Spiral Turning
--Single Spiral, Straight Shaft
--Tapered Shaft
--Double Spiral, Tapered Shaft
--Double Spiral, Straight Shaft
--Double Groove Spiral, Straight Shaft 49-55
PLATES--SPINDLE TURNING.
Straight Cuts, 57
Shoulder Cuts, 59-65
Taper Cuts, 67-77
V Cuts, 79-81
Concave Cuts, 83-87
Convex Cuts, 89-95
Combination Cuts, 97-101
Chisel Handles, 103-107
Cabinet File Handle, 109
Scratch Awl Handle, 111
Carving Tool Handle, 113
Turning Chisel Handle, 115
Mallets, 117-119
Gavels, 121-127
Darning Eggs, 129-133
Stocking Darner, 131
Potato Masher, 135
Rolling Pins, 139-141
Vise Handle, 143
Screw Driver Handles, 145-147
Pene Hammer Handle, 149
Claw Hammer Handle, 151
Indian Clubs, 153-155
Dumb Bells, 157-159
Ten Pins, 161
PLATES--CHUCK TURNING.
Straight Cuts, 167-169
Shoulder Cuts, 171-173
Taper Cuts, 175-177
V Cuts, 179-181
Concave Cuts, 183-185
Convex Cuts, 187-189
Combination Cuts, 191-195
Match Boxes, 197-201
Pin Trays, 203-205
Hair Pin Receivers, 207-209
Hat Pin Receivers, 211-213
Ornamental Vases, 215-219
Spinnet, 221
Towel Rings, 223-227
Card Trays, 229-235
Picture Frames, 237-243
Nut Bowls, 245-251
Napkin Rings, 253-257
Jewel Boxes, 259-273
Collar Boxes, 275-279
Sphere, 281
Checker Men, 283
Candle Sticks, 285-293
Shaving Stands, 295-301
Reading Lamp Stands, 303-307
Pedestal, 309
Smokers' Stands, 311-313
Pin Cushion and Spoon Holder, 315
Chess Men, 317-319
Pedestals, 321-325
Electric Reading Lamps, 327-335
Magazine Holders, 337-339
CLASSIFICATION OF PLATES
A. SPINDLE TURNING
I. Exercises
1. Straight Cuts, a
2. Shoulder Cuts, a-b-c-d
3. Taper Cuts, a-b-c-d-e-f
4. V Cuts, a-b
5. Concave Cuts, a-b-c
6. Convex Cuts, a-b-c-d
7. Combination Cuts, a-b-c
II. Models
1. Chisel Handles, a-b-c-d-e-f-g
2. Mallets, a-b
3. Gavels, a-b-c-d
4. Stocking Darners, a-b-c
5. Potato Mashers, a-b
6. Rolling Pins, a-b
7. Vise Handles, a
III. Oval Turning
1. Screw-driver Handles, a-b
2. Hammer Handles, a-b
IV. Duplicate Turning
1. Indian Clubs, a-b
2. Dumb-bells, a-b
3. Tenpins, a
4. Drawer Pulls, a-b
B. FACE-PLATE AND CHUCK TURNING
I. Exercises
1. Straight Cuts, a-b
2. Shoulder Cuts, a-b
3. Taper Cuts, a-b
4. V Cuts, a-b
5. Concave Cuts, a-b
6. Convex Cuts, a-b
7. Combination Cuts, a-b-c
II. Face-Plate Models
1. Match Boxes, a-b-c
2. Pin Trays, a-b
3. Hair Pin Receivers, a-b
4. Hat Pin Receivers, a-b
5. Ornamental Vases, a-b-c
6. Spinnet, (game) a
III. Chuck Models
1. Towel Rings, a-b-c
2. Card Trays, a-b-c-d
3. Picture Frames, a-b-c-d
4. Nut Bowels, a-b-c-d
5. Napkin Rings, a-b-c
6. Jewel Boxes, a-b-c-d-e-f-g-h
7. Collar Boxes, a-b-c
8. Spheres, a
9. Checker Men, a
IV. Assembling Exercises
1. Candle Sticks, a-b-c-d-e
2. Shaving Stands, a-a´-b-b´
3. Reading Lamp Stands, a-b-c
4. Pedestals, a
5. Smoking Stands, a-b
6. Pin Cushions and Spool Holder, a
7. Chess Men, a-a´
V. Spiral Turning
1. Pedestal, (Single) a-a´, (Double) b
2. Reading Lamps, (Single) a-a´-a´´ (Double) b-b´
3. Magazine Holder, a-a´
CHAPTER I
INTRODUCTORY
Wood turning has had a definite place in the commercial world for a
great many years. It is used in various forms in making furniture and
furniture parts, building trim, tool parts, toys, athletic paraphernalia
and many other useful and beautiful articles in common use.
When properly taught in the schools it is one of the most valuable types
of instruction. It appeals to pupils more than any other type of manual
work, as it embodies both the play and work elements. It is very
interesting and fascinating and, in the hands of a skilled instructor,
is readily correlated with other work.
Wood turning gives a pupil preliminary experience necessary in pattern
making and machine shop work. It brings into play the scientific element
by demonstrating the laws governing revolving bodies. In bringing the
chisel into contact with the revolving surface, the mathematical
principle of the "point of tangency" is illustrated. Excellent tool
technique is developed in wood turning as on the exactness of every
movement depends the success of the operator, and any slight variation
will spoil a piece of work. This brings in a very close correlation of
the mental and motor activities and also gives the student an
opportunity for observing and thinking while at work. When his tool
makes a "run" he must determine the reason and figure out why a certain
result is obtained when the chisel is held in a given position. Certain
cuts must be fully mastered, and it takes a good deal of experience and
absolute confidence in one's self in manipulating the tools before it is
possible to attempt skilful work. If scraping is allowed the educational
value of the work is lost.
In wood turning a vast field for design and modeling is opened, and art
and architecture can be correlated. The pupil will see for himself the
need of variety in curves and must use his judgment in determining
curves that are so harmonious and pleasing that they will blend
together. If properly taught the beauty in the orders of architecture
can be brought out in the making of the bead, fillet, scotia, cove, etc.
A feeling of importance is excited in a boy when he sees his hands
shaping materials into objects of pleasing form. Wood turning properly
taught awakens the aesthetic sense and creates a desire for the
beautiful. The boy or man who has learned to make graceful curves and
clean-cut fillets and beads will never be satisfied with clumsy effects
which are characteristic in cheap commercial work, made only to sell.
Success in turning depends on the following:
1. Care of lathe, tools, selection of materials.
2. Study of the scientific elements of--
a. Revolving bodies.
b. Points of tangency.
c. Study of results by reasoning and observing.
3. Development of technique and exactness.
4. Correlation of mental and motor activities.
CHAPTER II
THE LATHE
The sizes of turning lathes are given as 10", 12", etc. These figures
denote the diameter, or size, of the largest piece of work that can be
turned on them. The measurement is taken from the center point of the
live center to the bed of the lathe (usually 5" or 6") and is one-half
the diameter of the entire circle. The length of a lathe is determined
by the length of a piece of work that can be turned. This measurement is
taken from the points of the live and dead centers when the tail stock
is drawn back the full extent of the lathe bed. Fig. 1 shows a turning
lathe with sixteen principal parts named. The student should learn the
names of these parts and familiarize himself with the particular
function of each.
CARE OF THE LATHE
The lathe should be oiled every day before starting. At the end of the
period the lathe should be brushed clean of all chips and shavings,
after which it should be rubbed off with a piece of waste or cloth to
remove all surplus oil. All tools should be wiped clean and put in their
proper places. If a student finds that his lathe is not running as it
should, he should first call the attention of the instructor to that
fact before attempting to adjust it; and then only such adjustments
should be made as the instructor directs.
