PROPER USE AND CARE OF HAND TOOLS
 

SCREWDRIVERS
Basic Safety Rules | Driving the Screw | Clearance Holes | Screwdrivers for Slotted Screws | Ratchet Screwdrivers | Screwdrivers for Recessed Openings | Recessed Screws | Specialty Screwdrivers | Do's and Don'ts When Using Screwdrivers

INTRODUCTION

Next to the hammer, the screwdriver is probably the most abused tool in the homeowner's or professional's tool kit. Screwdrivers are available in a wide variety of shapes, sizes, and materials. But, they are all intended for one simple use: driving and withdrawing threaded fasteners such as wood screws, machine screws, and self-tapping screws. Unfortunately, the screwdriver is misused for prying, chiseling, scraping, scoring – and only sometimes for its intended use of driving screws!

However, the most common abuse is using a screwdriver that doesn't match or fit the screw. You wouldn't wear a pair of shoes that is too small or too big for your feet – you would be abusing your feet. For the same reason you should not use a screwdriver that is too small or too big for the screw it is to drive. Use the right screwdriver and you won't chew up the screw head, damage the screwdriver or bark your knuckles.

The abuse of a screwdriver – and the screw – is most often due to the fact that the homeowner or professional simply does not have a proper assortment of screwdrivers on hand.

A screwdriver should never be used as a pry bar. If it is over-stressed in this manner, the blade might break and send a particle of steel into the operator's arm or perhaps even into his eye.

Bear these points in mind when using a screwdriver; always match the size of the screwdriver to the job and always match the type of screwdriver to the head of the screw.


FIG. 1. Typical screwdrivers

  1. Stubby screwdriver for working in close quarters
  2. Screwdriver with a square shank to which a wrench can be applied to remove stubborn screws.
  3. Screwdriver for Phillips screws.
  4. Cabinet screwdriver has a thin shank to reach and drive screws in deep, counterbored holes.

After all, you wouldn't want to drive a large No. 12 screw with a small 3/32-or 3/16-inch screwdriver and neither would you drive a Phillips screw or other recessed screw with a conventional screwdriver.

Be careful not to confuse a Phillips screwdriver with other "cross point" screwdrivers. They are not interchangeable. See Page 41 for how they differ.

 



BASIC SAFETY RULES THAT APPLY TO THE USE OF A SCREWDRIVER

  1. Make sure that the tip fits the slot of the screw; not too loose and not too tight.
  2. Do not use a screwdriver as a cold chisel or punch.
  3. Do not use a screwdriver near live wires (or any other tool, for that matter).
  4. Do not expose a screwdriver to excessive heat.
  5. Redress a worn tip with a file in order to regain a good straight edge.
  6. Discard a screwdriver that has a worn or broken handle.
  7. A screwdriver should never be used as a pry bar. If it is over-stressed in this manner, the blade might break and send a particle of steel into the operator's arm or perhaps even into his eye.

FIG.2

  1. This tip is too narrow for the screw slot; it will bend or break under pressure.
  2. A rounded or worn tip. Such a tip will ride out of the slot as pressure is applied.
  3. This tip is too thick. It will only serve to chew up the slot of the screw.
  4. A chisel ground tip will also ride out of the screw slot. Best to discard it.
  5. This tip fits, but it is too wide and will tear the wood as the screw is driven home.
  6. The right tip. This tip is a snug fit in the slot and does not project beyond the screw head.

COMMON SLOTTED HEAD SCREWS

 

 

DRIVING THE SCREW

Always make a pilot hole before driving a screw. This is especially important when driving a screw into hardwood or when the screw is near the edge of a board. Pilot holes can be made in softwood, and in some hardwoods, with an awl – if the screws to be used are small. However, if you are driving No. 6 and larger screws it is best to drill a pilot hole or use a threaded screw hole starter. Pilot holes should always be made if the screws are to be driven into dense hardwoods.

If the screw is a flathead, the pilot hole should also be countersunk so the head of the screw will be flush with the work when it is driven home.


