The office of the shaping machine is to dress or cut to shape such
surfaces as can be most conveniently cut by a tool moving across the
work in a straight line.
The positions occupied among machine tools at the present time by
shaping and planing machines are not as important as was the case a few
years ago, because of the advent of the milling machine, which requires
less skill to operate, and produces superior work.
All the cutting tools used upon shaping and planing machines have
already been described with reference to outside tools for lathe work,
and it may be remarked that a great deal of the chucking done on the
shaping and planing machine corresponds to face plate chucking in the
lathe. Both shaping machines and small planing machines, however, are
provided with special chucks and work-holding appliances that are not
used in lathe work, and these will be treated of presently. On large
planing machines chucks are rarely used, on account of the work being
too large to be held in a chuck. Shaping machines are also known as
shapers and planing machines as planers.
[Illustration: Fig. 1496.]
The simplest form of shaping machine, or shaper as it is usually termed
in the United States, is that in which a tool-carrying slide is
reciprocated across the work, the latter moving at the end of each back
stroke so that on the next stroke the tool may be fed to its cut on the
work. Fig. 1496 represents a shaper of this kind constructed by Messrs.
Hewes and Phillips, of Newark, New Jersey, in which P is a cone pulley
receiving motion from a countershaft, and driving a pinion which
revolves the gear-wheel Q, whose shaft has journal bearing in the frame
of the machine. This shaft drives a bevel pinion gearing with a
bevel-wheel in one piece with the eccentric spur-wheel S, which is upon
a shaft having at its lower end the bevel-wheel B to operate the
work-feeding mechanism. S drives an eccentric gear wheel R, fast upon
the upper face of which is a projection E, in which is a [T]-shaped
groove to receive and secure a wrist or crank pin which drives a
connecting rod secured to the slide A by means of a bolt passing through
A, and secured to the same by a nut D.
When the gear-wheel R revolves, the connecting rod causes slide A to
traverse to and fro endways in a guideway, provided on the top of the
frame at X. On the end of this slide is a head carrying a cutting tool
T, which, therefore, moves across the work, the latter being held in the
vise V, which is fast upon a table W upon a carriage saddle or slider
_p_, which is upon a horizontal slide that in turn fits to a slide
vertical upon the front of the machine, and may be raised or lowered
thereon by means of an elevating screw driven by a pair of mitre-wheels
at F. The slider and table W (and therefore the vise and the work) are
moved along the horizontal slide to feed the work to the tool cut as
follows. A short horizontal shaft (driven by the bevel pinions at B),
drives at its outer end a piece C, having a slot to receive a crank pin
driving the feed rod N, which operates a pawl K engaging a ratchet wheel
which is fast upon the horizontal screw that operates slider _p_.
[Illustration: Fig. 1497.]
The diameters of the eccentric gear-wheels E and S are equal; hence, C
makes a revolution and the cross feed is actuated once for every cutting
stroke. The swivel head H is bolted to the end of the slide or ram, as
it is sometimes called, A, and is provided with a slide I upon which is
a slider J, carrying an apron containing the tool post holding the
cutting tool, the construction of this part of the mechanism being more
fully shown in Fig. 1497. The eccentric gear-wheels R S are so geared
that the motion of the slide A during the cutting stroke (which is in
the direction of the arrow) is slower than the return stroke, which on
account of being accelerated is termed a quick return. Various
mechanisms for obtaining a quick return motion are employed, the object
being to increase the number of cutting strokes in a given time, without
accelerating the cutting speed of the tool, and some of these mechanisms
will be given hereafter.
[Illustration: Fig. 1498.]
Referring again to the mechanism for carrying the cutting tool and
actuating it to regulate the depth of cut in Fig. 1497, G is the end of
the slide a to which the swivel head H is bolted by the bolts _a_ _b_.
The heads of these bolts pass into [T]-shaped annular grooves in G, so
that H may be set to have its slides at any required angle. I is a
slider actuated on the slide by means of the vertical feed screw which
has journal bearing in the top of H, and passes through a nut provided
in I. To I is fastened the apron swivel J, being held by a central bolt
not seen in the cut, and also by the bolt at _c_. In J is a slot, which
when _c_ is loosened permits J to be swung at an angle. The apron K is
pivoted by a taper pin L, which fits into both J and K. During the
cutting stroke the apron K beds down upon J, but during the back stroke
the tool may lift the apron K swinging upon the pivot L. This prevents
the cutting edge of the tool from rubbing against the work during the
return stroke.
Thus in Fig. 1498 is a piece of work, and it is supposed that a cut is
being carried down the vertical face or shoulder at A; by setting the
apron swivel at an angle and lifting the tool during the return stroke,
its end will move away from the face of the shoulder. The slider I
obviously moves in a vertical line upon slides M.
[Illustration: Fig. 1499.]
To take up the wear of the sliding bar A, various forms of guideways and
guides are employed, a common form being shown in Fig. 1499. There are
two gibs, one on each side of the bar, and these gibs are set up by
screws to adjust the fit. In some cases only one gib is used, and in
that event the wear causes the slide to move to one side, but as the
wear proceeds exceedingly slowly in consequence of the long bearing
surface of the bar in its guides, this is of but little practical
moment. On the other hand, when two gibs are used great care must be
taken to so adjust the screws that the slide bar is maintained in a line
at a right angle to the jaws of the work-holding vice, so that the tool
will cut the vertical surfaces or side faces of the work at a right
angle to the work surface that is gripped by the vice.
To enable the length of stroke of slide A, Fig. 1496, to be varied to
suit the length of the work, and thus not lose time by uselessly
traversing that slide, E is provided with a [T]-slot as before stated,
and the distance of the wrist pin (in this slot) from the centre of
wheel E determines the amount of motion imparted to the connecting rod,
and therefore to slide A. The wrist pin is set so as to give to A a
rather longer stroke than the work requires, so that this tool may pass
clear of the work on the forward stroke, and an inch or so past the work
on the return stroke, the latter giving time to feed the tool down
before it meets the work.
The length of the stroke being set, the crank piece E (for its slot and
wrist pin correspond to a crank) is, by pulling round the pulley P,
brought to the end of a stroke, the connecting rod being in line with
slide A. The nut D is then loosened and slide A may then be moved by
hand in its slideway until the tool clears the work at the end
corresponding to the connecting rod position when nut D is tightened and
the stroke is set.
[Illustration: Fig. 1500.]
Now suppose it is required to shape or surface the faces _f_ and _f´_,
the round curve S and the hollow curve C of the piece of work shown held
in a vice chuck in Fig. 1500, and during the cutting stroke the slide
_a_ will travel in the direction of _n_ in the figure, while during its
return stroke it will traverse back in the direction of _i_. The sliding
table W in Fig. 1496 would continuously but gradually be fed or moved
(so much per tool traverse, and by the feeding mechanism described with
reference to Fig. 1501) carrying with it the vice chuck, and therefore
the work. When this feeding brought the surface of curve S, Fig. 1500,
into contact with the tool, the feed screw handle in figure would be
operated by hand so much per feed traverse, thus raising the slider, and
therefore the tool, in the direction of _l_, and motion of the work to
the right and the left of the tool (by means of the feed handle) would
(if the amount of tool lift per tool stroke is properly proportioned to
the amount of work feed to the right) cause the tool to cut the work to
the required curvature. When the work had traversed until the tool had
arrived at the top of curve S, the direction of motion of the feed-screw
handle Z in Fig. 1496 must be reversed, the tool being fed down so much
per tool traverse (in the direction of _m_) so as to cut out the curves
from the top of S to the bottom of _c_, the face _f´_ being shaped by
the automatic feed motion only.
The feed obviously occurs once for each cutting stroke of the tool and
for the vertical motion of the tool, or when the tool is operated by the
hand feed-screw handle in Fig. 1496, the handle motion, and therefore
the feed should occur at the end of the back stroke and before the tool
again meets the work, so as to prevent the cutting edge of the tool from
scraping against the work during its back traverse.
