Tap and die question

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I need to re tread a bolt on my jointer fence.  It's a 1/2" - 14.  I went and bought a set at harbor freight which had the requisite die size but when I got it home it's way too large.  I must be missing something on how they designate sizing.  Below is a pic of the nut and the die side by side. I want to order the correct one but am worried I'll get the wrong size again. 


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The 1/2-14 would be the tread size. The 1/2" would be the outside diameter of the threads and the 14 is the pitch = 14 threads per inch. How do you determine that is was the thread you needed? 


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NPT stands for national pipe threads. Pipe threads are different than bolt threads. 1/2" refers to the inside pipe diameter and the outside is close to .9"

I believe what you are looking for is 1/2"-13 NC or 7/16"-14 NC.

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34 minutes ago, jussi said:

Because the nut does partially go in the bolt.  About an inch in however it gets stuck.  Plus I actually counted the treads.

Are you sure you don't need metric bolts/nuts?


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To be sure, take the nut to HD or Lowe’s and they have a bolt sample chart that you can screw it onto. Yep, what you have is a 1/2” pipe die as others have said.

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Thanks for the replies guys. You’re I didn’t realize there was a difference between pipe and nut / bolt treads.  And rainjer might be right that it is metric treads. 

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