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COMBINED DRILL & TAP This high production tool is specially designed to drill and tap in one pass only. By design, this value-added tool reduces machining operations and subsequent parts handling. The drill end features a self-centering helical point, and the tool shank and square fit standard tap holders.

ACME-C Acme Thread-Centralizing ACME-G Acme Thread-General Purpose AMO American Standard Microscope Objective Thread ANPT Aeronautical National Form Taper Pipe Thread (Ground thread tap marked NPT) BA British Association Standard Thread BSF British Standard Fine Thread Series BSP British Standard Pipe (Parallel) Thread BSSPI British Standard Pipe (Parallel) Thread BSPF British Standard Pipe (Parallel) Thread BSPG British Standard Pipe (Parallel) Thread BSPP British Standard Pipe (Parallel) Thread BSPT British Standard Taper Pipe Thread BSPTr British Standard Taper Pipe Thread BSPT British Standard Taper Pipe Thread BSW British Standard Whitworth Coarse Thread Series G British Standard Pipe (Parallel) Thread KR British Standard Taper Pipe Thread M Metric ScrewThread Series N American National 8, 12 and 16 Thread Series (8N, 12N, 16N) N BUTT American Buttress Screw Thread NC American National Coarse Thread Series NEF American National Extra Fine Thread Series NF American National Fine Thread Series NGO National Gas Outlet Thread NGT National Gas Taper Thread (see "SGT") NH American National Hose Coupling and Fire Hose Coupling Threads NPS For tap marking only (See NPSC, NPSM) NPSC American National Standard Straight Pipe Thread in Pipe Couplings (Tap marked NPS) NPSF Dryseal American National Standard Fuel Internal Straight Pipe Thread NPSH American National Standard Straight Pipe Thread for Hose Couplings NPSI Dryseal American National Standard Intermediate Internal Straight Pipe Thread NPSL American National Standard Straight Pipe Thread for Loose Fitting Mechanical Joints with Locknuts NPSM American National Standard Straight Pipe Threads for Free-Fitting Mechanical Joints for Fixtures (Tap marked NPS) NPT American National Standard Taper Pipe Thread (See ANPT, NPTR) NPTF Dryseal American National Standard Taper Pipe Thread NPTR American National Standard Taper Pipe Thread for Railing Joints (Tap marked NPT) NS American National Thread-Special PS British Standard Pipe (Parallel) Thread PT British Standard Taper Pipe Thread PTF Dryseal SAE Short Taper Pipe Thread R British Standard Pipe (Parallel) Thread Rc British Standard Taper Pipe Thread SGT Special Gas Taper Thread SPL-PTF Dryseal Special Taper Pipe Thread STI Special Thread for Helical Coil Wire Screw Thread Inserts Stub Acme Stub Acme Thread *UN Unified Constant Pitch Thread Series *UNC Unified Coarse Thread Series *UNEF Unified Extra Fine Thread Series *UNF Unified Fine Thread Series UNJ Unified Thread Series with a 0.15011P to 0.18042P Controlled Root Radius on External Thread only. UNJC Unified Coarse Thread Series with a 0.15011P to 0.18042P Controlled Root Radius on External Thread only. UNJF Unified Fine Thread Series with a 0.15011P to 0.18042P Controlled Root Radius on External Thread only. UNM Unified Miniature Thread Series UNR Unified Constant Pitch Thread Series with a 0.108P to 0.144P Controlled Root Radius; Ext. thread only. UNRC Unified Coarse Thread Series with a 0.108P to 0.144P Controlled Root Radius; Ext. thread only. UNRF Unified Fine Thread Series with a 0.108P to 0.144P Controlled Root Radius; External thread only. *UNS Unified Thread-Special V A 60¡ "V" thread with Truncated Crest and Root. The theoretical "V" Form is usually flatted to the user's specifications. WHIT British Standard Whitworth Special Thread

TRAPEZOIDAL THREAD TAP Trapezoidal screw threads were devised to allow rotary and transversing motion on machines; and are also used in jacks, valves, presses and other mechanisms where heavy loads are encountered. The trapezoidal thread is characterized by a 30° included angle. Trapezoidal taps typically require specialized engineering and design due to the nature and severity of cut required in producing trapezoidal threads.

