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What TYPE of tap is this?

52 Ford

May 20, 2021
So, I found an old 1/4" NPT tap in a toolbox. Most of the tools in the box were from around 1900. Some of the tools had patent dates from much earlier, so I think 1900 is a good guess.

It IS 1/4" NPT. I used it to tap some holes in plastic and the threads were actually a really good fit. But, again, that's plastic.

What I'm wondering, is what TYPE of tap this is. I has a rectangular "tang" instead of the square drive that most taps have.

Seems like some sort of "repairman's tap" or something like that. Perhaps mean't to be driven with an adjustable wrench or pliers? Maybe to chase/clean threads?

If you look at the second picture, you can see where it's stamped "1/4". Sorry the picture is blurry. Bad lighting, so the exposure was a bit long.

There's a LOT of thread length there.

Sorry I forgot to add something for scale. I'll add a picture with some tape measures or maybe some steel rules (if I feel like getting fancy :) ) in it tomorrow.

To get a production 1/4" pipe nipple to fit the hole, I tapped a little under 3/4 of the length of the tap.

Sent using Morse code on - .- .--. .- - .- .-.. -.-
By the way, the original owner was an engineer. Maybe something shop made?
I just threw away about 100 of these for regular and odd pitch threads

They came in a cabinet I have had for 25 years, Came out of 'The Shoe'

I have always assumed that they are old taps that are of low quality steel so they make the long lead in to minimize wear, but that is jut an assumption

Is saved one...marked 11 mm 20 tpi, whitworth

You know just in case I need it

They are definitely blacksmith taps and had a simple slotted plate type of holder to drive them by hand. I have a few that I keep with my regular taps. They are very old so....

The blacksmiths often made their own screw plates to match their swages and ran these taper taps into the nuts to match and create the desired fit.

That's all I have to say about that.

Bob....not the cat.
I sort of feel the need to buy a lot more of these.

Nostalgia? I dunno. I like old tools and I still use a lot of tools.