p. 7
Judging from the favorable comments of educators, on the general arrangement of the subject matter in the work on "Carpentry for Boys," I am disposed to follow that plan in this book in so far as it pertains to tools.
In this field, as in "Carpentry," I do not find any guide which is adapted to teach the boy the fundamentals of mechanics. Writers usually overlook the fact, that as the boy knows nothing whatever about the subject, he could not be expected to know anything about tools.
To describe them gives a start in the education, but it is far short of what is necessary for one in his condition. If he is told that the chisel or bit for a lathe has a diamond point, or is round-nosed, and must be ground at a certain angle, he naturally wants to know, as all boys do,whyit should be at that angle.
So in the setting of the tools with relation to the work, the holding and manipulation of the file, of the drill for accurate boring, together with numerous little things, are all taken for granted, and the boy blunders along with the ultimate obp. 8ject in sight, without having the pathway cleared so he may readily reach the goal.
Varied Requirements.—The machinist's trade is one which requires the most varied tools of all occupations, and they are by all odds the most expensive to be found in the entire list of vocations.
Fig. 1. Bench Vise.Fig. 1.BenchVise.ToList
This arises from the fact that he must work with the most stubborn of all materials. He finds resistance at every step in bringing forth a product.
List of Tools.—With a view of familiarizingp. 9the boy with this great variety the following list is compiled, from which we shall select the ones essential in the initial equipment of a small shop.
Vises.—One small, good vise is infinitely preferable to two bad ones. For ordinary work a 3-inch jaw is preferable, and it should be firmly mounted on the bench. So many kinds are now made that it would be a costly thing to purchase one for each special use, therefore the boy will find it profitable to make some attachments for the ordinary vise.
Fig. 2. Pipe Grip for Vise.Fig. 2.PipeGripforVise.ToList
Swivel Vises.—A swivel vise is always a good tool, the cost being not excessive over the ordinary kind. Then a pair of grips for holding pipe, or round material which is to be threaded, can readily be made.
The drawing (Fig. 2) shows a serviceable pair of grips, made to fit the jaws of a vise, and willp. 10be acceptable in much of the work. Then, the vise should be provided with copper caps for the jaws to be used when making up articles which would otherwise be injured by the jaws.
Fig. 3. Swivel Vise.Fig. 3.SwivelVise.ToList
Let us get a comprehensive view of the different kinds of tools necessary in a fully equipped shop.
Parts of Lathe.—The first thing of importance is the lathe, and of these there is quite a variety, and among the accompaniments are the slide rest, mandrel, back gear, division plate, angle plate, cone plate and various chucks
p. 11
There must also be change wheels, studs and quadrant plates, self-acting feed for surfacing and cross slide, and clamping nuts.
Drilling machines, both hand and power, hand and ratchet braces and breast-drill stocks.
Fig. 4—Speed Lathe.Fig. 4.—Speed Lathe.ToList
Chisels.—Chisels of various kinds, for chipping and cross-cutting; round-nosed, centering, set punches, tommies and drifts.
Back, tee and centering square; bevels, spirit level, inside and outside calipers, straight edges, rules and surface plates
p. 12
Gages for boring, scribing blocks, steel and brass scribes, stocks and dies, screw-plates, taps for bolts, reamers.
Fig. 5. CalipersFig. 5.CalipersToList
Files for various descriptions, countersinks, frame and hack saws.
Grinding Apparatus.—Emery wheel, cloth and paper, paper, flour emery, polishing powders, laps and buffs, and polishing sticks
p. 13
Fig. 6. Engine Lathe.Fig. 6.EngineLathe.ToList
p. 14
Forge, anvils, tongs, swages, punches, bolt tools, hot and cold chisels, blow-pipe, soldering iron, hard and soft solders, borax, spirits of salts, oil, resin and spelter.
To this may be added an endless variety of small bench tools, micrometers, protractors, arbors, collets, box tools and scrapers.
Fig. 7. Center Gage.Fig. 7. Center Gage.ToList
Large Machines.—The list would not be complete without the planer, shaper and milling machine, with their variety of chucks, clamps and other attachments, too numerous to mention.
The foregoing show what a wonderful variety of articles are found in a well-equipped shop, all of which can be conveniently used; but to the boy who has only a small amount of money, a workable set is indicated as follows:
A small lathe, with an 8-inch swing, can be obtained at a low cost, provided with a countershaft complete.
Chucks.—With this should go a small chuck,p. 15and a face-plate for large work, unless a large chuck can also be acquired. This, with a dozen tools of various sizes, and also small bits for drilling purposes.
