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Home Screws Thread

The point style of screws is for tapping, cutting, or drilling through the desired material. Threaded fasteners are used in varied industries and applications around the world. You will get here the minute details vital to identifying the thread type and size suited for a given application.

The screw threads designed for industrial use are known as machine screw threads and they are manufactured to align the threaded nuts or holes with a matching diameter & thread count. The screws use UTS (Unified Thread Standards) for styling and are available in UNF (Unified National Fine) & UNC (Unified National Coarse). The sizes below ¼" use numbers to describe the diameter and fractions are used for screw measuring ¼" & higher.

Coarse Coarse (UNC) Fine (UNF) 8-Thread (UNS) Other Other
#0   0-80      
#1 #1-64 #1-72      
#2 #2-56 #2-64      
#3 #3-48 #3-56      
#4 #4-40 #4-48   #4-36 #4-32
#5 #5-40 #5-44      
#6 #6-32 #6-40      
#8 #8-32 #8-36      
#10 #10-24 #10-32      
#12 #12-24 #12-28      
1/4" (#14) 1/4-20 1/4-28      
5/16" 5/16-18 5/16-24      
3/8" 3/8-16 3/8-24      
7/16" 7/16-14 7/16-20      
1/2" 1/2-13 1/2-20      
9/16" 9/16-12 9/16-18      
5/8" 5/8-11 5/8-18      
3/4" 3/4-10 3/4-16      
7/8" 7/8-9 7/8-14      
1" 1-8 1-12 1-14    
1 1/8" 1 1/8-7 1 1/8-12 1 1/8-8    
1 1/4" 1 1/4-7 1 1/4-12 1 1/4-8    
1 3/8" 1 3/8-6 1 3/8-12 1 3/8-8 1 3/8-4  
1 1/2" 1 1/2-6 1 1/2-12 1 1/2-8    
1-5/8"     1 5/8-8 1 5/8-8  
1-3/4" 1 3/4-5   1 3/4-8 1 3/4-12  
1-7/8" 2-4.5     1 7/8-12 1 7/8-5
2" 2-4 1/2   2-8 2-12  
2-1/4" 2 1/4-4 1/2   2 1/4-8 2 1/4-12  
2-1/2" 2 1/2-4   2 1/2-8 2 1/2-12  
2-3/4" 2 3/4-4   2 3/4-8 2 3/4-12  
3" 3-4   3-8 3-12  
3 1/4" 3 1/4-4   3-1/4-8    
3 1/2" 3 1/2-4   3-1/2-8    
3 3/4" 3 3/4-4   3-3/4-8    
4" 4-4   4-8    

Machine Screw Threads are designed to mate with preformed threads in the following:

  • Machine Screws
  • Socket Screws
  • Hex Head Cap Screws
  • Socket Screws
  • Socket Set Screws
  • Socket Shoulder Screws
  • Self Tapping Screws
  • Precision Shoulder Screws
  • Thumb Screws
  • Wing Screws
  • Types F, 1 and 23 Thread Cutting Screws
  • Thread Forming Screws for Metal
  • Some Self-Drilling Screws
  • Weld Screws
  • Serrated Hex Flange Screws
  • Hanger Bolts (1 Side Only)
  • Threaded Rod
  • Most Bolts
  • All Nuts

The most common thread type is machine screw threads. Screws with machine screw threads are designed to align with a threaded nut or hole with a matching diameter and thread count. They use Unified Thread Standard (UTS), and are generally available in UNC (Unified National Coarse) and UNF (Unified National Fine) options. Sizes below 1/4" (0.25") use numbers to describe their diameter, while screws 1/4" and higher use fractions. Their sizes are described first with the diameter, followed by a hyphen, and then with the count of threads per inch. (Examples: 4-40, 10-32, ¼-20)

What is the pitch? It is the distance between threads, measured in millimeters. Metric Machine Screws are noticed in metric diameter and thread pitch. Have a look at the metric screw and bolt sizes –

M1.6-0.35 M2-0.4 M2.5-0.45 M3-0.5 M3.5-0.6
M4-0.7 M5-0.8 M6-1.0 M7-1.0 M8-1.25
M10-1.5 M12-1.75 M14-2.0 M16-2.0 M18-2.5
M20-2.5 M24-3.0      

Concrete screws are considered 'self-tapping' screws as they cut their own threads into concrete, brick and other masonry materials. The hole must be drilled using a carbide drill bit that meets ANSI standards. The hole drilled in the masonry must be slightly deeper than the screw will penetrate to allow space for the dust that is created during the taping process to fall into and out of the way. Concrete screws feature high and low double lead threads with notched high threads. Diamond shaped, nail point helps with self starting in hard, dense material.

