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engineer-mechanical:inventor-threads [2019/06/14 14:55]
jjensen [Screw Thread Designation]
engineer-mechanical:inventor-threads [2019/10/17 14:26] (current)
jjensen [Screw Thread Designation]
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 ==== Threads, Bolts, Nuts, Washers ==== ==== Threads, Bolts, Nuts, Washers ====
 +
 +===== Thread Introduction =====
 +  * Thread Terminology - either external threads (male) or internal threads (female)
 +  * Thread Forms - each thread form is designed to meet a specific requirement
 +  * Unified Threads - abbreviated as UN and further broken down in coarse (UNC), fine (UNF), and extra fine (UNEF)
 +  * Metric Threads - abbreviated as M, based on the nominal outside (major) diameter of an external thread and the pitch.
 +  * Acme Threads - use to transmit power as in jacks for lifting loads
 +  * Buttress Threads - use to transmit power as in jacks for lifting loads
 +  * Taper Pipe Threads - V-shaped thread with a taper and designed to produce a seal between the threads of the mating parts
 +  * Methods of Displaying Threads - simplified, schematic and detailed
 +  * Designations - general tolerances on prints do not apply to thread features. Must lookup the ASME standard to determine the thread tolerances
 +  * Unified Threads - example 1/4-20 UNC-2A
 +    * 1/4 = 0.25" nominal bolt diameter
 +    * 20 = Threads Per Inch (TPI)
 +    * UNC = Unified Coarse
 +    * 2 = class of fit
 +    * A = external threads
  
 ==== Screw Thread Designation ==== ==== Screw Thread Designation ====
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   * {{engineer-mechanical:​inventor-threads:​general-thread-symbols.png|General Thread Symbols}}   * {{engineer-mechanical:​inventor-threads:​general-thread-symbols.png|General Thread Symbols}}
     * see Unified Inch Screw Threads (UN and UNR Thread Form) ASME B1.1-2003, p. 71     * see Unified Inch Screw Threads (UN and UNR Thread Form) ASME B1.1-2003, p. 71
 +  * {{engineer-mechanical:​inventor-threads:​threadprofile-basic-blueprint-reading2010.png|Thread Profile from Basic Blueprint Reading}}
 +    * Basic Blueprint reading and Sketching by Thomas P. Olivo and C. Thomas Olivo, Publisher Cengage Learning, 2010, p. 100 [[https://​www.dropbox.com/​s/​r2socom76w3zs95/​BasicBlueprintReadingAndSketching9th-Olivo.pdf?​dl=0|pdf]]
  
 ==== Thread Basics ==== ==== Thread Basics ====
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       * [[http://​www.wewilliams.net/​docs/​1936%20-%20How%20to%20Cut%20Screw%20Threads%20in%20the%20Lathe%20-%20Bulletin%2036A.pdf#​page=15|How to Cut Screw Threads in the Lathe, Bulletin No. 36A by South Bend Lathe, p. 13]]       * [[http://​www.wewilliams.net/​docs/​1936%20-%20How%20to%20Cut%20Screw%20Threads%20in%20the%20Lathe%20-%20Bulletin%2036A.pdf#​page=15|How to Cut Screw Threads in the Lathe, Bulletin No. 36A by South Bend Lathe, p. 13]]
  
