pipe taper tap thread depth?

[meowkat]

I'm not entirely clear on what this print is asking for with the depth here, is it the top of the hole to the bottom or is it somehow a measurement of the depth of the tapping?

 

[npinson]

That is similar to what my Solidworks spits out on a drawing. Basically Solidworks says NPT has to be that depth. I use that z value when threadmilling NPT.


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[mhajicek]

Calling a thread depth on a taper pipe thread is an error. The spec of the thread determines the depth. You have the gauge, right?

 

[npinson]

That z depth won’t work with a NPT tap


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[meowkat]

Calling a thread depth on a taper pipe thread is an error. The spec of the thread determines the depth. You have the gauge, right?

I am going to buy one right now, I don't have them for NPT stuff. Is using them the same?

 

[meowkat]

Wait... "1/4-18 NPT TAP DRILL THRU NS ONLY" what does "tap drill thru NS only" mean? I though it was NPT not National Straight.

 

[doug8cat]

When a normal call out is printed such as 1/4-18 NPT. I was taught by a master tool and die guy (30 years in the trade & wicked skills and knowledge). The proper depth to thread to is 6 threads from the top of tap. I never had a problem with this method, or at least know one called me on it.
That being said in view of the nomenclature on the print I would put in a call to the customer for clarification.

 

[dave morgan]

what does "tap drill thru NS only" mean?

Could NS = Near Side?



Dave

 

[upm2019]

It looks like some one relied too much on their Cad program fo the call out . I believe the NS means near side so it’s gonna be a blind hole . As to the depth refer to machinist hand book .Depending on the hole depth you may have to cut the tap back to get it to gage properly. If you don’t have a gage you can use a fitting count 3 turns plus or minus 1/2 and you should be fine.
Pete

 

[meowkat]

It looks like some one relied too much on their Cad program fo the call out . I believe the NS means near side so it’s gonna be a blind hole . As to the depth refer to machinist hand book .Depending on the hole depth you may have to cut the tap back to get it to gage properly. If you don’t have a gage you can use a fitting count 3 turns plus or minus 1/2 and you should be fine.
Pete

Okay, near-side makes perfect sense there is a center hole in the piece. So it's saying to only drill through one side.

I've already asked the customer for clarification, but it's nice to have some other opinions while I'm waiting to hear back.

 

[Nibleswick]

I am going to buy one right now, I don't have them for NPT stuff. Is using them the same?

NPT gauges have a little flat at the top of the thread that should line up flush with the surface of the material if the thread is the right depth +- a half a turn.

 

[ondori]

what does "tap drill thru NS only" mean?

Could NS = Near Side?

Dave

Correct, NS means Near Side.

Also that depth should not be trusted, it is a arbitrary value that the CAD software spit out based on the actual 3D models hole depth.

Although there is lots of room for NPT depth. For example if you go 1/8" deeper than you need to, the tapped hole will still work because the NPT thread is a cone, somewhere below the surface (i.e. 1/8" deeper) is the exact NPT thread you are looking for. The top portion will be loose.

The only issue is that you will eventually break your tap..

 

[aj]

Depending on the hole depth you may have to cut the tap back to get it to gage properly.

Pete

They make a "short projection" pipe tap for shallow holes. Had to use one once on an alum manifold.

 

[SeymourDumore]

That z depth won’t work with a NPT tap


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Sure it will. Note that it says .402 MIN.

1/8-18 NPT has an effective thread length of .4018, so your internal thread depth must be no less than that.
( Doesn't make the callout any less retarded tho.... )