SPEED OF THE LATHE
The speed of the lathe should range from 2400 to 3000 revolutions per
minute when the belt is on the smallest step of the cone pulley. At this
speed stock up to 3" in diameter can be turned with safety. Stock from
3" to 6" in diameter should be turned on the second or third step, and
all stock over 6" on the last step. The speed at which a lathe should
run depends entirely upon the nature of the work to be done and the kind
of material used. Pieces that cannot be centered accurately and all
glued-up work with rough corners should be run slowly until all corners
are taken off and the stock runs true. At high speed the centrificial
force on such pieces is very great, causing the lathe to vibrate, and
there is a possibility of the piece being thrown from the lathe thus
endangering the worker as well as those around him. After the stock is
running true the speed may be increased.
[Illustration: Fig. 1. - Wood Turning Lathe]
TO FIGURE THE DIAMETER OF PULLEYS
Suppose a motor runs 1500 R.P.M. and is fitted with a 4" pulley. Suppose
also, a main shaft should run 300 R.P.M.
Then, 1500 : 300 :: x : 4;
Or, 300x = 6000,
x = 20, or the diameter of the large pulley on the main shaft.
Suppose again that a line shaft runs 300 R.P.M., and a counter shaft 600
R.P.M. The counter shaft has a pulley 4" in diameter. The pulley on the
line shaft must then have a diameter of 8".
300 : 600 :: 4 : x;
Or, 300x = 2400,
x = 8"
Suppose the cone pulley on the counter shaft runs 600 R.P.M.; a lathe
spindle runs 2200 R.P.M., when connected with the small cone pulley
which has a diameter of 3". The large cone pulley has then a diameter of
11".
600 : 2200 :: 3 : x
Or, 600x = 6600;
x = 11"
RULES FOR FINDING THE SPEEDS AND SIZES OF PULLEYS
1. To find the diameter of the driving pulley:
Multiply the diameter of the driven by the number of revolutions it
should make and divide the product by the number of revolutions of the
driver. (20 x 300 = 6000; 6000 ÷ 1500 = 4"--diameter of motor pulley.)
2. To find the diameter of the driven pulley:
Multiply the diameter of the driver by its number of revolutions and
divide the product by the number of revolutions of the driven. (4 x 1500
= 6000; 6000 ÷ 300 = 20"--diameter of the driven pulley.)
3. To find the number of revolutions of the driven pulley:
Multiply the diameter of the driver by its number of revolutions and
divide by the diameter of the driven. (4 x 1500 = 6000; 6000 ÷ 20 =
300--revolutions of driven pulley.)
POINTS ON SETTING UP LATHE AND SHAFTING
The counter shaft should be about 7' above the lathe. A distance of 6'
from the center of the shaft to the center of the spindle is sufficient.
In setting a lathe or hanging a counter shaft it is necessary that both
be level. The counter shaft must be parallel to the line shaft. When the
counter shaft is in position a plumb bob should be hung from the counter
shaft cone to the spindle cone; the lathe should be adjusted so that the
belt will track between the two cone pulleys. The axis of the lathe must
be parallel to that of the counter shaft. The lathe, however, need not
be directly beneath the counter shaft as the belt will run on an angle
as well as perpendicular.
CHAPTER III
WOOD TURNING TOOLS
A wood turning kit should consist of one each of the following tools.
Fig. 2 shows the general shape of these tools.
1-1/4" Gouge
3/4" Gouge
1/2" Gouge
1/4" Gouge
1-1/4" Skew
3/4" Skew
1/2" Skew
1/4" Skew
1/8" Parting Tool
1/2" Round Nose
1/4" Round Nose
1/2" Square Nose
1/4" Square Nose
1/2" Spear Point
1/2" Right Skew
1/2" Left Skew
Slip Stone with round edges
6" Outside Calipers
6" Inside Calipers
8" Dividers
12" Rule
1/2 pt. Oil Can
Bench Brush
GRINDING AND WHETTING TURNING TOOLS
Skew Chisel
The skew chisel is sharpened equally on both sides On this tool the
cutting edge should form an angle of about 20° with one of the edges.
The skew is used in cutting both to the right and to the left, and
therefore, must be beveled on both sides. The length of the bevel should
equal about twice the thickness of the chisel at the point where it is
sharpened. In grinding the bevel, the chisel must be held so that the
cutting edge will be parallel to the axis of the emery wheel. The wheel
should be about 6" in diameter as this will leave the bevel slightly
hollow ground. Cool the chisel in water occasionally when using a dry
emery. Otherwise the wheel will burn the chisel, taking out the temper;
the metal will be soft and the edge will not stand up. Care should be
exercised that the same bevel is kept so that it will be uniformly
hollow ground. The rough edge left by the emery wheel should be whetted
off with a slip stone by holding the chisel on the flat side of the
stone so that the toe and heel of the bevel are equally in contact with
it. Rub first on one side and then on the other. The wire edge is thus
worn off quickly as there is no metal to be worn away in the middle of
the bevels. The chisel is sharp when the edge, which may be tested by
drawing it over the thumb nail, is smooth and will take hold evenly
along its entire length. If any wire edge remains it should be whetted
again.
[Illustration: Fig. 2. - Lathe Tools]
Gouge
The gouge used in wood turning is beveled on the outside and is ground
so that the nose is approximately semi-circular in shape. The tool is a
combination of the round nose chisel and the ordinary gouge. The bevel
should extend well around to the ends so that the cutting edge extends
to each side. This is necessary to avoid the abrupt corners which would
be present if the nose were left straight across as in the ordinary
wood-working gouge. In making shearing cuts the round nose permits the
tool to be rolled to the side to avoid scraping the work. The length of
the bevel should be about twice the thickness of the blade at the point
where the sharpening begins.
The sharpening of a gouge for turning is rather difficult for the
average student. The ordinary gouge which has a square nose may be
beveled by merely turning it half way around and back again. In working
out the round nose of a gouge for wood turning, it is necessary that the
handle be swung from one side to the other while, at the same time, the
chisel is revolved to cut the bevel evenly. It is sometimes necessary to
allow some pupils to use the side of the emery wheel in sharpening the
gouge. This kind of grinding, however, does not leave the tool hollow
ground as when the face of the wheel is used.
To complete the sharpening the rough edge is worked smooth on a slip
stone, the cross section of which is wedge-shaped and the edges of which
are rounded. The toe and heel of the beveled side of the gouge are
brought into contact with the flat side of the stone. As the sharpening
proceeds the wire edge is worked to the inside of the gouge. The rounded
edge of the stone is then placed inside the gouge and is worked back and
forth until the rough edge disappears. Great care must be taken not to
bevel the inside of the gouge when whetting with the round edges of the
stone, as the result will be the same as with an ordinary chisel or
plane bit.
Parting Tool
The parting tool is sharpened on both sides. This tool differs from the
ordinary chisel in that it is between 5/8" and 3/4" thick and only about
1/8" wide at the widest point, which is in the center of its entire
length. The bevels must meet exactly at the center, or the widest
point, and should make an angle of about 50° with each other. If the
bevels do not meet at the widest point the tool will not clear, and the
sides will rub against the revolving stock; the tool will be burned and
will thus lose its temper. The bevel should be hollow ground slightly as
then comparatively little metal need be removed when whetting.
Scraping Tools
The round nose, square nose, spear point, right skew and left skew are
scraping tools, used chiefly in pattern work and sometimes in face-plate
work. They are sharpened on one side only, and the bevel is about twice
the thickness of the chisel at the point where sharpened. These tools
should be slightly hollow ground to facilitate the whetting. Scraping
tools become dull quite easily as their edges are in contact with the
wood almost at right angles. After sharpening, the edges of these tools
may be turned with a burnisher or the broad side of a skew chisel in the
same manner that the edge of a cabinet scraper is turned though not
nearly to so great a degree. This will help to keep the tool sharp for,
as the edge wears off, the tool sharpens itself to a certain extent. The
chisel is of harder material than a cabinet scraper so that it will not
stand a great amount of turning over on the edge. Small pieces will be
broken out, unless a flat surface is rubbed against the edge at a more
acute angle than was used in the whetting. If a narrow burnisher is
used, pieces are more likely to be broken out from the sharp edge and
thus make the tool useless.
