Pipe Tap? Machinists might know.

[Oregon Viking]

I have tap & die sets. I have never seen a tap like this. It looks like a pipe tap? It has holes in either end so made for a lathe....?
Garage sale find, I had to.

 

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[BosnMate]

You forgot the picture. Bummer, I've done that.

 

[Oregon Viking]

You forgot the picture. Bummer, I've done that.

Whoops!! Thanks!

 

[Ant]

The basic difference between a regular tap and a pipe tap is that a pipe tap is tapered. The therads on a pipe die only go back 3/4 of an inch:

 

[DeepseekerADS]

Good call Ant.

As a "Piper", I was looking for a taper, and found none - or are my eyes askew?

 

[Tony in SC]

It is A tap. Some type of custom tap, but not a pipe tap. Looks just pre CnC. Tony

 

[pepperj]

Precision bore tap, not thinking for gunsmithing but where an accurate bore thread has to obtained.

 

[Bullet:Mich.]

The reason this tool has holes drilled in the center is because it was made on a lathe then heat treated for hardest. This is a precision tap or thread chaser out of a mechanics set such as Snap-On tools.

 

[cudamark]

Whatever needed to be tapped, had to have a precise angle. The pilot extending beyond the tap section ensures that it stays exactly straight. They make reamers that do the same thing when precision is needed.

 

[NOLA_Ken]

It's really similar to the taps used to thread shotgun barrels to put in chokes. What it's actually for I have no idea

 

[Anduril]

I agree this item was made on a lathe - explaining the holes on each end.
Perhaps the part is defective, so the machinist making it never finished it by grinding off the excess?
This is my theory and I'm sticking with it!

Another option (possibly?) is maybe the tap is designed as a combination punch and tap for soft materials.
Done right, you theoretically could perform both operations at once with the same tool: Punch the material pilot hole, and then tap it.

But I don't know. It's unusual, that's for sure!
Nice find!

 

[Fletch88]

The holes in each end are called "centers" used to put blank "between centers" to cut/grind any cylindrical type part.
It is definitely a special made, straight tap. I have never seen one exactly like it in 30 years of machining trade.

 

[cudamark]

With all the info stamped on this item, I think it's a finished product and not a reject or partially made tool. If some of the wording is any indication, it might be for a high pressure union fitting, which requires precise joints to prevent leaks. Probably something that they didn't make a jig for or that wouldn't fit in a milling machine.

 

[Sidevalve45]

I could see where a tap like that would be used when the application has long studs coming out of the threaded holes. The hole the threads are going into would also need to be drilled accurately. If the angle is off by 1° in one inch of travel it will be off location by .0175 on the other end. Now multiple that by five inches and now your off by .0875. If you have a two mounting flange with multiple holes they will likely not assemble unless the mating part has way oversize holes.......At least that's what I think.

 

[Oregon Viking]

I talked to a gunsmith today.....he was unsure of it's use. Hmmmm.