The amateur mechanic

Front matter

H

ECHANIC

/V.FREDERICK COLLINS

Contents

I. Rules and Tools for Measuring ... 1

A carpenter's boxwood rule — The triangular boxwood rule and scale — A pattern maker's shrinkage rule — The use of flexible rules — About tape measures — The carpenter's steel square — Laying out an octagon or 8-square — The brace measure table — The essex board measure table — The rafter framing table — The vernier — The vernier caliper — The micrometer caliper — Gauges for testing and comparing — The protractor — The planimeter.

II. When You Build Your House ... 25

Chapter I Rules And Tools For Measuring

All tools for measuring may be divided into two classes, and these are (1) rules and instruments for making actual measurements, and (2) gauges for testing and comparing.

A rule is simply a strip of wood, or metal, or other material, having a straight edge and whose surface is graduated into inches or centimeters * and fractions thereof. This graduated surface is called a scale, and sometimes the rule itself is spoken of as a scale.

A Carpenter's Boxwood Rule. — Carpenters' rules are not all made alike, for some are 1 foot-4 fold, some are 2 foot-2 fold, those in general use are 2 foot- 4 fold, others are 3 foot-4 fold and, finally, there are 4 foot-4 fold rules.

But a regular carpenter's rule is taken to mean a 2 foot-4 fold hoxwood rule, the scales heing divided into eighths, tenths, twelfths and sixteenths of an

1A unit of lineal measurement used in the Metric System.

i inch. To measure closely, turn the rule on its edge so that the graduated lines set against the board or whatever it is you are measuring. A rule of this kind is shown at A in Eig. 1.

The Triangular Boxwood Rule and Scale. — If you are making machine or architectural drawings you should by all means have one of these scales, for with it you can draw to scale, or get the actual dimensions from drawings that have been made to scale, both easily and quickly.

This rule, which is shown at B, has, as you will see, three sides and each side has two surfaces, making six surfaces in all. On one of these surfaces there is an ordinary twelve-inch scale graduated in inches and a different scale is graduated on each end of the other five surfaces, thus making eleven scales all told. These other ten scales are graduated to 3V, i*y i> h h h 5> 1) li and 3 inches to the foot.

To Learn the Rule. — Lay it on the table with the twelve-inch scale away from you, just as though you were going to draw a line and so that it reads from 0 on the left to 12 on the right. Now turn the rule toward you until the next side is uppermost, and you will see that the upper left-hand scale reads to f of an inch toward the right, and that the upper right-hand scale reads to f of an inch toward the left.

The lower left-hand scale, you will observe, reads to 3 inches toward the right, and that the lower right-hand scale reads to li inches toward the left. You will also note that the left-hand upper and lower

A CARPENTERS RULE

B ARCHITECTS SCALE i.i,i!l.i.i,fl.i.i.a,i,i..l!ii,i.iJR,i;B,i,i!B,i,ffl>.i.ffl'.i.i.i?Bi.i.f?Ri.i,

C PATTERN MAKERS RULE

0 /? FLEXIBLE RULE

Fig. 1. — Rules and Scales scales are just twice as long as their respective right-hand scales.

Further at the beginning of each scale there is a space marked into either 12 or 24 smaller spaces. These spaces represent 1 foot, or 12 inches, and each space represents -J inch when there are 24 of them, or 1 inch when there are 12 of them.

How to Use the Rule. — Now suppose you are drawing the plans for a drawer and that you want your plan when it is done to he § as large as the drawer will really be, that is, you want your plans drawn to a scale so that f inch will equal 1 inch.

If the drawer is to be Vi inches wide and you drew it with an ordinary rule, you would have to multiply § by 7J and the product will tell you that you must measure off f f inches or forty-five iV inch spaces from the end. And you would do this two or three times over, because you would be the exception if you didn't lose count of them.

By using the triangular rule you do away with all this bother, for, if in the drawing you are making J inch equals 1 inch and the width is YJ inches, you simply use the scale marked f inch and mark off 1\ spaces. Or if your drawing is to a scale of § inch to 1 foot you start at the 0 end of the § inch scale and measure off 7 big spaces to the left; next measure off 6 of the small spaces to the right of 0, since each of these represents 1 inch and since 6 inches equals J a foot ; and thus you have measured off 7J feet with the scale where § equals 1 foot

In the same way you can use any scale on the rule and make working drawings to any scale within its limitations and without any calculation whatever. The chief thing to remember is that each of these scales starts off with a space divided into 12 parts or 24 parts depending on the size of the scale and whether this space represents 1 foot and the smaller spaces i an inch or 1 inch, as the case may be. A rule of this kind can be bought 2 for as little as sixty cents.