CHAPTER IV
SPINDLE TURNING
Spindle turning is the term applied to all work done on a lathe in which
the stock to be worked upon is held firmly between the live and dead
centers. There are two methods in common use in wood turning: first, the
scraping or pattern-makers' method; and second, the cutting method. Each
has its advantages and disadvantages, but it is necessary that both be
learned in order to develop a well rounded turner. Care should be
exercised, however, that each method be used in its proper place. The
first is slower, harder on the cutting edge of tools, and less skill is
required to obtain accurate work; the second is faster, easier on the
cutting edge of tools, and the accuracy of results obtained depends upon
the skill acquired. As skill is the one thing most sought for in high
school work, the use of the cutting method is advocated entirely for all
spindle turning and, with but few exceptions, for face-plate and chuck
turning.
TO CENTER STOCK
If the wood to be turned is square or rectangular in shape the best way
to locate the center is to draw diagonals across the end of the stock.
The point of intersection locates the center.
CLAMPING STOCK IN THE LATHE
Take the live center from the spindle and with a wooden mallet drive the
spur deep into the wood. Never drive the wood onto the live center while
in the spindle because serious injury may be done the machine by such
practice. When extremely hard wood is being used, it is a good practice
to make saw cuts along the diagonal lines and bore a hole at the
intersection, thus allowing the spur to enter the wood more freely. Oil
the other end of the wood while holding it in a vertical position, and
give the oil a chance to penetrate into the wood. Then replace the live
center by taking the stock and center and forcing it into the spindle by
a sudden push of the hand. The tail stock is then moved about 1/2" to 1"
from the end of the piece to be turned, having the tail spindle well
back in the tail stock. The tail stock is then clamped to the lathe bed.
Turn the tail stock hand wheel until the wood is held firmly. Work the
cone pulley by hand at the same time, so that the cup or dead center
will be forced deeply into the wood, so deeply that the live center will
not continue to turn. Now turn the dead spindle back until the live
spindle begins to turn freely and clamp the dead spindle fast.
[Illustration: Fig. 3]
ADJUSTING THE TOOL REST
Horizontally the tool rest should be set about 1/8" from the farthest
projecting corner of the wood and should be readjusted occasionally as
the stock diminishes in size. The vertical height varies slightly
according to the height of the operator. It is even with the center of
the spindle for a short person; 1/8" above for a medium person; and 1/4"
above for a tall person. So long as the stock is in its square form the
tool rest should never be adjusted while the machine is in motion as
there is danger of the rest catching the corners and throwing the stock
from the machine. Also see that everything is clamped tight before
starting the lathe.
POSITION OF THE OPERATOR
The operator stands firmly on the floor back far enough from the lathe
to allow him to pass the tools from right to left in front of his body
without changing the position of the feet. It may be found convenient
to turn slightly, bringing the left side of the body a little closer to
the lathe. In no case, however, should the tools be brought in contact
with the body as the cutting operation from right to left should be
accomplished by a movement of the arms alone and not the swaying of the
body. (Fig. 3.)
HOLDING THE TOOLS
All tools should be held firmly but not rigidly. The right hand should
grasp the handle at the extreme end for two reasons: first, to give as
much leverage as possible so that the tool will not be thrown from the
hands in case it should catch in the wood; second, a slight wavering of
the hand will not cause as much variance in the cuts as when held closer
up to the rest. The left hand should act as a guide and should be held
over the tool near the cutting edge. The little finger and the back part
of the palm of the hand should touch the tool rest thus assuring a
steady movement. The left hand should not grasp the tool at any time.
(Fig. 3.)
USE OF THE TOOLS IN SPINDLE TURNING
The correct use of the various tools used in spindle turning will be
explained in detail as the steps are worked out in the sequence of
operations on the exercises in Section A-I.
CHAPTER V
TOOL PROCESSES IN SPINDLE TURNING
Exercise A-I--1-a. Straight Cuts
1. THE ROUGHING CUT (LARGE GOUGE).
FIG. 4. Place the gouge on the rest so that the level is above the wood
and the cutting edge is tangent to the circle or surface of the
cylinder. The handle should be held well down.
[Illustration: Fig. 4.]
Roll the gouge over slightly to the right so that it will make a
shearing cut instead of a scraping cut. This rolling of the tool will
also throw the chips from the operator.
Then lift the handle slowly, forcing the cutting edge deep enough into
the wood to remove all or nearly all of the corners, at the end of the
work which is being turned. This cut is begun about 3/4" from the dead
center end. Work back another 3/4", moving toward the live center and
make a second cut, and so on until the entire length of the cylinder is
gone over. This method of removing corners should always be followed to
avoid any possibility of breaking a large sliver from the stock, with
consequent danger to the worker.
The tool may then be worked from one end to the other, getting a
fairly-smooth, regular surface, slightly above the diameter required.
However, do not begin on the very edge of the cylinder end. It is better
to begin about 2" from one end and work to the other, and then reverse
and work back.
The tool should also be held at a slight angle to the axis of the
cylinder, with the cutting point always in advance of the handle.
[Illustration: Fig. 5.]
2. THE SIZING CUT (SMALL GOUGE). FIG. 5.
Set the calipers to the required diameter of the cylinder.
With a small gouge held in the right hand scrape grooves about 1" apart,
holding the calipers in the left hand perpendicular to the cylinder and
measuring the cuts as they are made. The scraping should continue until
the calipers will pass easily over the cylinder. It will be well while
scraping to work the handle of the gouge a little from side to side so
that the nose has more clearance. This will prevent the piece which is
being turned from chattering or vibrating.
The calipers will be slightly sprung by coming in contact with the
revolving stock but this error in diameter will be removed by the
finishing cut which removes these marks from the finished cylinder.
3. THE SMOOTHING CUT (LARGE SKEW).
FIG. 6. Lay the skew chisel on the rest with the cutting edge above the
cylinder and at an angle of about 60° to the surface.
Slowly draw the chisel back and at the same time raise the handle until
the chisel begins to cut about 1/4" to 3/8" from the heel. The first cut
is begun from 1" to 2" from either end and is pushed toward the near
end. Then begin at the first starting point and cut toward the other
end. One should never start at the end to make a cut as there is danger
that the chisel will catch and cause the wood to split or that the
chisel will be torn from the hands.
The first cut takes off the bumps and rings left by the gouge, and takes
the stock down so one can just see where the scraping to size was done.
Then take the last cut and remove all traces of these, leaving the
cylinder perfectly smooth and of the required diameter at each end. Test
the cylinder for accuracy with a straight edge.
[Illustration: Fig. 6.]
4. TESTING FOR SMOOTHNESS. In testing for smoothness place the palm of
the hand, with the fingers extended straight, lightly on the back of the
cylinder opposite the tool rest. This position will avoid any
possibility of the hand being drawn in between the cylinder and the
rest.
[Illustration: Fig. 7.]
5. MEASURING FOR LENGTH (RULE AND PENCIL). FIG. 7. Hold the back edge of
the rule in the left hand and place it on the tool rest so that the
front edge is almost in contact with the revolving cylinder.
With a sharp pencil mark off the required length, starting from the dead
center end. The first mark should be just far enough in on the cylinder
to insure cutting past the point of the dead center. This will leave all
surplus stock at the live center end where it is needed, because, if not
enough stock is left at this end, there is danger of striking the live
center spur with the tool and of injuring the chisel and perhaps the
work.
In case several measurements are to be made, as in some of the following
exercises, the rule should not be moved until all are marked. This will
insure more accurate work than if the rule be changed several times.
6. SQUARING ENDS (SMALL SKEW AND PARTING TOOL). FIG. 8. This operation
is done with the toe or acute angle of the 1/2" or 1/4" skew chisel.
Place the chisel square on the tool rest. Swing the handle out from the
cylinder so that the grind, which forms the cutting edge, next to the
stock is perpendicular to the axis of the cylinder. The heel of the
chisel is then tipped slightly from the cylinder in order to give
clearness. Raise the handle and push the toe of the chisel into the
stock about 1/8" outside the line indicating the end of the cylinder.
Swing the handle still farther from the cylinder and cut a half V. This
will give clearance for the chisel point and will prevent burning.
Continue this operation on both ends until the cylinder is cut to about
3/16" in diameter.
