Learning Mechanical Forms
: HOW THE DIFFERENT STRUCTURAL PARTS ARE DESIGNATEDSuppose, for example, we take the words segment and sector. Without a thorough understanding in your own mind you are likely to confuse these terms by taking one for the other. But let us assume you are to be called upon to explain a sector to some one who has no idea of terms and their definitions. How would you describe it? While it is true it is wedge-shaped, you will see by examining the drawing that it is not like a wedge. The sector has two sides running from
If you were called upon to define a segment you might say it had one straight line and one curve, but this would not define it very lucidly. Therefore, in going over the designations given, not only fix in your mind the particular form, but try to remember some particular manner in which you can clearly express the form, the shape or the relation of the parts.
For your guidance, therefore, I have given, as far as possible, simple figures to aid you in becoming acquainted with structures and their designations, without repeating the more simple forms which I have used in the preceding chapters.
55. Arcade.—A series of arches with the columns or piers which support them, the spandrels above, and other parts.
56. Arch.—A curved member made up, usually, of separate wedge-shaped solids, A. K, Keystone; S, Springers; C, Chord, or span.
57. Buttress.—A projecting mass of masonry. A, used for resisting the thrust of an arch, or for ornamentation; B, a flying buttress.
58. Chamfer.—The surface A formed by cutting away the arris or angle formed by two faces, B, C, of material.
59. Cotter or Cotter Pin.—A pin, A, either flat, square or round, driven through a projecting tongue to hold it in position.
60. Crenelated.—A form of molding indented or notched, either regularly or irregularly.
61. Crosses.—1. Latin cross, in the Church of Rome carried before Bishops. 2. Double cross, carried before Cardinals and Bishops. 3. Triple or Papal cross. 4. St. Andrew's and St. Peter's cross. 5. Maltese cross. 6. St. Anthony or Egyptian cross. 7. Cross of Jerusalem. 8. A cross patté or fermé (head or first). 9. A cross patonce (that is, growing larger at the ends). 10. Greek cross.
62. Curb Roof.—A roof having a double slope, or composed on each side of two parts which have unequal inclinations; a gambrel roof.
63. Cupola.—So called on account of its resemblance to a cup. A roof having a rounded form. When on a large scale it is called a dome.
Crown Post.—See King Post.
64. Console.—A bracket with a projection not more than half its height.
65. Corbels.—A mass of brackets to support a shelf or structure. Largely employed in Gothic architecture.
More
-
Fly-wheel
It now remains only to provide a fly-wheel and treadle with the communicating belt. The fly-wheel may be of any convenient size, or it may be some discarded pulley or wheel. Suppose it is two feet in diameter; then, as your small pulley is 2 inches ... Focal Points
The focal point of a circle is its center, and is called the <em>focus</em>. But an ellipse has two focal points, called <em>foci</em>, represented by F, F in Fig. 148, and by B, B in Fig. 149. A <em>produced line</em> is one which extends out beyo... For Cross-cutting
For ordinary cross-cutting the angle of the saw should be at 45 degrees. For ripping, the best results are found at less than 45 degrees, but you should avoid flattening down the angle. An incorrect as well as a correct angle are shown in Figs. 21 a... Forcing A Saw
Forcing a saw through the wood means a crooked kerf. The more nearly the saw is held at right angles to a board, the greater is the force which must be applied to it by the hand to cause it to bite into the wood; and, on the other hand, if the saw... Forcing Saws In Wood
One of the reasons why the forcing of saws is such a bad practice will be observed in cutting white or yellow pine. For cross-cutting, the saw should have fine teeth, not heavily set, and evenly filed. To do a good job of cross-cutting, the saw must... Forming Lines And Shadows
It is not my intention to furnish a complete treatise on this subject, but to do two things, one of which will be to show, among other features, how simple lines form objects; how shading becomes an effective aid; how proportions are formed; and, ... Framework
As we now know the sizes, the first thing is to build the framework. The legs should be dressed square and smoothed down with the fore plane to make them perfectly straight. Now, lay out two mortises at the upper end of each leg. Follow the illust... Front And Side Lines
From the floor diagram, and the door and window spaces, as marked out, we may now proceed to lay out rough front and side outlines of the building. The ceilings are to be 9 feet, and if we put a rather low-pitched roof on the square structure (Fig. ... Fundamental Truss Form
In every form of truss, whether for building or for bridge work, the principles of the famous A-truss must be employed in some form or other; and the boy who is experimentally inclined will readily evolve means to determine what degree of strength t... Fundamentals Of Designing
A great deal of the pleasure in making articles consists in creative work. This means, not that you shall design some entirely new article, but that its general form, or arrangement of parts, shall have some new or striking feature. A new design in... Gages