In this connection it may be remarked that by setting the apron swivel
over, as in Fig. 1498, the tool is relieved from rubbing on the back
stroke for two reasons, the first having been already explained, and the
second being that to whatever amount the tool may spring, bend, or
deflect during the cutting stroke (from the pressure of the cut), it
will dip into the work surface and cut deeper; hence on the back stroke
it will naturally clear the surface, providing that the next cut is not
put on until the tool has passed back and is clear of the work.
[Illustration: Fig. 1501.]
Referring now to the automatic feed of the sliding table W, in Fig.
1496, the principle of its construction may be explained with reference
to Fig. 1501, which may be taken to represent a class of such feeding
mechanisms. A is a wheel corresponding to the wheel marked M in Fig.
1496, or, it may be an independent wheel in gear with the feed wheel. On
the same shaft as A is pivoted an arm B having a slot S at one end to
receive a pin to which the feed rod E may connect. F is a disk rotated
from the driving mechanism of the shaping machine, and having a
[T]-shaped slot G G, in which is secured a pin to actuate the rod E. As
F rotates E is vibrated to and fro and the catch C on one stroke falls
into the notches or teeth in A and causes it to partly rotate, while on
the return stroke of E it lifts over the teeth, leaving A stationary.
The amount of motion of B, and therefore the quantity of the feed, may
be regulated at either end of E; as, for example, the farther the pin
from the centre of G the longer the stroke of E, or the nearer the pin
in S is to the centre of B the longer the stroke, but usually this
provision is made at one end only of E.
To stop the feed motion from actuating, the catch C may be lifted to
stand vertically, as shown in dotted lines in position 2, and to actuate
the feed traverse in an opposite direction, C may be swung over so as to
occupy the position marked 3, and to prevent it moving out of either
position in which it may be set a small spring is usually employed.
Now suppose that the tool-carrying slide A, Fig. 1496, is traversing
forward and the tool will be moving across the work on the cutting
stroke, as denoted by the arrow _k_ in Fig. 1502, the line of tool
motion for that stroke being as denoted by the line _c_ _a_. At _a_ is
the point where the tool will begin its return stroke, and if the work
is moved by the feeding mechanism in the direction of arrow _e_, then
the line of motion during the return stroke will be in the direction of
the dotted line _a_ _b_, and as a result the tool will rub against the
side of the cut.
[Illustration: Fig. 1502.]
It is to obviate the friction this would cause to the tool edge, and the
dulling thereto that would ensue, that the pivot pin L for the apron is
employed as shown in Fig. 1497, this pin permitting the apron to lift
and causing the tool to bear against the cut with only such force as the
weight of the apron and of the tool may cause. Now suppose that in Fig.
1503 we have a piece of work whose edge A A stands parallel to the line
of forward tool motion, there being no feed either to the tool or the
work, and if the tool be set to the corner _f_ its line of motion during
a stroke will be represented by the line _f_ _g_. Suppose that on the
next stroke the feed motion is put into action and that feeding takes
place during the forward stroke, and the amount of the feed per stroke
being the distance from _g_ to _h_, then the dotted line from _f_ to _h_
represents the line of cut. On the return stroke the line of tool motion
will be from _h_ along the dotted line _h_ _k_, and the tool will rest
against the cut as before. Suppose again that the feed is put on during
the return stroke, and that _c_ _c´_ represents the line of tool motion
during a cutting stroke, and the return stroke will then be along the
line from _c´_ to _b_, from _c_ to _b_ representing the amount of feed
per stroke; hence, it is made apparent that the tool will rub against
the cut whether the feed is put on during the cutting or during the
return stroke. Obviously then it would be preferable to feed the work
between the period that occurs after the tool has left the work surface
on the return stroke and before it meets it again on the next cutting
stroke. It is to be observed, however, that by placing the pin actuating
the rod E, Fig. 1501, on the other side of the centre of the slot G in
F, the motion of E will be reversed with relation to the motion J of the
slide; hence, with the work feeding in either direction, the feed may be
made to occur during either the cutting or return stroke at will by
locating the driving pin on the requisite side of the centre of G.
[Illustration: Fig. 1503.]
An arrangement by Professor Sweet, whereby the feed may be actuated
during the cutting or return stroke (as may be determined in designing
the machine), no matter in which direction the work table is being fed,
is shown in Fig. 1504. Here there are two gears A and D, and the pawl or
catch C may be moved on its pivoted end so as to engage either with A or
D to feed in the required direction.
[Illustration: Fig. 1504.]
Suppose the slide to be on its return stroke in the direction of L, and
F be rotated as denoted by the arrow, then the pawl C will be actuating
wheel A as denoted by its arrow, but if C be moved over so as to engage
D as denoted by the dotted outline, then with the slide moving in the
same direction, C will pull D in the direction of arrow K´, and wheel A
will be actuated in the opposite direction, thus reversing the direction
of the feed while still causing it to actuate on the return stroke.
Since the feed wheel A must be in a fixed position with relation to the
work table feed screw, and since the height of this table varies to meet
the work, it is obvious that as the work table is raised the distance
between the centres of A and F in the figure is lessened, or conversely
as that table is lowered the distance between those centres is
increased; hence, where the work table has much capacity of adjustment
for height, means must be provided to adjust the length of rod E to suit
the conditions. This may be accomplished by so arranging the
construction that the rod may pass through its connection with wheel F,
in the figure, or to pass through its connection with B.
Fig. 1505 represents a shaper that may be driven either by hand or by
belt power. The cone pulley shaft has a pinion that drives the
gear-wheel shown, and at the other end of this gear-wheel shaft is a
slotted crank carrying a pin that drives a connecting rod that actuates
the sliding bar, or ram, as it is sometimes termed. The fly-wheel also
affords ready means of moving the ram to any required position when
setting the tool or the work.
Fig. 1506 represents a shaping machine by the Hewes and Phillips Iron
Works, of Newark, N.J. The slide or ram is operated by the Whitworth
quick return motion, whose construction will be shown hereafter. The
vice sets upon a knee or angle plate fitting to vertical slideways on
the cross slide, and may be raised or lowered thereon to suit the height
of the work by means of the crank handle shown in front. The vice may be
removed and replaced by the supplemental table shown at the foot of the
machine. Both the vice and the supplemental table are capable of being
swivelled when in position on the machine. The machine is provided with
a device for planing circular work, such as sectors, cranks, &c., the
cone mandrel shown at the foot of the machine bolting up in place of the
angle plate.
[Illustration: Fig. 1505.]
[Illustration: Fig. 1506.]
HOLDING WORK IN THE SHAPER OR PLANER VICE.--The simplest method of
holding work in a shaper is by means of a shaper vice, which may be
employed to hold almost any shape of work whose size is within the
capacity of the chuck. Before describing, however, the various forms of
shaper vices, it may be well to discuss points to be considered in its
use.
The bottom surface _a_ _a_, Fig. 1507, of a planer vice is parallel with
the surfaces _d_, _d´_ and as surface _a_ is secured to the upper face
of the slider table shown in figure, and this face is parallel to the
line of motion of the slide A, and also parallel with the cross slide in
that figure, it follows that the face _d_ is also parallel both with the
line of motion of slide A and with the surface of the slider table.
Parallel work to be held in the vice may therefore be set down upon the
surface _d_ (between the jaws), which surface will then form a guide to
set the work by. The work-gripping surfaces _b_ and _e_, Fig. 1507, of
the jaws are at a right angle to surface _a_, and therefore also to _d_,
therefore the upper surface of work that beds fair upon _d_, or beds
fair against _b_, will be held parallel to the line of motion X of the
tool and the line Z of the feed traverse. Similarly the upper surfaces
A, B of the gripping jaws are parallel to _a_ _a_, hence they may be
used to set the work true with the line of feed traverse. The sliding
jaw, however, must be a sufficiently easy fit to the slideways that
guide it to enable it to be moved by the screw that operates it, and as
a result it has a tendency to lift upon its guideways so that its face
_e_ will not stand parallel to _b_ or at a right angle to _d_. In Fig.