A Pattern Maker's Shrinkage Rule. — When a casting is made the metal shrinks on cooling, and to allow for this shrinkage the pattern must be made a little larger than the casting is to be.

A shrinkage rule, see C, is graduated to allow for the shrinkage of the metal you are using. The spacing of the graduations is used to measure the patterns you are making, while the figures on the graduations show the actual size the castings will be.

The Use of Flexible Rules. — Rules made of cardboard, celluloid, thin steel and wood are useful for measuring curved surfaces.

Cardboard rules can be bought 3 for a couple of cents each; celluloid rules 6 inches long can be had for five cents each, and very thin spring-tempered rules for machinists 4 can be purchased in any lengths

•Triangular boxwood rules can be bought of the L. E. Knott Apparatus Co., Boston, Mass., and also of KeuiFel and Esser Co., 127 Fulton St., New York.

'The L. E. Knott Apparatus Co. sells these.

4 These rules are sold by Hammacher, Schleinmer and Co., Fourth Ave. and. 13th St., New York.

from 1 inch up to 48 inches for fifteen cents for the shortest up to $7 for the longest.

Where measurements of doors, windows, boilers,

Fig. 2. — The Steel Tape Measure etc., are to be made a flexible folding wood rule will be found very convenient, while a flexible steel folding rule, as shown at D, is a good one to use for metal work.

About Tape Measures. — These elongated rules are used by every carpenter, mason, contractor, surveyor and engineer and you ought to have one in your kit of tools.

An ordinary tape measure, see A in Fig. 2, consists of a thin, flexible steel tape from \ to f inch wide and from 25 to 100 feet long; it is graduated on one side into feet, inches and eighths and is fitted into a hard leather case. The tape can he reeled up by a handle which folds in flush with the side of the case.

The Roe tape measure has a right angle attachment which permits it to be used quickly and accurately for laying out right angles as shown at B. It is based on the well-known trigonometrical formula that a triangle whose sides measure 6, 8 and 10 feet makes a right angle. Hence, by using this tape measure you can get a perfect right angle without a surveyinginstrument or tools or help of any kind.

The Carpenter's Steel Square. — The ordinary carpenter s square, or steel square, or framing square, as it is variously called, is used not only as a rule, a straight edge and a try square in building construction but also for laying out octagons, or 8 squares, as they are called, finding the square feet in boards, or hoard measure as it is termed, finding the lengths and cuts of braces and also of common, hip, valley and jack rafters for different pitches of roofs.

The ordinary steel square is formed of two parts though these are usually made of one piece of steel about -§■ of an inch thick and which set at right angles to each other as shown at A in Fig. 3. The long

Fig. 3A.~-The Carpenter's Steel Squam piece of the square is called the blade and is about 2 inches wide and 24 inches long; the short piece is called the tongue and this is about li inches wide and 16 inches long.

The side of the square with the maker's name stamped on it is called its face and the other and opposite side is called its bach. It is usually divided into tvtt, A, tV, tV, tV and -J inch scale divisions.

Laying Out an Octagon or 8-Square. — Along the middle of the tongue of the square you will find

€ a. 5 J1ETHOO OFCONSTRUCTING AN OCTAGON IN A SQUARE WITH ANOCTAGON SCALE SHOWING HOW TO

CUT BRACE FROMTABLE OF BRACE LENGTHS

Fig. 3B. — Using the Steel Square

a scale for drawing octagons, or 8-squares, as shown at B in Fig. 3.

To draw an octagon you must first draw a square which is just large enough to contain the sized octagon you are going to make. Having drawn your square, bisect it, that is, find the middle of each side of it with your dividers, as at (a) which is the middle point.

Next take your dividers and, using the 8-squaro 9 scale of the square, set them to as many spaces of the scale as there are inches in any one side of the square you have drawn. Lay this distance off on both sides of each middle point, as shown at B 1,

2, 3, 4, 5, 6, 7 and 8. Then connect these points with lines starting at 1 and drawing to 2, from 2 to

3, and so on until the octagon is complete.

You will observe that it is the 8-square scale on the square and not the square itself that is the important part of laying out octagons and that a scale of this kind marked on a rule would serve the purpose just as well.

The Brace Measure Table. — Along the center of the back of the tongue of your square you will find a table of numbers and you will see that there are two numbers, one above the other, which are equal and one number to the left of them.

The purpose of this table is to make it possible for a carpenter to instantly determine the length of a brace when its ends are to be fixed at equal distances from the intersecting post, beam, shelf, wall or any other like construction.

