its back stroke, from dulling its cutting edge.
Fig. 1650Fig. 1650.
Fig. 1650.
It will be noted that the radius from the point of supportais less for the tool inFig. 1649than for that inFig. 1648, although both tools are at an equal height from the work, which enables that inFig. 1649to operate more firmly. In these two figures the extremes of the two systems are shown, but a compromise between the two is shown inFig. 1650, the cutting edge coming even with the centre of the body of the steel, which makes the tool easier to forge and grind, and keeps the cutting edge in plainer view when at work, while avoiding the evils attending the shape shown inFig. 1648.
Fig. 1651Fig. 1651.
Fig. 1651.
Fig. 1652Fig. 1652.
Fig. 1652.
It is sometimes necessary, however, that a tool of the form inFig. 1652be used, as, for example, to shape out the surface of a slot, and when this is the case the tool should be shaped as inFig. 1651, the bottom face having ample clearance (as, say, 15°) from the heelato about the pointb, and about 3° frombto the front end. The front face should have little or no clearance, because it causes the tool to dig into the work. A tool so shaped will clear itself well on the back stroke, whereas if but little clearance and front rake be given as inFig. 1652, the tool will not only dig in, but its cutting edge will rub on the back or return stroke.
Fig. 1653Fig. 1653.
Fig. 1653.
For broad feed finishing cuts the shape of tool shown inFig. 1653is employed, the cutting edge near the two corners being eased off very slightly with the oilstone. The amount of clearance should be very slight indeed, only just enough to enable the tool to cut as is shown in the figure, by the linea a. The amount of front rake may be varied to suit the nature and hardness of the metal, and the tool should be held as close in as possible to the tool clamp.
Fig. 1654Fig. 1654.
Fig. 1654.
Smoother work may be obtained in shaping and in planing machine tools when the tool is carried in a holder, such as inFig. 1654, which is taken fromThe American Machinistbecause in this case any spring or deflection either in the tool or in the shaper head acts to cause the tool to relieve itself of the cut instead of digging in, as would be the case were the tool put in front of thetool post as inFig. 1654. In finishing large curves this is of great importance, because to obtain true and smooth curves it is necessary to shape the tool to cut upon the whole of the curve at once, and this gives so great a length of cutting edge, that the tool is sure to chatter if held in front of the tool post.
Fig. 1655Fig. 1655.
Fig. 1655.
It is essential, therefore, to carry the tool at the back of the tool post as shown, and for curves that are arcs of circles tools such as inFig. 1655may be employed, or a circular disk will answer, possessing the advantage that its shape may be maintained by grinding its flat face to resharpen it.
Cutters of the kind shown inFig. 1655may be made to possess several important advantages aside from their smooth action: thus they may be made after the principle explained with reference to the Brown & Sharpe rotary cutters for gear-teeth, in which case the front face only need be ground to resharpen them, and their shapes will remain unaltered, and they may be given different degrees of front rake by placing packing between one side and the holder, and any number of different shaped cutters may be fitted to the same stock.
Tool Holders for Planing Machines.—The advantages of tool holders for planing machines are equally as great as those already described for lathes, but as applied to planing machines there is the additional advantage that the clearance necessary on the tool is less variable for planer work than for lathe work, because in lathe work the diameter of the work as well as the rate of tool feed affects the tool clearance, whereas in planer work the tool feed is put on before the tool begins its cutting action; hence the degree of clearance is neither affected by the size of the work nor by the rate of feed, and as a result the tools may be given a definite and constant amount of clearance.
Fig. 1656Fig. 1656.
Fig. 1656.
Fig. 1657Fig. 1657.
Fig. 1657.
Fig. 1656represents a planer tool holder (by Messrs. Smith & Coventry), in which what is, in effect, a swivel tool post is attached to the end of the holder, thus enabling the tool to be used on either the right or left-hand of the holder at will. The shape of the tool steel is shown in section on the right-hand of the engraving, being narrow at the bottom, which enables the tool to be very firmly held and reduces the area to be ground in sharpening the tool. A side and end view of the holder is shown inFig. 1657, in which it is seen that the tool may be given top rake or angle to render it suitable for wrought iron or steel or may be set level for brass work.
Fig. 1658Fig. 1658.
Fig. 1658.
InFig. 1658the tool and holder are shown in position on the planer head, the front rake on the tool being that suitable for wrought iron.
It is to be noted, however, that the amount of front rake should, to obtain the best results, be less for steel than for wrought iron, and less for cast iron than for wrought, while for brass there should be none; hence the tool post should be made to accomplish these different degrees of rake in order to capacitate such holders for the four above-named metals. It is an advantage, however, that by inclining the tool to give the top rake, this rake may be kept constant by grinding the end only of the tool to sharpen it, and as the end may be ground to a gauge it is very easy to maintain a constant shape of tool. Furthermore as the tool is held by one binding screw only, it may be more readily adjusted in position for the work than is the case when the two apron clamp nuts require to be operated.
Fig. 1659Fig. 1659.
Fig. 1659.
Fig. 1660Fig. 1660.
Fig. 1660.
Fig. 1661Fig. 1661.
Fig. 1661.
Figs. 1659to1661, show this tool-holder applied to various kinds of work, thus inFig. 1659the tool is planing under the underneath side of a lathe bed flange, while inFig. 1660it is acting upon aV-slideway and escaping an overhanging arm, andinFig. 1661it is shown operating on aV-slideway and in aT-groove.
Fig. 1662Fig. 1662.
Fig. 1662.
Fig. 1662represents a tool holder by Messrs. Bental Brothers, the tool being held in a swivelled tool post, so that it may be used as a right or left-hand tool. In this case the front rake must be forged or ground on the tool, and there is the further objection common to many tool holders, that the tool if held close in to the tool post is partly hidden from view, thus increasing the difficulty of setting it to the depth of cut.
