Various - Scientific American Supplement, No. 312, December 24, 1881
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Various >> Scientific American Supplement, No. 312, December 24, 1881
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The relative position of the tool and work is shown in Figs. 25, 26,
27, and 28; Fig. 25 shows the position for brass; Fig. 26 for iron and
steel; Fig. 27 the relative position of the engine rest tool and its
work; and Fig. 28 the position of the tool for soft metal and wood.
In all of these cases the point of the tool is above the center of the
work. In the matter of the adjustment of the tool, as well as in all
other operations referred to, experiment is recommended as the best
means of gaining valuable knowledge in the matter of turning metals.
ROTARY CUTTERS.
The saving of files, time, materials, and patience, by the employment
of such rotary cutters as may be profitably used in connection with a
foot lathe, can hardly be appreciated by one who has never attempted
to use this class of tools. It is astonishing how much very hard labor
may be saved by means of a small circular saw like that shown in Fig.
1. This tool, like many others described in this series of articles,
can, in most instances, be purchased cheaper than it can be made, and
the chances are in favor of its being a more perfect article. However,
it is not so difficult to make as one might suppose. A piece of sheet
steel may be chucked upon the face plate, or on a wooden block
attached to the face plate, where it may be bored to fit the saw
mandrel, and cut in circular form by means of a suitable hand tool. It
may then be placed upon the mandrel and turned true, and it is well
enough to make it a little thinner in the middle than at the
periphery.
[Illustration: Rotary Cutting Tools.]
There are several methods of forming the teeth on a circular saw. It
may be spaced and filed, or it may be knurled, as shown in Fig. 2, and
then filed, leaving every third or fourth tooth formed by the knurl,
or it may, for some purposes, be knurled and not filed at all. Another
way of forming the teeth is to employ a hub, something like that used
in making chasers, as shown in Fig. 3, the difference between this hub
and the other one referred to, is that the thread has one straight
side corresponding with the radial side of the tooth. The blank from
which the saw is made is placed on a stud projecting from a handle
made specially for the purpose, and having a rounded end which
supports the edge of the blank, as the teeth are formed by the cutters
on the hub.
The saw, after the teeth are formed, may be hardened and tempered by
heating it slowly until it attains a cherry red, and plunging it
straight down edgewise into cool, clean water. On removing it from the
water it should be dried, and cleaned with a piece of emery paper, and
its temper drawn to a purple, over a Bunsen gas flame, over the flame
of an alcohol lamp, or over a hot plate of iron. The small saw shown
in Fig. 4 is easily made from a rod of fine steel. It is very useful
for slotting sheet brass and tubes, slotting small shafts, nicking
screws, etc. Being quite small it has the advantage of having few
teeth to keep in order, and it may be made harder than those of larger
diameter. A series of them, varying in diameter from one eighth to
three eighths of an inch, and varying considerably in thickness, will
be found very convenient.
These cutters or saws, with the exception of the smaller one, may be
used to the best advantage in connection with a saw table, like that
shown in Fig. 8. This is a plane iron table having a longitudinal
groove in its face to receive the guiding rib of the carriage, shown
in Fig. 9, and a transverse groove running half way across, to receive
a slitting gauge, as shown in Fig. 8. The table is supported by a
standard or shank, which fits into the tool-rest socket. The saw
mandrel is supported between the centers of the lathe, and the saw
projects more or less through a slot formed in the table. The gauge
serves to guide the work to be slotted, and other kinds of work may be
placed on or against the carriage, shown in Fig. 9.
It is a very simple matter to arrange guiding pieces for cutting at
any angle, and the saw table may be used for either metal or wood. The
saws for wood differ from those used for metal; the latter are filed
straight, the former diagonally or fleaming. Among the many uses to
which metal saws may be applied we mention the slitting of sheet
metals, splitting wires and rods, slotting and grooving, nicking
screws, etc. Fig. 10 shows a holder for receiving screws to be nicked.
It is used in connection with the saw table, and is moved over the saw
against the gauge.
To facilitate the removal of the screws the holder may be split
longitudinally and hinged together. Another method of nicking screws
is illustrated by Fig. 11. A simple lever, fulcrumed on a bar held by
the tool post, is drilled and tapped in the end to receive the screw.