1508, for example, is a side view of a vice holding a piece of work W,
the face _f_ of the work being at an angle. As a consequence there is a
tendency to lift in the direction of C. If the jaw does lift or spring
in this direction it will move the work, so that instead of its lower
face bedding down upon face _d_, Fig. 1507, it will lie in the direction
of H, Fig. 1508, while its face parallel to _f_, instead of bedding fair
against the face of jaw J, will lie as denoted by the line _g_, and as a
result the work will not be held fair with either of those faces and the
value of faces _b_, _d_ and _e_ in Fig. 1507 is impaired.
This lifting of the movable or sliding jaw is prevented in some forms of
chuck, to be hereafter described, by bolts passing through which hold it
down, but the tendency is nevertheless present, and it is necessary to
recognise it in treating of chucking or holding work in such vices.
[Illustration: Fig. 1507.]
[Illustration: Fig. 1508.]
The work gripping face _b_, Fig. 1507, of the fixed jaw, however, is not
subject to spring, hence it and the surface _d_ are those by which the
work may be set. The work, however, is held by the force of the screw
operating the sliding jaw, hence the strain is in the direction of the
arrow P in Fig. 1508, which forces it against the face of the fixed jaw.
All the pressure that can be exerted to hold work down upon the surface
_d_, Fig. 1507, is that due to the weight of the work added to whatever
effort in that direction there may be induced by driving the work down
by blows upon surface _d_ after the jaws are tightened upon the work.
This, however, is not to be relied upon whenever there is any tendency
for the work not to bed down fair. It follows, then, that surface _b_ of
the work-gripping jaw is that to be most depended upon in setting the
work, and that the surface that is to act as a guide at each chucking
should be placed against this surface unless there are other
considerations that require to be taken into account.
[Illustration: Fig. 1509.]
For example, suppose we have a thin piece of work, as in Fig. 1509, and
the amount of surface bearing against the fixed jaw is so small in
comparison to its width between the jaws that _e_ would form no
practical guide in setting the work. If then the edges of such a piece
of work were shaped first the face or faces may or may not be made at a
right angle to them, or _square_ as it is termed. But if the faces were
shaped first, then when the work was held by them to have the edges
shaped there would be so broad an area of work surface bedding against
the jaw surface, that the edges would naturally be shaped square with
the faces.
In cases, therefore, where the area of bedding surface of the work
against the faces of the jaws is too small to form an accurate guide and
the work is not thick enough to rest upon the surface _d_, Fig. 1507, it
is set true to that surface by a parallel piece.
If the work is wide or long enough to require it, two parallel pieces
must be used, both being of the same thickness, so that they will keep
the work true with the surface _d_.
[Illustration: Fig. 1510.]
Pieces such as P, Fig. 1510, are also used to set work not requiring to
be parallel. Thus in figure are a number of keys placed side by side and
set to have their edges shaped, and piece P is inserted not only to lift
the narrow ends of the keys up, but also to maintain their lower edges
fair one with the other, and thus insure that the keys shall all be made
of equal width.
They are also serviceable to interpose between the work and the vice
jaws when the work has a projection that would receive damage from the
jaw pressure.
[Illustration: Fig. 1511.]
Thus in Fig. 1511 the work W has such a projection and a parallel piece
P is inserted to take the jaw pressure. By placing the broadest work
surface _g_ against the fixed jaw the work will be held true whether the
movable jaw springs or not, because there will be surface _g_ and
surface H guiding it.
[Illustration: Fig. 1512.]
But if the work were reversed, as in Fig. 1512, with the broadest
surface against K, then if K sprung in the direction of C, the work
would not be shaped true.
[Illustration: Fig. 1513.]
When the work is very narrow, however, the use of a parallel piece to
regulate its height is dispensed with, and the top surface B of the jaw,
in Fig. 1513, is used to set the work by. A line is marked on the work
surface to set it by and a surface gauge is set upon the face B, its
needle point being set to the line in a manner similar to that already
explained with reference to chucking work in the lathe.
All work should be so set that the tool will traverse across the longest
length of the work, as denoted by the tool in Fig. 1502, and the arrow
marking its direction of traverse.
The general principles governing the use of the shaper vice having been
explained, we may now select some examples in its use.
Fig. 1514 represents a simple rectangular piece, and in order to have
the tool marks run lengthwise of each surface (which is, as already
stated the most expeditious) they must be in the direction of the
respective arrows. In a piece of such relative proportions there would
be little choice as to the order in which the surfaces should be shaped,
but whatever surface be operated on first, that at a right angle to it
should be shaped second; thus, if _a_ be first, either _b_ or _d_ should
be second, for the following reasons.
[Illustration: Fig. 1514.]
All the surfaces have sufficient area to enable them to serve as guides
in setting the work, hence the object is to utilize them as much as
possible for that purpose. Now, suppose that surface _a_ has been trued
first, and if _c_ be the next one, then the bedding of surface _a_ upon
the vice surface or the parallel pieces must be depended upon to set _a_
true while truing _c_. Now the surfaces _b_ and _d_ may both, or at
least one of them, may be untrue enough to cause the work to tilt or
cant over, so that _a_ will not bed fair, and _c_ will then not be made
parallel to _a_. It will be preferable then to shape _a_ first and at
the second chucking to set _a_ against the stationary jaw of the vice,
so that it may be held true.
[Illustration: Fig. 1515.]
The sliding jaw will in this case be against face _c_, and if that face
is out of true enough to cant the work so that _a_ will not bed fair,
then a narrow parallel piece may be inserted between the sliding jaw and
the work, which will cause _a_ to bed fair. The third face should be
face _c_, in which case face _a_ will rest on one surface and face _b_
will be against the fixed jaw, and there will be two surfaces to guide
the work true while _c_ is being trued. In this case also, however, it
is better to use a parallel piece P, Fig. 1515, between the work and the
sliding jaw, so as to insure that the work shall bed fair against the
fixed jaw; and if necessary to bring up the top surface above the jaws,
a second parallel piece P´ should be used.
[Illustration: Fig. 1516.]
Suppose now that we have a connecting rod key to shape, and it is to be
considered whether the faces or the edges shall be shaped first. Now if
the side faces are out of parallel it will take more filing to correct
them than it will to correct the same degree of error in the edges;
hence it is obviously desirable to proceed with a view to make all
surfaces true, but more especially the side faces. As the set of the key
while shaping these faces is most influenced by the manner in which the
fixed jaw surface meets the work, and as an edge will be the surface to
meet the fixed jaw faces when the side faces are shaped, it will be best
to dress one edge first, setting the key or keys, as the case may be, as
was shown in Fig. 1510, so as to cut them with the tool operating
lengthways of the key; one edge being finished, then one face of each
key must be shaped, the key being set for this purpose with the surfaced
edge against the fixed jaw. As the width of the key is taper, either a
chuck with a taper attachment that will permit the sliding jaw to
conform itself to the taper of the key must be used (vices having this
construction being specially made for taper work as will be shown
hereafter), or else the key must be held as in Fig. 1516, in which K
represents the key with its trued edge against the fixed jaw, at P is a
piece put in to compensate for the taper of the key, and to cause the
other edge to bed firmly and fairly against the fixed jaw.
The first side face being trued, it should be placed against the fixed
jaw while the other edge is shaped. For the remaining side face we shall
then be able to set the key with a trued edge against the fixed jaw, and
a true face resting upon a parallel piece, while the other edge will be
true for the piece P, Fig. 1516, to press against, and all the elements
will be in favor of setting the key so that the sides will be parallel
one to the other, and the edges square with the faces.
In putting in the piece P, Fig. 1516, the key should be gripped so
lightly that it will about bear its own weight; piece P may then be
pushed firmly in with the fingers, and the vice tightened up.
