Difference between revisions of "Tapping"
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*[[NPT]] (National Pipe Taper) | *[[NPT]] (National Pipe Taper) | ||
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| − | *NF (National Fine | + | *NF (National Fine) |
*NC (National Course) | *NC (National Course) | ||
Revision as of 00:01, 25 October 2005
Tapping is the process of cutting threads on the inside diameter of a hole with a tool called a tap. It is used to thread holes for mounting:
- Pressure gauges
- Fuel meters
- Electrodes (Bolts)
- Safety valves
- Other
Types of threads
There are a few diffent thread systems that are used in spudgun construction
- NPT (National Pipe Taper)
- BSP
- NF (National Fine)
- NC (National Course)
The process
- Mark and drill an appropriatly sized hole
- The hole should be in an area where fittings or pipe overlap (double thickness)
- Find correct hole size with a Tap/Drill Chart
- Insert the tap into the tap wrench
- If you don't have a tap wrench, a normal crescent wrench can be used
- Cut the threads
- Be careful to keep the tap straight or you will end up with crooked threads
- If cutting anything other than plastic, use a cutting fluid to lubricate the tool
- Apply downward pressure while slowly turning the tap clockwise 180 degrees, then back out 90 degrees counterclockwise to clear some shavings.
- For tapered threads, stop as soon as the entire length of the hole is threaded
