1. Home
  2. ⏣ General Metalworking
  3. real jacobs 3/8" keyed chuck disassembly

real jacobs 3/8" keyed chuck disassembly

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?

Reply to
Cydrome Leader
Loading thread data ...

formatting link

Reply to
Jim Wilkins

I made a kludge gol pressing things out of a couple of pieces of 4 inch cha nnel and a couple of pieces of big all thread. And then used it with a 4 t on 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

Reply to
dcaster

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.

formatting link

Reply to
Cydrome Leader

Reply to
Cydrome Leader

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?

Reply to
Jim Wilkins

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.

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

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.)

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.

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

Good Luck, DoN.

Reply to
DoN. Nichols

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.

Reply to
Cydrome Leader

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.