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techtalk:ref:tools032 [2022/03/27 01:47] – [Metric Nut/Bolt Threads] hippysmack | techtalk:ref:tools032 [2024/01/23 01:55] (current) – 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/ | You can purchase a cheap template with different size threads to size screws/ | ||
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/ | ||
+ | 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)) | ||
+ | |{{: | ||
|SAE thread gauge: ((photos by Hippysmack))||Tap/ | |SAE thread gauge: ((photos by Hippysmack))||Tap/ | ||
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====== Pitch to TPI Conversion Table ====== | ====== Pitch to TPI Conversion Table ====== | ||
- | |||
The table below is a reprint from THA ((https:// | The table below is a reprint from THA ((https:// | ||
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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 " | Metric bolts are written down as an " | ||
The first number is the diameter, the second the thread pitch, and the third the length in millimeters. ((http:// | The first number is the diameter, the second the thread pitch, and the third the length in millimeters. ((http:// | ||
The diameter is the outside diameter of the thread peaks. \\ | The diameter is the outside diameter of the thread peaks. \\ | ||
- | In this example of a 10mm bolt; M10x1.25x35 states that the diameter of the threads is 10mm, the thread pitch is 1.25mm and it's 35mm long. \\ | + | In example of a 10mm bolt; M10x1.25x35 states that the diameter of the threads is 10mm, the thread pitch is 1.25mm and it's 35mm long. \\ |
- | ^{{techtalk: | + | ^{{techtalk: |
- | | Metric Thread Pitch |||| | + | | Metric Thread Pitch |
- | |Thread OD|Inch|Standard Pitch (mm)|Fine Pitch (mm)|Extra Fine Pitch (mm)| | + | |Thread OD \\ Metric|Thread OD \\ Inches (app)|Standard |
|**4mm**|0.157" | |**4mm**|0.157" | ||
|**5mm**|0.197" | |**5mm**|0.197" | ||
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|**20mm**|0.787|2.50| | |**20mm**|0.787|2.50| | ||
|**24mm**| | |**24mm**| | ||
+ | |||
+ | **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. \\ | ||
+ | |||
+ | {{: | ||
====== 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 | + | NPT stands for National Pipe Thread. Descriptions are commonly used as either straight (NPS) or tapered (NPT). ((DR DICK of the XLFORUM |
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 | + | 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 |
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 | + | * 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 |
- | * 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 | + | * 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 |
^{{techtalk: | ^{{techtalk: |