1. Hardware and Fastener Identification Screws, with Descriptions
By Dave Wilson
Information Technology and Communication Services
ITCS Instructional Materials
College of Agricultural, Consumer and Environmental Sciences
University of Illinois at Urbana-Champaign
Copyright © 2008 – University of Illinois Board of Trustees
D-JH

2. Table of Contents - Screws
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Flat head wood slotted ….……………..…...
Flat head wood (brass) ..……………………
Round head wood (brass) ..……………......
Round head wood slotted ……………....…
Oval head wood slotted ….….………...……
Phillips-drive bugle head ……
Phillips-drive galvanized bugle head .……
Round head machine slotted .……….……
Round head machine slotted ……….…....
Flat head machine slotted …………..….…
Fillister head machine slotted ……….…...
Oval head machine slotted ………….…....
Pan head machine slotted …………….….
Round head machine (with square nut) ...
Phillips pan head self-drilling ……..……...
Hex washer head self-drilling ….....……..
Pan head sheet metal square-drive …..…
Phillips pan head sheet metal …… 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Oval head tamper proof ………………….…
Hex washer head sheet metal slotted …….
Pan head sheet metal slotted ……………...
Hex washer head with neoprene washer ....
Square head lag bolt ………………….……..
Phillips bugle head deck ……………….……
Hollow-wall fastener (molly screw) …….…..
Thumbscrew …………………………….…...
Eye hook ……………………………….……..
Screw hook ……………………………….…..
L-hook …………………………………….…..
Hex drive cup pointed set ……………....….
Phillips flat head wood ………………….…..
Stove bolt ……..……………………………...
Phillips flat head masonry …… ……..
Hex washer head masonry ……….………...
Pole barn …………………….………...…….. 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
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3. Screw, flat head wood slotted
Screws with a smooth shank and a tapered point are for use on wood and simulated-wood products. Flat head wood screws are designed to be installed until the head is flush with the wood surface. The slotted wood screw is driven with a standard screwdriver blade.
Wood screws range in size from #3 to #14. Length is measured from the top of the screw head to the end of the point. Flat head wood screw sizes are written, for example, as #8 x 1-1/4 to represent a #8 screw that is 1.25 inches long.
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4. Screw, flat head wood (brass)
Flat head wood screws are available in different materials, such as steel, brass, stainless steel, and aluminum. Screws made of the softer metals are easily damaged if caution is not used when driving them.
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5. Screw, round head wood (brass)
Round head wood screws are available in different materials, such as steel, brass, stainless steel, and aluminum. Screws made of the softer metals are easily damaged if caution is not used when driving them.
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6. Screw, round head wood slotted
Screws with a smooth shank and a tapered point are for use on wood and simulated-wood products. Round head wood screws are designed to be installed until the head makes contact with the wood surface. The slotted wood screw is driven with a standard screwdriver blade.
Wood screws range in size from #3 to #14. Length is measured from the bottom of the screw head to the end of the point. The size of a round head wood screw is written as, for example, #8 x 1-1/4 to represent a #8 screw that is 1.25 inches long.
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7. Screw, oval head wood slotted
Screws with a smooth shank and a tapered point are for use on wood and simulated-wood products. Oval head wood screws are designed to be installed until the center of the head is flush with the wood surface. The slotted wood screw is driven with a standard screwdriver blade.
Wood screws range in size from #3 to #14. Length is measured from the center of the screw head to the end of the point. Oval head
wood screw sizes are written, for example, as #8 x 1-1/2 to represent a #8 screw that is 1. 5 inches long. Oval head wood screws are typically used with trim washers.
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8. Screw, Phillips-drive bugle head (drywall or wallboard)
Phillips bugle head screws are also called drywall screws and are used to attach drywall to both wood and metal studs. These screws are made from hardened steel, with a very sharp point. Drywall screws are typically #6 or #8 in diameter and range in length from 3/4 inch to 4 inches.
Drywall is typically installed with the 1-1/4 inch length. The head of the screw is normally driven so the paper side of the drywall is just dimpled and not broken. This dimple leaves a space for joint compound to hide the screw head. Drywall screws are driven in drywall about every 8 inches.
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9. Screw, Phillips-drive galvanized bugle head
Bugle head screws have become very popular with wood projects and are available with various surface treatments to be used in both outdoor and indoor applications.
Galvanized screws are dipped in zinc and have a silver/zinc color.
Galvanized bugle head screws are available in lengths from 1 inch to 4 inches.
Use caution when installing long screws, as excess torque can twist the head off the screw.
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10. Screw, round head machine slotted
Machine screws are recognized by the nontapered shank and machine threads. Machine screws are widely used in general assembly. They are manufactured in several head styles.
Screw diameter is listed as a number ranging from #0 to 1/2 inch and in lengths from 1/8 inch to 3 inches. Metric sizes are also manufactured.
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11. Screw, round head machine slotted
Machine screws with slotted heads are turned with a standard screwdriver. The length of a round head machine screw is the distance from the bottom of the screw head to end of the screw.
