BENCH WORK IN WOOD
A COURSE OF STUDY AND PRACTICE DESIGNED FOR THE USE OF SCHOOLS AND COLLEGES
BY W. F. M. GOSS,
Professor of Practical Mechanics, Purdue University, Lafayette, Indiana.
BOSTON, PUBLISHED BY GINN & COMPANY, 1888.
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Bench work in wood
To avoid confusion, the subject herein treated is considered in three divisions. Part I. contains the essential facts concerning common bench tools for wood ; it describes their action, explains their adjustments, and shows how they may be kept in order. Part II. presents a course of practice by which ability to use the tools may be acquired ; and Part III. discusses such forms and adaptations of joints as will meet the requirements of ordinary construction. It is not expected that the student will complete Part
I. before entering upon Part II., or that he will finish Part II. before commencing Part III. He will find greater profit in using them together. For example, a shop exercise involving the chisel (Part II.) should be accompanied or preceded by a study of the chisel (Part I.) ; again, the various forms of mortise and tenon joints (Part III.) will be better understood and more easily remembered, if considered during the time when types of such joints are under construction in the shops (Part II.). In the writer's experience with classes of students, one hour has been given to class-room work for every five hours given to shop work. By this apportionment, Parts I. and III. can be mastered in the class-room while Part II. is in progress in the shops.
The equipment necessary for carrying out the course of practice given in Part II. is much less expensive than may at first appear.
If provision is to be made for more than one student, the items printed in small type need not be duplicated. One set of these will suffice for any number less than thirty. The writer is indebted to Mr. M. Golden, of the School of Mechanics and Engineering, Purdue University, for the execution of many of the drawings and for valuable suggestions.
INTRODUCTION - INTERPRETATION OF MECHANICAL DRAWINGS.
- Mechanical Drawings Defined
- Method of showing Parts Obscured from Sight
- Sections, Section Lines, Cross-hatching, Incomplete Sections
- Broken Drawings
- Dimensions. Dimension Lines,
MEASURING AND LINING APPLIANCES.
- Early Standards of Length
- English Standard Yard
- United States Standard of Length
- The Troughton Scale.
- Board-measure Table.
- Brace-measure Table
- Try-and-Miter Square
- Scribing with Dividers
- Combining Square and Rule
- Combining Square and Bevel
- Setting the Bevel at an Angle of 60 Degrees
- Setting the Bevel at any Given Angle
CHISELS AND CHISEL-LIKE TOOLS
- Chisel Handles
- Action of Cutting Wedges
- Angle of Cutting Wedge in Chisel and Gouge
- Size of Teeth
- Ripping-Saw and Cross-Cutting-Saw Defined
- Teeth of Ripping-Saws
- Teeth of Cross-Cutting-Saws
APPLIANCES FOR FILING AND SETTING SAWS
- Sets for Bending the Tooth
- Sets for Swedging the Tooth
SAW FILING AND SETTING
- Top- Join ting
- Side- Jointing
PLANES AND PLANE-LIKE TOOLS
- Description of Planes
- Length of Stock
- Angle of Cutting Wedge
- Outline of Cutting Edge
- Use of Different Bench Planes
- Action of Smooth-Plane and Fore-Plane Compared
- The Cap
- Narrowness of Mouth
- Adjusting the Iron
- Jointing a Plane
- Iron Planes
- Planes of Wood and Iron Combined
- Hollows and Rounds
- Combination Planes
- Sharpening Augers and Auger-Bits
- Expansive Bits
- Small Bits.
- Angular Bit-Stock
- Automatic Boring Tool
- Hand Screw-Driver
- Brace Screw-Driver
- Wooden Miter-Box
- Iron Miter-Box
- Use of Water on a Grindstone
- Truing a Grindstone
- Truing Devices for Grindstones
- Oil for Oilstones
- Form of Oilstones
- Oilstone Slips.
- Truing an Oilstone
- Good Lines a Necessity
- Location of Points
- Jointed Face
EXERCISE No. I. MEASURING AND LINING.
- Spacing: Pencil and Rule
- Lining: Pencil, and Framing-Square
- Lining: Pencil, and Try-Square
- Lining: Pencil and Bevel.
- "Gauging" Lines: Pencil and Rule
- Spacing: Scriber and Rule
- Lining: Scriber, and Try-Square.
- Lining: Scriber and Bevel
- Lining for Exercise No. 3
EXERCISE No. 2. CHISELING AND GOUGING.