FIG. 4 THE RIGHT WAY TO DRIVE A SCREW

  1. Insert the tip of the screw in the pilot hole. Insert the screwdriver tip in the slot of the screw. Hold the tip steady with one hand and make sure the shank of the screwdriver is perpendicular to the head of the screw and in line with the shank of the screw.
  2. Use the left hand (if you are right-handed) to keep the blade steady as you turn the handle of the screwdriver.
  3. After the screw is almost in, it is safe to use both hands as shown for extra turning power to seat the screw. Note the position of the left hand (if you are right-handed). This will allow additional downward pressure to be applied, thus making certain that the driver tip is firmly seated in the screw slot. If the screw is a flathead, make sure that the pilot hole has a countersunk recess at top and screwdriver tip is narrow enough to avoid touching wood.

The job of driving the screw can be eased considerably if the threads are given an application of wax – this is preferable to soap, as soap has a tendency to rust the screw threads making possible future withdrawal difficult.

Unless you have drilled or made some sort of a pilot hole, a screw will tend to follow the grain of the wood. So, having drilled or made a pilot hole, hold the screw as indicated in Fig. 4 with the screwdriver tip firmly engaged in the slot. Turn the screwdriver gently to engage the first one or two threads of the screw and make sure that the screw is being driven straight. After the screw has been started, and you know it will be driven straight, remove your fingers from the screw and apply your talents and attention to the screwdriver. The screw should now be absolutely perpendicular to the surface of the work (unless the screw is to be driven at an angle) with the screwdriver held in line with the screw.

It is much easier to drive a screw straight if the handle of the screwdriver is large enough to maintain the necessary torque for the size of the screw to be used.

A good quality blade, properly hardened, is a must especially when driving large diameter screws into tough woods.




 

CLEARANCE HOLES

Sometimes a clearance hole, in addition to a pilot hole should be drilled in order to do a workmanlike job. For example, when fastening a metal bracket to wood or when screwing two pieces of wood together, a clearance hole equal to the diameter of the crew body or shank is necessary. Without the clearance hole, the body or the threads of the screw will hang up on the metal, or the leading piece of wood, preventing them from being drawn together tightly. See Fig.6.

FIG. 5. Screws are available in many lengths. However, the number by which a screw is designated, such as No. 10, always refers to its shank diameter. This drawing shows actual size screws and their corresponding number.

FIG. 6. A clearance hole is necessary when screwing two pieces of wood together.

FIG. 7. Cal is using the right technique in driving this screw home. The blade of the screwdriver is a snug fit in the slot of the screw and does not quite project to the edge.


RIGHT

 

 

SCREWDRIVERS FOR SLOTTED STYLE SCREWS

Now that we have learned a little bit of how to use a screwdriver, let's consider the various kinds of screwdrivers that are available and the right and wrong way to use – and abuse – these screwdrivers.

The so-called standard, or conventional screwdriver is used for screws with slotted heads. These screwdrivers are usually classified according to tip width and blade length. Generally, the longer the length, the wider the tip – but not always as some rather long screwdrivers may have a narrow tip. Cabinet style screwdrivers, which have long shanks and narrow tips, are useful for driving screws into recessed and counterbored openings in fine furniture and, obviously, cabinets. On the other hand there are short, stubby screwdrivers with rather wide tips for driving screws in confined quarters.


FIG. 8. Don't use a screwdriver whose tip extends beyond the length of the slot in the screw. Too wide a tip will chew up the wood as the screw is being driven home.

WRONG

The great assortment of screwdrivers available today means that you can buy a screwdriver in practically any length and in any tip size desired.

Most screwdriver tips are tapered. The tip thickness determines the size of the screw that the screwdriver will drive without damaging the screw slot. The taper permits the screwdriver to drive more than one size of screw.

FIG. 9. Careful Cal knows enough to drill plot and clearance holes when driving screws that are near the edge of a board. A little wax on the threads will ease the job.

RIGHT

Heavy duty screwdrivers are available with square shanks so that a wrench can be used on the shank for extra turning power. Never use pliers on a screwdriver shank when the going gets tough. You will only wind up by chewing up the shank. What to do in such a case? Use the largest possible screwdriver that will fit the slot of the screw. As a rule, the bigger the screwdriver, the larger the diameter of the handle, and the larger the diameter of the handle, the greater the torque, or turning power. If absolutely necessary, use a wrench on the shank to apply the extra power (torque) needed. But, use a wrench only on a screwdriver with a square shank especially designed for that purpose.