The lathe will answer all purposes for drilling, but small drilling machines are now furnished at very low figures, and such a machine will take off a great deal of duty from the lathe.
Fig. 8. Pocket Screw and Wire Gage.Fig. 8. Pocket Screw and Wire Gage.ToList
As the lathe is of prime importance, never use it for drilling, if you have a driller, as it always has enough work to do for tuning up work.
Bench Tools.—Of bench tools, a 3-inch vise, various files, center punch, two hammers, round and A-shaped peons, hack saw, compasses, inside and outside calipers, screw driver, cold chisels, metal square, level, straight edge, bevel square, reamers, small emery wheel and an oil stone, make a fairly good outfit to start with, and these can be added to from time to time.
Everything in the machine shop centers aboutp. 16the lathe. It is the king of all tools. The shaper and planer may be most efficient for surfacing, and the milling machine for making grooves and gears, or for general cutting purposes, but the lathe possesses a range of work not possible with either of the other tools, and for that reason should be selected with great care.
Fig. 9. Handy Bench Vise.Fig. 9.HandyBenchVise.ToList
Selecting a Lathe.—The important things about a lathe are the spindle bearings and the ways for the tool-holder. The least play in either will ruin any work. Every other part may bep. 17defective, but with solidly built bearing-posts and bearings, your lathe will be effective.
For this reason it will not pay to get a cheap tool. Better get a small, 6-inch approved tool of this kind, than a larger cheap article. It may pay with other tools, but with a lathe never.
Never do grinding on a lathe. The fine emery, or grinding material, is sure to reach the bearings; it matters not what care is exercised. There is only one remedy for this—overhauling.
Fig. 10.—Combination Square.Fig. 10.—Combination Square.ToList
Combination Square.—A tool of this kind is most essential, however small. It can be used as a try-square, and has this advantage, that the head can be made to slide along the rule and be clamped at any point. It has a beveling and a leveling device, as well.
p. 18Fig. 11.—Uses of the Combination Square.Fig. 11.—Uses of the Combination Square.ToList
The combination square provides a means forp. 19doing a great variety of work, as it combines the qualities of a rule, square, miter, depth gage, height gage, level and center head.
Fig. 12.—A Quick Adjusting Micrometer.Fig. 12.—A Quick Adjusting Micrometer.ToList
The full page illustration (Fig. 11) shows some of the uses and the particular manner of holding the tool.
Micrometers.—Tools of this description are made which will accurately measure work in dip. 20mensions of ten-thousandths of an inch up to an inch.
The illustration (Fig. 12) shows an approved tool, and this is so constructed that it can instantly be changed and set by merely pressing the end of the plunger as shown.
Fig. 13.—A Universal Bevel Protractor.Fig. 13.—A Universal Bevel Protractor.ToList
Protractors.—As all angles are not obtainable by the square or bevel, a protractor is a most desirable addition to the stock of tools. As one side of the tool is flat it is convenient for laying on the paper when drafting, as well as for use on the work.
The protractor has a graduated disk, and is adjustable so it can be disposed at any angle.
p. 21
Fig. 14.—Universal Bevel Protractor, showing its uses.Fig. 14.—Universal Bevel Protractor,showing its uses.ToList
p. 22
All special tools of this kind are serviceable, and the boy should understand their uses, even though he is not able for the time being to acquire them. To learn how they are applied in daily use is an education in itself.
Utilizing Bevel Protractor.—Examine the full-page illustration (Fig. 14), and see how the bevel protractor is utilized to measure the angles of work, whether it is tapering heads or different kinds of nuts, or end and side surfacing, and it will teach an important lesson.
Fig. 15.—Grindstone Truing Device.Fig. 15.—Grindstone Truing Device.ToList
Truing Grindstones.—Devices for truing up grindstones are now made, and the illustration (Fig. 15) shows a very efficient machine for this purpose. It can be applied instantly to the facep. 23of the stone, and it works automatically, without interfering with the use of the stone.
It is frequently the case that an emery wheel will become glazed, due to its extreme hardness. This is also caused, sometimes, by running it at too high a speed. If the glazing continues after the speed is reduced, it should be ground down an eighth of an inch or so. This will, usually, remedy the defect.
Fig. 16.—Set of Tools and Case.Fig. 16.—Set of Tools and Case.ToList
Sets of Tools.—A cheap and convenient set ofp. 24precision tools is shown inFig. 16, which is kept in a neat folding leather case. The set consists of a 6-inch combination square, complete center punch, 6-inch flexible steel rule center gage, 4-inch calipers, 4-inch outside caliper with solid nut, 4-inch inside caliper with solid nut, and a 4-inch divider with a solid nut.