Machine screw size is stated, for example, as #8 – 1 to represent a #8-diameter machine screw that is 1 inch long.
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12. Screw, flat head machine slotted
Flat head machine screws are designed to be installed so the head is flush with the surface. The length of a flat head machine screw is the measured distance from the top of the head to the end of the screw.
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13. Screw, fillister head machine slotted
The standard oval fillister head has a smaller diameter than the round head, but is thicker, with a correspondingly deeper slot. The smaller-diameter head increases the pressure applied on the smaller area and can be assembled close to flanges and raised surfaces.
The head is formed in counterbored dies to ensure a round head. These screws may be used successfully in counterbored holes.
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14. Screw, oval head machine slotted
Oval head machine screws are similar to other machine screws, with the exception that the head is oval when viewed from the side. When an oval head screw is installed, a portion of the head is below the surface, and only a small portion of the screw head projects above the surface.
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15. Screw, pan head machine slotted
Pan heads are recommended for new designs to replace round, truss, and binding heads. This type of machine screw provides a low, large-diameter head, but a characteristically high outer edge along the outer periphery of the head. The outer edges of the head are where driving action is most effective for high-tightening torques. Recessed heads have a slightly different head contour.
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16. Screw, round head machine (with square nut)
Round head screws are not recommended for new designs; the pan head is the recommended replacement for round head machine screws. The round head was the most universally used design in the past.
A disadvantage of the round head is the thin layer of metal near the outer edges of the head, where most of the drive torque is applied. This head design is prone to stripping out the slot when a high torque is applied.
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17. Screw, Phillips pan head self-drilling
Pan heads are recommended for new designs to replace round, truss, and binding heads. This head style provides a low, large-diameter head, but characteristically high outer edge along the outer periphery of the head. The heads are thickest where driving action is most effective for high-tightening torques.
The heads have a slightly different contour where manufactured with a slotted head. Slotted pan heads are a little less crowned in the center, as compared to a Phillips drive head.
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18. Screw, hex washer head self-drilling
Hexagon washer head screws are produced in the same manner as the standard hexagon head but with a washer section in the base of the head to protect the finish of the assembly from the wrench during assembly.
The self-drilling point makes this screw well suited for installation with drill drivers. Self-drilling screws remove metal to make a hole, compared to self-tapping screws that displace metal as they create a hole for the screw shank.
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19. Screw, pan head sheet metal square-drive
A square-drive screw is less prone to torque out of the screw head (compared to Phillips) and creates a positive drive. Tapping screws fall into two categories: thread-cutting and thread-forming. Thread-cutting screws remove metal during the formation of threads. Thread-forming screws displace metal when driven, instead of removing it; thus, they form a chip-free mating thread.
The threads extend the entire length
of the screw. This makes it possible to join metal that is held tightly against the underside of the screw head. The sharp point on sheet metal screws enables the screw to pierce thin sheet metal and start forming threads.
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20. Screw, Phillips pan head sheet metal
The pan head provides greater driving torque in these screws. The sheet metal screw design has a pointed tip that is very sharp so it can penetrate and start in sheet metal.
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21. Screw, oval head tamper proof
This ingenious tamper proof type of head, once assembled, cannot be removed but is driven with a standard screwdriver.
This screw is popular due to the amazing economy in producing it in large quantities. This simple design can frequently solve costly assembly problems and maintain tamper proof construction.
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22. Screw, hex washer head sheet metal slotted
An indented hexagon head sheet metal screw is an inexpensive wrench head fastener made to standard hexagon dimensions. The hex head lends the screw to power-driver installation. The hex is created completely in a counterbored die and has an identifying depression in the top surface of the head.
The washer section in the base of the head protects the finish of the assembly from the wrench during assembly.
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23. Screw, pan head sheet metal slotted
Pan heads are recommended for new designs and to replace round, truss, and binding heads. The design provides a low, large-diameter head. The head is characteristically thicker at the outer edges, compared to other designs. This is important, as the outer periphery of the head is where driving action is most effective for high-tightening torques.
The sheet metal point on the screw is tapered at the tip and threaded the entire length of the shank. These screws work best when a clearance hole is predrilled.
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24. Screw, galvanized hex washer head with neoprene washer
Hex washer head screws with a neoprene washer are typically used to install finished metal siding without damaging the siding and roofing. The neoprene washer also makes a weather-tight seal where the screw passes through the metal.
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25. Square head lag bolt
A lag bolt is described as a heavy wood screw with a square or hexagonal head that is to be driven in with a wrench. Lag bolts are used in wood construction and may have other uses.
Minimum thread length is normally equal to half the nominal length of the bolt plus 1/2 inch or 5 inches, whichever is less.
Hex lag bolts larger than 3/4 inch in diameter and all square lag bolts are rarely available in the marketplace as stock items. The square head lag bolts are used for aesthetic applications and provide a rustic look.
Lag bolt sizes range from 1/4 inch to 1-1/2 inches in diameter and are manufactured up to 18 inches long.