[Illustration: Fig. 1517.]
If there are two keys the edges and one face may be trued up as just
described, and both keys K, Fig. 1517, chucked at once by inverting
their tapers as shown in figure. But in this case unless the edges are
quite true they may cause the keys not to bed fair on the underneath
face, and the faces therefore to be out of parallel on either or both of
the keys. If there are a number of keys to be cut to the same thickness
it may be done as follows:--
[Illustration: Fig. 1518.]
Plane or shape first one edge of all the keys; then plane up one face,
chucking them with one planed edge against each vice jaw, and put little
blocks (A, B, C, D, Fig. 1518) between the rough edges; then turn them
over, chuck them the same way and plane the other face, resting them on
parallel pieces; then plane the other edges last.
In place of the small blocks A, B, C, D, a strip of lead, pasteboard, or
wood, or for very thin work a piece of lead wire, may be used.
[Illustration: Fig. 1519.]
[Illustration: Fig. 1520.]
Cylindrical work may be held in a vice chuck, providing that the top of
the vice jaws is equal in height to the centre of the work, as in Fig.
1519, a parallel piece being used to set the work true. When, however,
the work is to be shaped at one end only, it is preferable to hold it as
in Fig. 1520, letting its end project out from the side of the chuck. In
some vices the jaws are wider than the body of the chuck, so that
cylindrical work may be held vertical, as in Fig. 1521, when the end is
to be operated upon.
Fig. 1522 represents a simple form of shaper or planer chuck, such
chucks being used upon small planing machines as well as upon shaping
machines.
[Illustration: Fig. 1521.]
[Illustration: Fig. 1522.]
The base A is bolted to the work table, and is in one piece with the
fixed jaw B. The movable jaw C is set up to meet the work by hand, and
being free to move upon A may be used for either taper or parallel work.
To fasten C upon the work, three screws threaded through F abut against
the end of C; F being secured to the upper surface of A by a key or
slip, which fits into a groove in F, and projects down into such of the
grooves in the upper surface of A as may best suit the width of work to
be held in the vice; C is held down by the bolts and nuts at G.
The operation of securing work in such a chuck is as follows:--The
screws both at F and at G being loosened, and jaw C moved up to meet the
work and hold it against the fixed jaw B, then nuts G should be set up
lightly so that the sliding jaw will be set up under a slight pressure,
screws F may then be set up and finally nuts G tightened.
[Illustration: Fig. 1523.]
This is necessary for the following reasons:--The work must, in most
cases, project above the level of the jaws so that the tool may travel
clear across it; hence, the strain due to holding the work is above the
level of the three screws, and the tendency, therefore, is to turn the
jaw C upwards, and this tendency the screws G resist. A similar chuck
mounted upon a circular base so that it may be swivelled without moving
the base on the work table is shown in Fig. 1523. The capacity to swivel
the upper part of the chuck without requiring the base of the chuck to
be moved upon the table is a great convenience in many cases.
[Illustration: Fig. 1524.]
Fig. 1524 represents an English chuck in which the fixed jaw is composed
of two parts, A which is solid with the base G, and D which is pivoted
to A at F. The movable jaw also consists of two parts, B which carries
the nut for the screw that operates B, and C which is pivoted to B at E.
The two pivots E, F being above the surface of the gripping jaws C, D,
causes them to force down upon the surface of G as the screw is
tightened, the work, if thin, being rested, as in the case of the chuck
shown in Fig. 1523, upon parallel pieces.
[Illustration: Fig. 1525.]
Fig. 1525 represents a chuck made by W. A. Harris, of Providence. The
jaws in this case carry two pivoted wings A, B, between the ends of
which the work C is held, and the pivots being above the level of the
work the tendency is here again to force the work down into the chuck,
the strain being in the direction denoted by the arrows.
Here the work rests on four pins which are threaded in the collars H, so
that by rotating the pins they will stand at different heights to suit
different thicknesses of work, or they may be set to plane tapers by
adjusting their height to suit the amount of taper required. The spiral
springs simply support the pins, but as the jaws close the pins lower
until the washer nuts H meet the surface of recess I.
[Illustration: Fig. 1526.]
[Illustration: Fig. 1527.]
Figs. 1526 and 1527 represent Thomas's patent vice, which possesses some
excellent conveniences and features.
In Fig. 1526 it is shown without, and in Fig. 1527 with a swivel motion.
The arrangement of the jaws upon the base in Fig. 1526 is similar to
that of the chuck shown in Fig. 1522, but instead of there being a key
to secure the piece F to the base, there is provided on each side of the
base a row of ratchet teeth, and there is within F a circular piece G
(in Fig. 1528) which is serrated to engage the ratchet teeth. This
piece may be lifted clear of the ratchet teeth by means of the pin at H,
and then the piece F may be moved freely by hand backwards or forwards
upon the base and swung at any required angle, as in Fig. 1528, or set
parallel as in Fig. 1527; F becoming locked, so far as its backward
motion is concerned, so soon as H is released and G engages with the
ratchet teeth on the base. But F may be pushed forward toward the fixed
jaw without lifting H, hence the adjustment of the sliding jaw to the
work may be made instantaneously without requiring any moving or setting
of locking keys or other devices.
[Illustration: Fig. 1528.]
It is obvious that it is the capability of G to rotate in their sockets
that enables F to be set at an angle and still have the teeth of G
engage properly with those on the base plate.
[Illustration: Fig. 1529.]
[Illustration: Fig. 1530.]
The mechanism for swivelling the upper part or body upon the base and
for locking it in its adjusted position is shown in Figs. 1529 and 1530.
The body D is provided with an annular ring fitting into the bore of the
base, which is coned at Q. The half-circular disks R fit this cone and
are held to the body of the chuck by four bolts N, which are adjusted to
admit disks R to move without undue friction. K is a key having on it
the nut V, which receives a screw whose squared end is shown at S. By
operating S in one direction key K expands disks R, causing them to
firmly grip the base at the bevel Q, hence the base and the body are
locked together. By operating S to unscrew in the nut V, K is moved in
the opposite direction and R, R release their grip at Q and the body D
may be swung round in any position, carrying with it all the mechanism
except base P.
To enable the body to be readily moved a quarter revolution, or in other
words, moved to a right angle, there is provided a taper pin, the base
having holes so situated that the body will have been moved a quarter
revolution when the pin having been removed from one hole in the base is
seated firmly home in the other.
Referring again to Fig. 1526, there are shown one pair of parallel
pieces marked respectively A, having bevelled edges, and another pair
marked respectively B. Both pairs are provided with a small rib fitting
into a groove in the jaws of the chuck, as shown in the figure.
[Illustration: Fig. 1531.]
These ribs and grooves are so arranged that the upper pair (A, A) may be
used in the place of the lower ones, and the uses of these pieces are as
follows:--
Suppose a very thin piece of work is to be planed, and in order to plane
it parallel, which is ordinarily a difficult matter, it must bed fair
down upon the face of the vice, which it is caused to do when chucked as
in Fig. 1531, in which the work is shown laid flat upon the face of the
vice, and gripped at its edges by the pieces A, A.
[Illustration: Fig. 1532.]
These pieces, it may be noted, do not bed fair against the gripping
faces of the jaws, but are a trifle open at the bottom as at _e_, _e_,
hence when they are pressed against the work they cant over slightly and
press the work down upon the chuck face causing it to bed fair.
Furthermore, the work is supported beneath its whole surface, and has,
therefore, less tendency to spring or bend from the holding pressure;
and as a result of these two elements much thinner work can be planed
true and parallel than is possible when the work is lifted up and
supported upon separate parallel pieces, because in the latter case the
work, being unsupported between the parallel pieces, has more liberty to
bend from the pressure due to the tool cut, as well as from the holding
pressure.
[Illustration: Fig. 1533.]
Fig. 1532 shows the chuck holding a bracket, having a projection or eye.