The table is used like this : Suppose that you have a shelf you want to iix to the wall with a pair of braces, and that you want to have each end of each brace 9 inches from the point where the wall and the shelf intersect each other. Look at the table and you will see that after the set of number 9 the number 12. 72 is just to the left of it.

This number — 12.72 — is the length in inches, then, 10 that you must make the short side of the brace, so cut a piece of wood a little longer than 12.72 inches — say 15 inches — if the brace is to be made 12.72 inches on one side. ]STow put it in your miter box and cut off each end at an angle of 45 degrees, when it will just fit into the corner with each end 9 inches away from the intersection of the shelf and wall, as shown at C.

This table is based on the same trigonometrical relations between the lengths of the sides of a right triangle as that described under the caption of Tape Measures.

The Essex Board Measure Table.— The term hoard measure means the number of square feet in a board 1 inch thick. A board 2 inches thick will have twice as many hoard feet in it as a board 1 inch thick, and so on.

Of course a board 12 inches wide will have as many feet in it as it is feet long and you don't have to do any figuring to know the answer. But if the board is more or less than 12 inches wide you will have to make a small calculation to find the board feet in it. If, for instance, the board is 8 inches wide and 10 feet long, to figure out the board feet you will have to find the number of square inches in it first and then divide the product by 144.

But if you use the Essex board measure table on the square you can instantly find the number of board feet in a board without any calculation. The starting point in this table is always the figure. 12. If, now, you want to find the board feet in a board 8 inches wide and 10 feet long, simply follow the graduated line on the left of the table down to the figure 10, then follow the cross line toward the left to 8, and you will find that the number under 8 is 6 ; you will also see that 6 is to the left of the cross line and 8 is to the right, which means that there is 6 feet and t% inches, board measure, in the board.

But if the board is wider than 12 inches, then you follow the cross line toward the right to the number representing the^ length of the board you want to measure. If the board is 2 inches, multiply the result you get by 2, which will give you the board measure for that thickness.

The Rafter Framing Table. — On the back of a good steel square you will find a table of numbers marked between the scales of inches on the tongue.

With this table you can find the lengths for rafters of known rise and run for a given 'pitch. The rise of a rafter is the vertical height from its ridge end to a horizontal line on a level with its foot.

The run of a rafter is the reach in length from the outside edge of its foot to a point exactly under its ridge end on a horizontal line level with its foot. The pitch of a rafter is the ratio of the rise to twice the run, which is usually equal to the width of the building.

Now, if you will look at the left- of the table you will see a series of figures, thus :

PITCH

12—4

1/6

12—6

1/4

12—8

1/3

12—10

5/12

12—12

1/2

12—15

5/8

12—18

3/4

These numbers are the common pitches at which, rafters are set. Now if your rafter is to be set at such a slant that for every horizontal foot of run, or 12 inches, it rises 4 inches vertically, then the pitch, or slant, of the rafter is £.

Let's suppose you have a rafter with, a known pitch of £ and a run of 4 feet and you want to find the length. Follow the horizontal line on the table on your square from J until you come under the 4 on the inches scale at the top of the table, and the number you find under 4 will be the length of the rafter needed, thus:

Pitch

12—6

1/64 2

Hence, for a rafter having a pitch of £ and a run of 4 feet, the required length will be 4 feet, 2 inches and -it of an inch. The first number 4 represents the feet, the second inches and the third twelfths of an inch. In the same way you will see that a rafter having a J pitch and a run of 20 feet will be 24' 0" tV, or 24 feet and \ inch.

The Vernier.— It is easy to measure small fractions of an inch with the vernier which cannot be measured at all with an ordinary rule.

The vernier, as shown at A, in Fig. 4, consists of

BLADE VERNIER

A VERNIER

HOW THE VERNIER

/S READ

B

JAWS THE VERNIER* CALIPER

M/CROMETER VERNIER READING TO /OtOOO TJ1?

OF AN INCH Fig. 4. — The Vernier

a short rule the scale of which slides against the scale of an ordinary rule. Because the scale divisions of the vernier and rules are of different widths, it is possible to read very small parts of the spaces with a good deal of accuracy. Jt is called a vernier after Pierre Vernier, the French mathematician, who invented it.

The principle on which the vernier works is this : First the scale of the ordinary rule is divided, let's say, into lOths of an inch, and that the vernier is 1 inch long and is divided into 9ths of an inch — that is, it has one less scale division or space to the inch than the rule it slides against.

Now when the end lines of both the scales of the vernier and the rule meet, that is, when they are in a line with each other, the 10th line on the vernier will exactly coincide with the 9th line on the rule.