-=== Standards and Industry ===+==== Standards and Industry ​====
   * ASME B1.1-2003 Unified Inch Screw Threads (UN and UNR Thread Form), ([[http://​www.techstreet.com/​products/​1183305|PDF preview]])   * ASME B1.1-2003 Unified Inch Screw Threads (UN and UNR Thread Form), ([[http://​www.techstreet.com/​products/​1183305|PDF preview]])
   * Hex Bolt Standard - American National Standard (ANSI)and American Society of Mechanical Engineers (ASME) [[http://​webstore.ansi.org/​RecordDetail.aspx?​sku=ASME+B18.2.1-2012|ASME B18.2.1-2012]] ([[http://​www.techstreet.com/​products/​preview/​1855300|PDF preview]] and [[http://​jefferyjjensen.com/​secure/​pdf/​Standards/​ASME-B18.2.1-2012.pdf|secure PDF]])   * Hex Bolt Standard - American National Standard (ANSI)and American Society of Mechanical Engineers (ASME) [[http://​webstore.ansi.org/​RecordDetail.aspx?​sku=ASME+B18.2.1-2012|ASME B18.2.1-2012]] ([[http://​www.techstreet.com/​products/​preview/​1855300|PDF preview]] and [[http://​jefferyjjensen.com/​secure/​pdf/​Standards/​ASME-B18.2.1-2012.pdf|secure PDF]])
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   * {{engineer-mechanical:​inventor-threads:​inventorthreadspec.png|Figure 4-0 Inventor Thread Specification}}   * {{engineer-mechanical:​inventor-threads:​inventorthreadspec.png|Figure 4-0 Inventor Thread Specification}}
   * {{engineer-mechanical:​inventor-threads:​inventorthreadspecdesignation.png|Figure 5-0 Inventor Thread Designation}}   * {{engineer-mechanical:​inventor-threads:​inventorthreadspecdesignation.png|Figure 5-0 Inventor Thread Designation}}
 +    * UNR = only applies to external threads, has a rounded root contour
 +      * "UNR applies only to external threads; the difference between UN and UNR threads, in addition to designation,​ is that a flat or optional rounded root contour is specified for UN threads, while only a rounded root contour is specified for UNR threads."​ (ASME B1.1-2003 Unified Inch Screw Threads, p. 1) 
     * UNC = Unified Coarse     * UNC = Unified Coarse
     * UNF = Unified Fine     * UNF = Unified Fine
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   * {{engineer-mechanical:​inventor-threads:​threadcount.png|Figure 7-0 Determine thread count}}   * {{engineer-mechanical:​inventor-threads:​threadcount.png|Figure 7-0 Determine thread count}}
   * {{engineer-mechanical:​inventor-threads:​techdraw4thp516.png|Figure 8-0 Calculate Threads Per Inch (TPI)}}   * {{engineer-mechanical:​inventor-threads:​techdraw4thp516.png|Figure 8-0 Calculate Threads Per Inch (TPI)}}
 +  * {{engineer-mechanical:​inventor-threads:​threads-max-minor-diameter.png|Maximum Minor Diameter}}
  
 === Nuts === === Nuts ===
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   * Create a 3/8" Hex Nut - ASME/ANSI Method   * Create a 3/8" Hex Nut - ASME/ANSI Method
   * {{engineer-mechanical:​inventor-threads:​hexnut3-8inchasme-b18.2.2.png|Figure 4-0 3/8" Hex Nut with corner Chamfers on both sides}}   * {{engineer-mechanical:​inventor-threads:​hexnut3-8inchasme-b18.2.2.png|Figure 4-0 3/8" Hex Nut with corner Chamfers on both sides}}
 +
 +==== Height of UN External Thread ====
 +  * Height of UN External Thread = h<​html><​sub>​s</​sub></​html>​ = 0.54126588 * Pitch
 +  * Machinery'​s Handbook 27th, Table 1. American Standard Unified Inch Screw Thread Form Data, p. 1734
 +    * {{engineer-mechanical:​inventor-threads:​machineryhandbook27-p1734-threadheight.png|Thread Height}}
 +    ​
 +==== Pitch Diameter Tolerance ====
 +  * {{engineer-mechanical:​inventor-threads:​pitch-diameter-tolerance.png|Pitch Diameter Tolerance}}
  
 ==== AutoCAD Drafting Threads ==== ==== AutoCAD Drafting Threads ====
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     * <​html><​iframe width="​560"​ height="​315"​ src="​https://​www.youtube.com/​embed/​pkam6UR5Pfk"​ frameborder="​0"​ allow="​accelerometer;​ autoplay; encrypted-media;​ gyroscope; picture-in-picture"​ allowfullscreen></​iframe></​html>​     * <​html><​iframe width="​560"​ height="​315"​ src="​https://​www.youtube.com/​embed/​pkam6UR5Pfk"​ frameborder="​0"​ allow="​accelerometer;​ autoplay; encrypted-media;​ gyroscope; picture-in-picture"​ allowfullscreen></​iframe></​html>​
  