The work rests on pieces B, B, and is gripped by pieces A, A. It will be
observed that A, A being beveled enables the cut to be carried clear
across the work.
Fig. 1533 represents the chuck in use for holding a piece of shafting S
to cut a keyway or spline in it. In this case a bevelled piece J is
employed, its bevelled face holding the work down upon the chuck face.
[Illustration: Fig. 1534.]
Fig. 1534 represents a chuck termed shaper centres, because the work is
held between centres as in the case of lathe work. The live spindle is
carried in and is capable of motion in a sleeve, the latter having upon
it a worm-wheel, operated by a worm, so that it can be moved through any
given part of a circle, and has index holes upon its face to determine
when the wheel has been moved to the required amount.
For work that is too large to be operated upon in the class of shaping
machine shown in Fig. 1506, and yet can be more conveniently shaped than
planed, a class of machine is employed in which the tool-carrying slide
is fed to the work, which is chucked to a fixed table or to two tables.
[Illustration: Fig. 1535.]
Fig. 1535 represents a machine of this class. The tool-carrying slide A,
in this case, operates in guideways provided in B, the latter being
fitted to a slideway running the full length of the top of the frame M.
The base slider B is fed along the bed by means of a screw operating in
a nut on the under side of B, this screw being operated once during each
stroke of the tool-carrying slide A, by means of a pawl feeding
arrangement at F, which corresponds to the feeding device shown in Fig.
1501.
Two vertical frame pieces D, D are bolted against the front face of the
machine, being adjustable along any part of the bed or frame length,
because their holding bolts have heads capable of being moved (with the
frame pieces D) along the two [T]-shaped grooves shown, their [T]-shape
being visible at the end of the frame or bed. To frames D are bolted the
work-holding tables E, E, the bolts securing them passing into vertical
[T]-grooves in D, so that E may be adjusted at such height upon D as may
be found necessary to bring the work within proper range of the cutting
tool. The work tables E, E are raised or lowered upon D by means of a
vertical screw, which is operated by the handle H, this part of the
mechanism accomplishing the same end as the elevating mechanism shown in
Fig. 1496. The swivel head J is here provided at its top with a segment
of a worm-wheel which may be actuated to swivel that head by the worm G.
The swivel head may thus be operated upon its pivot, causing the tool
point to describe an arc of a circle of which the pivot is the centre.
To steady the swivel head when thus actuated, there is behind the worm
segment a [V]-slide that is an arc, whose centre is also the centre of
the pivot.
The tool-carrying slide A is operated as follows: The driving pulley P
rotates a shaft lying horizontal at the back of the machine. Along this
shaft there is cut a featherway or spline driving a pinion which
operates a link mechanism such as described with reference to Fig. 1550.
The means of adjusting the distance the head of A shall stand out from
B, are similar to that described for Fig. 1496, a bolt passing through
A, and in both cases attaching to a connecting rod or bar.
At K is a cone mandrel such as has been described with reference to
lathe work upon which is chucked a cross-head C. By means of suitable
mechanism, this mandrel is rotated to feed the circular circumference of
the cross-head jaws to the cut, the slider B remaining in a fixed
position upon the bed M.
To support the outer end of the cone mandrel a beam L is bolted to the
two tables E, E. On L is a slideway for the piece P. At S is a lug upon
E through which threads a screw R, which adjusts the height of the piece
P, while Q is a bolt for securing P in its adjusted position. This cone
mandrel and support is merely an attachment to be put on the machine as
occasion may require.
Fig. 1536 represents a shaping machine by the Pratt and Whitney Company.
In this machine a single sliding head is used and the work remains
stationary as in the case of the machine shown in Fig. 1535. The vice is
here mounted on a slide which enables the work to be finely adjusted
beneath the sliding bar independently of that bar, which is provided
with a Whitworth quick-return motion.
As the tool-carrying slide of a shaping machine leaves its guideways
during each stroke, the tool is less rigidly guided as the length of
slide stroke is increased, and on this account its use is limited to
work that does not require a greater tool stroke than about 18 inches,
and in small machines not to exceed 12 inches. The capacity of the
machine, however, is obviously greatest when the length of the work is
parallel to the line of motion of the feed traverse. Work whose
dimension is within the limit of capacity of the shaper can, however, be
more expeditiously shaped than planed because the speed of the cutting
tool can be varied to suit the nature of the work, by reason of the
machine having a cone pulley, whereas in a planing machine the cutting
speed of the tool is the same for all sizes of work, and all kinds of
metal. In shaping machines such as shown in Fig. 1537, or in similar
machines in which the work table is capable of being traversed instead
of the head, the efficiency of the work-holding table and of the
chucking devices may be greatly increased by constructing the table so
that it will swivel, as in Fig. 1538, which may be done by means of the
employment of Thomas's swivelling device in Fig. 1530. By this means the
ends of the work may be operated upon without removing it from the
chuck. Or the work may be shaped taper at one part and parallel at
another without unchucking it.
Fig. 1539 shows a circular table swivelled by the same device, sitting
upon a work table also swivelled.
[Illustration: Fig. 1540.]
Fig. 1540 represents a general view of a shaping machine having the
motion corresponding in effect to a planing machine, the object being to
give a uniform rate of speed to the tool throughout, both on its cutting
and return stroke. The feed always takes place at the end of the return
stroke, so as to preserve the edge of the tool, and the length of the
stroke may be varied, without stopping the machine, by simply adjusting
the tappets or dogs, the range of stroke being variable from 1/4 inch to
20 inches, while the return stroke is 40 per cent. quicker than the
cutting one. There are two different rates of cutting speed, one for
steel and the other for the softer metals.
[Illustration: Fig. 1541.]
The ram or bar is provided with a rack (Z, Fig. 1545) which engages with
a pinion S, Fig. 1541, H being the driving shaft driven by the belt
cones A and B. These two cones are driven by separate belts, but from
the same counter-shaft, one being an open and the other a crossed belt.
The open belt drives either the largest step of pulley B, giving a
cutting speed suitable for steel, or the smaller step, giving a cutting
speed for softer metals, as cast iron, &c. The crossed belt drives, in
either case, the pulley A for the quick-return stroke, and this pulley
revolve upon a sleeve or hub C, which revolves upon the shaft H. The
sleeve or hub C is in one piece with a pulley C, whose diameter is such
as to leave an annular opening between its face and the bore of the
largest step of cone pulley B, and pulley A is fast to the hub or sleeve
C. It will be seen that as the driving belts from the counter-shaft are
one open and one crossed, therefore pulley A runs constantly in one
direction, while pulley B runs constantly in the other, so that the
direction of motion of the driving shaft H depends upon whether it is
locked to pulley A or to pulley B.
[Illustration: Fig. 1542.]
[Illustration: _VOL. I._ =SHAPING MACHINES AND TABLE-SWIVELING DEVICES.=
_PLATE XVI._
Fig. 1536.
Fig. 1537.
Fig. 1538.
Fig. 1539.]
In the annular space left between the face of pulley C and the cone B is
a steel band G, Fig. 1542, forming within a fraction a complete circle,
and lined inside and out with leather, and this band is brought, by
alternately expanding and contracting it, into contact with either the
bore of the largest cone step of B or with the outside face of pulley C.
The ends of this band are pivoted upon two pins F, which are fast in two
arms E and D, in Fig. 1542. Arm E is fastened to the driving shaft H,
and its hub has two roller studs K, Fig. 1541, these being diametrically
opposite on the said hub. The hub of arm D is a working fit upon the
hub of E, and has two slots to admit the above rollers. Hub D is also
provided with two studs and rollers placed midway between the studs K.
These latter rollers project into the spiral slots K´ of the ring in
Fig. 1543, this ring enveloping the hub of D and being enveloped by the
sleeve M, which contains two spiral grooves diametrically opposite, and
lying in an opposite direction to grooves K´, Fig. 1543. Sleeve M is
prevented from revolving by rollers on the studs O, which are screwed
into the bearing bush R, and carry rollers projecting into the slots in
M.