The remaining 1/8" is then removed by taking very thin cuts (about
1/32") holding the chisel as first stated. After each cut is made the
end should be tested for squareness by holding the edge of the chisel
over the end of the cylinder.
[Illustration: Fig. 8.]
This is an easy cut after it is mastered, but is one of the hardest to
learn. Should the operator lose control of the tool and allow any part
other than the point to touch the cylinder, a run or gashing of the
wood will be caused.
In large cylinders where considerable stock has to be cut away in order
to square the ends, time will be saved by sizing the ends down with the
parting tool to within 1/8" of the desired line, leaving enough stock at
the base of the cuts to still hold the cylinder rigid while cutting on
the ends.
[Illustration: Fig. 9.]
For this operation hold the parting tool on the rest with the cutting
edge parallel to the axis of the cylinder and the lower grind tangent to
the cylinder. Lift the handle and force the cutting edge into the wood;
at the same time push the chisel forward to keep it at the proper
tangency.
7. CUTTING OFF (SMALL SKEW). FIG. 9.
After both ends have been squared cut away stock, at both ends, to leave
just enough to hold the cylinder from separating from the waste ends.
With the chisel held in the right hand in the same position as in
squaring the ends, and the fingers of the left hand around the stock to
catch it, slowly force the point of the chisel into the stock at the
live center end, until it is cut free and the cylinder stops in the
operator's hand. Too much pressure should not be used in this operation
or it will cause the cylinder to twist off instead of being cut, and
will leave a ragged hole in the end.
The dead center end, which has been scored heavily before cutting off at
the live center, is then removed by holding the grind of the chisel flat
on the end of the cylinder. The latter is revolved by hand until the
stock is cut away.
Exercise A-I--2-a. Shoulder Cuts
1. Turn a cylinder to the largest diameter required.
2. Lay off measurements with rule and pencil.
3. With the gouge (where space permits) or the parting tool (in narrow
spaces) rough out surplus stock, keeping 1/16" away from the lines
indicating shoulders.
4. Caliper to the diameter of the second step.
5. The shoulders are cut down as described in "Squaring Ends, Step 6,
Straight Cuts."
6. The new diameter or step is then trued up with a skew chisel in the
same manner as a cylinder; except that in nearing the shoulder the
chisel is pushed up on the cylinder until the heel, which is the only
part that can be worked into the corner, becomes the cutting point. Fig.
10. In very narrow steps it will be advisable to use the heel entirely
as a cutting point.
In spaces between shoulders, too narrow to permit the use of the skew
chisel, very effective work can be accomplished by slightly tipping the
parting tool sideways to allow a shearing cut to be taken with the
cutting edge.
7. Where several steps are required on the same cylinder, each
successive one is worked out as above described.
Note:--All preliminary steps in working stock to size, laying of
dimensions, etc., in preparation for the exercise in hand, will be
omitted in the following exercises:
Exercise A-I--3-a. Taper Cuts
[Illustration: Fig. 10.]
Calipering for New Diameters. For all diameters on tapers the calipers
should be set 1/16" larger than the desired measurement in order to
avoid working under size in the finishing cut which removes all caliper
marks.
If the taper runs to the extreme end of the cylinder, as in Plate
A-I--3-a, a parting tool should be used, instead of a gouge, to take off
a very thin shoulder.
If the taper forms an internal angle as in Plate A-I--3-b, a gouge is
used as in Step 2--Sizing Cut--Plate A-I--1-a.
In other cases where tapers connect with straight cylindrical shoulders
it is best to turn the shoulders to size before working the tapers.
In cutting a long straight taper the skew chisel is used, much in the
same manner as in ordinary cylinder work, except that at the start of
each cut the heel must be the cutting point. This will avoid any chance
of the chisel catching and drawing back and thus gouging the wood beyond
the starting point. As soon as the cut is well under way the chisel may
be pushed up on the cylinder so that the cutting point is a little above
the heel. All cuts should be made from the highest point on the cylinder
to the lowest and thus cut across the grain of the wood.
In making the cut, care should be taken to see that the chisel is not
tipped to a greater angle than that of the taper wanted. Should that be
done a hollow, or dished out, taper is sure to be the result instead of
a straight one.
Exercise A-I--4-a. V Cutting
In cutting V's a small skew is almost always used and the cutting is
done with the heel.
Place the chisel square on the tool rest so that the cutting edge is
perpendicular to the axis of the cylinder. Draw the chisel back and
raise the handle so that the heel is driven into the wood, thus scoring
it. This cut should not be too deep or the chisel will burn. This
scoring should be at the exact center of the V cut.
Swing the handle a little to the right and at the same time tip the
chisel so that the grind, which forms the cutting edge, is at an angle
of about 45° with the axis of the cylinder. The handle is then raised at
an angle of 45° bringing the heel down to make a good cut. The chisel is
then swung to the other side and a similar cut is taken. These cuts are
continued, together with the center scoring, until quite close to the
pencil marks. Test the angle before the finishing cut is taken.
It will be found best to have the V slightly greater than 90° at the
base until the final cut is made, at which time it can be trued up.
The V should be tested with the square end of a rule. The cylinder
should not be in motion while testing.
When angles other than 45° are cut, the cutting edge of the chisel
should be tipped so that it is parallel or nearly so to the side of the
cut desired.
A-I--5-a. Concave Cuts
The concave cuts as a rule will give the pupil considerable trouble at
first owing to the fact that the grind, which forms the cutting edge and
which must be held perpendicular to the cylinder at the start, is on the
under side of the tool and cannot be seen. However, as soon as the
correct angle of the tool is located, the cut will be found as easy as
any. Concaves are usually made with a medium sized gouge either the 1/2"
or 3/4".
Place the gouge on the rest with the grind or cutting edge well above
the wood. The tool is then rolled on its side so that the grind at the
cutting point, which is on the lip of the gouge well below the center,
is perpendicular to the axis of the cylinder. Fig. 11.
Slowly raise the handle to force the gouge into the wood. As soon as the
gouge has taken hold, the tool is forced forward and upward by a slight
lowering of the handle, while at the same time it is rolled back toward
its first position. Care should be taken not to roll the chisel too fast
or a perfect arc will not be cut.
[Illustration: Fig. 11.]
By this triple action the grind, which comes in contact with the surface
of the curve, forces the lip sidewise and cuts one quarter of a circle.
Reverse the position of the gouge and cut from the other side in the
same manner to form the other half of the semi-circle. The cutting
should always stop at the base of the cut as there is danger that the
tool will catch when cutting against the grain of the wood on the other
side. Repeat this operation until within about 1/16" of the required
size. At the end of each successive cut the tool should have been forced
far enough forward and upward to bring the grind or nose of the chisel
well out on top of the cut. Fig. 12.
The exact depth of the concave is then calipered in the usual manner as
described before. A finishing cut is then taken after the cut has been
tested with a templet.
[Illustration: Fig. 12.]
A-I--6-a. Convex Cuts
The convex cut, or Bead as it is usually called, is generally considered
the hardest cut to make.--The cut is made with the heel of a small skew
chisel, usually the 1/4" or 1/8".
After the cylinder has been marked off, rough out all stock between the
beads with a parting tool. The base of the cuts is finished the same as
described in Plate A-I--1-a, for shoulder cutting. With a sharp pencil
mark the center of each bead to be made. This line is the starting point
for all cutting.
Place the chisel on the rest, with the cutting edge above the cylinder
and the lower grind tangent to it. Draw the chisel back and raise the
handle to bring the heel of the chisel in contact with the cylinder at
the line indicating the center of the bead. The chisel is then moved to
the right (if cutting the right side of the bead); at the same time the
chisel is continually tipped to keep the lower grind tangent to the
revolving cylinder and also to the bead at the point of contact. Fig.
13. This cut is continued until the bottom of the bead is reached. It is
well in turning a series of beads to work the same side of all before
reversing to the other side.
Note:--The same principles employed in this exercise are also used in
working out long convex curves such as are found in chisel handles,
mallet handles, etc. The only exception is that in most cases the point
of contact need not be the heel of the chisel but higher up as in
ordinary straight work.
A-I--7-a--Combination Cuts
These exercises are so designed as to include one or more of each of the
foregoing cuts. The student here is given an opportunity of combining
these cuts into one finished product.
