Vintage Jacobs No. 381 hand tap chuck

Years ago I saw pictures of these chucks but found no useful information on the Internet. My curiosity go the better of me and I finally bought a couple of them. They are a bit unusual. Think of them as two 2 jaw chucks mated together. The top two jaws closest to the MT2 taper are flat and parallel. They grip the two opposing flats on the tap. These jaws also prevent the tap from sliding further into the chuck. The are actuated by the top knurled ring. The lower two jaws keep the tap pointed straight and centered. These are tightened using a conventional chuck key. The chuck says it holds 3/16 to 1/2" taps. As expected, it holds #10 to 1/2" taps from my testing.

Later, it appears Jacobs came out with the rubber flex collet type tap holders. I have a 441-J9 collet type tap holder (#10 to 1/2" tap range) shown for size comparison.

Does anyone have an idea of the vintage of this chuck? the listed 3/16" tap rage makes me think it is pretty old as 3/16" taps are obsolete. It is listed as "pat pending" but no patent number.

Thanks

Additional photos...

crrmeyer said:

Later, it appears Jacobs came out with the rubber flex collet type tap holders. I have a 441-J9 collet type tap holder (#10 to 1/2" tap range) shown for size comparison.

Click to expand...

How were the Jacobs 421 and 441 tap chuck intended to be used? I have a couple of 421-j8 tap chucks that came out of an old shop and the end opposite the rubberflex collett accepts a square shank.

reggie_obe said:

How were the Jacobs 421 and 441 tap chuck intended to be used? I have a couple of 421-j8 tap chucks that came out of an old shop and the end opposite the rubberflex collett accepts a square shank.

Click to expand...

Jacobs has versions to fit Morse Tapers and also square shanks. I presume the 441 1/2" square shank version was meant to put on a large torque driver. The MT may have been used on tapping heads, etc.

The one use I was thinking for the 441 was on a 1/2" speed handle for cleaning out threaded holes as shown in the attached photo. The one problem is that speed handles were not usually made straight enough for this application. I tried about eight of them from the junk pile to find two that were remotely straight enough. I'll have to see if I can hold it straight enough to be useful.

My undersea funding is that they 441 with the square hole could be used with a ordinary ratchet for close quarters or a posted socket driver for field use.

crrmeyer said:

Years ago I saw pictures of these chucks but found no useful information on the Internet.

Click to expand...

Thanks for sharing your pics and info about these chucks, and I hope it's ok to resurrect this old thread. I bought three tapping heads at an auction today, and one of them has a Jacobs 381 chuck. I'd never seen one before, so I was happy to find your description. Unfortunately, I had a look at the inner jaws and they look like they're a bit chewed up from loose taps that started spinning.

Have you ever tried taking your chucks apart? I wonder if it's possible to remove those jaws to attempt a repair.

I was planning to share some pics of my tapper and chuck, but I don't see that option on my phone.

Thanks.

I have never tried to take them apart. But with self-isolating and a rather dull Saturday night, I gave it a try. As it turns out, removing the inner jaws is pretty easy.

1) Gently remove the wire clip. I usually pry up one end and the wind it off carefully


2) Once the wire is off, you can just unscrew the inner collar


3) Then you can slide the two inner jaws + compression springs carefully out.


4)Here is one of the two jaws and its return spring.



I suspect disassembling the front jaws require pressing off the front collar like every other Jacobs chuck. There are lots of Youtube videos on that procedure.

Good luck!

Thanks very much for the quick reply! I'll give it a try. I guess I'll have to remove the chuck from the tapper first. Is it a pressed on Jacobs taper? I'm able to post pics from my desktop computer, so here's a few.

The two I have use a Jacob's taper.