One of the most valuable tools in the whole set is the gage, but it is, in fact, the least known. This is simply a straight bar, with a sharpened point projecting out on one side near its end, and having an adjustable sliding head or cheekpiece. Thi... General House Building
We are to treat, generally, on the subject of house building, how the work is laid out, and how built, and in doing so I shall take a concrete example of the work. This can be made more effectual for the purpose if it is on simple lines. ... General Observations
If the workman will carefully observe the foregoing requirements he will have taken the most important steps in the knowledge of the art. If he permits himself to commence work without having his tools in first-class condition, he is trying to do wo... Good Taste In Staining
Oak, mahogany, cherry, black walnut, and like imitations are always good in an artistic sense, but imitations of unfamiliar woods mean nothing to the average person. The too common mistake is to try to imitate oak by staining pine or poplar or birch... Great Contrasts Bad
Violent contrasts in furniture staining have the effect of cheapness, unless the contrasting outlines are artistically distributed throughout the article, from base to top finish. ... Hard Wood Imitations
It would be better to use, for instance, ash or oak for one portion of the work, and a dark wood, like cherry or walnut, for the other part; but usually a cherry cabinet should be made of cherry throughout; while a curly maple chiffonier could not b... Hard Woods
Of the hard woods, cherry is the most desirable for the carpenter's tool. For working purposes it has all the advantages of a soft wood, and none of its disadvantages. It is not apt to warp, like poplar or birch, and its shrinking unit is less than ... Harmonizing Wood
Imagine a chiffonier with the base of dark wood, like walnut, and the top of pine or maple, or a like light-colored wood. On the other hand, both walnut and maple, for instance, may be used in the same article, if they are interspersed throughout th... Harmony Of Parts
But one thing should be observed in the making of furniture, namely, harmony between the parts. For instance, a table with thin legs and a thick top gives the appearance of a top-heavy structure; or the wrong use of two different styles is bad fro... Heavy Lines
But there is an exception to this rule. See two examples (Fig. 140). Here two parallel lines appear close together to form the edge nearest the eye. In such cases the second, or upper, line is heaviest. On vertical lines, as in Fig. 141, the secon... Holding The Gage
The hand serves to keep the cheekpiece against the board, while the thumb pushes the gage forward. The hand must not, under any circumstances, be used to move the gage along. In fact, it is not necessary for the fingers to be clasped around the gage... How Any Structure Is Built Up
It should be observed that each structure, however small, is usually built from the base up. Just the same as the more pretentious buildings are erected: First, the sill, then the floor supports, then the posts and top plates, with their connecting ... How To Characterize Surface
Suppose we commence simply with straight lines. How shall we determine the character of the surface of the material between the two straight lines shown in Fig. 125? Is it flat, rounded, or concaved? Let us see how we may treat the surface by simp... How To Set
To set a saw accurately, that is, to drive out each tooth the same distance, is the first requirement, and the second is to bend out the whole tooth, and not the point only. In the illustration (Fig. 10), the point is merely bent out. This is wrong.... How To Start A Saw
If the untried apprentice has such an opinion set him to work at the task of cutting off a board accurately on a line. He will generally make a failure of the attempt to start the saw true to the line, to say nothing of following the line so the ker... How To Start On A Line
The first mistake he makes is to saw <em>on the line</em>. This should never be done. The work should be so laid out that the saw kerf is on the discarded side of the material. The saw should cut alongside the line, and <em>the line should not</em> ... Illustrating Cube Shading
In Fig. 137 I show merely nine lines joined together, all lines being of equal thickness. As thus drawn it may represent, for instance, a cube, or it may show simply a square base (A) with two sides (B, B) of equal dimensions. ... In The Use Of Grindstones
There are certain things to avoid and to observe in the use of stones. Never use one spot on the stone, however narrow the tool may be. Always move the tool from side to side. Never grind a set of narrow tools successively. If you have chisels to gr... Incorrect Way To Hold Tool For Grinding
The incorrect way of holding a tool is shown in Fig. 18. This, I presume, is the universal way in which the novice takes the tool. It is wrong for the reason that the thumbs of both hands are on top of the blade, and they serve as pivots on which t... Intermediate Studding
It will then be an easy matter to put in the intermediate 2" × 4" studding, placing them as nearly as possible 16 inches apart to accommodate the 48-inch plastering lath. <div> <img src="/images/fig232.jpg" alt="Fig. 232." title=""... Irregular Curves
