Braces and Drills
The carpenter's brace appeared in early fifteenth century Europe. Its main advantage for boring holes was that it gave a continuous and positive turning movement to the bit, instead of the intermittent action of gimlets, augers or bow and strap drills used previously.
The first braces all had fixed bits. By the sixteenth century each bit fitted into a wooden holder or "pad", which could then be held in a tapered hole in the stock with pins, wedges or screws. After the eighteenth century, the pads were dispensed with and a V-shaped notch was filed in the tangs of the bits which engaged with a springed pawl in the chuck. Wooden braces of this type were in common use until about 1900.
The Spofford split chuck brace of 1859 with a metal sweep did away with the need to notch the bits. In 1864 it was superseded by the "Barber" screwed shell chuck with springed jaws. This was soon fitted with a ratchet and is the standard type in present use.
Most early braces were fitted with shell or spoon bits similar in shape to the contemporary augers and gimlets. The first twist or screw augers appeared before 1800, but auger bits for use in braces came later; the Jennings pattern in 1855 and the solid core Irwin bits in 1884. Early forms of centre bit were used in the eighteenth century; the present form was finalized about 1800. The French call them "English three-point bits", indicating their probable origin. The expanding forms of centre bit date from Clarke's patent of about 1890.
The hand drill seems to have been first developed in France or Germany; one of the earliest was shown by Bergeron in 1816. The bevel gear wheels, with a ratio of 1:1, were carried in a U-shaped forging and driven by a small crank. In 1846 a side handle had been fitted and the gear ratio raised to about 3:1. The first American hand drills, introduced about 1870, carried the gears on an open-work iron frame and had a long, turned handle.
Brace
SIZE: Sweep: 5in., 8in., 10in., 12in., 14in.
MATERIAL: Frame: steel;
Head handle: hardwood, plastic
ACCESSORIES: Drill bits, screwdriver bit, countersink bit
USE: To bore holes in wood
The brace applies a turning force to the bit by the rotation of the frame in a clockwise direction. The amount of space taken up by this action is known as "the sweep", and the size of tilt- brace is given in terms of this measurement. Many braces have a ratchet fitted to the chuck, which allows the tool to be used in confined spaces where a complete sweep is impossible.
The plain brace, without the ratchet attachment, is the standard model.
Fitting the bits
Most bits used with the brace have a square tang at the end of the shank, which is gripped by "V" grooves in the jaws. Some braces have universal jaws, which will also take round shank bits. AH brace bits have their diameter size stamped into the tang. Engaging the ratchet To engage the ratchet on a ratchet brace turn the cam ring clockwise against the stop.
This will provide torque in a clockwise direction only, leaving the frame to move freely in the anti-clockwise direction. For the reverse effect, turn the cam ring in an anti-clockwise direction. Using the brace For easy location of the bit, you can either mark the centre of the hole with a bradawl or, if working in hardwood, drill a ^m. pilot hole.
Fitting a bit to a ratchet
Locate the cam ring in its central position. Turn the frathe clockwise until the jaws open to take the bit. Locate the tang in the "V" grooves. Check that the bit is square in the jaws before turning the frame anticlockwise to tighten the chuck.
Drilling horizontally
Position the bit, hold the head of the brace in one hand, supported by the body, and place the other, hand on the handle. Move the head to square up the brace with the work and turn the frame clockwise while applying pressure to the head.
Drilling vertically
Apply pressure to the head with one hand. A square placed close to the brace will help as a guide to alignment.
Clearing waste
The waste from a deep hole must be cleared periodically. To extract the bit, reverse the action on a couple of turns releasing the lead screw, then turn the frame clockwise while pulling on the tool.
Avoid splitting out the back of the work by either clamping a block of waste lumber to the back or removing tie tool as soon as the lead screw appears. Then pick up the exit hole and drill out the remaining waste from the back.
Joist Brace
SIZE: Handle: 11-1/2 in.