After adjusting the tool all that is required is to insert the screw
and press down the handle so as to bring the screw head into contact
with the saw.
Where a lathe is provided with an engine rest, the cutter shown in
Fig. 6, mounted on the mandrel shown in Fig. 5, is very useful; it is
used by clamping the work to the slide rest and moving it under the
cutter by working the slide rest screw.
To make a cutter of this kind is more difficult than to make a saw,
and to do it readily a milling machine would be required. It may be
done, however, on a plain foot lathe, by employing a V-shaped cutter
and using a holder (Fig. 7) having an angular groove for receiving the
cylinder on which the cutting edges are formed. The blank can be
spaced with sufficient accuracy, by means of a fine pair of dividers,
and after the first groove is cut there will be no difficulty in
getting the rest sufficiently accurate, as a nib inserted in the side
of the guide enters the first groove and all of the others in
succession and regulates the spacing.
One of the best applications of this tool is shown in the small
engraving. In this case a table similar to the saw table before
described is supported in a vertical position, and arranged at right
angles with the cutter mandrel. The mandrel is of the same diameter as
the cutter, and serves as a guide to the pattern which carries the
work to be operated upon. The principal use of this contrivance is to
shape the edges of curved or irregular metal work. The casting to be
finished is fastened--by cement if small, and by clamps if large--to a
pattern having exactly the shape required in the finished work.
[Illustration: METAL SHAPING.]
By moving the pattern in contact with the table and the mandrel, while
the latter revolves, the edges of the work will be shaped and finished
at the same time. By substituting a conical cutter for a cylindrical
one, the work may be beveled; by using both, the edge may be made
smooth and square, while the corner is beveled.
The tool shown in Fig. 12 might properly be called a barrel saw. It is
made by drilling in the end of a steel rod and forming the teeth with
a file. To avoid cracking in tempering a small hole should be drilled
through the side near the bottom of the larger hole. To insure the
free working of the tool it should be turned so that its cutting edge
will be rather thicker than the position behind it. This tool should
be made in various sizes.
Tools for gear cutting and also cutters for wood have not been
mentioned in this paper; as they are proper subjects for separate
treatment.
WOOD WORKING.
It is not the intention of the writer to enter largely into the
subject of wood working, but simply to suggest a few handy attachments
to the foot lathe which will greatly facilitate the operations of the
amateur wood worker, and will be found very useful by almost any one
working in wood. It is not an easy matter to split even thin lumber
into strips of uniform width by means of a handsaw, but by using the
circular saw attachment, shown in Fig. 1, the operation becomes rapid
and easy, and the stuff may be sawed or slit at any desired angle or
bevel. The attachment consists of a saw mandrel of the usual form, and
a wooden table supported by a right angled piece, A, of round iron
fitted to the toolpost and clamped by a wooden cleat, B, which is
secured to the under side of the table, split from the aperture to one
end, and provided with a thumbscrew for drawing the parts together.
By means of this arrangement the table may be inclined to a limited
angle in either direction, the slot through which the saw projects
being enlarged below to admit of this adjustment.
[Illustration: WOODWORKING ATTACHMENTS FOR THE FOOT LATHE.]
The back of the table is steadied by a screw which rests upon the back
end of the tool rest support, and enters a block attached to the under
side of the table. The gauge at the top of the table is used in
slitting and for other purposes which will be presently mentioned, and
it is adjusted by aid of lines made across the table parallel with the
saw.
For the purpose of cross cutting or cutting on a bevel a thin sliding
table is fitted to slide upon the main table, and is provided with a
gauge which is capable of being adjusted at any desired angle. For
cutting slots for panels, etc., thick saws may be used, or the saw may
be made to wabble by placing it between two beveled washers, as shown
in Fig. 2.
The saw table has an inserted portion, C, held in place by two screws
which may be removed when it is desired to use the saw mandrel for
carrying a sticker head for planing small strips of moulding or
reeding. The head for holding the moulding knives is best made of good
tough brass or steam metal. The knives can be made of good saw steel
about one-eighth inch thick. They may be filed into shape and
afterward tempered. They are slotted and held to their places on the
head by means of quarter-inch machine screws. It is not absolutely
necessary to use two knives, but when only one is employed a
counterbalance should be fastened to the head in place of the other.