NUT TAP Nut taps feature a long chamfer which assists in entering the drilled hole, and distributes the cutting action over several teeth. These taps were initially designed for tapping nuts and have a long thread length. The shank diameter is smaller than the tap's minor diameter to allow the accumulation of several nuts after tapping. Nut taps also feature an extended square length.

*Taps are not marked with "U" but with the symbol for the corresponding American Standard thread form with which it is compatible.

HAND TAP These standard style taps have straight flutes of a number specified as either standard or optional. Hand taps are for general purpose applications such as production tapping or hand tapping operations. Taper, plug and bottoming styles provide versatility in tough materials, blind and through holes.

The descriptions, illustrations, specifications, dimensions, and part numbers are subject to change without notice.

INTERRUPTED THREAD TAP These taps have an odd number of lands with alternate teeth in the thread helix removed. The removal of every other tooth helps to break the chip and allows a greater supply of lubrication to reach the cutting teeth, reducing the incidence of torn threads. Ideal for tapping non ferrous metals and low carbon steel; as well as use in titanium and high hardness alloys.

PIPE TAP These taps are for producing standard straight or tapered pipe threads in a wide range of pipe connections. Manufactured with the appropriate design variations to cut specified pipe thread forms.

Bottoming Taps ( Finishing Tap) - This style, with a 1-2 thread chamfer, is made with just enough chamfer for starting in the hole; as the name implies, it is designed to thread blind holes to the bottom.

The tap chamfer is the tapering of the threads to distribute cutting action over several teeth. The type of hole to be tapped has much to do with the chamfer style of that tap that's best suited. Some holes go all the way through; some, while not through-holes, are relatively deep; some are quite shallow (a little deeper than diameter). Each of these three kinds of holes - through, deep-bottoming blind, and shallow bottoming - has a tap chamfer best suited to threading requirements.

