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techtalk:ref:tools032 [2022/03/27 02:31] – [Metric Nut/Bolt Threads] hippysmacktechtalk:ref:tools032 [2025/10/14 18:14] (current) – [JIC] hippysmack
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 \\ \\
 ====== Measuring Threads In General ====== ====== Measuring Threads In General ======
 +**Thread TPI or Pitch**: \\
 You can purchase a cheap template with different size threads to size screws/bolts or go by your local hardware store to use theirs. \\ You can purchase a cheap template with different size threads to size screws/bolts or go by your local hardware store to use theirs. \\
 But you don't really need one to accurately find the size of most bolts or thread patterns. \\ But you don't really need one to accurately find the size of most bolts or thread patterns. \\
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 You can buy tap/drill and metric conversion charts pretty cheap online or at some bolt or hardware stores. \\ You can buy tap/drill and metric conversion charts pretty cheap online or at some bolt or hardware stores. \\
-Then hang them up in your shop where you can always find them when needed. \\ +Then hang them up in your shop where you can always find them when needed. \\ 
 + 
 +**Bolt/Screw Length**: \\ 
 +Length is measured from the very end of a bolt/screw to where the fastened surface is assumed to be. \\ 
 +Panhead screws / hex bolts / cap screws etc. are measured from under the head to the end. \\ 
 +Flat head screws, tapered shanks under the head, are measured for overall end to end length (head is assumed to end flush with fastened piece). \\ 
 + 
 +|  Measuring length ((composite of photos used with permission))  | 
 +|{{:techtalk:ref:tools:measuring_different_type_bolts_or_screws.jpg?direct&300|}}|
  
 |SAE thread gauge: ((photos by Hippysmack))||Tap/drill and metric conversion charts.| |SAE thread gauge: ((photos by Hippysmack))||Tap/drill and metric conversion charts.|
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 ====== Pitch to TPI Conversion Table ====== ====== Pitch to TPI Conversion Table ======
- 
 The table below is a reprint from THA ((https://traininghandsacademy.com/wp-content/uploads/2020/11/Pitch-mm-to-TPI-inches-Conversion-Table.pdf)) \\ The table below is a reprint from THA ((https://traininghandsacademy.com/wp-content/uploads/2020/11/Pitch-mm-to-TPI-inches-Conversion-Table.pdf)) \\
  
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 ====== US Nut/Bolt Threads ====== ====== US Nut/Bolt Threads ======
- 
 US threads generally have 3 numbers although the last can be left off unless required. \\ US threads generally have 3 numbers although the last can be left off unless required. \\
 The first number is a whole number and/or fraction, the second number is the threads per in (TPI), followed by the length in inches. \\ The first number is a whole number and/or fraction, the second number is the threads per in (TPI), followed by the length in inches. \\
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 ====== Metric Nut/Bolt Threads ====== ====== Metric Nut/Bolt Threads ======
- 
 Metric bolts are written down as an "M" followed by 3 numbers and again the last can be left off unless required.   \\  Metric bolts are written down as an "M" followed by 3 numbers and again the last can be left off unless required.   \\ 
 The first number is the diameter, the second the thread pitch, and the third the length in millimeters. ((http://raygirling.com/metthrpt.htm)) \\ The first number is the diameter, the second the thread pitch, and the third the length in millimeters. ((http://raygirling.com/metthrpt.htm)) \\
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 |**20mm**|0.787|2.50|  -  |  -  | |**20mm**|0.787|2.50|  -  |  -  |
 |**24mm**|  |3.00|  -  |  -  | |**24mm**|  |3.00|  -  |  -  |
 +
 +**Methods of measuring in pics**: \\
 +Metric screw thread OD can be deduced by using an imperial (US) scale caliper using the chart above. \\
 +Your measurements may not be an exact match to the dims above but will be close enough to make a judgement on the metric counterpart size. \\
 +
 +{{:techtalk:ref:tools:measuring_metric_screw_threads_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) {{:techtalk:ref:tools:measuring_screw_pitch_by_hippysmack.jpg?direct&300|}} ((photo by Hippysmack)) \\
  
 ====== Common Brake Line Threads ====== ====== Common Brake Line Threads ======
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 ====== NPT Pipe Threads ======  ====== NPT Pipe Threads ====== 
- NPT stands for National Pipe Thread. Descriptions are commonly used as either straight (NPS) or tapered (NPT). ((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2)) \\+ NPT stands for National Pipe Thread. Descriptions are commonly used as either straight (NPS) or tapered (NPT). ((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/168660-any-thread-experts-around/page2?t=1810036&highlight=tap+die&page=2)) \\
 Pipe thread sizes do not refer to any physical dimension. \\ Pipe thread sizes do not refer to any physical dimension. \\
 NPT has flattened peaks and troughs where BSP is rounded. NPT has a thread angle of 60º where BSP is 55º. \\  NPT has flattened peaks and troughs where BSP is rounded. NPT has a thread angle of 60º where BSP is 55º. \\ 
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 ** Little known fact**: \\ ** Little known fact**: \\
-All iron heads pipe threads used in cases, rocker boxes, and oil pumps are straight female thread, fitted with tapered thread male fittings.((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2)) \\+All iron heads pipe threads used in cases, rocker boxes, and oil pumps are straight female thread, fitted with tapered thread male fittings.((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/168660-any-thread-experts-around/page2?t=1810036&highlight=tap+die&page=2)) \\
 This holds true for Evo Sportsters also. \\ This holds true for Evo Sportsters also. \\
  
