"Boring tools are very interesting," said Ralph. The brace and bit for soft woods have practically taken the place of the old fashioned augers, gimlets, etc. The reason is not hard to find. An auger or gimlet could bore but one size of hole, while with a brace and set of bits almost any diameter can be secured. A little later on, I'll tell you about a Yankee invention along this line.

"The brace is a sort of universal tool holder, and any tool designed to fit into it is known as a bit, as for example a countersink bit, or a screw driver bit, and several varieties of drills.

"The shank, or part that fits into the brace, is usually square and tapering, and the part of the brace which engages this shank is called the 'chuck.' (Fig. 120.)

"The centre bit, an old-fashioned form, had all the necessary features of a good boring tool but one. It had a sharp centre for accurately locating the hole, a knife edge for cutting the fibres, and a chisel for removing the wood, but it lacked the spiral screw thread of the modern tool, and had to be forced through the wood by main strength. On a modern auger bit, this spiral screw relieves the worker of a large part of the labour; all he has to do is to turn the brace and keep it straight, supposing of course that the bit is sharp. (Fig. 121.)

"The auger bit is most commonly used by woodworkers. It has two knife edges and two chisels besides the spiral spur in the centre. A short form of this tool, called the dowel bit, has the advantage of bending less readily than the ordinary auger bit. The size in sixteenths of an inch is stamped into the metal shank, but if this number is not distinct or for any reason is missing, the diameter may be measured by holding the rule across the knife edges."

"What's the Yankee invention you were going to tell me about?" interrupted Harry."Well, suppose you wanted to bore a large hole, say 2¹/₂ inches in diameter, the probabilities are that you wouldn't have a bit that size. In fact, to have a full set of bits from ³/₁₆ inch up to 3 inches would mean a very expensive lot of tools. This difficulty has been overcome by a very clever invention called the extension or expansive bit. (Fig. 122). On this tool the knife edge and chisel are part of a moving lip, which may be fastened at any desired point by means of a set screw.

"Besides being adjustable in diameter, the lip of the bit has a scale, and the body a single line engraved on it. By bringing this line to the various measurements on the scale, you can set it to a definite size without the trouble of measuring it.

"The tool has certain limitations, of course. It is made in two sizes; one will bore holes of any size from ¹/₂ inch up to 1¹/₂ inches, and the other any size from ⁷/₈ inch to 3 inches, while extra lips or cutters are made to bore as large as 4 inches, but if you ever try to bore a hole of this size you will want all your muscle."

The screw-driver bit is simply a screw-driver with a bit shank instead of a wood handle, and the countersink has a cone-shaped end with enough grooves cut in it to give one or more cutting edges. Its use was illustrated in making the bench hook and shooting board.

The gimlet bit may be used for boring holes for screws. It is made from ²/₃₂ inch up to ¹²/₃₂ inch, and is valuable for preparing articles for the smaller-sized screws where the auger bit would be too large.

We find for sale drill bits for electricians, warranted to go through a nail if necessary, and dozens of special bits.

In working with thin wood, the auger bit is very apt to split it, especially brittle woods, like red gum. Even this contingency is provided for in the Forstner bit, which will bore a hole in a sheet of paper (Fig. 123), and is therefore very valuable for work in veneering or other very thin material.

The brace is represented by several styles and makers, but the beginner must look for the same qualities in the brace as he would in any other tool—good workmanship and material, simplicity and durability.

The old-fashioned Spofford brace was strong, simple, and reliable. For working in corners or any place where a full revolution of the tool is not possible, a ratchet attachment is necessary. This is found on most of the modern tools, and may be obtained at any hardware store. (Fig. 124).

The hand drill (Fig. 125) is one of the most useful tools any one can have about the shop or the house. To be able to make holes in soft or hard wood, tin, zinc, brass, copper, or iron is certainly a great advantage, and some form of the tool should be in every establishment. Our boys found it useful in making moving toys, wind vanes, anemometers, and dozens of other pieces, and never regretted its cost. It may be bought for fifty cents and upward, a very good one costing about $1.50. The drills designed to be used with this tool vary by ¹/₆₄ inch, beginning with ⁵/₆₄ inch up to ³/₈ inch. Above this a larger chuck is required. They have round shanks instead of the ordinary square bit shank.