But the irregular curves require the most care to form properly. Let us try first the elliptical curve (Fig. 148). The proper thing is, first, to draw a line (A), which is called the "major axis." On this axis we mark for our guidance tw... Isometric Cube
I enclose this cube within a circle, as in Fig. 143. To form this cube the circle (A) is drawn and bisected with a vertical line (B). This forms the starting point for stepping off the six points (C) in the circle, using the dividers without resetti... Joints
For joining together boards at right angles to each other, such as box corners, drawers and like articles, tenons and mortises should never be resorted to. In order to make fine work the joints should be made by means of dovetails, rabbets or reba... Knowledge Of Tools
A knowledge of tools and their uses is the first and most important requirement. The saw, the plane, the hatchet and the hammer are well known to all boys; but how to use them, and where to use the different varieties of each kind of tool, must be l... Lap-and-butt Joint
The lap-and-butt is the form of uniting members which is most generally used to splice together timbers, where they join each other end to end. <div> <img src="/images/fig210.jpg" alt="Fig. 210." title="" height="140" width="400" /> Fig. 210. </div> ... Laying Out The Legs
Fig. 27 shows a leg with square cross marks (A) at each end. These marks indicate the finished length of the leg. You will also see crosses on two sides. These indicate what is called the "work sides." The work sides are selected because they are th... Learning Mechanical Forms
Suppose, for example, we take the words <em>segment</em> and <em>sector</em>. Without a thorough understanding in your own mind you are likely to confuse these terms by taking one for the other. But let us assume you are to be called upon to expla... Lessons From The Doric Column
As an example, suppose we take a plain cabinet, and endeavor to embellish it with the types of molding described, and you will see to what elaboration the operation may be carried. ... Materials
Then procure the following bolts: <div> <table summary="Materials." border="0" cellpadding="2" cellspacing="0" width="40%"> <tbody> <tr> <td align="left">4⅜"</td> <td align="left">bolts,</td> <td ali... Mission Style
The Mission style of architecture also lends itself to the making of chairs and other articles of furniture. A chair is, probably, the most difficult piece of household furniture to make, because strength is required. In this type soft wood may be u... Moldings
The use of moldings was early resorted to by the nations of antiquity, and we marvel to-day at many of the beautiful designs which the Phœnecians, the Greeks and the Romans produced. If you analyze the lines used you will be surprised to learn... Natural Effects
If effects are wanted, the skilled workman will properly rely upon the natural grain of the wood; hence, in staining, you should try to imitate nature, because in staining you will depend for contrast on the natural grain of the wood to help you o... Natural Wood Stains
It should be said, in general, however, that a stain is, at best, a poor makeshift. There is nothing so pleasing as the natural wood. It always has an appearance of cleanliness and openness. To stain the wood shows an attempt to cover up cheapness b... Observations About A Box
As simple a little article as a box frequently becomes a burden to a beginner. Try it. Simply keep in mind one thing; each box has six sides. Now, suppose you want a box with six equal sides—that is, a cubical form—it is necessary to mak... Ornamental Bead Finish
These figures show how the bead may be used for finishing corners, edges and projections. Fig. 216 has a bead at each corner of a stile (A), and a finishing strip of half-round material (B) is nailed to the flat edge. Fig. 217 has simply the corners... Perpendicular And Vertical
A few words now as to terms. The boy is often confused in determining the difference between <em>perpendicular</em> and <em>vertical</em>. There is a pronounced difference. Vertical means up and down. It is on a line in the direction a ball takes whe... Perspective
A perspective is a most deceptive figure, and a cube, for instance, may be drawn so that the various lines will differ in length, and also be equidistant from each other. Or all the lines may be of the same length and have the distances between them... Picture Frames
In picture frames the mitered corners may have a saw kerf (C) cut across the corners, as shown in Fig. 44, and a thin blade of hard wood driven in, the whole being glued together. ... Plain Molded Base
The base may be treated in the same manner. The main strip (4) has its upper corner chamfered off, as at I, and on this is nailed a thin, narrow finishing strip (J). The upper part or molded top, in this case, has eleven distinct lines, and the base... Plain Structures
A house with a plain façade, having a roof properly pitched and with a simple cornice, if joined to a wing which is not ungainly or out of proper proportions, is infinitely more beautiful than a rambling structure, in which one part suggests ... Planes
The plane may be called the æsthetic tool in the carpenter's kit. It is the most difficult tool to handle and the most satisfactory when thoroughly mastered. How to care for and handle it will be referred to in a subsequent chapter. We are n... Plastering And Inside Finish