[Illustration: Fig. 13.]
An analysis of the exercise chosen should be made to determine which of
the various cuts should be made first, second, etc., in order to produce
the exercise in the shortest time and with the least amount of tool
manipulation.
After the student has mastered these cuts with a certain degree of skill
and accuracy, he is ready to apply them in working out various models in
Section II.
A-II--1-a. Chisel Handles
At this point it is well to state that the small end of all work should
be turned at the dead center. In the case of chisel handles the socket
or ferrule end is at the dead center where the stock can safely be cut
away to permit the fitting of the ferrule or the socket.
After the stock is turned to a cylinder of the largest dimension
desired, the taper, for the socket chisel, should be turned first and
fitted to the chisel in which it is to be used. Then the rest of the
handle is worked out. Ferrules should also be fitted in the same manner.
A drive fit should be used for all ferrules.
A-II--2 and 3. Mallets and Gavels
The biggest source of trouble in these models is getting the handles to
fit true. This is caused by not getting the hole in the head straight.
Turn the head to a cylinder 3/16" larger than the finished dimension.
Then bore the hole perpendicular to the axis as near as possible,
either by leaving it between the lathe centers or by placing it in a
vise. The handle is then fitted into the head. A snug fit is necessary.
If one side "hangs" or is lower than the other the centers are moved
sufficiently to correct it. The head is then turned to exact size and
finished.
A-II--7. Vise Handles.
Turn the spindle with the solid head to dimensions. Bore a hole through
a 1-1/4" square block and fit the block snugly to the end of the
spindle. Turn this block to the same dimensions as the other head. This
method will save chucking the second head and is much quicker.
CHAPTER VI
OVAL TURNING
Oval work as a problem in turning will be found to be a very good one as
well as interesting to the pupil. It brings in the principle of the oval
as used in ordinary shop practice; (arcs from points on the major and
minor axes). For thick heavy ovals the off-centering is very slight,
while for long, thin ones the off-centering is greater. The measurements
given on Plates A-III--1-a, b and A-III--2-a, b will give a good idea of
approximate distances to be used.
While the tool operations are much the same as in other spindle turning
there is one notable difference. The design must be worked out by eye,
because of the nature of the work no caliper measurements can be made
for depth of cuts.
To get the best results the stock of oval turning should be cut square
or slightly rectangular in cross-section and about 3" longer than the
model to be made. The thickness of the stock should be about 1/8"
greater than the major axis of the oval wanted.
The centers are located in the usual manner after which perpendicular
lines are drawn from the sides, passing through the points of the
centers. From the ends of one of these, perpendicular lines are extended
lengthwise of the stock (on opposite sides) meeting the corresponding
perpendicular at the other end of the stock. These lines form the ridge
of the oval. On the other perpendiculars, the points for off-centering
are laid off, measuring the required distance on both sides of the
center point.
With a 1/8" drill bore holes 1/4" deep at each of the off-centering
points as well as the original center. This will insure the lathe
centers penetrating the stock at the proper point. The stock is then
placed in the lathe, using two corresponding off-center points as
centers.
With the lathe running at third speed turn down the stock to the
horizontal line forming the ridge of the oval, excepting for a distance
of about 1-1/4" at the ends. The stock at the ends is necessary for the
off-centering and, if cut away, will spoil the centering for the other
side, especially at the live center end. The stock is then changed to
the other off-center points and the second side is cut down to the line.
All measurements are then laid out and the design is cut, changing the
stock in the lathe when necessary. Care should be taken that the sharp
ridge left on the work forms a straight line the full length of the
stock. After the design has been finished, the stock is centered on the
true center and a very thin cut is taken the full length of the object
to remove the sharp corners. The model is then sandpapered while the
lathe is running very slowly.
CHAPTER VII
DUPLICATE TURNING
Under the head of duplicate turning have been classified only such
models as clearly indicate the necessity of making two or more articles
to complete the model or set of articles desired. But it is not intended
to convey the idea that other models may not be made in duplicate as in
many cases it is very desirable and even preferable that they should be
made that way. Whatever the problem may be the suggestions offered at
this point may be applied effectively.
Whenever two or more models are to be made identically alike there are
always two possibilities of inaccuracies that will render the work
dissimilar: First, inaccurate measuring both for length and points of
new diameters and also on the new diameters themselves; second, a
variation in the curved surfaces either on long convex or concave cuts.
The first difficulty can be overcome to a great extent by the use of a
measuring stick. This stick should be made of any soft wood. It should
be straight on one edge and about the thickness of an ordinary rule. On
the straight edge lay off very carefully measurements for length,
shoulders, beads, concaves and all points where calipering for new
diameters will be necessary. Insert at each point measured a small brad
which has been sharpened at both ends, leaving the end protrude about
1/8". Care should be taken that all brads protrude the same distance.
After the stock has been turned to the largest diameter, the stick is
held in the position of the rule while measuring and the points are
forced against the revolving cylinder, thus scoring it. This stick can
be used as many times as the model is to be made and the measurements
will always be the same.
To avoid dissimilar curves it is well to cut out a full sized templet of
the model to be made. This templet can be made of any thin, stiff
material, preferably light sheet iron. In some cases it will be
necessary to make the templet in several pieces in order to help
facilitate the tool operations.
The use of this templet will not only be a help to getting all curved
surfaces the same, but will also check up on the various new diameters
on the model. The cylinder should never be in motion while the templet
is being used.
CHAPTER VIII
FINISHING AND POLISHING
To get a high and lasting polish on wood, the work must be first sanded
so as to be perfectly smooth. In addition to this, open grained wood,
such as oak, must be properly filled with a wood filler. If properly
sharpened tools have been used very little sanding is required, and then
worn sandpaper should be used as it does not cut into the work as new
paper cuts. Remember sandpaper is not to be used as a tool in cutting
down stock when working to dimensions. In using old sandpaper run the
lathe at a moderate speed to avoid burning the wood, especially on
square or round fillets. Keep the edges of the work sharp and do not
wear them round. In using new sandpaper use a fine grit (00 or 0) and
move the paper from one end of the work to the other slowly, so that no
scratches result on the surface of the work.
The work may be finished by one of two methods. In the first method as
in finishing ordinary cabinet work, the pieces should be stained and
filled. In applying filler, run the lathe at the slowest speed after the
material has dried sufficiently to rub into the pores of the wood. If
the highlights are to be brought out, as in the case of oak, stain and
then give a light coat of shellac, and apply the filler after the
shellac is dry. The shellac keeps the dark filler from staining the
flakes of the oak darker, and the pores of the wood fill in as before.
The pores become darker than the flakes, and at the same time a smooth
surface is produced. After the filler has hardened the wood may be waxed
or varnished.
The second method, or French polishing, is rather difficult to apply and
requires a little skill. A close grained wood, like maple, will be found
more satisfactory for the beginner. An open grained wood may be filled
in the ordinary way, or the grain may be filled by rubbing into the
pores of the wood a combination of shellac, rotten stone or pumice, oil
and alcohol. Rotten stone is used for dark wood and pumice is used for
light wood. The wood may be left in the natural or stained as in the
first method. The mixture of shellac, rotten stone, oil and alcohol, is
applied to the work with a pad made of cotton waste, wrapped in cheese
cloth to keep it from sticking to the work. It should be about 1-1/2" in
diameter and 1/2" thick. Hold the pad over the mouth of a bottle of
shellac and tip the bottle so that the shellac comes in contact with the
pad. The shellac will remain clean in a bottle and will be handy. The
mouth of the shellac bottle should be about 1" in diameter and should be
dipped once. Do likewise with a bottle, having a mouth 1/2" in diameter,
containing alcohol. This should be dipped twice allowing the alcohol to
dilute the shellac. Then drop on a couple of drops of oil and rub over
the pad evenly; this aids in distributing the shellac properly and keeps
the pad from sticking to the work. A bottle may also be used for this.
For the rotten stone use a pepper shaker so that it may be sifted on the
work as needed.