Fig. 17. The Work Bench.Fig. 17.TheWorkBench.ToList
The Work Bench.—This is the mechanic's fort. His capacity for work will depend on its arrangement. To the boy this is particularly interesting, and for his uses it should be made full three inches lower than the standard height.
A good plan to judge of the proper height is to measure from the jaws of the vise. The top of the jaw should be on a level with the elbows. Grasp a file with both hands, and hold it as thoughp. 25in the act of filing across the work; then measure up from the floor to the elbows, when they are held in that position.
The Proper Dimensions.—This plan will give you a sure means of selecting a height that is best adapted for your work. The regulation bench is about 38 inches high, and assuming that the vise projects up about 4 inches more, would bring the top of the jaws about 42 to 44 inches from the floor. It is safe to fix the height of the bench at not less than 34 inches.
This should have a drawer, preferably near the right-hand end of the bench. The vise should be at the left side, and the bench in your front should be free of any fixed tools.
How Arranged.—Have a rack above the bench at the rear, for the various tools when not in use, and the rear board of the bench should be elevated above the front planks several inches, on which the various tools can be put, other than those which are suspended on the rack above.
The advantage of this is, that a bench will accumulate a quantity of material that the tools can hide in, and there is nothing more annoying than to hunt over a lot of trash to get what is needed. It is necessary to emphasize the necessity of always putting a tool back in its proper place, immediately after using
p. 26
It is singular, that with the immense variety of tools set forth in the preceding chapter, how few, really, require the art of the workman to grind and sharpen. If we take the lathe, the drilling machine, as well as the shaper, planer, milling machine, and all power-driven tools, they are merely mechanism contrived to handle some small, and, apparently, inconsequential tool, which does the work on the material.
Importance of the Cutting Tool.—But it is this very fact that makes the preparation of that part of the mechanism so important. Here we have a lathe, weighing a thousand pounds, worth hundreds of dollars, concentrating its entire energies on a little bit, weighing eight ounces, and worth less than a dollar. It may thus readily be seen that it is the little bar of metal from which the small tool is made that needs our care and attention.
This is particularly true of the expensive milling machines, where the little saw, if not in perfect order, and not properly set, will not only do improper work, but injure the machine itself.p. 27More lathes are ruined from using badly ground tools than from any other cause.
In the whole line of tools which the machinist must take care of daily, there is nothing as important as the lathe cutting-tool, and the knowledge which goes with it to use the proper one.
Let us simplify the inquiry by considering them under the following headings:
1. The grinder.
2. The grinding angle.
The Grinder.—The first mistake the novice will make, is to use the tool on the grinder as though it were necessary to grind it down with a few turns of the wheel. Haste is not conducive to proper sharpening. As the wheel is of emery, corundum or other quickly cutting material, and is always run at a high rate of speed, a great heat is evolved, which is materially increased by pressure.
Pressure is injurious not so much to the wheel as to the tool itself. The moment a tool becomes heated there is danger of destroying the temper, and the edge, being the thinnest, is the most violently affected. Hence it is desirable always to have a receptacle with water handy, into which the tool can be plunged, during the process of grinding down.
Correct Use of Grinder.—Treat the wheel asp. 28though it is a friend, and not an enemy. Take advantage of its entire surface. Whenever you go into a machine shop, look at the emery wheel. If you find it worn in creases, and distorted in its circular outline, you can make up your mind that there is some one there who has poor tools, because it is simply out of the question to grind a tool correctly with such a wheel.
Fig. 18-23 Hook, Parting, Knife, Right-hand, Internal, Left-hand side Tools.Fig. 18-23.Tools.ToList
Coarse wheels are an abomination for tool work. Use the finest kinds devised for the purpose. They will keep in condition longer, are not so liable to wear unevenly, and will always finish off the edge better than the coarse variety.
Lathe Bits.—All bits made for lathes are modifications of the foregoing types (Figs. 18-23, 19, 20, 21, 22, 23).
As this chapter deals with the sharpening methods only, the reader is referred to the next chapp. 29ter, which deals with the manner of setting and holding them to do the most effective work.
When it is understood that a cutting tool in a lathe is simply a form of wedge which peels off a definite thickness of metal, the importance of proper grinding and correct position in the lathe can be appreciated.
Roughing Tools.—The most useful is the roughing tool to take off the first cut. As this type of tool is also important, with some modifications, in finishing work, it is given the place of first consideration here.