Deck screws and construction screws both fall under the general heading of wood screws. In addition to their identical classification, deck and construction screws exhibit the same basic design – prominent, notched threads take up about half of the screw's length, while the other half consists of a solid metal bar that ends in the screw head. Most construction and decks screws also possess a shoulder, or textured area between the thread and bar that helps anchor the screw in wood.Used in woods with medium density. Dacrotized steel provides corrosion resistance and doesn't discolor wood. ACQ compatible screws are designed to use in treated lumber. Stainless steel options are also offered in a type 17 point which has a chip cavity to assist with driving.As a general rule, the major difference between construction screws and deck screws lies in their size. Construction screws are much longer than deck screws.

Drywall screws (sometimes called sheetrock screws) provide a stronger hold, but cost a bit more than nails.

Coarse drywall screws feature coarse threads to secure gypsum boards to studs and .feature an extra sharp point, spaced threads and typically a black phosphate finish. Coarse-thread drywall screws work best for most applications involving drywall and wood studs. The wide threads are good at gripping into the wood and pulling the drywall against the studs.

Fine drywall screws feature double lead threads for easier self starting which makes them work well for metal studs. Coarse threads have a tendency to chew through the metal, never gaining proper traction. Fine threads work well with metal because they are self-threading.

Self-drilling screws you're attaching drywall to heavy-gauge metal, look for self-drill/self-tapping drywall screws. A self-drill/self-tapping drywall screw features a small drill tip, deep-grooved threading and the trumpet head of a drywall screw.

High Low Thread drywall screws High-Low Thread style screws exceed the holding power of standard drywall screws in wood due to their design of alternating high and low thread heights. They can also be used with metal studs up to 20 gauge.

Lag screws are some of the toughest types of screws out there. Also called lag bolts, lag screws are generally used to connect heavy lumber and other materials that bear an intense load. Featuring a hex head, widely spaced threads and a gimlet point, lag screws are most commonly used in wood or with lag screw shields. Larger diameters generally require pre-drilled pilot holes.The hex head lag screw is designed that way since hex headed fasteners are made to hold up in applications where a lot of torque is necessary. Lag screws have sharp lead thread points (gimlet) and are available in Steel/Zinc, Stainless Steel, and Steel/Hot Dip Galvanized.

Self-Drilling Screws (sometimes incorrectly referred to as self-tapping screws) enable drilling without first creating a pilot hole. Self-drilling screws or (SDS's) are usually used to join materials like sheet metal to other materials, such as metal or wood.Similar to sheet metal screws, but self-drilling screws have a drill-shaped point to cut through sheet metal or steel which eliminates the need for drilling a pilot hole. We offer the best self-drilling screws that are designed for use in soft steel or other metals. Self-drilling screw points are numbered from 1 through 5, the larger the number, the thicker metal it can go through without a pilot hole. A 5 point can drill a 1/2 inches (13 mm) of steel.

• BSD thread- Standard Self-Drilling Style Screws – featuring spaced threads and a drill bit styled point. This is the most popular style of thread. Most standard self-drilling screws don't conform to UNC (Unified Coarse Thread) or UNF (Unified Fine Thread) standards.Screws of this type are classified as BSD

• CSD Thread (Machine Screw Thread) - machine screw thread pitch and a drill point which drills its own hole. Normally used with thicker materials. A ¼" diameter screw would be shown as ¼"-20 with 20 threads per inch (similar the machine screws).

Also called 'ZIP' screws, needlepoint screws, speed, pencil point,'saber' or twin-fast screws, self-piercing screws have extra sharp tips that can penetrate even the thickest sheet metal. Designed for fastening the hardest substances and the most precise applications, stainless steel and zinc plated steel Zip screws are offered with a huge variety of lengths and thicknesses to meet the needs of any industry.Used in thin metals, often metal roofing for barns and other outbuildings. The sharp tip allows for self starting without drilling pilot holes, while the twin lead threads reduce driving torque. These are externally threaded fasteners with the ability to self-pierce light gauge metal and tap their own mating threads when driven. Self-Piercing zip screws are high strength fasteners with sharp angles of 25 to 30 degrees.