MATERIAL: Lever chuck: steel; Head handle: plastic
ACCESSORIES: Drill bits, screwdriver bit, countersink bit
USE: To drill in restricted space, such as between joists
The chuck and ratchet of the joist brace is constructed in the same way as a standard brace, but instead of the conventional frame there is a lever at right angles to the line of the drill bit. With the ratchet set correctly, the lever is worked back and forth to turn the bit, while force is applied to the head mounted directly behind the chuck. This makes it a useful too! for work in a confined space where the handle of the conventional brace could not be fully rotated.
Maintenance
A modern brace requires very little maintenance other than an occasional oiling of the chuck mechanism, head and handle. Keep the bits sharp to produce clean accurate work.
Corner Brace
OTHER NAME: Gear frame brace SIZE: Sweep: 8 and lOin.
MATERIAL: Frame: steel; Headihandle: hardwood, plastic
ACCESSORIES: Drill bits, screwdriver bit, countersink bit
USE: To drill in a restricted space such as into a baseboard
On a corner brace the conventional brace frame is fitted at an angle to a gear housing. This allows the chuck to be turned even when it is operating against a surface which would prevent a normal sweep.
Pressure is applied on a handle mounted at the back of the tool.
Centre Bit
OTHER NAME: Screw point bit
SIZE: Length: 4 to 6in.; Diameter: 1/4 to 2-1/4 in.
MATERIAL: Steel
USE: To drill holes in wood
The centre bit has a solid, cylindrical shank with a square section tang which fits into the chuck of a brace. The cutting end of the bit has a helical twist which gives two cutting edges, a lead screw in the centre, and a single spur on one side to score the surface grain of the wood before the bit enters.
Once the lead screw has "taken" in the work, it will draw the bit after it with the minimum of pressure.
Auger Bit
OTHER NAME: Twist bit
SIZE: Jennings pattern: Length: 8 to 10in.; Diameter: 1/4 to 1-1/2
in.
Solid centre: Length: 8 to 10in.; Diameter: 1/4 to 1-1/2 in; Length:
12 to 18in.; Diameter: 1/4 to 1in.
MATERIAL: Steel
USE: To drill holes in wood
There are two patterns of auger bit: the Jennings, or double twist, and the solid centre.
The Jennings pattern has a double helical twist which clears the waste from the hole as it progresses into the work. The solid centre has a single helical twist around a solid shank, which runs the whole length of the bit. This is the stronger version and is favored for very long bits.
The main advantage of the auger bit, apart from efficient waste clearance, is that it is easier to keep centreed in a deep hole.
Expansive Bit
SIZE: Small: 1/2 to 1-1/2 in.; Large: 7/8 to 3in.
MATERIAL: Steel
USE: To drill holes of various size in wood
The expansive bit is similar in form to a solid centre bit, but has an additional, adjustable spurred cutter which moves out from the centre to enlarge the cutting diameter of the bit.
Adjusting the bit
The cutter is calibrated to show the diameter it will cut at any one setting.
It is held by a screw fixed packing piece which releases for resetting, or a
toothed, calibrated dial, which is turned for resetting.
Forsther Bit
SIZE: 3/8 to 2in.
MATERIAL: Steel
USE: To drill holes in wood
Unlike the bits with a lead screw at the centre, the Forsther bit must be used under pressure in order to cut into the work. The cutting end has a deep rim and a small pointed centre, which means that it cuts a clean hole with a flat bottom and will not wander off centre by following the grain. Its accuracy makes it very useful for veneer work and pattern making.
Countersink Bit
SIZE: 3/8. 1/2. 5/8 in.
MATERIAL: Steel USE: To recess a hole to accept a countersunk head screw
The cone-shaped cutting end of the countersink bit matches the countersunk head of a wood screw. The bit is fitted into a brace and held vertically in the centre of a clearance hole already drilled in the work. Then it is rotated until it cuts a recess that will allow the screw head to lie flush with the wooden surface.