- Chiseling by Hand
- Chiseling by Use of Mallet
EXERCISE No. 3. SAWING.
- Handling the Saw
- Guiding the Saw
- Correcting the Angle of the Cut
EXERCISE No. 4. PLANING.
- Handling the Plane
- Why a Plane Clogs
- Planing to a Square
- Method of Performing
- Similar Operations
- Smooth Surfaces
EXERCISE No. 5. BOX.
- Jointing to Width
- Sawing to Length
- Hammer Marks
- Setting Nails
- With-drawing Nails
- Fastening the Box Bottom. Finishing the Box
- Planing End Grain
EXERCISE No. 6. bench-hook.
- Lining and Sawing
- Using the Auger-Bit
EXERCISE No. 7. HALVED SPLICE.
- Value of Working-Face Illustrated
- Cutting the Joint
- Sawing a Fit
- Toeing Nails
EXERCISE No. 8. SPLAYED SPLICE.
- Cutting and Finishing the Joint
EXERCISE No. 9 SIMPLE MORTISE-AND-TENON JOINT.
- Cutting the Mortise
- Cutting the Tenon.
- Making a Pin
EXERCISE No. 10. KEYED MORTISE-AND-TENON JOINT.
- Lining and Cutting
EXERCISE No. 11. PLAIN DOVETAIL.
- Lining and Cutting
- Short Method of Lining and Cutting the Joint
EXERCISE No. 12. LAP DOVETAIL.
- Lining and Cutting
EXERCISE No. 13. BLIND DOVETAIL.
- Lining and Cutting
- A Modified Form of the Joint
EXERCISE No. 14. FRAME AND PANEL.
- Panel Door Described
- Making the Joint between Stile and Rail
- Cutting Chamfers
- Keying the Joint
- Finishing the Panel. Fastening Panel to Frame
- Inserting Screws
- Using the Brad-Awl
EXERCISE No. 15. FRAME AND PANEL
- Making Joint between Stile and Rail
- Forming the Panel
PART III. ELEMENTS OF WOOD CONSTRUCTION.
- Timber Defined
- Effect of Shrinkage on Cross-section
- Effect of Shrinkage on Length
- Work of Carpenter and Joiner Compared
- Compressionaly Tensional, and Cross-Strain Defined
- Effect of Cross-Strain, Neutral Axis, Relation between the Depth of a Timber and its Resistance to Cross-Strain
- Rankine's Principles concerning Joints and Fastenings
JOINTS CONNECTING TIMBERS IN THE DIRECTION OF THEIR LENGTH.
- Lapped Joint
- Fished Joint
- Scarfed Joints
- Scarfed Joint for Resisting Compression
- Scarfed Joint for Resisting Tension
- Scarfed Joint for Resisting Cross-Strain
- Scarfed Joint for Resisting Tension and Compression
- Scarfed Joint for Resisting Tension and Cross-Strain
JOINTS CONNECTING TIMBERS AT RIGHT ANGLES.
- Mortise-and-Tenon Joints
- Mortise and Tenon Joining a Vertical to a Horizontal Timber
- Mortise and Tenon Joining a Horizontal to a Vertical Timber
- Mortise and Tenon Joining One Horizontal Timber to Another. Tusk Tenon
- Oblique Mortise and Tenon
- Joinery Described
BEADS AND MOLDINGS.
- Use of Beads
- Stop Chamfer
- Moldings Described
- Round Nose
- Some Typical Forms of Moldings. Fillet
- Joints in Joinery Defined
HEADING-JOINTS, OR JOINTS UNITING PIECES IN THE DIRECTION OF THEIR LENGTH.
- Square Heading-Joint. Splayed Heading-Joint
JOINTS UNITING PIECES IN THE DIRECTION OF THEIR WIDTH.
- Their Office
- Butt-joint. Filleted Joint, Rabbeted Joint, Matched Joint
- Glued Butt-joint
- Side Cleats
- End Cleats
- Relieving Cleats from Strain
JOINTS UNITING PIECES AT RIGHT ANGLES.