-    * The sizes in the chart below are the major dia of the male straight thread (as the pipe OD is the major). \\ And the major dia. of a tapered male thread at it's big end. ((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2)) +    * The sizes in the chart below are the major dia of the male straight thread (as the pipe OD is the major). \\ And the major dia. of a tapered male thread at it's big end. ((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/168660-any-thread-experts-around/page2?t=1810036&highlight=tap+die&page=2)) 
-    * The tapered thread has it's diameter reduced on a taper of .0625" per inch of thread length. Almost all hardware store fittings will be tapered thread.((DR DICK of the XLFORUM  http://xlforum.net/forums/showthread.php?t=1810036&highlight=tap+die&page=2))+    * The tapered thread has it's diameter reduced on a taper of .0625" per inch of thread length. Almost all hardware store fittings will be tapered thread.((DR DICK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/ironhead-sportster-motorcycle-talk-1957-1985/168660-any-thread-experts-around/page2?t=1810036&highlight=tap+die&page=2))
  
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 ====== AN and JIC Flared Fitting Threads ====== ====== AN and JIC Flared Fitting Threads ======
 +==== Flare Angle Compatibility ====
 +  * Flared connections generally consist of 2 parts (a flared fitting or a flared tubing end connected to another part that has the same receiving flared angle seat so that both flared portions ensure metal-to-metal contact between the mated parts to preventing leaks and maintain system pressure. ((https://kingdaflex.com/what-is-a-flare-fitting/#elementor-toc__heading-anchor-2))
 +  * It's important that the flare angle is the same for the fitting/tubing and it's mating seat to maintain the integrity of the seal. JIC and AN fittings have 37° flare angles while SAE fittings have 45° flare angles. Fittings with different flare angles are not compatible and should not be mated. An incorrect angle prevents proper seating, leading to leaks even if other dimensions are accurate, compromising the entire hydraulic or fluid system’s integrity.
 +  * Accurately identifying the flare angle requires a dedicated flare gauge. This tool confirms if the angle is precisely 37 or 45 degrees, eliminating guesswork. Visual inspection alone is often insufficient and can lead to costly fitting errors. ((https://kingdaflex.com/what-is-a-flare-fitting/#elementor-toc__heading-anchor-2))
 +  * Thread sizes have nothing to do with flare angles. While flare fittings have threads, the flare angle is independent of the thread size or pitch. Two fittings can have identical threads but different flare angles, making angle verification a distinct and essential step in proper fitting identification and selection. ((https://kingdaflex.com/what-is-a-flare-fitting/#elementor-toc__heading-anchor-2))
 +
 ==== AN ==== ==== AN ====
 AN (or Army/Navy) was never intended to characterize an entire fluid system, and is mostly designed as a thread specification. \\ AN (or Army/Navy) was never intended to characterize an entire fluid system, and is mostly designed as a thread specification. \\
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 The sizes run the same as other SAE fittings (IE: SAE #4, #6, #12, etc) so they are very easy to size. \\ The sizes run the same as other SAE fittings (IE: SAE #4, #6, #12, etc) so they are very easy to size. \\
 JIC fittings are dimensionally identical to AN (Army-Navy) fittings, but are produced to less exacting tolerances and are generally less costly. ((https://en.wikipedia.org/wiki/JIC_fitting)) \\ JIC fittings are dimensionally identical to AN (Army-Navy) fittings, but are produced to less exacting tolerances and are generally less costly. ((https://en.wikipedia.org/wiki/JIC_fitting)) \\
-AE 45° flare fittings are similar in appearance, but are not interchangeable, though dash sizes 2, 3, 4, 5, 8, 10, 14, and 16 share the same thread size. \\+SAE 45° flare fittings are similar in appearance, but are not interchangeable, though dash sizes 2, 3, 4, 5, 8, 10, 14, and 16 share the same thread size. \\
  
   * You can measure male JIC threads by either using a caliper or simply laying a fitting across a tape measure. \\ Measure the OD of the threads and count the number of threads per inch to confirm with the chart below. \\ Thread OD will not exactly match the SAE thread size but will get you close enough if you have a JIC fitting.   * You can measure male JIC threads by either using a caliper or simply laying a fitting across a tape measure. \\ Measure the OD of the threads and count the number of threads per inch to confirm with the chart below. \\ Thread OD will not exactly match the SAE thread size but will get you close enough if you have a JIC fitting.
 +
 +==== SAE ====
 +SAE (Society of Automotive Engineers) is a global organization that develops engineering standards for the automotive industry. \\
 +Characteristics of SAE Flare Fittings are 45° flare angles (which distinguishes them from JIC fittings, which have a 37° flare angle.\\
 +Flared SAE fittings are also used in a wide range of applications including braking systems, fuel lines, hydraulic systems, refrigeration / air conditioning and plumbing systems. \\
  
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