The "rosehead" type shown here is the commonest, but there is a fiathead countersink bit, with two cutting edges and a flattened, V-shaped head, which is used to countersink hinges.
Turn Screw Bit
OTHER NAME: Screwdriver bit
SIZE: Length: 4 to 6in.; Blade width: 3/8 in., 1/2 in., 3/4 in.
MATERIAL: Steel
USE: To drive screws with the aid of a brace
The turn screw bit is useful for driving large screws. It has a fiat, screwdriver blade and a square tang which fits into the chuck of a brace. The pressure and extra torque provided by the brace make a very powerful screwdriver.
Hand Drill
OTHER NAME: Wheel brace
SIZE: Length: 9 to 13in.; Capacity: Up to 5/16-in.
MATERIAL: Frame body: cast iron, aluminum or zinc; Gear wheels: cast iron; Handles knobs: hardwood, plastic
ACCESSORIES: Twist drills
USE: To drill holes in wood and metal
The hand drill combines hand drive and gear ratio to provide a range of convenient speeds for different materials and types of work. The large gear wheel drives one or two pinions which apply torque to the chuck. On some models, the drive crank can be lengthened to provide greater torque. More modern drills have their gears completely enclosed in a cast body to protect ihem from dust.
The chuck usually has three self-centreing jaws.
Fitting the bits Holding the large gear wheel, turn the chuck shell anticlockwise to open the jaws. Centre the drill bit in the jaws and tighten them by turning the chuck clockwise. Check the accurate alignment of the bit before you finally tighten the jaws.
Using the hand drill
The hand drill is often used to drill pilot holes for screws or larger holes. With softwood and a small hole, it may not be necessary to mark the centre, but if the work is important or is in hardwood, start the hole with a bradawl.
For drilling in metal you will need a centre punch to mark the hole and prevent the drill wandering. Most metals need some sort of lubricant when they are being drilled.
Maintenance
Occasionally clean away dust from around the gear wheel and pinions and oil them lightly if necessary
Starting the drill
With the bit centreed, start the hole by gripping the gear wheel between thumb and fingers. Rotate the bit backward and forward to establish it then, grasping the gear wheel handle, use the tool at the required speed. A high speed with light feed will be necessary if you are drilling with small bits, to prevent them catching and possibly breaking as they enter the work.
Breast Drill
SIZE: Capacity: up to 1/2 in.; Length: 11 to 18in.
MATERIAL: Frame body: cast iron, steel, aluminuim or zinc; Gear wheels: cast iron Handles: hardwood, plastic; Breastplate: cast iron I
ACCESSORIES: Twist drills, masonry bit
USE: To drill holes in wood, metal and masonry
The breast drill is a larger version of the hand drill, the addition of saddle-shaped plate fited to the top of the frame. You can lean on this to apply pressure. They are also fitted with a handle with which you can steady the tool.
Most breast driills have two speeds. These are are selected by engaging different sized gear wheels either by fitting the drive crank onto the appopriate drive spigot, or by fitting the whole drive gear in one of two positions which automatically engages the required gear.
Push Drill
SIZE: Length: 10-1/2 to 11 in,
MATERIAL: Combination of steel, plastic and aluminum
ACCESSORIES: Driill points
USE: To drill small holes in wood and plastic
The push drill takes special bits known as drill points, which are single, straight fluted bits ranging in size from 1/16 to 11/64 in. The bits aire stored in the handle of the tool.Torque is applied to the drill point bv applying pressure to the handle of the drill.
Fitting the drill point
The drill point is fitted in the same way that bits are fitted to the hand drill. Take care to seat the point carei'miy before tightening the chuck.
Using the drill
To prevent the poiint wandering, start the hole with an awl. The drill point cuts on the forward stroke. When pressure is released, the handle returns, ready to repeat the action.