Fig. 24shows side and top views of a tool designed to rough off wrought iron, or a tough quality of steel. You will notice, that what is called the top rake (A) is very pronounced, and, as the point projects considerably above the body of the tool itself, it should, in practice, be set with its cutting point above the center.
p. 30
The Clearance.—Now, in grinding, the important point is the clearance line (B). As shown in this figure, it has an angle of 10 degrees, so that in placing the tool in the holder it is obvious it cannot be placed very high above the center, particularly when used on small work. The top rake is ground at an angle of 60 degrees from the vertical. The arc of the curved end depends on the kind of lathe and the size of the work.
The tool (Fig. 25), with a straight cutting edge, is the proper one to rough off cast iron. Note that the top rake (C) is 70 degrees, and the clearance 15 degrees.
The Cutting Angle.—Wrought iron, or mild steel, will form a ribbon when the tool wedges its way into the material. Cast iron, on the other hand, owing to its brittleness, will break off into small particles, hence the wedge surface can be put at a more obtuse angle to the work.
In grinding side-cutters the clearance should be at a less angle than 10 degrees, rather than more, and the top rake should also be less; otherwise the tendency will be to draw the tool into the work and swing the tool post around.
Drills.—Holders for grinding twist drills are now furnished at very low prices, and instructions are usually sent with the machines, but a few words may not be amiss for the benefit of thosep. 31who have not the means to purchase such a machine.
Hand grinding is a difficult thing, for the reason that through carelessness, or inability, both sides of the drill are not ground at the same angle and pitch. As a result the cutting edge of one side will do more work than the other. If the heel angles differ, one side will draw into the work, and the other resist.
Wrong Grinding.—When such is the case the hole becomes untrue. The sides of the bit will grind into the walls, or the bit will have a tendency to run to one side, and particularly if boring through metal which is uneven in its texture or grain.
Figs. 26and27show end and side views of a bit properly ground. If a bit has been broken off, first grind it off square at the end, and then grind down the angles, so that A is about 15 degrees, and be sure that the heel has sufficientp. 32clearance—that is, ground down deeper than the cutting point.
Chisels.—A machine shop should always have a plentiful supply of cold chisels, and a particular kind for each work, to be used for that purpose only. This may seem trivial to the boy, but it is really a most important matter.
Notice the careless and incompetent workman. If chipping or cutting is required, he will grasp the first chisel at hand. It may have a curved end, or be a key-way chisel, or entirely unsuited as to size for the cutting required.
The result is an injured tool, and unsatisfactory results. The rule holds good in this respect as with every other tool in the kit.Use a tool for the purpose it was made for, and for no other. Acquire that habit.
Cold Chisels.—A cold chisel should never be ground to a long, tapering point, like a wood chisel. The proper taper for a wood chisel is 15 degrees, whereas a cold chisel should be 45 degrees. A drifting chisel may have a longer taper than one used for chipping.
It is a good habit, particularly as there are so few tools which require grinding, to commence the day's work by grinding the chisels, and arranging them for business.
System in Work.—Then see to it that the drillsp. 33are in good shape; and while you are about it, look over the lathe tools. You will find that it is better to do this work at one time, than to go to the emery wheel a dozen times a day while you are engaged on the job.
Adopt a system in your work. Don't take things just as they come along, but form your plans in an orderly way, and you will always know how to take up and finish the work in the most profitable and satisfactory way.
Wrong Use of Tools.—Never use the vise as an anvil. Ordinary and proper use of this tool will insure it for a lifetime, aside from its natural wear. It may be said with safety that a vise will never break if used for the purpose for which it was intended. One blow of a hammer may ruin it.
Furthermore, never use an auxiliary lever to screw up the jaws. If the lever which comes with it is not large enough to set the jaws, you may be sure that the vise is not large enough for your work
p. 34
Some simple directions in the holding and setting of tools may be of service to the novice. Practice has shown the most effective way of treating different materials, so that the tools will do the most efficient work.
A tool ground in a certain way and set at a particular angle might do the work admirably on a piece of steel, but would not possibly work on aluminum or brass.
Lathe Speed.—If the lathe should run at the same speed on a piece of cast iron as with a brass casting, the result would not be very satisfactory, either with the tool or on the work itself.
Some compositions of metal require a high speed, and some a hooked tool. These are things which each must determine as the articles come to the shop; but there are certain well-defined rules with respect to the ordinary metals that should be observed.
The Hack Saw.—Our first observation should be directed to the hand tools. The hack saw is one of the most difficult tools for the machinist to handle, for the following reasons:p. 35
First, of the desire to force the blade through the work. The blade is a frail instrument, and when too great a pressure is exerted it bends, and as a result a breakage follows. To enable it to do the work properly, it must be made of the hardest steel. It is, in consequence, easily fractured.