servicing the Canadian provinces and territories of Newfoundland, NF, NL, Nova Scotia, NS, New Brunswick, NB, Prince Edward Island, PEI, PE, Quebec, PQ, QC, Ontario, ON, Manitoba, MB, Saskatchewan, SK, Alberta, AB, British Columbia, BC, Northwest Territories, NT, Nunavut, NU, Yukon, YT, servicing Canadian cities, Toronto, Mississauga, Scarborough, Laval , Montreal, Montréal, Vancouver, Ottawa, Gatineau, Calgary, Edmonton, Québec City, Winnipeg, Hamilton, Kitchener, Cambridge, Waterloo, London, St. Catharines , Niagara, Halifax, Oshawa, Victoria, Windsor, Saskatoon, Regina, Sherbrooke, St. John's, Barrie, Kelowna, Abbotsford, Mission, Sudbury Kingston, Saguenay, Trois-Rivieres, Trois Rivieres, Trois-Rivières, Guelph, Moncton, Brantford, Saint John, Thunder Bay, Peterborough, Ajax, Aurora, Brampton, Brock, Burlington, Caledon, Clarington, Durham Region, Oshawa, Pickering, Whitby, Halton Hills, Milton, Oakville, Mississauga, New market, Richmond Hill, Vaughn, Orangeville, servicing US cities, New York, Los Angeles, Chicago, Houston, Philadelphia, Phoenix, San Antonio, San Diego, Dallas, San Jose, Austin, Jacksonville, San Francisco, Indianapolis, Columbus, Fort Worth, Charlotte, Seattle, Denver, El Paso, Detroit, Washington, Boston, Memphis, Nashville, Portland, Oklahoma City, Las Vegas, Baltimore, Louisville, Milwaukee, Albuquerque, Tucson, Fresno, Sacramento, Kansas City, Long Beach, Mesa, Raleigh, Omaha, Miami, Oakland, Minneapolis, Tulsa, Wichita, New Orleans, Arlington, Cleveland, Bakersfield, Tampa, Aurora, Honolulu, Anaheim, Santa Ana, Corpus Christi, Riverside, St. Louis, Lexington, Stockton, Pittsburgh, Saint Paul, Anchorage, Cincinnati, Henderson, Greensboro, Plano, Newark, Toledo, Lincoln, Orlando, Chula Vista, Jersey City, Chandler, Fort Wayne, Buffalo, Durham, St. Petersburg, Irvine, Laredo, Lubbock, Madison, Gilbert, Norfolk, Reno, Winston Salem, Glendale, Hialeah, Garland, Scottsdale, Chesapeake, North Las Vegas, Fremont, Baton Rouge, Richmond, Boise, San Bernardino, Spokane, Birmingham, Modesto, Des Moines, Rochester, Tacoma, Fontana, Oxnard, Moreno Valley, Fayetteville, Huntington Beach, Yonkers, Glendale, Aurora, Montgomery, Columbus, Amarillo, Little Rock, Akron, Shreveport, Augusta, Grand Rapids, Mobile, Salt Lake City, Huntsville, Tallahassee, Grand Prairie, Overland Park, Knoxville, Worcester, Brownsville, Newport News, Santa Clarita, Port St. Lucie, Providence, Fort Lauderdale, Chattanooga, Tempe, Oceanside, Garden Grove, Rancho Cucamonga, Cape Coral, Santa Rosa, Vancouver, Sioux Falls, Peoria, Ontario, Jackson, Elk Grove, Springfield, Pembroke Pines, Salem, Corona, Eugene, McKinney, Fort Collins, Lancaster, Cary, Palmdale, Hayward, Salinas, Frisco, Springfield, Pasadena, Macon, Alexandria, Pomona, Lakewood, Sunnyvale, Escondido, Kansas City, Hollywood, Clarksville, Torrance, Rockford, Joliet, Paterson, Bridgeport, Naperville, Savannah, Mesquite, Syracuse, Pasadena, Orange, Fullerton, Killeen, Dayton, McAllen, Bellevue, Miramar, Hampton, West Valley City, Warren, Olathe, Columbia, Thornton, Carrollton, Midland, Charleston, Waco and the states of Alabama, AL, Alaska, AK, Arizona, AZ, Arkansas, AR, California, CA, Colorado, CO, Connecticut, CT, Delaware, DE, District of Columbia, DC, Florida, FL, Georgia, GA, Hawaii, HI, Idaho, ID, Illinois, IL, Indiana, IN, Iowa, IA, Kansas, KS, Kentucky, KY, Louisiana, LA, Maine, ME, Maryland, MD, Massachusetts, MA, Michigan, MI, Minnesota, MN, Mississippi, MS, Missouri, MO, Montana, MT, Nebraska, NE, Nevada, NV, New Hampshire, NH, New Jersey, NJ, New Mexico, NM, New York, NY, North Carolina, NC, North Dakota, ND, Ohio, OH, Oklahoma, OK, Oregon, OR, Pennsylvania, PA, Rhode Island, RI, South Carolina, SC, South Dakota, SD, Tennessee, TN, Texas, TX, Utah, UT, Vermont, VT, Virginia, VA, Washington, WA, West Virginia, WV, Wisconsin, WI, Wyoming, WY We can ship to Afghanistan , Aland Islands , Albania , Algeria , American Samoa , AS, Andorra , Angola , Anguilla , Antigua and Barbuda , Argentina , Armenia , Aruba , Australia , Austria , Azerbaijan , Azores , Bahamas , Bahrain , Bangladesh , Barbados , Belarus , Belgium , Belize , Benin , Bermuda , Bhutan , Bolivia , Bonaire , Bosnia , Botswana , Brazil , British Virgin Isles , Brunei , Bulgaria , Burkina Faso , Burundi , Cambodia , Cameroon , Canada , Canary Islands , Cape Verde , Cayman Islands , Central