Power Drill
SIZE: Chuck capacity: 1/4 in., 3/8 in., 1/2in. 3/4in. 1 in,1-1/4 in; Speed: 2,750 to 3,500 rpm
MATERIAL: Various
ACCESSORIES: Drill bits, countersink bit, screw driver bit, plug cutter, bit extension, depth gauge, flexible drive, angled drive
ATTACHMENTS: Circular saw, jig saw, hole saw, saw bench, horizontal drill stand, vertical drill stand, sanding disks, sanding drums, finishing sander, buffs, wire brushes, grindstones and disks, rasps and iiles, lathe, hedge trimmer, paint spraying compressor, paint stirrer, pump
USE: To drill holes in various materials and coupled with attachments to perform a multitude of tasks
The power drill together with its many attachments and accessories, is probably the most versatile power tool available. It is also manufactured in many forms and sizes, which makes choosing the tool to suit your needs a complex task. In most cases it is advisable to choose the most versatile tool, unless you have to perform one task repeatedly, which is normal only in an industrial situation. Generally speaking, the attachments will not perform any one task as well as a specially made machine. For domestic use you must weigh versatility against efficiency.
Sizes and speeds
There are many different types of drill manufactured around the world, and the specifications given must be regarded as a guide only. Drills are specified by their chuck capacity and fall into three categories for domestic use: 1/4 in., 3/8 in., and 1/2in.; 3/4in. and over are available for industrial use. Smaller capacity drills can be used to drill larger holes by-fitting them with spade bits, power bore bits or hole saws, which have narrow shanks compared with their heads.
Normally, the bigger the chuck capacity the larger the motor. As the power increases, the speed will reduce to give the extra torque needed when drilling large holes in masonry or steel.
Speed selection by slide
There is quite a variation in the speed rating of a drill. It may have from one to four fixed speeds selected by a slide control or turn button, which may be converted to constantly variable speeds controlled by pressure on the trigger. A variable speed is essential if you want to use the drill to drive screws, and is also very useful when starting a hole. A reversing switch will allow the drill to withdraw screws. Fast speeds make clear cuts in wood.
When using attachments, select the speed recommended by the manufacturer.
Slacken or tighten the self-centreing jaws with a chuck key. Before finally tightening the jaws check that the bit is centreed.
Removing the chuck
Engage the lowest speed and insert the chuck key. Holding the body of the drill firmly, strike the key with a mallet to spin the chuck rapidly and then unscrew it by hand. Some models are disconnected by using a wrench on the chuck.
OTHER FEATURES
Handgrips
Most drills have a secondary handle, which helps to steady the tool. This is particularly important with the larger drills, which could slip out of the operator's grip, if the bit becomes caught in the work. Heavy duty drills are provided with another grip at the back, where extra pressure can be applied.
Heavy duty drills A large extra handle at the back of the tool gives extra pressure and control.
Trigger lock
Once the trigger has been operated, it can be locked into a position for continuous running by a button, usually located to the left of the handgrip. Subsequent depression of the trigger will automatically release the button. This facility is essential if the tool is to be set up in any kind of bench attachment.
Variable speed drills either lock when the motor has reached top speed or, in a few cases, can be locked at any required speed.
Hammer action Some drills are fitted with a hammer action to assist when drilling concrete, stone or even hard brick. The tool will deliver 500 blows per second as the drilling progresses, which breaks up the masonry ahead of the drill tip. Even when the selector is engaged the hammer action is not activated until pressure is applied to the drill bit. Special percussion drill bits are needed for use with the hammer action.
Soft masonry such as brick or cement blocks can be drilled with standard masonry bits and the drill set on the slow speed only.
Safety factors
Before making any adjustments to the drill, disconnect it from the power supply to prevent accidental starting. Remove the chuck key before starting up the drill. Follow the safety advice given for specific attachments by the manufacturer.
Ensure that plugs are properly grounded and that your electrical circuit is fused to take the load of the drill.
Insulation
This is the international symbol for double insulation. Modern drills which are double insulated do not require grounding.
Do not pull out the plug, or carry the drill by the cable. Examine the cable regularly for signs of damage. Keep the cable away from the moving parts of of the drill when in use. Avoid wearing loose clothing or jewelry, which could get caught up in the moving parts of the drill.
