1/8" NPT tap - EGT question

[alIan]

I am having trouble finding the 1/8" NPT (27) tap that is needed for the greddy EGT probe. It seems to me that the tap is not 1/8" in diameter/circumfrence... but that this is the thread spacing...?

i assume this because i was looking for alternatives on the forums and i heard a 9mm - 1.0mm tap works as well.

I am only able to find the latter, and i have been to 4 hardware stores. There are plenty of 1/4" NC and NF 24 and 32 threads/inch taps, but no "NPT" tap (national pipe thread?).

 

[SlowSpyder]

go to sears, i got mine there.

 

[Shearer]

That is a standard pipe thread. Most hardware stores should carry that tap. If not find a local industrial tool supplier. that'll be a gaurantee.

 

[oldman]

I bought a set of metric and standard from ebay for $15 plus shipping, both set had the 1/8 npt.

 

[alIan]

So could somebody explain the NPT thread type to me so i could explain it to the hardware guy? the 1/8" CAN'T be the diameter... no probe would fit into that... so how can i explain this tap to somebody who is a total idiot (like the guy at sears) and doesn't know his own inventory?

-i

 

[oldman]

NPT = tapered National Pipe Thread, design for both joining and sealing. The pipe size, 1/8, does not refere to any physical dimensions. 27 means 27 threads per inch. The OD of a 1/8 npt is 13/32" or .405". I think your best bet is to either look for it yourself off the shelf or an old school auto parts store.

 

[steve]

The 1/8" CAN'T be the diameter.

It's not anywhere close to 1/8". The recommended drill bit is a "R" (.339") the closest fractional size is 11/32"

Steve

 

[fatafall]

I also got mine at sears, very easy to find on the wall of taps, thats where I would go if I were you.

 

[wret]

You probably already have your probe, but if not and you are keeping your heat shield, I found this to be a much simpler alternative:

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[Defiant]

Pipe is measured by the size of the hole that carries water. Tubing is measured by outside diameter.

When they were still called junior high schools, there were shop classes. It was a less dumber world.