All kinds of moulding, beading, tonguing, and grooving may be done
with this attachment, the gauge being used to guide the edge of the
stuff. If the boards are too thin to support themselves against the
action of the knives they must be backed up by a thick strip of wood
planed true. The speed for this cutter head should be as great as
possible.
Fig. 5 shows an attachment to be used in connection with the cutter
head and saw table for cutting straight, spiral, or irregular flutes
on turned work. It consists of a bar, D, carrying a central fixed arm,
and at either end an adjustable arm, the purpose of the latter being
to adapt the device to work of different lengths. The arm projecting
from the center of the bar, D, supports an arbor having at one end a
socket for receiving the twisted iron bar, E, and at the other end a
center and a short finger or pin. A metal disk having three spurs, a
central aperture, and a series of holes equally distant from the
center and from each other, is attached by its spurs to the end of the
cylinder to be fluted, and the center of the arbor in the arm, D,
enters the central hole in the disk while its finger enters one of the
other holes. The opposite end of the cylinder is supported by a center
screw. A fork attached to the back of the table embraces the twisted
iron, E, so that as the wooden cylinder is moved diagonally over the
cutter it is slowly rotated, making a spiral cut. After the first cut
is made the finger of the arbor is removed from the disk and placed in
an adjoining hole, when the second cut is made, and so on.
Figs. 6 and 7 show a convenient and easily made attachment for
moulding the edges of irregular work, such as brackets, frames, parts
of patterns, etc. It consists of a brass frame, F, supporting a small
mandrel turning at the top in a conical bearing in the frame, and at
the bottom upon a conical screw. A very small grooved pulley is
fastened to the mandrel and surrounded by a rubber ring which bears
against the face plate of the lathe, as shown in the engraving. The
frame, F, is let into a wooden table supported by an iron rod which is
received by the tool rest holder of the lathe. The cutter, G, is made
by turning upon a piece of steel the reverse of the required moulding,
and slotting it transversely to form cutting edges. The shank of the
cutter is fitted to a hole in the mandrel and secured in place by a
small set screw. The edge of the work is permitted to bear against the
shank of the cutter. Should the face plate of the lathe be too small
to give the required speed, a wooden disk may be attached to it by
means of screws and turned off.
Figs. 8, 9, and 10 represent a cheaply and easily made scroll saw
attachment for the foot lathe. It is made entirely of wood and is
practically noiseless. The board, H, supports two uprights, I, between
which is pivoted the arm, J, whose under side is parallel with the
edge of the board. A block is placed between the uprights, I, to limit
the downward movement of the arm, and the arm is clamped by a bolt
which passes through it and through the two uprights and is provided
with a wing nut.
A wooden table, secured to the upper edge of the board, H, is
perforated to allow the saw to pass through, and is provided with an
inserted hardwood strip which supports the back of the saw, and which
may be moved forward from time to time and cut off as it becomes worn.
The upper guide of the saw consists of a round piece of hard wood
inserted in a hole bored in the end of the arm, J. The upper end of
the saw is secured in a small steel clamp pivoted in a slot in the end
of a wooden spring secured to the top of the arm, J, and the lower end
of the saw is secured in a similar clamp pivoted to the end of the
wooden spring, K. Fig. 10 is an enlarged view showing the construction
of clamp.
The relation of the spring, K, to the board, H, and to the other part
is shown in Fig. 9. It is attached to the side of the board and is
pressed upward by an adjusting screw near its fixed end.
The saw is driven by a wooden eccentric placed on the saw mandrel
shown in Figs. 1 and 2, and the spring, K, always pressed upward
against the eccentric by its own elasticity, and it is also drawn in
an upward direction by the upper spring. This arrangement insures a
continuous contact between the spring, K, and the eccentric, and
consequently avoids noise. The friction surfaces of the eccentric and
spring may be lubricated with tallow and plumbago. The eccentric may,
with advantage, be made of metal.
The tension of the upper spring may be varied by putting under it
blocks of different heights, or the screw which holds the back end may
be used for this purpose.
The saw is attached to the lathe by means of an iron bent twice at
right angles, attached to the board, H, and fitted to the tool rest
support. The rear end of the sawing apparatus may be supported by a
brace running to the lower part of the lathe or to the floor.