Twist Drill
OTHER NAME: Morse drill
SIZE: Diameter: 1/64 to 1/2 in.; reduced shank drills: 1/2 to 3/4 in.
MATERIAL: Steel
USE: To drill holes in various materials
The twist or Morse drill (named after its inventor), was developed to clear the swarf or waste rnaterial from deep holes. There are two helical flutes running approximately two thirds along the length of the cylindrical drill, leaving the plain shank to fit into the drill chuck. The edges of the spirals, called the "margins", form the actual outside diameter of the bit, the rest being slightly cut away to reduce the friction on the sides of the hole. The cutting edge is known as the lip. The lip is ground to an angle of 59 for cutting metal. For practical purposes, this is also suitable for wood, although the recommended angle is approximately 45.
Carbon steel drills are only suitable for cutting wood, whereas a high speed drill can be used to work metal as well.
Maintenance
It is important to have sharp drills for accurate work. Before using the bit, clear away wood waste which may have become packed into the flutes.
Drills need to be lubricated when drilling metal to prevent overheating, as follows: steel and wrought iron: machine oil; aluminum: kerosene; cast iron and brass: can be drilled dry.
Drilling
Although twist drills can be used on wood they are more efficient for
drilling metal. The workpiece must be held securely by clamps or in a vise.
Mark the centre of the hole with a punch making a recess which will prevent
the tip of the drill wandering off line.
Check that the drill is centreed before the body of the tool enters the work. To realign the drill, use a round nosed or diamond point cold chisel to cut a groove in the side of the depression closest to the original centre. This will encourage the drill to move in that direction until it is centreed again.
Large holes must be started with a small pilot hole. The point of the larger drill will automatically follow the line of this hole. Drill very large holes with several drills gradually enlarging the pilot hole.
Do not force a drill to cut too fast as this will wear the drill. Try to prevent the drill suddenly emerging from the underside of the work. It is liable to catch in the resulting burrs and either break, or spin the workpiece. A slow controlled exit will not produce a large burr and will result in a clean cut.
If the drill catches as it exits when drilling thin sheet metal regrind the tip of the drill to a shallow angle. Backing up the workpiece with hardwood can prevent breaking out.
Twist drills can be used to work lumber, but tend to wander in the direction of the grain. Bits with a lead point or screw are more suitable.
Dowel Bit
SIZE: Diameter: 1/8 to 1/2 in.
MATERIAL: Steel
USE: To drill holes in side and end grain of wood
Dowel bits are similar in construction to the Morse drill, but they have two spurs and a centre point to prevent them following^ the grain and wandering off centre.
Brad Point Power Bore Bit
SIZE: Diameter: to lin.
MATERIAL: Steel
USE: To drill holes in wood when used with a power drill
The long lead point of the power bore bit gives excellent location in the centre of the hole to be drilled. The shank is narrowed to fit into the chuck of the average electric drill, and UTTING the shank end has flats ground into it for positive grip in the jaws of the chuck.
Spade Bit
OTHER NAME: Flat bit
SIZE: Diameter: f to l^in.
MATERIAL: Steel
USE: To drill holes in various materials when used with a power tool
The spade bit is suitable for use in both cross grain and end grain lumber and works equally well in both composite boards and plastic ones. The lead point gives positive location of the bit even when drilling at an angle. In order to work efficiently, it must be run at high revs, say between 1,000 to 2,000 rpm.
Countersink Bit
SIZE: Head diameter: 3/8 in., 1/2in., 5/8fin.; Length: 2in.
MATERIAL: Steel
USE: To recess a hole to accept a countersunk head screw when used with a power tool
Carbon steel countersink bits are available for cutting wood only, but a high speed bit, which wili cut metal, wood or plastic with equal ease, is preferable.
Both bits function in the same way.