FIG. 10. Harry, you will always split the wood if you drive a screw too close to the end of the work without first drilling a pilot and clearance hole.

WRONG

 



RATCHET SCREWDRIVERS

One type of rapid-action screwdriver is the spiral ratchet screwdriver. This screwdriver has a springloaded mechanism in the handle. Pushing down on the handle causes the bit of the screwdriver to turn rapidly, thus driving the screw in a shorter time than could be accomplished with the use of a conventional screwdriver. Letting up on the handle allows the operator to continue the action. These screwdrivers come in several styles. Some have the mechanism as part of the handle; others have it as part of the shank. In either case a small lever is set so that even though the operator moves the handle back and forth – or up and down – the bit of the screwdriver moves in only one direction, to drive the screw. The lever can also be set so that the ratchet action removes the screw. And it also can be set so that the screwdriver can be used as a conventional screwdriver, with no ratchet action.

FIG. 11. Two types of ratchet screwdrivers. The one at the top has the ratchet mechanism in the handle. The lower screwdriver has the ratchet in the handle and operates with a spiral action.

When using any spiral ratchet screwdriver, it is best to push down firmly and slowly – until the screw is properly started – otherwise you may find that the bit has slipped out of the slot. These screwdrivers should be stored only in the extended position to prevent the possibility of a sudden, unexpected release by someone unfamiliar with the tool.

Large screws in tough wood can be easily driven by using special bits that fit into a carpenter's brace. Because tremendous turning power is generated by the brace, make sure you have a proper pilot hole, as it is quite easy to shear off the head or even twist the screw in half if too much pressure is applied to a balky screw. Needless to say, it is always best to drill a pilot hole when driving large screws with a carpenter's brace.

FIG. 12. Special screwdriver bit that can be chucked into carpenter's brace.



FIG. 13. Hazardous Harry strikes out again. Please, Harry, don't use pliers on the shank of a screwdriver in order to remove a stubborn screw.

WRONG

FIG. 14. Never, never use a screwdriver as a cold chisel. Just look what Hazardous Harry has done to the tip of a perfectly good screwdriver. In addition, our hero is not even wearing safety goggles.

WRONG

 

 


SCREWDRIVERS FOR SCREWS WITH RECESSED OPENINGS

The most common screw with a recessed "slot" is the Phillips screw. These screws have what appears to be two slots at right angles to each other. But, a conventional screwdriver should never be used to drive a Phillips screw – or any other type of a a screw with a specialized opening. Such screws are shown in Fig. 16. Always use the screwdriver especially designed to drive these fasteners.

 



RECESSED SCREWS AND SCREWDRIVERS


FIG. 16.

 

 

 

SPECIALTY SCREWDRIVERS

In addition to the types of screws and screwdrivers described so far, there are many screwdrivers whose use is quite specialized. Let us look at some.

Jeweler's Screwdrivers. These are distinguished by a rotating head which is held by the forefinger to steady the screwdriver while the thumb and middle finger turn the screwdriver to remove or install the small screws used by the jewelers, model railroad fans, and persons who work with tiny parts and screws.

FIG. 17. Jeweler's screwdriver, used with tiny screws, is steadied by placing forefinger on the free-turning knob.

Offset Screwdrivers. These screwdrivers are designed for removing and inserting screws in place where it is impossible to use a straight shank screwdriver. They are available in many combinations; narrow tip on one side and a wide tip on the other side; Phillips tip on one side and a conventional tip on the other side; with two Phillips tips (one large and one small); with same size tips at each end, but one tip is at right angles to the handle while the other tip is parallel to the handle (this arrangement makes the screwdriver extremely handy when turning area is limited).


FIG. 19. Offset screwdrivers for driving screws in awkward places.

FIG 20. A ratchet-type offset screwdriver for working in tight spots; it is reversible.

FIG 21. The screw-holding screwdriver is a must for working in close quarters as shown. The type shown at the left uses clips to hold the screw. The one at the right has a sliding collar that spreads the split blade of the screwdriver to hold the screw. After the screw has been firmly started, further driving can be done with a conventional screwdriver.

