By ARCHIE S. MILTON

OTTO K. WOHLERS

THE BRUCE PUBLISHING COMPANY

MILWAUKEE, WISCONSIN

This book is the outgrowth of problems given to high school pupils by the writers, and has been compiled in logical sequence. Stress is laid upon the proper use of tools, and the problems are presented in such a way that each exercise, or project, depends somewhat on the one preceding. It is not the idea of the writers that all problems shown should be made, but that the instructor select only such as will give the pupils enough preliminary work in the use of the tools to prepare them for other models following.

The related matter on the care of the lathe and tools, the grinding of chisels, the polishing of projects, and the specific directions and cautions for working out the various exercises and projects with the drawings, make the book not only valuable for reference, but also as a class text to be studied in connection with the making of projects. The drawings show exact dimensions and are tabulated in the upper right-hand corner in such a way that they may be used in a filing case if desired. At least two designs are shown for each model, and these may be used as suggestions from which students, with the aid of the instructor, may work out their own designs.

The book has been divided into two parts: (A) Spindle Turning, and (B) Face-Plate Turning. The same order is followed in each part; the related information is supplied where required as the pupil progresses.

Part A takes up the following: (I) Exercises; (II) Models, involving the same tool processes, only in a somewhat different degree; (III) Oval Turning, explaining the use of two centers; (IV) Duplicate Turning, where identical pieces are turned.

Part B is arranged as follows: (I) Exercises; (II) Models, which are an application of cuts in exercises that involve only face-plate work; (III) Models, which require chucking; (IV) Assembling Exercises, involving spindle turning, face-plate work and chucking; (V) Spiral Turning, showing the method of turning a spiral on the lathe.

PLATES--SPINDLE TURNING.

PLATES--CHUCK TURNING.

CLASSIFICATION OF PLATES

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.

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.

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

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.)

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.

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.

1¼" Gouge
¾" Gouge
½" Gouge
¼" Gouge
1¼" Skew
¾" Skew
½" Skew
¼" Skew
⅛" Parting Tool
½" Round Nose
¼" Round Nose
½" Square Nose
¼" Square Nose
½" Spear Point
½" Right Skew
½" Left Skew
Slip Stone with round edges
6" Outside Calipers
6" Inside Calipers
8" Dividers
12" Rule
½ pt. Oil Can
Bench Brush

GRINDING AND WHETTING TURNING TOOLS

Skew Chisel

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

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.

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

Fig. 3

ADJUSTING THE TOOL REST

Horizontally the tool rest should be set about ⅛" 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; ⅛" above for a medium person; and ¼" 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

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.

TOOL PROCESSES IN SPINDLE TURNING

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 ¼" to ⅜" 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.

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.

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.

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 ½" or ¼" 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 ⅛" 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 ⅛" 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.

Fig. 8.

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 ⅛" of the desired line, leaving enough stock at the base of the cuts to still hold the cylinder rigid while cutting on the ends.

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.

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:

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.

Fig. 12.

A-II--7. Vise Handles.

Turn the spindle with the solid head to dimensions. Bore a hole through a 1¼" 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.