Most screws with pointed tips can fall under the "self tapping" name, but at Newport Fasteners we categorize self drilling and self tapping as separate styles.The baseline capability of the self-tapping screw is its enhanced penetrating capability, thanks to the 'tapping' action created by cuts in the screw threads to create a 'twin-lead' thread. Many self-tapping screws are also self-drilling, and apart from blunt-edged self-drilling screws used for closely fitted substrates, all self-tapping screws have sharp points to help them penetrate the metal or plastic.

Type A Point - Widely spaced threads and always fully threaded, these screws have the same thread counts as standard wood screws. The only difference being that wood screws are partially threaded.Type A Point Self-tapping screws require a pilot hole slightly smaller than the screw diameter to be created before they can be driven into the material with a screwdriver. They are used in thin metal, resinous plywood, and various composite boards.

Type AB Point - Features finer threads for better hold in thin sheet metal. Like the Type A, they are used in thin metal, resinous plywood, and various composite boards. Recommended over type A for resin filled plywood and other brittle materials.Type AB screws offer a wider range of applications over Type A screws.

Type B Point - Type B tapping screws have spaced threads and a blunt point with incomplete entering threads. They are used in thin metal, nonferrous castings, resinous plywood, plastics, and various composite boards.The point is applied to self tapping screws and generally specified where the screw is being driven into a shallow hole.Type B points provide for more full threads to be engaged in the material being fastened.

Type U Point (U Drive Screw) –U-drive screws (also known as hammer drive screws or metallic drive screws) are unslotted round head self tapping screws oftenused for attaching nameplates in castings and for sealing drain holes in corrosion proofing tubular structures.They possess multiple start threads with large helical angles and an unthreaded pilot point. Similar to nailsthey are driven into mating parts with a mallet or hammer for a quick and permanent assembly. No tappedthreads are required in the mating part. However, the u-drive screw must be of harder material than themating part and a undersized pre-drilled pilot hole is required.Designed for tamper proof fixing in plastic and metal castings. It features multiple start, very coarse spiral threads, is driven with a hammer and usually has a round or button shaped head.

These styles of screws cut matching threads into the materials into which they are installed. Sharp cutting edges assist with driving, while a variety of chip cavity styles help with clearance of cut materials.

Type F Machine screw threads, a blunt point and multiple cutting edges, these screws are used in heavy gauge sheet metal, aluminum, zinc and lead die castings, cast iron, brass and plastics.

Type 1 Point - Generally used in softer metals such as steel sheets, alloy steels, cast iron, brass and plastics. A thread cutting screw with single flute for general use. Produces a fine standard machine screw thread for field replacement.

Type 23 Point –In thicker building materials such as plywood, hardboard or cement sheet, the addition of wings cuts a slightly oversize. thread cutting screw in the fine thread series offeringmaximum thread cutting area and excellent chip clearing, with minimumtightening torques.

Type 25 Point – A point designed to cut through threads in plastic material. The presence of the shank slot provides theability and also the clearance of cutting chips.A thread cutting screw similar to type 23 point exceptwith coarse Type B thread. For plastics and other soft materials withlarge chip clearing and cutting edges.

Type 17 Point - Similar to the Type AB point, except that the screw material has been cut away this provides the ability for the screw toself drill through thin metal and then drill into timber members of the structure.

Rather than cutting threads into materials, thread forming screws create threads by compacting and creating pressure against the walls of the materials it is installed into.

High Low Style - Used in softer materials such as plastic, nylon and wood. Double lead thread design reduces torque requirements, improves pullout strength and lessens the risk of damaging or cracking materials. Designed for plastic materials it combines two thin walled threads, one higher, one lower. This gives a high pull out strength coupled with reduced incidence of plastic cracking.

Trilobe TFS for Metal - Generic alternatives to TAPTITE® screws, trilobular design allows for lower driving torque, eliminates chips and resists vibrational loosening.These screws have a tapered tri-lobular thread which roll forms its own mating thread whilst being driven into a prepared hole. Because of the resultant snug fit of the threads, the screw is vibration resistant. It can also be replaced by a conventional screw. Suitable for steel, die casting, aluminium.

TFS for Plastics -Generic alternatives to PLASTITE® screws, they also feature a trilobular design with widely spaced threads, offers easy starting into predrilled holes. Used in plastics and other soft materials.

It has a thread cutting style that combines deck and wood screws. The wide and sharp cavity of the screws helps cleaning of the materials.

Designed with a tapered point, and a sharp crested, spaced threads and a coarse pitch thread, they are able to self start in wood materials. Produces a mating thread which assists with pullout strength.


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