The simple attachments above described will enable the possessor to
make many small articles of furniture which he would not undertake
without them, and for making models of small patterns they are almost
invaluable.
* * * * *
A NEW METHOD OF KEEPING MECHANICAL DRAWINGS.[1]
[Footnote 1: A Paper by Chas. T Porter, read before the American
Society of Mechanical Engineers.]
The system of keeping drawings now in use at the works of the
Southwark Foundry and Machine Company, in Philadelphia, has been found
so satisfactory in its operation that it seems worthy of being
communicated to the profession.
The method in common use, and which may be called the natural method,
is to devote a separate drawer to the drawings of each machine, or of
each group or class of machines. The fundamental idea of this system,
and its only one, is, keeping together all drawings relating to the
same subject matter.
Every draughtsman is acquainted with its practical working. It is
necessary to make the drawing of a machine, and of its separate parts,
on sheets of different sizes. The drawer in which all these are kept
must be large enough to accommodate the largest sheets. The smaller
ones cannot be located in the drawer, and as these find their way to
one side or to the back, and several of the smallest lie side by side
in one course, any arrangement of the sheets in the drawer is out of
the question.
The operation of finding a drawing consists in turning the contents of
the drawer all up until it is discovered. In this way the smaller
sheets get out of sight or doubled up, and the larger ones are torn.
No amount of care can prevent confusion.
Various plans have been adopted in different establishments intended
to remedy this state of things, but it is believed that none has been
hit upon so convenient, in all respects, as the one now to be
presented.
The idea of keeping together drawings relating to the same machine,
or of classifying them according to subjects in any way, is entirely
abandoned, and in place of these is substituted the plan of keeping
together all drawings that are made on sheets of the same size,
without regard to the subject of them.
Nine sizes of sheets were settled upon, as sufficient to meet our
requirements, and on a sheet that will trim to one of these sizes
every drawing must be made. They are distinguished by the first nine
letters of the alphabet. Size A is the antiquarian sheet trimmed, and
the smaller sizes will cut from this sheet, without waste, as follows:
A, 51x30 in.; B, 37x30 in; C, 25x30 in.; D, 17x30 in.; E 121/2x30
in.; F, 81/2x30 in.; G, 17x15 in.; H, 81/2x15 in.; I, 14x25 in.
The drawers for the different sizes are made one inch longer and wider
than the sheets they are to contain, and are lettered as above. Those
of the same size, after the first one, are distinguished by a numeral
prefixed to the letter. The back part of each drawer is covered for a
width of from six to ten inches, to prevent drawings, and especially
tracings, from slipping over at the back.
The introduction of the blue printing process has quite revolutionized
the drawing office, so far at least as we are concerned. Our drawings
are studies, left in pencil. When we can find nothing more to alter,
tracings are made on cloth. These become our originals, and are kept
in a fire-proof vault. This system is found admirably adapted to the
plan of making a separate drawing for each piece. The whole combined
drawing is not generally traced, but the separate pieces are picked
out from it. All our working copies are blue prints.
Each drawer contains fifty tracings. They are two and a half inches
deep, which is enough to hold several times as many, but this number
is quite all that it is convenient to keep together. We would
recommend for these shallower drawers.
Each drawing is marked in stencil in the lower right hand corner, and
also with inverted plates in the upper left hand corner, with the
letter and number of the drawer, and its own number in the drawer, as,
for example, 3F--31; so that whichever way the sheet is put in the
drawer, this appears at the front right hand corner. The drawings in
each drawer are numbered separately, fifty being thus the highest
number used.
For reference we depend on our indices. Each tracing, when completed,
is entered under its letter in the numerical index, and is given the
next consecutive number, and laid in its place.
From this index the title and the number are copied into other
indices, under as many different headings as possible.
Thus all the drawings of any engine, or tool, or machine whatever,
become assembled by their titles under the heading of such particular
engine, or tool, or machine. So also the drawings of any particular
part, of all sizes and styles, become assembled by their titles under
the name of such piece. However numerous the drawings, and however
great the variety of their subjects, the location of any one is, by
this means, found as readily as a word in a dictionary. The stencil
marks copy, of course, on the blue prints, and these when not in use
are kept in the same manner as the tracings, except that only
twenty-five are placed in one drawer.