If, now, you slide the vernier toward the right so that the first lines on the vernier and rule meet, the vernier will have moved exactly tV of a scale division or space, which is tto- of an inch, for this is the difference between the two scales. By sliding the vernier over until the second lines meet, it will have moved tV of a scale division, or ?f v of an inch, or ^V of an inch, and so on. Verniers are put on and used with various measuring tools, such as calipers, protractors, etc.

The Vernier Caliper. — The vernier caliper shown at B is made to take inside as well as outside measurements. It is graduated on the front to read, by means of the vernier, to lOOOths of an inch and on the back to 64ths of an inch.

How to Read a Vernier Caliper. — There are three chief makes of vernier calipers, and these are (1) the Brown and Sharp, (2) the Starr ett and (3) the Columbia Pattern.

On either of the first two makes of calipers the 15 scale of the tool is graduated to 40ths, that is, in .025 ( tV ) of an inch, and every fourth division, which is tMtj- of an inch, is numbered.

On the vernier plate there is a space divided into 25 parts, and these are numbered 0, 5, 10, 15, 20 and 25. These 25 divisions on the vernier take up exactly the same space as the 24 divisions on the scale of the rule. This makes the difference between the width of one of the 25 spaces on the vernier and one of the 24 spaces on the scale -rs of A or ttrrt of an inch.

If now the vernier is set so that the 0 line on the vernier coincides with the 0 line on the rule, the next two lines will be tvVt of an inch apart, the next two lines will be tVW of an inch apart, and so on.

To read the caliper after having made a measurement, see how many inches, tV (or .100) and tV (or .025), the 0 mark on the vernier is from the 0 mark on the rule, and then count the number of divisions on the vernier from 0 to a line which exactly coincides with a line on the scale.

In the picture shown at C the vernier has been moved to the right 1 iV and tV inches, or 1.425 inches, as the 11th line on the vernier coincides with a line on the rule. tWtf of an inch must in consequence be added to the reading on the scale of the rule and the total reading is therefore 1.436 inches, which is the distance the jaws of the caliper have been opened.

The Micrometer Caliper.— The Micrometer caliper, or just micrometer for short, is a little tool which will measure very accurately from 0 to 1 inch in thousandths or even ten-thousandths of an inch.

A micrometer is formed of (1) a frame to which is fixed (2) the anvil and through which (3) the spindle passes; the spindle is fastened to (4) the thimble and these turn in (5) the sleeve, as shown at A in Fig. 5.

How to Read a Micrometer. — To measure the thickness of a sheet of paper or anything else, put it between the anvil and the end of the spindle and hold the frame with your left hand. Kow turn the thimble with your right hand and since the spindle is fixed to the thimble it of course turns with it. This makes it move through the nut in the frame and toward or away from the anvil.

The distance between the opposed surfaces of the anvil and the spindle is shown by the lines and figures on the sleeve and the thimble, and these tell the thickness of the thing you have measured.

The pitch of the screw threads on the inside part of the spindle which screws through the nut, is 40 to the inch ; one complete turn of the spindle, therefore, moves it up or down tV, or tMtj> of an inch. The sleeve is marked with 40 lines to the inch and these correspond to the number of threads on the spindle.

When the end of the spindle rests on the anvil the graduated edge of the thimble is exactly even with the line marked 0 on the sleeve and the 0 line on the thimble tallies with the horizontal line on the sleeve.

Now if you will open the micrometer by giving the thimble one full turn, or until the 0 line on the thimble again coincides with the horizontal line on the sleeve, the distance between the anvil and the sleeve is then tV of an inch, or .025 of an inch, and the graduated edge of the thimble will coincide with the second vertical line on the sleeve.

Each vertical line on the sleeve indicates a distance of tV of an inch; every fourth line is made

«m£ofA^'»»* m**em with

VERNIER READING TO /O.OOO™ Of AN INCH

Fig. 5. — The Micrometer

longer than the others and is numbered 0, 1, 2, 3, etc., and each line so numbered indicates a distance of four times j\ of an inch or iV.

The graduated edge of the thimble is marked in 25 divisions with every fifth line numbered from 0 to 25. When you turn the thimble from one of these marks to the next, you move the spindle up or down -jV of T!ihr or the T Av part of an inch. By turning it two divisions it shows two tcW, etc., while 25 divisions shows one complete turn or .025 of an inch, or ?V of an inch.