 


MAGNETIC TIP SCREWDRIVER

Interchangeable Magnetic Tip Screwdrivers. These screwdrivers have a magnet in the shaft so that they not only hold the bit but can also hold the screw. In addition, the variety of bits for this type of screwdriver is limitless and the unused bits can be stored in the handy compartmented handle.

Interchangeable Blade Screwdrivers. The hollow handle of this type of screwdriver will accept a number of different type blades. Sometimes the blades are double-ended with a narrow tip on one end and a wider tip on the other end. Combinations of Phillips, conventional, Clutch Head, Scrulox, and hex head are available.

Insulated Screwdrivers. These are used by electricians and maintenance workers. As their name implies, the shank as well as the handle are completely insulated with a dielectric material intended only as a secondary protection. Never depend on an insulated screwdriver handle, shank cover, or blade to insulate you from electricity. Insulated blades are intended only as a protective measure against shorting out components.

FIG. 22. Careful Cal is using an insulated screwdriver. Handle and shank are covered with an insulated material that is intended only for secondary protection. Turn off current when doing this kind of work.

RIGHT

FIG. 23. Two types of screwdrivers that use interchangeable bits. The one at the left has a hollow handle that will accept any one of the four bits shown. The screwdriver at the right has two double-ended bits held in each end of a tube. The tube is reversible in the handle and the bits are reversible in the tube.

FIG. 24. As usual, Hazardous Harry is wrong again. But this time on two counts. First of all, he never bothered to turn off the current before starting to work on that outlet. Secondly he doesn't seem to know enough to use an insulated screwdriver when doing such work.

WRONG

Non-sparking Screwdriver. Found chiefly on yachts and boats, these screwdrivers are made out of an alloy – usually beryllium copper – that will not emit a spark if accidentally struck against metal. They minimize the risk of explosion when used under hazardous conditions, such as when working in the hold of a ship that may be filled with gasoline fumes.

The Awl. A handy accessory to a screwdriver set is an awl. With it, you can make a starting hole in soft wood for a screw.

Force the awl into the wood with a twisting motion. The hole need not be as deep as the length of the screw. With large screws – and especially when working with hard wood – it is always advisable to first drill a pilot hole before attempting to drive the screw.

FIG 25. An awl can be used to make a starting hole for small screws in soft wood.

FIG 26. This device drills a pilot hole, a clearance hole, and countersunk recess for flathead screws all in one operation.

 


DO'S AND DON'T WHEN USING SCREWDRIVERS

  1. Don't hold the work in one hand while using the screwdriver with the other. If the screwdriver slips out of the slot (we told you to use the right size screwdriver!) you will be most likely to receive a gash on your hand.
  2. Don't use a screwdriver with rounded edges or tips; it will slip and cause damage to the work or yourself.
  3. A rounded tip should be redressed with a file; make sure the edges are straight.
  4. Don't use a screwdriver near a live wire or for electrical testing.
  5. Don't use a screwdriver to check a storage battery or to determine if an electrical circuit is live.
  6. Don't use a screwdriver for prying, punching, chiseling, scoring, or scraping.
  7. Use a screw-holding screwdriver to get screws started in awkward, hard-to-reach areas.
  8. Use an offset screwdriver in close quarters where a conventional screwdriver cannot be used.
  9. Use a ratchet-type screwdriver for speed and comfort when a great number of screws are to be driven.
  10. Don't use pliers on the handle of a screwdriver to get extra turning power. A wrench should only be used on the square shank or bolster of a screwdriver that is especially designed for that purpose.
  11. Don't expose a screwdriver blade to excessive heat as it may reduce the hardness of the blade.
  12. Don't use a screwdriver for stirring paint.
  13. Don't use a screwdriver with a split or broken handle.
  14. Screwdrivers used in the shop are best stored in a rack. This way, the proper selection of the right screwdriver can be quickly made.
  15. Keep the screwdriver handle clean; a greasy handle is apt to cause an accident.
  16. A screwdriver should never be used as a pry bar. If it is over-stressed in this manner, the blade might break and send a particle of steel into the operator's arm or perhaps even towards his eye.

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