Next in order is the plastering, then the base-boards and the casing; and, finally, the door and windows should be fitted into position. Enough has been said here merely to give a general outline, with some details, how to proceed with the work. ... Polishing Stained Surfaces
If, on the other hand, you wish to go to the labor of polishing the furniture to a high degree, staining becomes an art, and will add to the beauty and durability of any soft or cheap wood, excepting poplar. When the article is highly polished, so a... Preparing A Box Joint
In order to match a box joint for the inner end of a table drawer, the first step is to select two work sides. One work side will be the edge of the board, and the other the side surface of the board, and on those surfaces we will put crosses, as he... Proper Designations
Every part in mechanism, every point, curve and angle has its peculiar designation. A knowledge of terms is an indication of thoroughness in education, and, as heretofore stated, becomes really the basis of art, as well as of the sciences. When you ... Proper Terms
It is the application of the correct terms to things that lays the foundation for accurate thinking and proper expressions in describing work. A wise man once said that the basis of true science consists in correct definitions. ... Proportional Dividers
A useful tool is called the proportional dividers, the legs of which are hinged together intermediate the ends, so that the pivotal joint is adjustable. By means of this tool the scale of work may be changed, although its widest field of usefulness ... Representing Objects
But let him try to represent some object, and the pens become useless. There is a vast difference in the use of drawing tools and free-hand drawing. While the boy who is able to execute free-hand sketches may become the better artist, still that art... Room Measurements
We must now determine the dimensions of each room, and then how we shall build the roof. In Figs. 223 and 224, we have now drawn out in detail the sizes, the locations of the door and windows, the chimneys and the closets, as well as the bathroom... Rule For Mortises
Fig. 206 shows such an example. You will notice this in doors particularly, as an example of work. <div> <img src="/images/fig206.jpg" alt="Fig. 206." title="" height="89" width="156" /> Fig. 206. </div> <div> <img src="/images/fig207.jpg" alt="Fig. ... Saw Clamps
These are necessary adjuncts, and should be made of hard wood, perfectly straight and just wide enough to take in the narrow back saw. The illustration shows their shape and form. ... Saw Clamps
You may easily make a pair of saw clamps as follows: Take two pieces of hard wood, each three inches wide, seven-eighths of an inch thick, and equal in length to the longest saw. Bevel one edge of each as shown in A (Fig. 15), so as to leave an edg... Scarfing
This method of securing members together is the most rigid, and when properly performed makes the joint the strongest part of the timber. Each member (A, Fig. 212) has a step diagonally cut (B), the two steps being on different planes, so they form ... Sector And Segment
Now examine the shape of the body formed by two of the radial lines (E, E) and that part of the circle which extends from one radial line to the other. The body thus formed is a sector, and it is made by two radiating lines and a curved line. Learn ... Self-supporting Roofs
In putting up, for instance, self-supporting roofs, or ceilings with wide spans, and steeples or towers, the bridge principle of trussed members should be understood. The most simple bridge or trussed form is the well-known A-shaped arch. <div> <im... Setting Door And Window Frames
The next step in order is to set the door and window frames preparatory to applying the weather boarding. It is then ready for the roof, which should be put on before the floor is laid. ... Setting Up
First set up the corner posts, plumbing and bracing them. Cut a top plate for each side you are working on. <div> <img src="/images/fig231.jpg" alt="Fig. 231." title="" height="64" width="400" /> Fig. 231. </div> ... Shading Effects
Now, to examine it properly so as to observe what the draughtsman wishes to express, look at Fig. 138, in which the three diverging lines (A, B, C) are increased in thickness, and the cube appears plainly. On the other hand, in Fig. 139, the thicken... Shading With Beads And Rabbets
You will see from the foregoing, that these embellishments are serviceable because they provide the article with a large number of angles and surfaces to cast lights and shadows; and for this reason the boy should strive to produce the effects which... Shadows From A Solid Body
We can understand this better by examining Fig. 129, which shows a vertical board, and a beam of light (A) passing downwardly beyond the upper margin of the board. Under these conditions the upper margin of the board appears darker to the vision, by... Signs To Indicate Measurements
The small circle (°) is always used to designate <em>degree</em>. Thus 10° means ten degrees. Feet are indicated by the single mark '; and two closely allied marks " are for inches. Thus five feet ten inches should be written 5' 10"... Simple Saw Setter
Take a block of wood, a 4 by 4 inch studding, four inches long. Get a piece of metal one-half inch thick and two inches square. Have a blacksmith or machinist bore a quarter-inch hole through it in the center and countersink the upper side so it m...