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26. Screw, Phillips bugle head deck
Bugle head screws have been developed for several special uses. The deck screw is an example; these screws have coarse threads and have been treated with a green coating to resist corrosion and to match the green treated lumber. These screws are available with Phillips, square, and Torx drive heads. Both Phillips and Torx are positive drive with less tendency to torque out of the drive when high torques are applied. Screws are manufactured in several lengths. Select screws at least twice as long as the deck material.
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27. Hollow-wall fastener (molly screw)
Hollow-wall fasteners are used to support objects that hang on walls and cannot be attached to the structural framing material. A hole is drilled into the wall just large enough to insert the fastener. With the fastener inserted into the hole, the screw is tightened, causing the body of the fastener to expand, holding the washer end of the fastener tight to the wall. The screw can then be turned out to create an anchor to attach an item on the wall.
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28. Thumbscrew
A thumbscrew is typically used as a set screw on items that require frequent adjustment. The large, flat head makes gripping easy and provides some leverage while turning the screw. These screws are designed for light loads and are manufactured in many screw sizes to 3/8-inch diameter.
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29. Eye hook
An eye hook is a tapered screw shank with an eye where the head of a screw would be located. Eye hooks are also called eye screws. The screw shank can be screwed into a wooden object leaving the eye above the surface. The eye is typically round and has many uses.
Eye screws are sized starting with screw sizes and are available through 5/8-inch diameter; these screws are manufactured in several lengths.
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30. Screw hook
A screw hook is an open hook on one end, with a screw shank designed to be turned into wood or other materials. Screw hooks are manufactured in small screw sizes through 3/8-inch diameter. The length of the shank can vary and is selected for a specific application.
Screw hooks are inserted into a predrilled hole and turned by the hook end; use caution as the hook may cause injury.
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31. (square-bent screw hook)
L-hook
(square-bent screw hook)
The L-hook looks like a 90⁰ turn on the end of a screw shank. These hooks are used for many different tasks and are available in sizes starting with small screw diameters to 3/8-inch diameter and varying lengths; they are selected for a specific use.
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32. Screw, hex drive cup pointed set
Set screws are commonly used to hold a collar, pulley, gear or the like to a rotating shaft to keep their position relative to each other during use. Cup pointed set screws are some of the most commonly used set screws. The cup point on one end of the set screw cuts into the shaft through a threaded hole in the pulley, collar, or sprocket hub. The cup point then holds the piece in place during use.
Set screws have socket, slotted, square, or hex heads. Socket heads are popular, as selecting the set screw length is less important than with other head designs.
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33. Screw, Phillips flat head wood
Screws with a smooth shank and a tapered point are for use on wood and simulated-wood products. Flat head wood screws are designed to be installed until the head is flush with the wood surface. The Phillips wood screw is driven with a Phillips screwdriver blade. The three most common sizes are Phillips #1, #2 (most popular), and #3.
Wood screws range in size from #3 to #14. Length is measured from the top of the screw head to the end of the point.
Flat head wood screw sizes are written, for example, as #8 x 1-1/4 to represent a #8 screw that is 1.25 inches long. Phillips drive is popular with modern drills/ drivers, as they keep the bit centered in the screw head.
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34. Stove bolt
Stove bolts got their name because they were commonly used to assemble stoves and stove parts. These fasteners have screw heads (flat, oval or round) for use with screwdrivers and range in diameter from 1/8 to 1/2 inch. Lengths vary from 1/2 inch to 6 inches.
Because stove bolts have the screw drive on one end, they have limited application.
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35. Screw, Phillips flat head masonry
Concrete screws are used to attach items to concrete through a predrilled hole. The threads on the screw are designed to cut into the concrete to hold the screw in place. The flat head is typically used when the screw must be flush with the surface.
These screws are typically available in 5/32- and 3/16-inch diameters and in lengths from 3/4 inch to 4 inches. The shanks on these screws are hardened to withstand high torque loads during installation.
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36. Screw, hex washer head masonry
Concrete screws are used to attach items to concrete through a predrilled hole. The threads on the screw are designed to cut into the concrete to hold the screw in place. The hex head is typically used when the screw is not required to be flush with the surface.
These screws are typically available in 5/32- and 3/16-inch diameters and in lengths from 3/4 inch to 4 inches. The shanks on these screws are hardened to withstand high torque loads during installation.
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37. Screw, pole barn
Pole barn screws have been developed to attach metal siding and roofing material to pole buildings. The head is designed with a hex washer style for efficient installation with power tools. The screw also has a neoprene washer under the head to prevent leaks. The screw shank is threaded its entire length, with a pointed end, creating a self-starting feature.
When used to install metal roofing, the screw is typically inserted at one of the vertical or near vertical surfaces to reduce leaking. It is never inserted in the valley of the roofing material.
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38. University of Illinois
The End
This set of images was photographed by David Riecks and Dave Wilson, ITCS, College of Agricultural, Consumer and Environmental Sciences, University of Illinois. The presentation was reviewed by Dr. Joe Harper, Department of Agricultural and Biological Engineering at the University of Illinois.
University of Illinois
1917 South Wright Street
Champaign, IL 61820
(800)
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