All you have to -do to read the micrometer, then, is to multiply the number of vertical divisions which you can see on the sleeve by 25 and all the number of divisions on the graduated edge of the thimble from the 0 line to the line which tallies with the horizontal line on the sleeve; multiply this number by 25 and add the number of divisions shown on the

^ LEVEL WJTH PLUA/B GL/7SS #T E/?CH END

ALCOHOL CENTER.

BL

TUBE

\ (L/NESj BL

PLUMB GLASS MARKED /?T /TS CENTER OP CROWN /NG POINT BY TWO UHES

Pig. 6. — A Level and Its Plumb Glass

bevel of the thimble. In the cut shown at A the micrometer is open 7 X 25 = 175 -f- 3 = 178 or tWo of an inch.

A Micrometer Reading to Teiv-Thousandths. — A vernier is used on a micrometer, see B, in order to read it to ttt.Wtt of an inch. To read a ttf.ttgt micrometer, first find the thousandths of an inch as described above, and then note the line on the thimble. If it is the second line, marked 1, add ttf.W; if it is the third line, marked 2, add tt»;!o"o, etc.

Ganges for Testing and Comparing.— Ganges

for every purpose to facilitate or to make more accurate the work of the mechanic can be bought at almost any hardware store. If you cannot get what you want, write Hammacher, Schlemmer & Co., Fourth Avenue and 13th Street, New York, and they will most likely be able to supply you with the tool you need.

One of the most common and useful gauges is the carpenter s or masons level, shown at A in Fig. 6. When you are putting in a foundation for either a building or for machinery, the first thing to do is to find whether the top of it is level. This is done with a level ; and to ascertain whether the side of the wall is plumb, an upright level, or plumb, must be used.

A spirit level consists of a sealed glass tube nearly filled with alcohol and having a bubble floating in it, as shown at B. This plumb glass, as it is called, is set in a stock, or length of wood, when the whole device is*called a level. When the level is laid on a level surface the bubble will be in the middle of the glass, but if the surface is not level the bubble will flow to one end or the other to indicate it.

Levels are usually made with two plumb glasses, one in the upper edge and one in the top of and at right angles to it, so that it can be used to find if the side of a wall, as well as the top of it, is level. A few of the more common gauges used by machinists are shown in Fig. 7.

The Protractor. — To find any angle or to plot one 20

/?- OUTSIDE CALIPERS & INSIDE CALIPERS

C

CREW THREAD GAUGE

D' WIRE GAUGE

F- THICKNESS GAUGE

E- DEPTH GAUGE

G-THREPD. SCREW H- TAPER GAUGE

AND TWIST DRILL GAUGE

Fig. 7. — A Few Other Useful Gauges 21 from 0 to 360 degrees, a protractor is used. This instrument is usually made in the shape of a semicircle and, as there are 360 degrees in a circle, there

Fig. 8. — The Protractor for Finding Angles and Measuring Them in Degrees A. — A Brass Protector graduated in single degrees B. — A German Silver Protector graduated in ^2 degrees

with vernier arm reading to 1 minute

are, of course, 180 degrees in a semicircular protractor. Each degree can be further divided into 60 minutes and each minute into 60 seconds, like the hour in our time system.

A brass protractor 3 J inches in diameter can be bought 5 for as little as 25 cents. One of this kind is shown at A in Fig. 8. For all ordinary work scale divisions of 1 degree, or ^ degree, will be found close enough; but where readings to minutes are needed a vernier protractor, as shown at B, must be used.

To use an ordinary protractor, place it on a sheet

, POLE

<S MEASURING O WHEEL

Fig. 9. — A Cheap Planimeter fob Measuring the Area of Any Plane Surface

of paper, lay a rule on top of it and keep its edge exactly over the nick in the middle of its straight edge. Then move the edge of the rule until it is on the line of the degree you want to mark off. Draw a line and you will have the angle you want.

The Planimeter.— This instrument gets its name from planus, which is Latin for flat, and meter, which comes from the Greek metron, meaning to measure. It is shown in Fig. 9.

It is so constructed that by a simple mechanical 6 L. E. Knott Apparatus Co., Boston, Mass.

operation the area of any flat figure, however irregular the boundary line of it may be and drawn to whatever scale, such as a plot of ground, plans, indicator diagrams, etc., can be easily and quickly measured.

The area of the plane figure is measured by merely tracing the outline with the tracing point and figuring the result from the reading on the graduated wheel. This wheel is divided into 100 parts, each of which represents tV of a square inch, and each 10th can be read down to lOOths by the vernier on the instrument.

The simplest and cheapest planimeter measures up to 10 square inches and costs about $15. It can be bought of Keuffel and Esser, 101 Fulton Street, New York, or of the L. E. Knott Apparatus Company, Boston, Mass.