African Republic , Chad , Chile , China , Colombia , Comoros , Congo , Cook Islands , Costa Rica , Croatia , Curacao , Cyprus , Czech Republic , Democratic Republic of Congo , Denmark , Djibouti , Dominica , Dominican Republic , Ecuador , Egypt , El Salvador , England , Equatorial Guinea , Eritrea , Estonia , Ethiopia , Faeroe Islands , Fiji , Finland , France , French Guiana , French Polynesia , Gabon , Gambia , Georgia , Germany , Ghana , Gibraltar , Greece , Greenland , Grenada , Guadeloupe , Guam , GU, Guatemala , Guernsey , Guinea , Guinea-Bissau , Guyana , Haiti , Holland , Honduras , Hong Kong , Hungary , Iceland , India , Indonesia , Iraq , Ireland , Israel , Italy , Ivory Coast , Jamaica , Japan , Jersey , Jordan , Kazakhstan , Kenya , Kiribati , Kosrae , Kuwait , Kyrgyzstan , Laos , Latvia , Lebanon , Lesotho , Liberia , Libya , Liechtenstein , Lithuania , Luxembourg , Macau , Macedonia (Fyrom) , Madagascar , Madeira , Malawi , Malaysia , Maldives , Mali , Malta , Marshall Islands , MH, Martinique , Mauritania , Mauritius , Mayotte , Mexico , Micronesia , Moldova , Monaco , Mongolia , Montenegro , Montserrat , Morocco , Mozambique , N. Mariana Islands , Namibia , Nepal , Netherlands , Netherlands Antilles , New Caledonia , New Zealand , Nicaragua , Niger , Nigeria , Norfolk Island , Northern Ireland , Norway , Oman , Pakistan , Palau , PW, Panama , Papua New Guinea , Paraguay , Peru , Philippines , Poland , Ponape , Portugal , Puerto Rico , PR, Qatar , Reunion , Romania , Rota , Russia , Rwanda , Saba , Saipan , San Marino , Saudi Arabia , Scotland , Senegal , Serbia , Seychelles , Sierra Leone , Singapore , Slovakia , Slovenia , Solomon Islands , South Africa , South Korea , Spain , Sri Lanka , St. Barthelemy , St. Christopher , St. Croix , St. Eustatius , St. John , St. Kitts and Nevis , St. Lucia , St. Maarten , St. Martin , St. Thomas , St. Vincent/Grenadines , Suriname , Swaziland , Sweden , Switzerland , Syria , Tahiti , Taiwan , Tajikistan , Tanzania , Thailand , Timor Leste , Tinian , Togo , Tonga , Tortola , Trinidad and Tobago , Truk , Tunisia , Turkey , Turkmenistan , Turks and Caicos Islands , Tuvalu , Uganda , Ukraine , Union Island , United Arab Emirates , United Kingdom , United States , Uruguay, US Virgin Islands , VI, Uzbekistan , Vanatu , Vatican City State , Venezuela , Vietnam , Virgin Gorda , Wales , Wallia and Futuna Islands , Western Samoa , Yap , Yemen , Zambia , Zimbabwe we try to ship to the world largest cities Tokyo,Japan, Seoul, South Korea, Mexico City, Mexico , New York City, USA , Mumbai, India , Jakarta, Indonesia , Sáo Paulo, Brazil, Delhi, India , Osaka/Kobe, Japan , Shanghai, China , Manila, Philippines ,Los Angeles, USA ,Calcutta, India , Moscow, Russian Fed., Cairo, Egypt, Lagos, Nigeria, Buenos Aires, Argentina , London, United Kingdom , Beijing, China , Karachi, Pakistan , Dhaka, Bangladesh , Rio de Janeiro, Brazil ,Tianjin, China , Paris, France , Istanbul, Turkey , Lima, Peru , Tehrãn, Iran, Bangkok, Thailand , Chicago, USA , Bogotá, Colombia , Hyderabad, India , Chennai, India , Essen, Germany , Ho Chi Minh City, Vietnam , Hangzhou, China , Hong Kong, China , Lahore, Pakistan , Shenyang, China , Changchun, China , Bangalore, India , Harbin, China , Chengdu, China , Santiago, Chile ,Guangzhou, China , St. Petersburg, Russian Fed , Kinshasa, DRC , Baghdãd, Iraq , Jinan, China , Houston, USA , Toronto, Canada, Yangon, Myanmar (Burma), Alger, Algeria Philadelphia, USA, Qingdao, China , Milano, Italy , Pusan, South Korea, Belo Horizonte, Brazil, Almadabad, India , Madrid, Spain , San Francisco, USA, Alexandria, Egypt , Washington DC, USA , Wuhan, China , Dallas, USA , Guadalajara, Mexico, Chongging, China , Medellin, Colombia, Detroit, USA , Handan, China , Frankfurt, Germany , Porto Alegre, Brazil , Hanoi, Vietnam , Sydney, Australia, Santo Domingo, Dom. Rep., Singapore, Singapore , Casablanca, Morocco , Katowice, Poland , Pune, India , Bangdung, Indonesia, Monterrey, Mexico ,Montréal, Canada , Nagoya, Japan , Nanjing, China , Abidjan, Côte d'Ivoire, Xi'an, China , Berlin, Germany , Riyadh, Saudi Arabia, Recife, Brazil , Dusseldorf, Germany, Ankara, Turkey , Melbourne, Australia, Salvador, Brazil , Dalian, China , Caracas, Venezuela, Adis Abeba, Ethiopia, Athina, Greece, Cape Town, South Africa, Koln, Germany , Maputo, Mozambique, Napoli, Italy