Fig. 1663Fig. 1663.
Fig. 1663.
Another form of planer or shaper tool-holder is shown inFig. 1663, in which a tool post is mounted on a tool bar, and may be used as a right or left-hand tool at will.
Fig. 1664Fig. 1664.
Fig. 1664.
Fig. 1665Fig. 1665.
Fig. 1665.
Fig. 1666Fig. 1666.
Fig. 1666.
Fig. 1664represents a tool holder in which two tools may be held as shown, or a single tool right-hand or left-hand as may be required, or the tool may be held at the end of the holder as inFig. 1665. The advantage of such a holder is well illustrated in the case of cutting out aT-shaped groove, because with such a holder a straight tool can be used for the first cuts, its position being shown inFig. 1665, whereas in the absence of such a holder a tool bent as inFig. 1666would require to be used, this bend giving extra trouble in the forging, rendering the tool unfit for ordinary plain work, and being unable to carry so heavy a cut or to cut so smooth as the straight tool inFig. 1665. In cutting out the widest part of such a groove the advantage of the holder is still greater, because by its use a tool with one bend, as inFig. 1667, will serve, whereas without a holder the tool must have two bends, as shown in the figure, and would be able to carry a very light cut, while liable to dig into the work and break off.
Fig. 1667Fig. 1667.
Fig. 1667.
Fig. 1668Fig. 1668.
Fig. 1668.
The tool itself should be so forged that one side is flush with the side of the tool steel as shown atainFig. 1668, for if there is a shoulder, as atc, it sometimes prevents the tool from entering the work as shown in the figure.
Other examples in the use of this tool holder are given inFigs. 1669and1670.
Fig. 1669Fig. 1669.
Fig. 1669.
InFig. 1669, we have the case of cutting out theV-slideways of a planer bed, and it is seen that the tool point may be held close to the holder, the side of the tool box still clearing the side oftheV-slideway, whereas in the absence of the holder the tool would require to have a considerable bend in it, or else would have to stand out from the bottom of the tool apron to a distance equal to the length of one side of the slideway.
Fig. 1670Fig. 1670.
Fig. 1670.
InFig. 1670it is also seen that by the use of the holder the tool point may also be held as close as necessary to the holder, and still permit the side of the vertical slides′and the tool boxbto clear the vertical face of the work.
In all planer work it is an essential in the production of true and smooth surfaces that the tool be held as close in to the tool clamp or tool box as possible, and this forms one of the main advantages of tool holders.
Power Drilling Machines.—The drilling machine consists essentially of a rotating spindle to drive the drill, a work-holding table, and means of feeding the drill to its cut. The spindle speed and the force with which it is driven are varied to suit the work. The feeding is sometimes given to the spindle, and at others to the work table. In either case, however, the feeding mechanism should be capable of varying the rate of feed and of permitting a quick withdrawal of the drill. The spindle should be supported as near to its drill-holding end as possible. When the table feeds to the work the spindles may be held rigidly, because of their not requiring to pass so far out or down from the bearing supporting them; but when the spindle feeds, it must either pass through its bearings, or the bearing, or one of them, must either be capable of travel with the spindle or adjustable with relation to the machine framing.
In using small drills in a machine it is of the first importance that the amount of pressure necessary to feed the drill be plainly perceptible at the hand lever or other device for feeding the drill or the work, as the case may be, as any undue pressure causes the drills to break. To attain sensitiveness in this respect the parts must be light and easy both to move and to operate.
Fig. 1671represents the American Tool Company’s delicate drilling machine for holes of1⁄4inch and less in diameter. It consists of a head fixed upon a cylindrical column and affording journal bearing to the drill-driving spindle, which is driven by belt. The table on which the work is placed is carried by a knee that may be fixed at any required height upon the same round column. The knee and table may be swung out of the way, the column serving as a pivot. The table has journal bearing in the knee, and is fed upwards by the small lever shown.
Fig. 1672represents Elliott’s drilling machine for drills from1⁄32inch to3⁄4inch in diameter. The work table may be revolved in the arm that carries it, and this arm may be swung round the column or post. It is operated upwards for the feed by the hand lever shown. The conical chuck shown lying on the work table fits into the hole that is central in the table, and is used to receive the end of cylindrical work and hold it true while the upper end is operated upon.
The construction of the live spindle and its cone are shown inFig. 1673. The drill chuckqis attached to and driven by a one-inch steel spindle 19 inches long, which is accurately fitted through the sleeve bearings, within which it is free to move up and down, but is made to revolve with the cone by means of the connectiono, one end of which slides upon the rodsl. The drill is held up by means of the spiral springmacting from the bottom of cone to the collaro. The weight of cone and spindle is carried upon a raw-hide washer, beneath which is the cupped brasspwhich retains the oil. The thrust of the feed levergis also taken by a raw-hide washerr.
The machine is provided with a hand and a foot feed by means of the compound leverw z,Fig. 1674, actuating the feed rodj, which passes up within the column and connects to the leverk, the latter being suspended by a linkh.
Fig. 1675represents Slate’s sensitive drilling machine, in which the lower bearing for the live spindle is carried in a headhthat fits to a slide on the vertical face of the frame, so that it may be adjusted for height from the work tablewto suit the height of the work.lis a lever operating a pinion engaging a rack on the sleevesto feed the spindle. The tablewswings out of the way and a conically recessed cup chuckcis carried in a bracket fitting into a guideway in the vertical bedg. The cone of the cup chuck is central to or axially in line with the live spindle, hence cylindrical work may have its end rested in the cone of the cup chuck, and thus be held axially true with the live spindle.