real jacobs 3/8" keyed chuck disassembly

Cydrome Leader

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Jan 20, 2018, 6:09:21 PM1/20/18

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I've been fussing for way to long to take apart a real Jacobs made in USA
41BA 3/8" keyed drill chuck. Their website says to close the jaws 1/2 way
and press on the jaws while pressing against the botttom of the shell with
clearance to allow the inside to pop out.

Tried a 1-1/2 or 2 ton arbor press. No luck. Tried a vise. No luck. Made a
fixture from steel channel and 2x 7/16x20 bolts torqued as hard as I can
with wrenches. They bent but the thing won't break free. Tried heating it,
squirting the insides with pb blaster- no dice.

I've seen some poeople press on the jaws while others press on the body
part with the key holes that the jaws slide on. Does this matter at all?

Even bigger chucks see to come apart easier from watching some youtube
videos. What the heck would be holding this thing together to hard?

Could probably take it to a place with a hydraulic press, just to see it
break apart, but I'm pretty sure this will cost as much as an exact
replacement.

Any tips?

Jim Wilkins

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Jan 20, 2018, 6:57:08 PM1/20/18

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"Cydrome Leader" <pres...@MUNGEpanix.com> wrote in message
news:p40i6s$9u5$1...@reader2.panix.com...

http://wiki.vintagemachinery.org/JacobsChuckRebuild.ashx

dca...@krl.org

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Jan 20, 2018, 7:07:41 PM1/20/18

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On Saturday, January 20, 2018 at 6:09:21 PM UTC-5, Cydrome Leader wrote:
> I've been fussing for way to long to take apart a real Jacobs made in USA
> 41BA 3/8" keyed drill chuck. Their website says to close the jaws 1/2 way
> and press on the jaws while pressing against the botttom of the shell with
> clearance to allow the inside to pop out.
>
> Tried a 1-1/2 or 2 ton arbor press. No luck.
>

> I've seen some poeople press on the jaws while others press on the body
>

> replacement.
>
> Any tips?

I made a kludge gol pressing things out of a couple of pieces of 4 inch channel and a couple of pieces of big all thread. And then used it with a 4 ton hydraulic jack.Could easily use a bigger jack. The nice thing is that it breaks down and does not take up a lot of room to store it.

Dan

Cydrome Leader

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Jan 20, 2018, 7:40:30 PM1/20/18

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Tried this, less the partical board as the force I'me dealing with by far
has to exceed what's going on there.

This thing started to bend, which is why it's shored up on one side by the
jaws. Yup, they're pressing into the steel and leaving marks too.

http://www.panix.com/~presence/jacobs-jig.jpg

Cydrome Leader

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Jan 20, 2018, 8:38:57 PM1/20/18

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Jim Wilkins

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Jan 20, 2018, 8:41:46 PM1/20/18

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"Cydrome Leader" <pres...@MUNGEpanix.com> wrote in message

news:p40nhs$kf5$1...@reader2.panix.com...

I have to ask, are you sure ONLY the outer sleeve is supported, and
the central chuck body is free to slide into a hole?

DoN. Nichols

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Jan 20, 2018, 9:16:58 PM1/20/18

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On 2018-01-20, Cydrome Leader <pres...@MUNGEpanix.com> wrote:
> I've been fussing for way to long to take apart a real Jacobs made in USA
> 41BA 3/8" keyed drill chuck. Their website says to close the jaws 1/2 way
> and press on the jaws while pressing against the botttom of the shell with
> clearance to allow the inside to pop out.

Hmmm ... I would not press on the jaws (though the 1/2 way
setting is still necessary). I would turn a sleeve which would press on
the nose of the body and another which would press on the back edge of
the outer (keyed) part of the chuck. It should not take more pressure
than your 1-1/2 Ton arbor press could provide.

For reassembly, you'll need another sleeve, to go around the
body with the key holes, and to press on the gear teeth of the keyed
part.

Both sleeves can be made of aluminum -- it is strong enough.

> Tried a 1-1/2 or 2 ton arbor press. No luck. Tried a vise. No luck. Made a
> fixture from steel channel and 2x 7/16x20 bolts torqued as hard as I can
> with wrenches. They bent but the thing won't break free. Tried heating it,
> squirting the insides with pb blaster- no dice.

Does the chuck adjust properly? If so, it should press apart
fairly easily.

> I've seen some poeople press on the jaws while others press on the body
> part with the key holes that the jaws slide on. Does this matter at all?

Pushing on the jaws risks applying too much force to the partial
threads on the outside of the jaws, and breaking off a tooth, or perhaps
stripping the threads in the ID of the "broken" ring which is held in
place by the outer part of the chuck. (The ring is threaded cast iron,
which is then broken apart at two weak points made into it, so it can be
assembled over the chuck body (into a groove) and engage the threads on
the chuck jaws.)

> Even bigger chucks see to come apart easier from watching some youtube
> videos. What the heck would be holding this thing together to hard?

Is it possible that there was a hole in the outer part of the
chuck, and it was welded to the ring? Or perhaps someone applied
LocTite bearing mount to it prior to assembly. If the latter, it would
need to be heated to the temperature which would release the LocTite.
Look up the release temperature for it.

> Could probably take it to a place with a hydraulic press, just to see it
> break apart, but I'm pretty sure this will cost as much as an exact
> replacement.
>
> Any tips?

More of a question. What is wrong with it that it needs to come
apart?

Good Luck,
DoN.

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Gunner Asch

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Jan 22, 2018, 2:22:30 AM1/22/18

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Cydrome Leader

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Jan 26, 2018, 1:30:16 AM1/26/18

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No dice. They must have changed lots of their designs into throw away
trash. Surprise, the folks behind that probably go treated the same.

Got a real NOS chuck from Rohm on the way.