We employ printed classified lists of the separate pieces constituting
every steam engine, the manufacture of which is the sole business of
these works, and on these, against the name of every piece, is given
the drawer and number of the drawing on which it is represented. The
office copies of these lists afford an additional mode of reference
and a very convenient one, used in practice almost exclusively. The
foreman sends for the prints by the stencil marks, and these are thus
got directly without reference to any index. They are charged in the
same way, and reference to the numerical index gives the title of any
missing print.
We find the different sizes to be used quite unequal. The method of
making a separate tracing of each piece, which we carry to a great
extent, causes the smaller sizes to multiply quite rapidly. We are
marking our patterns with the stencil of the drawing of the same
piece; and also, gauges, templets, and jigs.
It is found best to permit the sheets to be put away by one person
only, who also writes up the indices, which are kept in the fire
proof.
We were ourselves surprised at the saving of room which this system
has effected. Probably less than one-fourth the space is occupied that
the same drawings would require if classified according to subjects.
The system is completely elastic. Work of the most diverse character
might be undertaken every day, and the drawings of each article,
whether few or many, would find places ready to receive them.
* * * * *
ACHARD'S ELECTRIC BRAKE.
[Illustration: ELEVATION.]
[Illustration: PLAN.
ACHARD'S ELECTRIC BRAKE--EASTERN RAILWAY OF FRANCE.]
The merits of a brake in which electric apparatus is used, that has
been adopted by one large railway company, and is about to be used on
the State railways, as well as the fact that arrangements are being
made to introduce it in England, demand consideration. It may be that
modifications will, under different circumstances, be introduced, or
that the system will ultimately be found too cumbersome or too
delicate, but before criticism it is necessary to know something of
the apparatus. We therefore endeavor to give somewhat in detail the
arrangement adopted by M.L. Regray, chief engineer of the Chemin de
Fer de l'Est, the electrical system being that of M. Achard. An
electro-magnet, A, is suspended on a hinged axis, so that the poles of
the magnet have for armatures cylinders of metal fixed upon the axle
of the carriage. Suppose now the poles, D D, of the magnet brought
into contact with the revolving armatures, the friction between them
causes the magnet to revolve. The chain attached to the brake is fixed
to the extended axle of the magnet, and consequently when that axle
revolves is wound up, bringing the brakes upon the wheels. The
friction between the poles and the armature depends upon the strength
of the magnet, and this can be regulated at will from a maximum to a
minimum. But it will be well to trace the whole action. The electric
current may be obtained by means of Plante secondary cells charged by
Daniell's cells--in other words, one or two Daniell's cells are
constantly in action charging three or six Plante cells, and it is the
Plante cells that are called into action to electrify the magnet. The
battery is carried in a box in the brake van. The engineers, however,
seem to prefer that the current be obtained by means of a small Gramme
machine, driven direct by a Brotherhood three-cylinder engine, the
steam for which is obtained from the locomotive. The velocity and
hence the current of the Gramme machine can be regulated, and so the
action of the brakes. M. Achard prefers the Plante cells; he informs
us that he has tried the Faure battery, but the results obtained were
not satisfactory. The regulator, R squared, consists of a cylinder of wood
around which, as shown, wire is wound. The length of this wire in the
circuit, increasing as it does the resistance of the circuit,
determines the current to the electro-magnet. The action is as
follows: When it is necessary to apply the brakes, a simple pressure
of a key or the turn of a handle sends the electric current into the
wires of the electro-magnet. An attraction immediately takes place,
and the poles and armatures are brought into contact. The friction
between these causes the revolution of the magnet, the winding of the
chain around the axle, and the application of the brakes. The whole of
the brakes of the train enter into action at one and the same time.
The brakes are taken off by stopping the current, and a small spring
pulls and keeps the magnet from the armatures. A frame--also
carriages--fitted with this brake, are shown by the Compagnie des
Chemins de Fer de l'Est, which company also shows several other pieces
of interesting apparatus, one of which is a carriage fitted with
elaborate mechanism, in which electricity plays, perhaps, but a
subsidiary part, to obtain the traction of the train under varying
circumstances, the pressure on the buffers when stopping, and various
phenomena connected with the engine.--_The Engineer._
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