[Illustration: Fig. 1543.]
It is evident that if the ring L, Fig. 1543, is moved endways with M,
then the arms E, D, together with the band G, will be expanded or
contracted according to the direction of motion of the ring, because the
motion of M, by means of its spiral grooves, gives a certain amount of
rotary motion to the ring L, and the spiral grooves in the ring give a
certain amount of rotary motion to the arms D and E, Fig. 1542. When
this rotary motion is in one direction the band is expanded; while when
it is reversed it is contracted, and the direction of motion of shaft H
is reversed.
[Illustration: Fig. 1544.]
[Illustration: Fig. 1545.]
The outer sleeve M carries the rod T, Figs. 1544 and 1545, which is
connected to the lever U, the upper arm of which is operated by the
tappets or dogs X on the ram or sliding bar, and it is obvious that when
U is vibrated sleeve M is operated in a corresponding direction, and the
ring L also is moved endwise in a corresponding direction, actuating the
band as before described, the direction of motion being governed,
therefore, by the direction in which U is moved by the tappets or dogs.
A certain degree of friction is opposed to the motion of lever U in
order to keep it steady, the construction being shown in Fig. 1546,
where it is seen that there is on each side of its nut a leather washer,
giving a certain amount of elasticity to the pressure of the nut holding
it in place on the shaft U.
[Illustration: Fig. 1546.]
The mechanism for actuating the feed at the end of the return stroke
only, is shown in Fig. 1547. The shaft V (which is also seen in a dotted
circle in Fig. 1545) carries a flange _c_, on each side of which is a
leather disk, so that the pressure of the bolts which secure _b_ to the
sleeve _a_ causes _c_ to revolve under friction, unless sleeve _a_,
slotted bar _b_, and flange _c_ all revolve together, or, in other
words, _c_ revolves under friction when it revolves within _a_ _b_.
[Illustration: Fig. 1547.]
[Illustration: Fig. 1548.]
Fig. 1548 is an end view of Fig. 1547.
[Illustration: Fig. 1549.]
Fig. 1549 gives a cross-sectional view of the shaft sleeve, &c. The
sleeve _a_ is provided with two pins _i_, _i_, and a pin _k_ is fast in
the frame of the machine, and it is seen that _a_ and V may revolve
together in either direction until such time as one of the pins _i_
meets the stationary pin _k_, whereupon the further revolving of _a_
will be arrested and V will revolve within _a_, and as flange _c_, Fig.
1547, revolves with V, it will do so under the friction of the leather
washers. The pins _i_ and the pin _k_ are so located that _a_ can have
motion only when the ram or sliding-bar is at the end of the return
stroke, and the feed-rod _f_, being connected to _b_, is therefore
actuated at the same time.
Among the various mechanisms employed to give a quick return to the
tool-carrying slide of shaping machines, those most frequently employed
are a simple crank, a vibrating link, and the Whitworth quick-return
motion, the latter being the most general one.
The principle of action when a vibrating link is employed may be
understood from Fig. 1550, in which P is a pinion driven by the cone
pulley and imparting motion to D. At L is a link pivoted at C. At A is a
link block or die capable of sliding in the slot or opening in the link
and a working fit upon a pin which is fast in the wheel D. As D rotates
the link block slides in the slot and the link is caused to travel as
denoted by the dotted lines. R is a rod connecting the tool-carrying
slide S to the upper end of link L, and therefore causing it to
reciprocate with L. But S being guided by its slide in the guideway
traverses in a straight line.
[Illustration: Fig. 1550.]
Since the rotation of P and D is uniform, the vibrations of the link L
will vary in velocity, because while the link block is working in the
lower half of the link slot it will be nearer to the centre of motion C
of the link, and the upper end of C will move proportionately faster.
The arrangement is such that during this time the tool-carrying slide is
moved on its return stroke, the cutting stroke being made while the link
block is traversing the upper half of the slot, or in other words,
during the period in which the crank pin in A is above the horizontal
centre of wheel D.
Now suppose the arrangement of the parts is such that the front of the
machine or the cutting tool end of the slide is at the end K of S, then
S will be pushed to its cut by the rod R at an angle which will tend to
lift S in the slideways. But suppose the direction of rotation of wheel
D instead of being as denoted by the arrow at D be as denoted by the
arrow at E, then S will be on its back stroke, the front of the machine
being at J. In this case rod R will pull S to the cut, and S will, from
the angularity of R, be pulled down upon the bed of the slideway guiding
it, and will therefore be more rigidly held and less subject to spring,
because the tendency to lift is resisted on one side by the adjustable
gib only, and on the other by the projecting V, whereas the tendency to
be pulled downwards is resisted by the strength of the frame of the
machine.
Furthermore, as the pressure on the cutting tool is below the level of
the tool-carrying slide it tends to force that slide down upon the
slideway, and it will therefore be more rigidly and steadily guided when
the force moving the slide and the tool pressure both act in the same
direction.
To vary the length of stroke of S pin A is so attached to wheel D that
it may be adjusted in its distance from the centre of D.
[Illustration: Fig. 1551.]
The Whitworth quick-return motion is represented in Fig. 1551. At P is
the pinion receiving motion from the cone pulley or driving pulley of
the machine and imparting motion to the gear-wheel G, whose bearing is
denoted by the dotted circle B. Through B passes a shaft C, which is
eccentric to B and carries at its end a piece A in which is a slot to
receive the pin X, which drives rod R whose end Z is attached to the ram
of the machine. At D is a pin fast in gear-wheel G and passing into a
slot in A.
Taking the position the parts occupy in the figures, and it is seen that
the axis of B is the centre of motion of G and is the fulcrum from which
the pin D is driven, the power being delivered at X. The path of motion
of the driving pin D is denoted by the dotted circle H´, and it is
apparent that as it moves from the position shown in the figure it
recedes from the axis of C, and as the motion of G is uniform in
velocity therefore D will move A faster while moving below the line M
than it will while moving above it, thus giving a quick return, because
the cutting stroke of the ram occurs while D is above the line M and the
return stroke occurs while D is below M.
In some constructions the pin X and pin D work in opposite ends of the
piece A, as shown in Fig. 1552. This, however, is an undesirable
construction because the shaft C becomes the fulcrum, and as the power
and resistance are on opposite ends of the lever A, the wheel G is
therefore forced against its bearing, and this induces unnecessary
friction and wear.
We may now consider the tool motion given by other kinds of slide
operating mechanism.
In Fig. 1553 is a diagram of the tool motion given when the slide is
operated by a simple crank C, the thickened line R representing the rod
actuating the slide and line on the line of motion of the cutting tool.
The circle H denotes the path of revolution of the crank pin, and the
black dots 1, 2, 3, 4, &c., equidistant positions of the crank pin.
[Illustration: Fig. 1552.]
Line _m_ represents the path of motion of the cutting tool.
If a pair of compasses be set to the full length of the thick line R,
that is from the centre of the crank pin to end B of line R, and these
compasses be then applied to the centre of crank pin position 1, and to
the line _m_, they will meet _m_ at a point denoted by line _a_, which
will, therefore, represent the position of the tool point when the crank
pin was in position 1. To find how far the tool point is moved while the
crank pin moves from position 1 to position 2, we place the compass
point on the centre of crank pin position 2 and mark line _b_. For crank
position 3 we have by the same process line _c_, and so on, the twelve
lines from _a_ to _l_ representing crank positions from 1 to 12.
Now let it be noted that since the path of the crank pin is a circle,
the tool point will on the backward stroke occupy the same position when
the crank pin is at corresponding positions on the forward and backward
strokes. For example, when the crank pin is in position 7 the tool point
will be at point _g_ on the forward stroke, and when the crank pin is in
position 17 the tool will be at point _g_ on the backward stroke, as
will be found by trial with the compasses; and it follows that the lines
_a_, _b_, _c_, &c., for the forward stroke will also serve for the
backward one, which enables us to keep the engraving clear, by marking
the first seven positions on one side of line _m_, and the remaining
five on the other side of _m_, as has been done in the figure.