 +==== Thread Depth ====
 +  * [[http://​www.homeshopmachinist.net/​resources/​downloads/​|The Home Shop Machinist - General Downloads]]
 +    * [[http://​www.homeshopmachinist.net/​wp-content/​uploads/​2015/​07/​Threading-Tables.zip|Threading Tables]]
 +    * {{engineer-mechanical:​inventor-threads:​threadingguide.png?​500|Threading Guide from Home Shop Machinist}}
 +
 +==== Thread Inspection ====
 +
 +=== NOT GO (LO) Thread Ring Gages ===
 +  * "​Starting threads on NOT GO (LO) thread ring gages are subject to greater wear than the remaining threads. Such wear in combination with the incomplete threads at the end of the product thread permit further entry in the gage. NOT GO (LO) functional diameter is acceptable when the NOT GO (LO) thread ring gage applied to the product external thread **does not pass over the thread more than three complete turns.** The gage should not be forced. Special requirements such as exceptionally thin or ductile material, small number of threads, etc., may necessitate modification of this practice."​ ([[https://​www.dropbox.com/​s/​6s5tul62vyy5dx4/​ASME-B1.2-ThreadGage.pdf?​dl=0|ASME B1.2-1983 Gages and Gaging for Unified Inch Screw Threads]], p. 128)
 +==== Thread Cutting Videos ====
 +  * Toms Techniques
 +    * Thread Cutting on the Lathe, Part One - Threading Tool Geometry
 +      * <​HTML><​iframe width="​560"​ height="​315"​ src="​https://​www.youtube.com/​embed/​VK8JfhD_FxY"​ frameborder="​0"​ allow="​accelerometer;​ autoplay; encrypted-media;​ gyroscope; picture-in-picture"​ allowfullscreen></​iframe></​HTML>​
 +    * Thread Cutting on the Lathe, Part Two - Calculating the Flat Width and Helix Angle
 +      * <​HTML><​iframe width="​560"​ height="​315"​ src="​https://​www.youtube.com/​embed/​R2tKBHy4vNY"​ frameborder="​0"​ allow="​accelerometer;​ autoplay; encrypted-media;​ gyroscope; picture-in-picture"​ allowfullscreen></​iframe></​HTML>​
 +    * Thread Cutting on the Lathe, Part Three - Grinding the Tool
 +      * <​HTML><​iframe width="​560"​ height="​315"​ src="​https://​www.youtube.com/​embed/​4S0AvIhNR7A"​ frameborder="​0"​ allow="​accelerometer;​ autoplay; encrypted-media;​ gyroscope; picture-in-picture"​ allowfullscreen></​iframe></​HTML>​
 +    * Thread Cutting on the Lathe, Part Four - Setting up the Lathe and Cutting the Thread
 +      * <​HTML><​iframe width="​560"​ height="​315"​ src="​https://​www.youtube.com/​embed/​f2y36EGHpts"​ frameborder="​0"​ allow="​accelerometer;​ autoplay; encrypted-media;​ gyroscope; picture-in-picture"​ allowfullscreen></​iframe></​HTML>​
 +  * Open Source Machine Tools
 +    * <​HTML><​iframe width="​560"​ height="​315"​ src="​https://​www.youtube.com/​embed/​90EuSPWkLrY"​ frameborder="​0"​ allow="​accelerometer;​ autoplay; encrypted-media;​ gyroscope; picture-in-picture"​ allowfullscreen></​iframe></​HTML>​
 +
 +===== Procedure Cutting a Thread on the Lathe =====
 +
 +==== Step 7 - Chamfer Workpiece at Beginning of Thread ====
 +  * <​html><​iframe width="​560"​ height="​315"​ src="​https://​www.youtube.com/​embed/​yz4OkXHvO_c"​ frameborder="​0"​ allow="​accelerometer;​ autoplay; encrypted-media;​ gyroscope; picture-in-picture"​ allowfullscreen></​iframe></​html>​
 +
 +===== William Sellers - Standard Screw Threads =====
 +  * [[https://​en.wikipedia.org/​wiki/​William_Sellers|Wikipedia - William Sellers]]
 +  * [[https://​babel.hathitrust.org/​cgi/​pt?​id=hvd.32044107216202&​view=1up&​seq=7|William Sellers, 1824-1905 Biography]]
 +
 +===== References =====
 +  * ASME B1.1-2003 Unified Inch Screw Threads
 +    * [[https://​www.dropbox.com/​s/​g1mihz52udgb8g4/​ASME-B1.1-2003-UnifiedInchScrewThreads.pdf?​dl=0|pdf]]
 +  * ASME B1.2-1983 Gages and Gaging for Unified Inch Screw Threads
 +    * [[https://​www.dropbox.com/​s/​6s5tul62vyy5dx4/​ASME-B1.2-ThreadGage.pdf?​dl=0|pdf]]
 +  * ASME B1.30-2002 Screw Threads: Standard Practice for Calculating and Rounding Dimensions
 +    * [[https://​www.dropbox.com/​s/​3ip7v88g0n1yd10/​ASME-B1.30-ScrewThreads.pdf?​dl=0|pdf]]
 +    * Al Barrows, Chair - [[https://​www.linkedin.com/​in/​al-barrows-09253714|LinkedIn]]
 +    * [[http://​www.swansongage.com|Swanson Tool Manufacturing,​ Inc]]
 +  * Screw Thread Calculations by Edward G. Hoffman
 +    * The Home Shop Machinist, ISSN 0744-6640, published bimonthly by Village Press, Inc
 +    * 198311-MachineShopCalculationsScrewThreadCalculationsP1
 +    * 198401-MachineShopCalculationsScrewThreadCalculationsP2
 +    * 198403-MachineShopCalculationsScrewThreadCalculationsP3
 +    * 198405-MachineShopCalculationsScrewThreadCalculationsP4
 +    * [[https://​www.dropbox.com/​s/​myf6065wk5lqxy1/​ScrewThreadCalcs-Hoffman.pdf?​dl=0|pdf]]
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