Fig. 28.—Hack Saw Frame. Fig. 29.—Hack Saw Blade.Fig. 28.—Hack Saw Frame.Fig. 29.—Hack Saw Blade.ToList
Second. The novice will make short hacking cuts. This causes the teeth to stick, the saw bends, and a new blade is required. Take a long sweeping cut, using the entire length of the blade. Do not oscillate the blade as you push it through the work, but keep the tooth line horizontal from one end of the stroke to the other. The moment it begins to waver, the teeth will catch on the metal on the side nearest to you, and it will snap
p. 36
Third. The handle is held too loosely. The handle must be firmly held with the right hand, and the other held by the fingers lightly, but in such a position that a steady downward pressure can be maintained. If loosely held, the saw is bound to sag from side to side during the stroke, and a short stroke accentuates the lateral movement. A long stroke avoids this.
The hack saw is one of the tools which should be used with the utmost deliberation, combined with a rigid grasp of the handle.
Files.—For remarks on this tool seeChapter IV, which treats of the subject specially.
Grindstones, Emery and Grinding Wheels.—A good workman is always reflected by his grinding apparatus. This is true whether it has reference to a grindstone, emery, corundum wheel, or a plain oil stone. Nothing is more destructive of good tools than a grooved, uneven, or wabbly stone. It is only little less than a crime for a workman to hold a tool on a revolving stone at one spot.
Carelessness in Holding Tools.—The boy must learn that such a habit actually prevents the proper grinding, not only of the tool he has on the stone, but also of the one which follows. While it is true that all artificially made grinders will wear unevenly, even when used with the utmost care, due to uneven texture of the materials in the stone, still,p. 37the careless use of the tool, while in the act of grinding, only aggravates the trouble.
Another fault of the careless workman is, to press the bit against the stone too hard. This cuts the stone more than it wears off the tool, and it is entirely unnecessary. Furthermore, it heats up the tool, which should be avoided.
Calipers.—A true workman, who endeavors to turn out accurate work, and preserve his tools, will never test the work with his calipers while the piece is turning in the lathe. A revolving cast iron disk will cut ruby, the hardest substance next to the diamond, so it is not the hardness of the material which resists wear, but the conditions under which it is used.
Care in Use of Calipers.—The calipers may be of the most hardened steel, and the work turned up of the softest brass, the latter, when revolving, will grind off the point of the tool, for the reason that the revolving piece constantly presents a new surface to the point of the calipers, and when tests are frequently made, it does not take long to change the caliper span so that it must be reset.
As stated elsewhere, the whole energy of the lathe is concentrated on the bit or cutting tool, hence, in order to get the most effective work out of it requires care; first, in grinding; and, second, in setting
p. 38
Machine Bits.—It does not always matter so much whether you use a square, pointed, or a round-nosed bit, provided it is properly ground and set in the tool holder. As a rule, the more brittle the metal the less the top rake or angle should be.
In the chapter relating to the grinding of tools, references were made as to the most serviceable bits for the various metals. We are concerned here with the setting or holding of these articles.
The two illustrations here given show a pair of plain bits, in whichFig. 30represents a hook-shaped formation, andFig. 31a straight grind, without any top rake. The hooked bit would do for aluminum, or steel, but for cast iron the form shown inFig. 31would be most serviceable.
Then the side bits, such as the round-nosed,Fig. 32and the square end,Fig. 33, may be ground hooked, or with a top rake, or left flat.
The too common mistake is to grind the lower or clearance side at too great an angle.Fig. 34p. 39shows the correct angle, and the dotted line A illustrates the common tendency to grind the clearance.
The Proper Angle for Lathe Tools.—Now there is a reason why the angle of from 10 to 15 should be maintained in the clearance. The point of the tool must have suitable support for the work it is required to do, so it will not chatter or yield in the slightest degree. A bit ground along the dotted line has a cutting edge which will spring down, and consequently break or produce a rough surface.
Figs. 32, 33, 34. Proper Angles for ToolsFigs. 32, 33, 34.Proper Angles for ToolsToList
Then, again, the angle of the clearance acts as a guide, or rather, a guard, to prevent the tool from going in too far, as will now be explained.
Setting the Bit.—In order to understand the correct setting, examine the work A, inFig. 35.
A is a cylinder being turned up in the lathe, and B the cutting tool, which approaches it on a horip. 40zontal line, C, extending out from the center of the cylinder A. This setting is theoretically correct, and in practice has been found most advantageous.
In this case let us assume that the clearance angle D is 15 degrees, as well as in the following figures.