- Strengthening of Miter-Joints
- Proportions of Mortise-and-Tenon Joints
- Single and Double Tenons
- Four Tenons
- Mortises and Tenons at an Angle in the Work
- Modifications of Mortise-and-Tenon Joints
- Joints between Panel and Frame
- Size of Nails
241. Pins are employed principally as a means of holding tenons in mortises. In carpentry one pin, generally, is used in each joint, its diameter varying from one-sixth to one-fourth the width of the tenon. It is commonly placed at a distance from the abutting cheeks of the mortise, equal to one-third the length of the tenon. But to secure the maximum strength of the joint, its exact location in any particular case must be fixed with reference to the character of the material, and also to the relative thickness of the tenon and the cheeks of the mortise. In joinery it is found best to use two or more pins, and, whatever the proportions of the joint may be, these rarely exceed three-eighths of an inch in diameter. They are inserted very near the abutting cheeks of the mortise, so that that part of the mortise between them and the shoulder of the tenon will not shrink enough to make an open joint.
Square pins are better than round ones, but the latter are more easily fitted and, therefore, more used. Drawboring has already been described (168).
242. Wedges. - The most common use of wedges is illustrated by Fig. 213 in connection with Exercise No. 14, which requires wedges to be dipped in glue and driven between the tenon and the e-ds of the mortise. Wedges are also driven in saw cuts made in the end of the tenon for the purpose of expanding it, as illustrated by Fig. 296, which shows at A a. section of a joint before the wedges are driven, and at B a. section of the finished joint. The saw cut should extend somewhat deeper than the point reached by the wedge. If the tenon is broad, or if a considerable increase in breadth is required, more than one wedge must be used. When there are more than two, a large one should be inserted in the center and smaller ones on each side, as shown by Fig. 297, the wedges ready for driving at A and the joint finished at B.
243. Blind-wedging is sometimes resorted to when the mortise does not extend through the piece. As shown by Fig. 298, the mortise is enlarged at the bottom and the wedges started in ; then, as the pieces are driven together, the ends of the wedges strike against the bottom of the mortise and spread the tenon. When driven, the tenon cannot be withdrawn.
244. Keys differ from wedges in respect to their sides, which are parallel or nearly so. The key may be a single piece, as shown in the joint. Fig. 197, or, what is better, made as two wedges. Fig. 299. These may be put in place when in the relative position shown by AB after which, by driving them upon each other, as indicated by A, B, the joint may be tightened. The parallelism of the outside edges, which are in contact with the joint, is always maintained.
245. Dowels are round wooden pins of small diameter used to strengthen a joint. They should be dipped in glue and driven at a tight fit into holes made for their reception. They may be carried entirely through one piece and into the other, Fig. 277, or inserted as shown by Fig. 274.
Dowels may be made at the bench by the plane, or they may be turned. When planed, they will be improved in section if driven through a round hole in a piece of iron or steel. They are supplied by the trade, of all ordinary diameters, and in lengths of several feet, so that the consumer has but to cut them to lengths suited to his purposes, and point them.
Shoe pegs serve well as small dowels. After being dipped in glue they should be driven in brad-awl holes. Whenever fastenings are required to be so placed that sub- sequent operations bring the cutting tools about them, dowels are preferable to brads or nails, since they may be planed off without injury to the tool.
246. Nails are classified according to the process by which they are made, the material used, their form and proportions, and the use for which they are intended. Iron and steel are the most common materials, but when these would be destroyed by corrosion, copper and "galvanized" iron are used.
The forms of most importance to the bench-worker may be classed as common and finishing (or casing) nails. Their comparative proportions are illustrated by Figs. 170 and 300, the former representing a common, and the latter a finishing nail. It is evident that the greater strength of the common nail makes its use desirable when there is sufficient material to receive it properly, and when the appearance of the head on the surface is not objectionable. The finishing nail may be used in more delicate material, and makes a smaller scar on the work. Cut nails are so called because, in the process of manufacture, each nail is cut from a plate of metal. The plate has a width equal to the length of the nail, and a thickness equal to its breadth. Generally speaking, all nails of the form shown by Figs. 170 and 300 are cut.
Their strength and tenacity are unequaled. They are made from drawn wire in sizes varying from that of the smallest brad to that of the largest spike. The terms used to describe cut nails, as to size and form, are also applied to wire nails. The holding power of a wire nail is often inferior to that of a cut nail.
248. Brads are small finishing nails, now usually of wire. Their size is expressed in inches and fractions of an inch, and ranges from one-fourth of an inch to two inches.
249. Tacks are useless for fastening pieces of wood to each other, but are indispensable when lighter material, such as cloth or leather, is to be fastened to wood. They vary in form and size with the particular use for which they are intended. Their size is expressed by a number prefixed to the word "ounce."
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