When the mixture has been applied to the pad, hold the pad against the
work lightly at first, until most of the moisture has been worked out of
it, and then gradually increase the pressure until the pad is almost
dry. In putting on the first coat, use more shellac and alcohol and just
enough oil at all times to prevent the pad from sticking to the work.
However, the pad should not contain as much shellac that it can be
squeezed out with the fingers. When the pad is dry, another mixture is
applied, and where open grained wood is used, rotten stone, or pumice
stone, is sprinkled on the work to gradually fill up the pores and to
build up a smooth surface. Run the lathe at a low speed, depending on
the size of the piece that is being polished. Allow the first coat to
dry before applying a second coat for, if too much is put on at any one
time, the heat generated in the rubbing will cause the shellac to pull,
and it will form rings by piling up. These rings may be worked out in
two ways, either by a slight pressure of the pad on the rings or by
cutting them with alcohol applied to the pad. If too much alcohol is
used it will cut through the shellac and remove what has already been
rubbed on. If at any time too much shellac is used it will pile up and
form rings. Too much rotten stone will cut down the polish and by
absorbing the mixture will leave the pad dry. If too much oil is used
the polish will become dull after a day or two.
After the first coat has hardened apply the second, but use less shellac
and more alcohol and just enough oil to prevent the pad from sticking.
This may be done by dipping the tip of a finger in the oil and spreading
it over the pad. The entire mixture should be so that only a dampness
can be felt on the pad. As the process goes on less oil and shellac are
used. All oil must be removed when applying the last coat, or the piece
will lose its polish. All the pores should be filled, and no rings
should be on the finished work. Where a natural finish is desired, apply
a coat of boiled linseed oil twelve hours before the work is to be
polished. This will bring out the grain and will also aid in applying
the first coat; no oil need then be used in the first coat.
A great amount of practice and patience is required to get a first class
polish. Polishing can only be learned by experience. Correct your
troubles in properly proportioning the mixture. Never use too much
shellac as it will build up too fast and will not harden, thus causing
rings; or it will pull and catch to the pad, thus forming bunches. The
purpose of alcohol is mainly to dilute the shellac and to prevent
against putting it on the work too fast, but care must be taken not to
use too much alcohol to cut the shellac entirely. The oil helps to
distribute the shellac evenly, but it must be removed when finishing the
last coat, or the polish will not remain. It also helps to keep the pad
from sticking to the work.
It is impossible to obtain a polish that will be as lasting and rich by
any method other than the one described. For success it is essential to
learn the proportions of the mixture and to acquire skill in applying
the materials by using exactly the right pressure and the right movement
of the pad.
CHAPTER IX
FACE-PLATE AND CHUCK TURNING
Face-plate and chuck turning open an entirely new field of work from
that taken up in previous chapters of this book. If handled correctly,
it has much greater educational and practical value than cylinder
turning. From the practical standpoint the field of work is broader and
the models to be made are of much greater value. Aside from this, trade
methods and practices can be applied and a broad insight into commercial
work can be given the student.
In some details of chuck turning the tool operations already learned can
be employed, but for the most part they are entirely different. In order
to preserve the educational value of the work as brought out by skill
and dexterity in handling tools, it will be necessary to use the cutting
method wherever possible. In some instances that method will be
impossible, and the scraping method must be used.
METHODS OF FASTENING STOCK
All the work thus far has been on models where the stock worked upon is
held between the live and dead centers. In face-plate and chuck turning
the work is done at the head stock only and the piece is supported by
means of a face-plate, or chuck, that is fastened to a face-plate, which
is screwed onto the end of the live spindle. There are three methods of
fastening stock to the face-plate, and it depends upon the nature of the
exercise or model to be made which method is used.
1. SMALL SINGLE SCREW FACE-PLATE. For all work that does not require
deep cutting in the center, such as in towel rings, picture frames,
etc., the small face-plate with a single screw should be used.
Note:--Should it be found difficult to keep the block from working loose
and turning, it is a good plan to fold a piece of sandpaper, grit side
out, and place it between the face-plate and the stock.
2. LARGE SURFACE SCREW FACE-PLATE. For all work that does not require
deep cutting on the outside, such as exercises, jewel boxes, etc., as
well as all large stock, and all stock from which chucks are to be
made, the large face-plate with the surface screws should be used.
3. GLUING TO WASTE STOCK. A block of scrap wood is fastened to a
face-plate the same as for a chuck and surfaced off square. The block
from which the model is to be made is planed square on one side and
glued to the block on the face-plate with a sheet of paper between the
two. To separate the model from the chuck, after it is completed, place
a chisel on the waste stock, 1/16" back of the glue joint at such a
point as will bring the chisel parallel to the grain of the model, and
strike lightly with a mallet. This will cause the paper to separate and
the model to become free.
This method will be found very convenient epecially on models where the
base is to be left straight. It will also be found to save much stock
when working with expensive woods.
LATHE ADJUSTMENTS
To get the best results in face-plate or chuck turning there should be
no end play in the spindle of the lathe. The spindle should always be
tested out, and if any play is found, should be adjusted before
attempting any work. It is almost impossible to make a true cut when
such a condition obtains.
POSITION OF TOOL REST
For all face-plate and chuck turning the tool rest should be kept as
close to the stock as possible, the same as in spindle turning,
regardless of the angle it may be set. Vertically, the rest in most
cases should be sufficiently below the center of the stock to bring the
center or cutting point of the tools used, when held parallel to the bed
of the lathe, even with the center of the stock. This last condition
will necessitate adjusting the height occasionally when changing from
large to small tools.
CHAPTER X
TOOL PROCESSES IN FACE-PLATE AND CHUCK TURNING
B-I--1-a. Straight Cuts
1. ROUGHING OFF CORNERS. (3/4" GOUGE.) FIG. 14. The tool rest is set
crosswise to the bed of the lathe and parallel to the face of the stock.
Place the gouge on the rest with the handle well down. Roll the gouge to
the left until the grind which forms the cutting edge is perpendicular
to the stock. The point of contact should be slightly below the center
or nose of the tool.
The handle of the gouge is then swung well to the back of the lathe or
to the operator's right. The gouge is then pushed forward into the stock
and to the left, making a shearing cut. The cut should not be too heavy.
The starting point for this cut should be a line which will indicate the
largest diameter or circle that can be made from the block.--This cut
should be repeated until the corners are removed from the block.
To complete the cutting of thick stock it will be found necessary to
change the tool rest to an angle of 45° with the bed of the lathe.
[Illustration: Fig. 14.]
When hardwood is being turned it is sometimes advisable to saw the block
almost round with a compass saw or bandsaw, if one is to be had. Should
this be done the preceding steps are omitted.
The tool rest is then placed parallel with the lathe bed and a roughing
cut is taken with the gouge the entire thickness of the block.
The lathe should be run on second or third speed until the corners are
removed, and then changed to first speed.
2. CALIPERING FOR DIAMETER. The true diameter is then calipered the same
as in spindle work.
3. SMOOTHING CUT. A smoothing cut is taken with a skew chisel the same
as in spindle work.
[Illustration: Fig. 15.]
4. ROUGHING CUT ON THE FACE. (3/4" GOUGE.) FIG. 15. The rest is now
placed parallel to the bed of the lathe and slightly above the center of
the spindle. Place the gouge on the rest on its edge with the grind
toward the stock and parallel to the face to be surfaced. The nose of
the gouge is the cutting point.
The handle is then raised and the cutting point is forced toward the
center. A very thin shaving should be taken. If the gouge is allowed to
roll back so the grind above the cutting point comes in contact with the
wood it is sure to catch and gash the wood.
5. SMOOTHING THE FACE. (SMALL SKEW CHISEL.) FIG. 16. For all work up to
3" in diameter, the surface may be smoothed by using a small skew chisel
in the same manner as in squaring the ends of Stock in cylinder work.
(Step 6--Exercise A-I--1-a, Straight Cuts.)
For larger work, place the chisel flat on the rest with the toe next to
the stock and the back edge of the chisel parallel to the face to be
surfaced.
The point of the chisel is then forced toward the center of the stock,
using the straight back of the tool as a guide against the finished
surface. Only a very thin cut should be taken at a time.