Drill and Countersink Bit
SIZE: Various: matched to screw sizes
MATERIAL: Steel
USE: To drill pilot hole, shank clearance hole and countersink in one operation
The drill and countersink bits are designed to give exactly the right length and clearance to match given screw sizes.
Drill and Counter Bore Bits
SIZE: Various: matched to screw sizes
MATERIAL: Steel
USE: To drill pilot hole, shank clearance hole and counterbore in one operation
Having drilled a pilot and clearance hole, the spurs will score the surface of the lumber before counter boring to the required depth.
Plug Cutters
SIZE: Various: matched to size of counter bore bits
MATERIAL: Steel
USE: To cut wooden plugs to fit the hole cut by counter bore bits
Sometimes it is necessary to cover a counter bored screw with a wooden plug. The plug cutter makes a plug which matches the grain of the work piece and is an exact fit in the hole allowing for the glue. Plugs can be flush or button tipped.
Masonry Drill
MATERIAL: Shank: toughened steel; Tip: tungsten carbide
USE: To drill holes in brick, stone, concrete and ceramic tiles
Masonry bits will drill a hole which is an exact fit for wall plugs. The hard tungsten carbide tip of a masonry drill is electronically brazed to the shank with either brass or copper. The copper brazed tip is able to withstand much higher temperatures. To make a hole for wall plugs, set the electric drill at a slow speed to avoid overheating.
During the operation, partially withdraw the bit occasionally to clear the spoil. It is usually necessary to drill slightly deeper than the length of the plug which will tend to pack down loose dust as it is inserted. When drilling through plaster always make sure that the hole goes right through to the solid masonry beyond.
Special percussion drills are needed when using a power tool with a hammer action on tough masonry. They have a shatter-proof tip and narrower fluting to provide maximum strength to the shank.
Glass Drill
OTHER NAME: Spear point drill
SIZE: 1/8 to 1/2 in.
MATERIAL: Shank: toughened steel; Tip: tungsten carbide
USE: To drill holes in glass, mirror and porcelain
The glass drill can be used in a hand or power drill set at a slow speed. Lay the glass on a flat surface, build a wall of putty or plasticine around the intended hole and fill with turpentine, kerosene or water to cool the drill. Place the drill bit in position before applying power; a variable speed power drill is ideal for this operation. As soon as the drill point exits from the underside of the glass, reverse the workpiece and drill from the other side.
Depth Gauge
OTHER NAME: Bit gauge
SIZE: Various
MATERIAL: Various
USE: To regulate-accurately the depth of a hole being drilled
The depth gauge for a power drill is an adjustable rod attached to the body of the drill Itself or to a secondary handle.
Using the gauge
Set the rod the required hole depth behind the drill tip and lock in place. When the rod comes into contact with the surface remove the drill.
Ready-made plastic gauges fit twist or masonry drills.
Improvising a gauge
The simplest method of marking a bit for the required depth is to wrap a
piece of self-adhesive, masking or insulating tape around it as your
guide
Power Drill Extension
SIZE: 12 and 18in.
MATERIAL: Steel
USE: To extend the reach of power bore bits
The socket of the extension takes the shank of whatever power bore bit you are using, and is secured with a set screw. The other end of the extension fits into the drill chuck.
Flexible Drive
OTHER NAME: Flex shaft
SIZE: 30 to 52in.
MATERIAL: Various
USE: To provide a flexible and portable power source
Small attachments such as rotary files and rasps, polishers and wire brushes are more easily controlled in one hand if they are fitted into a flexible drive. Power is transmitted from an electric drill through a spiral steel cable to a portable chuck. The cable is protected by a flexible steel casing.
The flexible drive also provides power in a restricted space which may be inaccessible to a power drill.
Right Angle Drive
MATERIAL: Various
USE: To provide torque to a drill bit, which is used at right angles to the power source
The right angle drive also reduces or increases the speed of the drill depending on which end of the accessory is attached to the tool. Remove the chuck from the drill, fit the right angle drive, and then fit the chuck to the other end of it.