[Illustration: Fig. 1553.]
Obviously the distances apart of the lines _a_, _b_, _c_, _d_, &c.,
represent the amount of tool motion during equal periods of time,
because the motion of the crank pin being uniform it will move from
position 1 to position 2 in the same time as it moves from position 2 to
position 3, and it follows that the cutting speed of the tool varies at
every instant in its path across the work, and also that since the crank
pin operates during a full one-half of its revolution to push the tool
forward, and during a full one-half to pull it backward, therefore the
speed of the two strokes are equal.
[Illustration: Fig. 1554.]
We may now plot out the motion of the link quick return that was shown
in Fig. 1550, the dotted circle H´, in Fig. 1554, representing the path
of the pin A, and the arc H representing the line of motion of the upper
end of link L, and lines N, O, its centre line at the extreme ends of
its vibrating motion. In Fig. 1554 the letters of reference refer to the
same parts as those in Fig. 1550. We divide the circle H´ of pin motion
into twenty-four equidistant parts marked by dots, and through these we
draw lines radiating from centre C and cutting arc H, obtaining on the
arc H the various positions for end Z of rod R, these positions being
marked respectively 1, 2, 3, 4, &c., up to 24. With a pair of compasses
set to the length of rod R from 1 on H, as a centre, we mark on the line
of motion of the slide line _a_, which shows where the other end of the
rod R will be (or, in other words, it shows the position of bolt B in
Fig. 1550), when the centre of A, Fig. 1550, is in position 1, Fig.
1554.
From 2 on arc H, we mark with the compasses line _b_ on line M, showing
that while the pin moved from 1 to 2, the rod R would move slide S, Fig.
1550, from _a_ to _b_, in Fig. 1554. From 3 we mark _c_, and so on, all
these marks being above the horizontal line M, representing the line of
motion, and being for the forward stroke. For the backward stroke we
draw the dotted line from position 17 up to arc H, and with the
compasses at 17 mark a line beneath the line M of motion, pursuing the
same course for all the other pin positions, as 18, 19, &c., until the
pin arrives again at position 24, and the link at O, and has made a full
revolution, and we shall have the motion of the forward stroke above and
that of the backward one below the line of motion of the slide.
On comparing this with the crank and with the Whitworth motion hereafter
described, we find that the cutting speed is much more uniform than
either of them, the irregularity of motion occurring mainly at the two
ends of the stroke.
In Fig. 1555 we have the motion of the Whitworth quick return described
in Fig. 1551, H´ representing the path of motion of the driving-pin D
about the centre of B, and H´ the path of motion of X about the centre
C, these two centres corresponding to the centres of B and C
respectively in Fig. 1551. Let the line M correspond to the line of
motion M in Fig. 1551. Now, since pin D, Fig. 1551, drives, and since
its speed of revolution is uniform, we divide its circle of motion H´
into twenty-four equal divisions, and by drawing lines radiating from
centre B, and passing through the lines of division on H´, we get on
circle H twenty-four positions for the pin X in Fig. 1551. Then setting
the compasses to the length of the rod (R, Fig. 1551), we mark from
position 1 on circle H as a centre, line _a_; from position 2 on H we
mark line _b_, and so on for the whole twenty-four positions on circle
H, obtaining from _a_ to _n_ for the forward, and from _n_ to _y_ for
the motion during the backward stroke. Suppose, now, that the mechanism
remaining precisely the same as before, the line M of motion be in a
line with the centres C, B, instead of at a right angle to it, as it is
in Fig. 1551, and the motion under this new condition will be as in Fig.
1556, the process for finding the amount of motion along M from the
motion around H being precisely as before.
[Illustration: Fig. 1555.]
[Illustration: Fig. 1556.]
The iron planing machine, or iron planer as it is termed in the United
States, is employed to plane such surfaces as may be operated upon by
traversing a work table back and forth in a straight line beneath the
cutting tool. It consists essentially of a frame or bed A, Fig. 1557,
provided on its upper surface with guideways, on which a work carrying
table T may be moved by suitable mechanism back and forth in a straight
line.
This frame or bed carries two upright frames or stanchions B, which
support a cross-bar or slide C, to which is fitted a head which carries
the cutting tool.
To enable the setting of the tool at such a height from the table as the
height of the work may require, the cross slide C may be raised higher
upon the uprights B by means of the bevel gears F, G, H, and T, the
latter being on a shaft at the top of the machine, and operating the
former, which are on vertical screws N, which pass down through nuts
that are fast upon the cross slide C.
To secure C at its adjusted height, the uprights are provided with
[T]-shaped slots H H, and bolts pass through C, their heads being in the
[T]-grooves, and their nuts exposed so that a wrench may be applied to
them.
The faces of the cross slide C are parallel one to the other, and stand
at a right angle to the [V]-guideways on which the work table (or platen
as it is sometimes termed) slides; hence the cross slide will, if the
table is planed true or parallel with this cross slide, be parallel with
the table at whatever height above the table it is set, providing that
the elevating screws, when operated, lift each end of C equally.
The construction of the head D corresponds to that of the head shown in
Figs. 1497 and 1498 for a shaper, except that in this case the swivel
head is secured to a saddle that slides along C, being provided with a
nut operated by a feed screw J, which moves D along C.
The mechanism for operating the work table or platen T is as follows:--P
P´ are two loose pulleys and P´´ is a driving pulley fast on the same
shaft. This shaft drives, within the casing at Q, a worm operating a
worm-wheel, which actuates inside the frame A and beneath the work table
a train of gears, the last of which gears with a rack, provided on the
underneath side of the table.
The revolutions of this last wheel obviously cause the work table to
slide back and forth while resting on the [V]-guideways provided on top
of the frame A, the direction of table motion being governed by the
direction in which the wheel revolves.
This direction is periodically reversed as follows:--The pulley P is
driven by a crossed belt, while pulley P´ is driven by an open or
uncrossed one, hence the direction of revolution of the driving pulley
P´´ will be in one direction if the belt is moved from P to P´´, and in
the other if the belt is moved from P´ to P´´. Mechanism is provided
whereby first one and then the other of these belts is moved so as to
pass over upon P´´ and drive it, the construction being as follows:--
To the edge of the work table there is fixed a stop R, which as the
table traverses to the right meets and moves a lever arm S, which
through the medium of a second lever operates the rod X, which operates
a lever _u_, which has a slot through which one of the driving belts
passes. The lever _u_ operates a second lever _w_ on the other side of
the pulleys, and this lever also has a slot through which the other
driving belt passes.
When the stop R moves the lever arm S levers _u_ and _w_ therefore move
their respective belts, one moving from the tight pulley P´´ to a loose
one as P, and the other moving its belt from the loose pulley as P´ to
the tight one P´´, and as the directions of belt motions are opposite
the direction of revolution of P´´ is reversed by the change of belt
operating it. There are two of the stops R, one on each side of the
lever S, hence one of these stops moves the lever S from left to right
and the other from right to left.
Suppose, then, that the table is moving from right to left, which is its
cutting stroke, and the driving belt will be on the pulley P´´ while the
other belt will be on pulley P. Then as the stop R moves S and operates
X the arm _u_ will move its belt from P´´ to P´, and arm _w_ will move
its belt from P to P´´, reversing the direction of motion of P´´, and
therefore causing the table T to move from left to right, which it will
continue to do until the other stop corresponding to R meets S and moves
it from right to left, when the belts will be shifted back again. The
stroke of the table, therefore, is determined by the distance apart of
the stops R, and these may be adjusted as follows:--
They are carried by bolts whose heads fit in a dovetail groove Z
provided along the edge of the table, and by loosening a set screw may
therefore be moved to any required location along the bed.
To give the table a quick return so that less time may be occupied for
the non-cutting stroke, all that is necessary is to make the
countershaft pulley that operates during the back traverse of larger
diameter than that which drives during the cutting traverse of the
table.