[Illustration: Fig. 16.]
Note:--While this operation may be termed a scraping cut, it will be
found to be much easier on the tool than if the cutting edge were held
flat against the work as in other scraping cuts.
The surface of the work should be tested for squareness by holding the
edge of the chisel or a straight edge across the face.
LAYING OFF MEASUREMENTS
In laying off measurements on the face of the stock a pencil compass or
dividers should be used. Set the compass or dividers to one-half the
diameter of the circle wanted. While one point is held at the exact
center of the stock, which is easily located while the stock is
revolving, the other is brought in contact with the revolving stock
until a circle of the correct diameter is marked.
[Illustration: Fig. 17.]
Should the center of the stock be cut away, rendering this method
impossible, the following method may be used: Set the compass or
dividers to the exact diameter wanted. Place one point in contact with
the stock a little to one side of the required line on the part that is
to be cut-away. Bring the other point to the stock and see if it touches
the line first made. If not, move the first point until the two points
track in the same line.
[Illustration: Fig. 18.]
The rest should be set at the exact center for measuring.
All measurements on the edge of the stock can be made with pencil and
rule as in cylinder turning.
B-I--2-a. Shoulder Cuts
1. EXTERNAL SHOULDERS. FIG. 18. The surplus stock at each successive
shoulder is roughed out with a 3/4" gouge, keeping well outside the
finished measurements. The gouge for this work is held in the same
position as described in B-I--1-a, Step 1, for Roughing Off Corners.
[Illustration: Fig. 19.]
2. For the finishing cut a small skew chisel is used, and the process
is the same as that used in squaring ends of stock. Both the vertical
and horizontal shoulders can be handled easily by this method. Fig, 19.
3. INTERNAL SHOULDERS. For internal shoulder cutting the same methods
may be used for roughing out and cutting the horizontal shoulders, but
for the vertical or base shoulder it will be necessary to use the
scraping process. (See "Use of Scraping Tools.")
B-I--3-a. Taper Cuts
Taper cutting will not be found hard as the gouge and skew chisel are
used in the same manner as described in B-I--1-a, Steps 4 and 5. After
the stock has been roughed away with the gouge to the approximate angle
desired, a smoothing cut is taken with the skew. Care should be taken
that the skew chisel is held at the exact angle of the taper desired.
B-I--4-a. V Cuts
V cutting will also be found easy as the tool process is exactly the
same as that used in spindle turning. Exercise A-I--4-a. Fig. 20.
B-I--5-a. Concave Cuts
Place the 3/4" gouge on the rest with the handle parallel to the bed of
the lathe. Roll the gouge on its edge and swing the handle so that the
grind is perpendicular to the stock with the nose of the tool as the
cutting point.
[Illustration: Fig. 20.]
Force the gouge forward into the wood. As soon as the cut is started,
the handle is lowered and swung to the left; (if cutting the left side
of the concave) at the same time the tool is rolled back toward its
original position. This movement brings the cutting point farther down
on the lip and the grind, resting on the side of the cut, will force the
gouge sidewise and will form one-quarter of the circle. Fig. 21.
[Illustration: Fig. 21.]
This cut is continued from alternate side until the concave is nearly to
size. The cut should be tested with a templet before the finishing cut
is taken.
B-I--6-a. Convex Cuts
Rough out the stock between the beads with a parting tool.
Hold the edge of the gouge on the rest with the handle, parallel to the
bed of the lathe, to make the nose the cutting point.
Swing the handle to the left so that the grind will form a tangent to
the bead at its highest point.
The gouge is then forced into the stock and to the right; at the same
time the handle is swung to the right; keeping the grind tangent to the
bead at the point of contact. Fig. 22. This cut is continued until the
base of the bead is reached.
B-I--7-a. Combination Cuts
As in spindle turning, a combination exercise should be given at this
point to provide an opportunity for studying out the best methods of
working the various cuts just described into a finished product.
USE OF SCRAPING TOOLS
When scraping is to be employed, it should be done with only those tools
that are made for that purpose, i.e., Square Nose, Round Nose, Spear
Point, Right and Left Skew. The handling of these tools will be found
easy. The only point to remember is that they should be held flat on the
tool rest and parallel to the bed of the lathe when in use.
In general practice the ordinary skew chisel should not be used as a
scraping tool, for the cutting edge is not sharpened to withstand the
heavy strain required by such work. Should it be necessary, however, to
use a skew chisel as a scraper, the tool should be held so that the top
grind is parallel to the bed of the lathe while in use.
INTERNAL BORING
In roughing out the center for Napkin Rings, Jewel Boxes, etc., the
quickest method is to work it out with a small gouge.
Place the gouge on the rest parallel to the bed of the lathe, having the
point even with the center of the stock.
Force the gouge into the wood until a hole is bored to the depth
required. If the hole is deeper than 1", remove the tool often and clear
out the shavings in order not to burn the point.
In order to enlarge the hole to the proper size the point of the gouge
is pressed against the left side of the hole a little above the center
and a shearing cut is taken. To obviate the danger of the tool catching,
all cuts should start from the back of the hole and proceed toward the
front.
[Illustration: Fig. 22.]
B-III--8-a. Sphere
After the sphere is turned as nearly perfect as is possible when working
between centers (Steps 1 to 4) it is cut free from the waste stock and
is centered in a chuck.
The chuck is made of any soft wood and should be cut in the end grain,
which will insure equal pressure on all sides. Equal pressure cannot be
obtained if the Chuck is cut in cross grain wood, owing to the tendency
of side grain to give more than the end grain. The sphere should be
forced into the chuck with slightly over half protruding. Very thin cuts
should be taken and the sphere should be revolved one-quarter turn after
each until true. As the sphere becomes smaller during the cutting, it
will be necessary to cut the face of the chuck down and bore the hole
deeper and smaller in order to keep more than half of it protruding at
all times.
[Illustration: Mirror (See Pages 299-301).]
To remove the sphere tap the chuck lightly with a hammer just above it,
at the same time pull out on the sphere.
CHAPTER XI
SPIRAL TURNING
Spiral turning is a subject that has received very little attention by
most schools in which wood turning is taught. Spiral work is seen in
antique furniture and also in the modern furniture of the present day.
It seems that it takes the wheel of fashion about a century to make a
complete turn, for what our forefathers neglected and destroyed the
people of the present day value and cherish.
Spiral work gives excellent practice in shaping and modelling wood. It
brings into play the principle of the helix as used in cutting threads,
etc.; and its form, size and shape may be varied according to the taste
of the individual. As in threads so in spiral work we have single and
double spirals, and their form and proportion depend upon their use and
application in furniture making. A variation of the spiral may be made
in several ways: First, by changing the number of turns of the spiral on
a straight shaft; second, by running a spiral on a tapered shaft; third,
by changing the shape or form of the spiral itself; and fourth, by
making more than one spiral on a shaft. It is uncommon to see ten or
twelve spirals running around a single shaft.
Some of the forms of the above types are fully taken up and explained in
the work that is to follow.
PLATES B-V--1-a, a´. SINGLE SPIRAL. STRAIGHT SHAFT
To work out a single spiral for a pedestal proceed as follows:
1. Turn a cylinder 2-1/4" in diameter. Make the ends slightly larger in
order that the design may be turned on each, after the spiral has been
worked out.
2. Lay off spaces 2-1/16" apart on the cylinder while the spindle is
turning in the lathe and divide each of these into four equal parts.
Each one of these large spaces represents one turn of the spiral. A good
proportion is slightly less than the diameter of the cylinder; thus the
diameter of the cylinder equals 2-1/4" and the width of the space
2-1/16".
3. On the cylinder parallel to the axis draw lines A-A B-B C-C D-D.
These lines should be 90° apart as shown in the top diagram (Plate
B-V--1-a´). Line D-D is on the other side of the cylinder as shown in
the top and middle diagrams.
[Illustration: Fig. 23.]
4. Start on line A-A at point X, circle 1, and draw a line connecting it
with line B-B on circle 1´. Then connect B-B on circle 1´ with C-C on
circle 2 and so on until a spiral has been drawn the entire length of
the cylinder. This line will form the ridge of the spiral as shown in
the middle diagram.