L1 = Basic to Basic minus .0005 H1 = Basic to Basic plus .0005 H2 = Basic plus .0005 to Basic plus .0010 H3 = Basic plus .0010 to Basic plus .0015 H4 = Basic plus .0015 to Basic plus .0020 H5 = Basic plus .0020 to Basic plus .0025 H6 = Basic plus .0025 to Basic plus .0030

SPIRAL FLUTED TAP These taps, as the name implies, are made with spiral flutes instead of straight flutes. This spiral fluting feature aids in drawing chips out of a hole, or serves to bridge a gap inside the hole such as a keyway or cross-hole. Commonly available in slow spiral (25-30¡ helix angle) or fast spiral (45-60¡).

PULLEY TAP The hub portion of pulley parts contain oil cups and set screw holes, most of which cannot be reached with ordinary hand taps. Pulley taps have the same basic thread dimensions as hand taps, but pulley taps differ in that they have a longer shank which is of the same basic major diameter as the threaded portion. When tapping pulley hub holes, the taps are inserted through holes in the rims which are slightly larger than the shanks of the taps. These holes serve as guides or bushings for the taps to assure proper alignment when tapping. Pulley taps can also be used for general tapping in parts where an extra long length is required to reach the holes being tapped.

EXTENSION TAP These taps are made to conventional tap dimensions, except that they have an extended shank to reach inaccessible holes. Thread length, shank diameter, and shank square are made to standard specifications listed in Table 302. Extension taps are available in both hand and spiral point styles, and in small shank style.

All standard ground thread taps are marked with the letter "G" to designate Ground Thread. The letter G will be followed by the letter "H" to designate above basic; or the letter "L" to designate below basic. The number following H or L signifies the number of .0005" steps above or below the basic pitch diameter.

SOLID CARBIDE TAP These taps allow higher metal removal rates through higher speeds, which are possible through the micrograin structure of carbide. Users will also benefit from a dramatic increase in tap life, less downtime, fewer tool changes, and consistent high quality thread finishes.