In order that one belt may have passed completely off the driving pulley
P´´ before the other moves on it the lever motions of _u_ and _w_ are so
arranged that when the belt is moving from P´´ to P lever _u_ moves in
advance of lever _w_, while when the other belt is being moved from P´´
to P´ lever _w_ moves in advance of lever _u_.
To enable the work table to remain at rest, one driving belt must be
upon P and the other upon P´, which is the case when the lever arm S is
in mid position, and to enable it to be moved to this position it is
provided with a handle K forming part of lever S.
To cause the tool to be fed to its cut before it meets the cut and thus
prevent it from rubbing against the side of the cut, as was described
with reference to Fig. 1503, the feed takes place when the table motion
is reversed from the back or return stroke to the cutting or forward
stroke by the following mechanism:--
[Illustration: Fig. 1557.]
At _a_ is a rack that is operated simultaneously with S and by the same
stop R. This rack operates a pinion _b_, which rotates the slotted piece
_c_, in which is a block that operates the vertical rod _d_, which is
attached to a segmental rack _e_, which in turn operates a pinion which
may be placed either upon the cross-feed screw J, or upon the rod above
it; the latter operates the vertical feed of the tool through mechanism
within the head D and not therefore shown in the engraving. Thus the
self-acting tool feed may take place vertically or across the work table
at will by simply placing the pinion upon the cross-feed screw or upon
the feed rod, as the case may be.
[Illustration: Fig. 1558.]
Fig. 1558 represents a planer by David W. Pond, of Worcester,
Massachusetts, in which the rod _x_ is connected direct from S to a
pivoted piece _y_ in which is a cam-shaped slot through which pass pins
from the belt-moving arms _u_ and W. The shape of the slot in _y_ is
such as to move the belt-moving arms one in advance of the other, as
described with reference to Fig. 1566.
The feed motions are here operated by a disk C, which is actuated
one-half a revolution when the work table is reversed. This disk is
provided on its face with a slide-way in which is a sliding block that
may be moved to or from the centre of C by the screw shown, thus varying
at will the amount of stroke imparted to the rod which moves the rack by
means of which the feed is actuated through the medium of the
gear-wheels at _f_. The handle _g_ is for operating the feed screw when
the self-acting feed is thrown out of operation, which is done by means
of a catch corresponding in its action to the catch shown in Fig. 1501.
S and S´ are in one piece, S´ being to move the two driving belts on to
the loose pulleys so as to stop the work table from traversing.
The size of a planer is designated from the size of work it will plane,
and this is determined by the greatest height the tool can be raised
above the planer table, the width between the stanchions, and the length
of table motion that can be utilized while the tool is cutting; which
length is less than the full length of table stroke, because in the
first place it is undesirable that the rack should pass so far over the
driving wheel or pinion that any of the teeth disengage, and,
furthermore, a certain amount of table motion is necessary to reverse
after the work has passed the tool at the end of each stroke.
Fig. 1559 represents a method employed in some English planing machines
to drive the work table and to give it a quick return motion. In this
design but one belt is used, being shifted from pulley A, which operates
the table for the cutting stroke, to pulley J, which actuates the table
for the return stroke. The middle pulley K is loose upon shaft B, as is
also pulley J, which is in one piece with pinion J´. Motion from A is
conveyed through shaft B and through gear C, D, E to F, and is reduced
by reason of the difference in diameter between D and E and between F
and G. Motion for the quick return passes from J direct to F without
being reduced by gears D, E, hence the difference between the cutting
speed and the speed of the return stroke is proportionate to the
relative diameters or numbers of teeth in D and E, and as E contains 12
and D 20 teeth, it follows that the return is 8/12 quicker than the
cutting stroke.
In this design the belt is for each reversal of table motion moved
across the loose pulley K from one driving pulley to the other, and
therefore across two pulleys instead of across the width of one pulley
only as in American machines.
[Illustration: Fig. 1559.]
[Illustration: Fig. 1560.]
In American practice the rack R, Fig. 1559, is driven by a large gear
instead of by a pinion, so that the strain on the last driving shaft S,
in Fig. 1560, shall be less, and also the wheel less liable to vibration
than a pinion would be, because in the one case, as in Fig. 1559, the
power is transmitted through the shaft, while in the other, as in Fig.
1560, it is transmitted through the wheel from the pinion P to the rack
R.
[Illustration: Fig. 1561.]
Fig. 1561 represents a planer, designed for use in situations where a
solid foundation cannot be obtained, hence the bed is made of unusual
depth to give sufficient strength and make it firm and solid on unstable
foundations, such as the floors in the upper stories of buildings. In
all other respects the machine answers to the general features of
improved planing machines.
[Illustration: Fig. 1562.]
As the sizes of planing machines increase, they are given increased
tool-carrying heads; thus, Fig. 1562 represents a class in which two
sliding heads are used, so that two cutting tools may operate
simultaneously. Each head, however, is capable of independent operation;
hence, one tool may be actuated automatically along the cross slide to
plane the surfaces of the work, while the other may be used to carry a
cut down the sides of the work, or one tool may take the roughing and
the other follow with the finishing cut, thus doubling the capacity of
the machine.
In other large planers the uprights are provided with separate heads as
shown in the planer in Fig. 1563, in which each upright is provided with
a head shown below the cross slide. Either or both these heads may be
employed to operate upon the vertical side faces of work, while the
upper surface of the work is being planed.
The automatic feed motion for these side heads is obtained in the
Sellers machine from a rod actuated from the disk or plate in figure,
this rod passing through the bed and operating each feed by a pawl and
feed wheel, the latter being clearly seen in the figure.
To enable the amount of feed to be varied the feed rod is driven by a
stud capable of adjustment in a slot in the disk.
[Illustration: _VOL. I._ =EXAMPLES OF PLANING MACHINES.= _PLATE XVII._
Fig. 1561.
Fig. 1563.]
Fig. 1563 represents a planing machine designed by Francis Berry & Sons,
of Lowerby Bridge, England. The bed of the machine is, it will be seen,
[L]-shaped, the extension being to provide a slide to carry the
right-hand standard, and permit of its adjustment at distances varying
from the left-hand standard to suit the width of the work. This
obviously increases the capacity of the machine, and is a desirable
feature in the large planers used upon the large parts of marine
engines.
[Illustration: Fig. 1564.]
ROTARY PLANING MACHINE.--Fig. 1564 is a rotary planing machine. The
tools are here carried on a revolving disk or cutter head, whose spindle
bearing is in an upper slide with 2 inches of motion to move the bearing
endways, and thereby adjust the depth of cut by means of a screw. The
carriage on which the spindle bearing is mounted is traversed back and
forth (by a worm and worm-wheel at the back of the machine) along a
horizontal slide, which, having a circular base, may be set either
parallel to the fixed work table or at any required angle thereto.
By traversing the cutter head instead of the work, less floor space is
occupied, because the head requires to travel the length of the work
only, whereas when the work moves to the cut it is all on one side of
the cutter at the beginning of the cut, and all on the other at the end,
hence the amount of floor space required is equal to twice the length of
the work.
The disk or cutter head is in one piece with the spindle, and carries
twenty-four cutters arranged in a circle of 36 inches in diameter. These
cutters are made from the square bar, and each cutting point should have
the same form and position as referred to one face, side, or square of
the bar, so that each cutter may take its proper share of the cutting
duty; and it is obvious that all the cutting edges must project an equal
distance from the face of the disk, in which case smooth work will be
produced with a feed suitable for the whole twenty-four cutters, whereas
if a tool cuts deeper than the others it will leave a groove at each
passage across the work, unless the feed were sufficiently fine for that
one tool, in which case the advantage of the number of tools is lost.
The cutters may be ground while in their places in the head by a
suitable emery-wheel attachment, or if ground separately they must be
very carefully set by a gauge applied to the face of the disk.