5. Next begin on line C-C at circle 1, and draw a line connecting it
with D-D on circle 1´ then to line A-A on circle 2, and so on as before.
This spiral represents the center of the groove or the portion which is
to be cut away. This is not shown in the diagram because more or less
confusion would be caused with the line representing the ridge of the
spiral.
6. Begin on line C-C at circle 1, and saw to a depth of 3/4". Saw the
entire length of the cylinder leaving about 1-1/2" at the ends. Do not
follow the line here, but switch off gradually and follow circles 1 and
15, so as to allow the spiral to begin and end gradually and not
abruptly.
7. Rough out with a knife or chisel by cutting on both sides of the saw
cut. Then use a wood rasp to finish shaping out the spiral. When
properly shaped out allow the lathe to turn slowly and smooth with
sandpaper by following the spiral as the lathe turns.
[Illustration: Fig. 24.]
[Illustration: Fig. 24-a.]
[Illustration: Fig. 25.]
8. Cut the design on both ends of the cylinder and polish.
PLATES B-V--2-a, a´, a´´. SINGLE SPIRAL. TAPERED SHAFT
To lay off a single spiral for the electric lamp shown in Figs. 24 and
24a proceed as follows:
1. Select your wood and bore a hole through it. Plug the hole and center
the piece in the lathe. This insures getting the hole exactly in the
center, and it will not be cut into while the cutting of the groove of
the spiral proceeds. A groove may also be cut in two pieces of stock and
glued together to form a hole through the stock.
2. Turn a cylinder 2-1/2" in diameter, tapering it to 1-1/2" at the one
end; this part should be 12-1/8" long. Both ends should be left larger
than 2-1/2" as the lower and upper designs must be cut here.
3. Let the spindle revolve in the lathe and draw circles as shown in the
layout (Plate B-V--2-a´). The number of circles will vary with the
taper. Since seven turns are needed in the present spiral, 28 circles
will be necessary--four circles for each turn of the spiral as shown in
the middle diagram. A good proportion to follow is to measure the
diameter of the spindle at circle 2 and lay off this distance from
circle 1 to circle 3. Then measure the diameter at circle 4 and lay off
this diameter from circle 3 to circle 5 and so on until all circles have
been made. Then divide these large divisions into four equal parts.
4. Draw four lines the entire length of the spindle, each 90° apart as
shown by the heavy lines in the middle diagram. The heavy circles of the
same diagram represent the complete turns of the spiral.
5. Lay out the line representing the ridge of the spiral as shown in the
middle diagram. Begin on circle 1, where the straight line crosses it,
draw to circle 1´ at the point where the next straight line crosses it,
then to 2--2´--3--3´ and so on until the end is reached. This forms the
ridge of the spiral as shown in diagram 3. Next it may be more
convenient to draw another line representing the groove. In this case
begin at point X in the middle diagram, opposite the point where first
started, and continue in the preceding manner, making this line parallel
to the other line.
6. Saw on the line last made, being careful not to saw too deeply. The
depth must be 1/4" less than half the diameter of the spindle where the
cut is made. This saw cut forms the groove of the spiral. The groove is
then cut out by hand with a chisel or knife, by working down the wood on
both sides of the saw cut. After the spirals have been roughed out, a
rasp is used to finish shaping them. The work is then sandpapered
smooth, while the spindle is revolved slowly in the lathe.
7. Cut designs on the ends of the cylinder and polish.
PLATES B-V--2-b, b´. DOUBLE SPIRAL. TAPERED SHAFT
To work out a double spiral for the electric lamp illustrated in Fig. 25
proceed as follows:
1. Turn up the spindle in the usual manner. Since the base of the shaft
is larger than the top, the spiral must also be in proportion and lines
A-A´, B-B´, C-C´, D-D´, and E-E´, are drawn around the shaft. To get the
approximate spacing from circles A-A to B-B measure the diameter at A-A´
plus about 3/16" and lay off from A-A´ to B-B´. Then take the diameter
of B-B´ plus about 3/16" and lay off from A-A´ to B-B´. Then take the
diameter at B-B´ plus about 3/16" and lay off from circle B-B´ to C-C´
and so on. If the shaft is tapered more, a different proportion must be
used. Also if it is desired to have the twist wind around the shaft
three times, a variation must be made in the number of circles.
[Illustration: Fig. 27.]
2. If it is desired to have the twist wind around the shaft twice, draw
circles 1-1´, 2-2´, 3-3´, and 4-4´ and the spaces will grow
proportionately smaller at the small end.
3. Draw four lines running lengthwise on the spindle and 90° apart as
shown in the midde figure in heavy lines (Plate B-V--2-b´).
4. Begin at A and draw a curved line to where the 90° line crosses
circle 1-1´. From there extend the line to where the next 90° line
crosses circle B-B´ at point B´. Continue in this manner until the other
end of the shaft is reached. Begin at A´ and draw a line on the opposite
side of the shaft. These two lines running around and along the shaft
form the grooves while the portion in between forms the beads of the
double spiral.
5. Saw to the desired depth, being 1/4" less than half the diameter at
the point where cut. With a chisel or knife form the grooves and beads.
It is necessary to be careful about not ending the grooves too abruptly.
(See point 6 in Plates B-V--1-a, a´.) Smooth with a rasp and sandpaper
while the lathe is revolving slowly.
6. Cut the design on the ends and polish.
PLATES B-V--3-a, a´. DOUBLE GROOVE SPIRAL. STRAIGHT SHAFT
To work out the double groove spiral for the magazine holder
illustrated, proceed as follows:
1. Square up the stock to 1-3/8". Center carefully and turn the design
on both ends as shown, in the upper diagram (Plate B-V--3-a´). Turn the
cylinder between the top and bottom, making it 5-1/2" long and 1-3/8" in
diameter.
[Illustration: Fig. 26.]
2. Divide the cylinder into two equal parts. Each part represents one
revolution of the spiral.
3. Divide each half into four equal parts as shown in the top and center
diagrams (Plate B-V--3-a´), 1-1´, 2-2´, 3-3´ and so on. The proportion
of the distance between these circles should be one-half the diameter of
the cylinder.
4. Draw lines A-A, B-B, C-C, and D-D, parallel to the axis of the
cylinder 90° apart.
5. With a band 3/16" wide of any substantial material (preferably a
narrow strip of tin or a watch main spring) begin on the line A-A at
circle 1, and connect circle 1´ at line B-B, and then connect circle 2
at C-C, and so on until the spiral is made the entire length. Mark on
both sides of the 3/16" band so as to keep the spiral parallel.
6. Next begin at the line C-C where circle 1 crosses it and connect from
here to 1´ at B-B. Proceed as in Step 5, as shown in the center diagram.
7. Now erase the extreme ends of the spiral near circles 1 and 5, and
deviate from the original spiral and follow the circles in a more
parallel direction so as to allow the spiral to begin and end gradually
and not too abruptly. Refer to the lower diagram for this.
8. Cut out portions of wood between the bands previously marked around,
as shown in the lower figure. The wood should be cut out with a knife so
as to leave the corners sharp on the narrow bands. The portion cut out
should be a semi-circle and can be sanded by making a spindle a little
smaller than the distance between the bands and fastening sandpaper on
the spindle. Place in the lathe and hold the spiral on the sandpaper
cylinder at an angle so that the spiral will fit. Turn gradually and the
sandpaper will smooth up the portion between the bands and true it up.
At the ends where the grooves are smaller, use a smaller stick around
which sandpaper has been wound and work out by hand.
9. It is well to cut straight down, about 1/32" deep, along the lines
marking out the narrow bands. Then the wood will not be so likely to
split while removing the stock which forms the grooves between the
bands.
10. Cut out the mortises in the square portions which have been left at
both ends. Make the frame work for the sides and cane. Glue together and
polish.
Note:--By making the posts smaller and using the same construction for a
side a nice looking book stall may be made. The proportions for the
posts are the same as mentioned in Step 3.
[Transcribers note: There are 142 line art illustrations after this
point in the book. They are all provided in the illustrated HTML
edition of this book.]