SPIRAL POINT TAP As to general physical dimensions, spiral point taps are identical with the standard hand tap. However, the spiral point tap has the cutting face of the first few threads cut at a pre-determined angle relative to the tap's axis angle to force the evacuation of chips ahead of the cutting action. This feature, plus the excellent shearing action of the flute, make spiral pointed taps ideal for production tapping of through holes. Typically, this type of tap has a shallower flute passage than conventional taps. This gives the spiral point tap more cross-sectional area, which means greater strength, allows higher tapping speeds, and requires less power to drive.

Taps, dies and other types of threading tools are marked according to the Standard System of Marking Ground Thread Taps. Tools are marked with the nominal size, number of threads per inch (pitch), and the appropriate thread form symbol and pitch diameter symbol. Symbols typically used are listed.

THREAD FORMING TAP These taps are fluteless except as optionally designed with one or more lubrication grooves. The thread form is lobed so there is a finite number of points contacting the work. This tap does not cut, so it is 'chipless', and consequently will not cause a chip problem. The tool forms the thread by extrusion, thus thread size can be closely maintained. The fluteless design allows high quality threads, faster tapping speeds, higher production, and generates no chips which simplifies tapping of blind bottoming holes (threads can be formed the full depth of the hole).

CARBIDE INSERT TAP These taps are an economical alternative to solid carbide taps, especially in larger diameter tools. Solid carbide cutting face inserts are brazed to a H.S.S. tap body, then threaded to exacting specifications. Carbide cutting teeth allow higher performance and production.

Taper Taps - This style, with a 8-10 thread chamfer, has the longest chamfer of the three to distribute action over the maximum number of teeth; and the taper also acts as a guide in starting the cutting action in the hole. Taper style taps start the thread square with the workpiece. Taper taps are commonly used in through holes and in materials where a tapered guide is necessary.

TANDEM ACME TAP These taps combine the initial roughing cut with the final finishing cut, in one pass, to achieve an acme screw thread. These taps are economical and enhance production levels by saving on the operation of two tools. Since acme thread pitches are generally coarse relative to diameters, these taps are subjected to heavy chip loads. To achieve a high quality acme thread in a cost-effective manner, roughing and finishing operations are recommended.

Standard System of Tap Marking Taps, dies and other types of threading tools are marked according to the Standard System of Marking Ground Thread Taps. Tools are marked with the nominal size, number of threads per inch (pitch), and the appropriate thread form symbol and pitch diameter symbol. Symbols typically used are listed. Pitch Diameter Limit Symbols All standard ground thread taps are marked with the letter "G" to designate Ground Thread. The letter G will be followed by the letter "H" to designate above basic; or the letter "L" to designate below basic. The number following H or L signifies the number of .0005" steps above or below the basic pitch diameter. For instance, the tap pictured above is a 3/8" dia. tap with 20 threads per inch (pitch), and has a NS (American National Special Thread) thread form. The tap is made from High Speed Steel, and the GH-3 pitch diameter limit symbol indicates a Ground Thread tap with pitch diameter limits .0010 to .0015 over basic. Pitch Diameter Limits for taps to 1" diameter inclusive: L1 = Basic to Basic minus .0005 H1 = Basic to Basic plus .0005 H2 = Basic plus .0005 to Basic plus .0010 H3 = Basic plus .0010 to Basic plus .0015 H4 = Basic plus .0015 to Basic plus .0020 H5 = Basic plus .0020 to Basic plus .0025 H6 = Basic plus .0025 to Basic plus .0030 Taps larger than 1" dia. are ground to a .0010" tolerance on the pitch diameter and are, for example, H4 (Basic plus .0010" to Basic plus .0020"). Back to Top of Page   Thread Form Symbols ACME-C Acme Thread-Centralizing ACME-G Acme Thread-General Purpose AMO American Standard Microscope Objective Thread ANPT Aeronautical National Form Taper Pipe Thread (Ground thread tap marked NPT) BA British Association Standard Thread BSF British Standard Fine Thread Series BSP British Standard Pipe (Parallel) Thread BSSPI British Standard Pipe (Parallel) Thread BSPF British Standard Pipe (Parallel) Thread BSPG British Standard Pipe (Parallel) Thread BSPP British Standard Pipe (Parallel) Thread BSPT British Standard Taper Pipe Thread BSPTr British Standard Taper Pipe Thread BSPT British Standard Taper Pipe Thread BSW British Standard Whitworth Coarse Thread Series G British Standard Pipe (Parallel) Thread KR British Standard Taper Pipe Thread M Metric ScrewThread Series N American National 8, 12 and 16 Thread Series (8N, 12N, 16N) N BUTT American Buttress Screw Thread NC American National Coarse Thread Series NEF American National Extra Fine Thread Series NF American National Fine Thread Series NGO National Gas Outlet Thread NGT National Gas Taper Thread (see "SGT") NH American National Hose Coupling and Fire Hose Coupling Threads NPS For tap marking only (See NPSC, NPSM) NPSC American National Standard Straight Pipe Thread in Pipe Couplings (Tap marked NPS) NPSF Dryseal American National Standard Fuel Internal Straight Pipe Thread NPSH American National Standard Straight Pipe Thread for Hose Couplings NPSI Dryseal American National Standard Intermediate Internal Straight Pipe Thread NPSL American National Standard Straight Pipe Thread for Loose Fitting Mechanical Joints with Locknuts NPSM American National Standard Straight Pipe Threads for Free-Fitting Mechanical Joints for Fixtures (Tap marked NPS) NPT American National Standard Taper Pipe Thread (See ANPT, NPTR) NPTF Dryseal American National Standard Taper Pipe Thread NPTR American National Standard Taper Pipe Thread for Railing Joints (Tap marked NPT) NS American National Thread-Special PS British Standard Pipe (Parallel) Thread PT British Standard Taper Pipe Thread PTF Dryseal SAE Short Taper Pipe Thread R British Standard Pipe (Parallel) Thread Rc British Standard Taper Pipe Thread SGT Special Gas Taper Thread SPL-PTF Dryseal Special Taper Pipe Thread STI Special Thread for Helical Coil Wire Screw Thread Inserts Stub Acme Stub Acme Thread *UN Unified Constant Pitch Thread Series *UNC Unified Coarse Thread Series *UNEF Unified Extra Fine Thread Series *UNF Unified Fine Thread Series UNJ Unified Thread Series with a 0.15011P to 0.18042P Controlled Root Radius on External Thread only. UNJC Unified Coarse Thread Series with a 0.15011P to 0.18042P Controlled Root Radius on External Thread only. UNJF Unified Fine Thread Series with a 0.15011P to 0.18042P Controlled Root Radius on External Thread only. UNM Unified Miniature Thread Series UNR Unified Constant Pitch Thread Series with a 0.108P to 0.144P Controlled Root Radius; Ext. thread only. UNRC Unified Coarse Thread Series with a 0.108P to 0.144P Controlled Root Radius; Ext. thread only. UNRF Unified Fine Thread Series with a 0.108P to 0.144P Controlled Root Radius; External thread only. *UNS Unified Thread-Special V A 60¡ "V" thread with Truncated Crest and Root. The theoretical "V" Form is usually flatted to the user's specifications. WHIT British Standard Whitworth Special Thread *Taps are not marked with "U" but with the symbol for the corresponding American Standard thread form with which it is compatible.

ACME THREAD TAP Acme screw threads were devised to allow rotary and transversing motion on machines; and are also used in jacks, valves, presses and other mechanisms where heavy loads are encountered. The acme thread is characterized by a 29° included angle. Acme taps typically require specialized engineering and design due to the nature and severity of cut required in producing Acme threads.

For instance, the tap pictured above is a 3/8" dia. tap with 20 threads per inch (pitch), and has a NS (American National Special Thread) thread form. The tap is made from High Speed Steel, and the GH-3 pitch diameter limit symbol indicates a Ground Thread tap with pitch diameter limits .0010 to .0015 over basic.

Plug Taps ( Seconding Tap)- This style, with a 4-6 thread chamfer, is most widely used in through holes and where there is sufficient room at the bottom in blind holes.