Getting Jacobs chuck off arbor

I have a Jacobs 14N 1/2" chuck for the tailstock of my lathe. The MT2
arbor it is mounted on has spun in some past life and is a bit munged
up.
I ordered a new JT3 to MT2 arbor for it, but now I find I can't budge
the existing arbor out of the chuck. It's not rusty. I've soaked it
penetrating oil for about a day. I tried heating it with a torch and
then later by baking it in the oven. Quickly cooled the arbor with a wet
sponge while the chuck was still several hundred degrees from the oven.
I've succeded in slightly bending a Starrett center punch trying to
pound the arbor through the center hole in the chuck.
Any tips on things I could try to break up this long-term relationship?
Reply to
xray
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I guess the good news is that if tapers are that well locked, there probably isn't any scoring on the taper surfaces, maybe.
I've released some stubborn chucks and other parts by using a drift, then tamping the assembly down on a hard surface. The drift would just be a section of mild steel that is capable of passing thru the hole at the back of the chuck cavity. A 6" to 12" piece of round stock inserted into the chuck with the jaws loosely adjusted to the round stock (so the jaws can slipalong the stock).
A good set of gloves should protect your hands from injury. With the chuck opening pointed down, and with the weight of the chuck and arbor resting on the drift, raise it in the air over a solid mass, then tamp down hard, allowing the force to be transmitted thru the drift to the inner end of the arbor taper.
If a few solid tamps don't release the taper lock, some bad voodoo is going on in there, requiring the steady pressure of a press.
WB ..............
xray wrote:
Reply to
Wild Bill
I have two wedges with slots in them. Put one on each side and they overlap some and then tighten in a "C" clamp or vise and the chuck comes right off. I've had them forever and I'm farily certain they are commercial but they could be fabricated easily.
Reply to
Tom Gardner
If you have, or can get a front end fork tool of the right size from an automotive store you could tap it in between the chuck and the barrel to loosen the taper. If the barrel has turned, it means the traveler screw that rides in a slot has been lost or broken. If you can get it apart it's no big deal to repair. Bugs
Reply to
Bugs
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is the thingy you need, or a press. The wedges are cheaper. Tom
Reply to
Tom Wait
Since you've got a lathe, put the argor in the chuck and bear a wood stick against the chuck. The side forces will quickly walk the chuck off of the arbor. If the chuck is on really hard, you may want to try some aluminum instead or even just run the toolpost up against the chuck.
-- Why do penguins walk so far to get to their nesting grounds?
Reply to
Bob May
Yes I've seen the wedges before. Others here have suggested them also.
In this case, it won't work because the small MT-2 arbor I'm trying to remove has no lips for the wedges to butt against.
Reply to
xray
I've had a similar problem. Never did get the sucker off, gave it away and got another chuck, raised some eyebrows locally when people saw a Jacobs 14N on my free table at the club meeting ..
Before resorting to my non-solution, I'd certainly try making a short stub pin which fits over the ram on your press, and try pressing it out with 12-20 tons. I believe that sometimes people epoxy arbors into chucks ..
GWE
Reply to
Grant Erwin
Are you sure it's a Jacob's taper and not screwed on? I had that same problem once where there was no lip for a wedge for removal and it turned out that it was made for no removal. Dick
Reply to
Dick
I ran into exactly that same problem a few months back. Like yours, there was no shoulder to bear wedges against. I did the hammer and punch thing, the soak in penatrant & bigger hammer and another punch (the first one started to bend) trick, and finally the hardened steel pin and 10 ton press trick. None budged the chuck. In frustration, and figuring the chuck may be lost anyhow, I cut the arbor off flush, chucked the chuck in my lathe and drilled and then began carefully boring out the remains. I tried to approach slowly, hoping that I could cut into what was left of the arbor thin enough to collapse with a chisel, without hitting the chuck. As I apporached what i thought would be close enough, I noticed that there was a pattern in the bore. A close look revealed that the end of the arbor was THREADED! Duh. Color me stupid. Not sure why that possibility never occured to me, but my excuse was that I did not put the chuck on there, so i couldn't have known. A few taps with a chisel and what remained of the arbor easily unscrewed. So if you did not put that chuck on there yourself, you may want to double check...
-AL A.
Reply to
Al A.
Since we sell used machine tools I have solved this problem at least a dozen times. Saw the arbor off approximately flush with the chuck. You were going to throw it away any way. Run the chuck up tight and tighten it with the chuck key. Chuck it in your lathe spindle chuck and drill a pilot hole for something like a 5/16" - 18 thread and tap it. Put a small 1/2" drive socket over the Jacobs chuck arbor drive end and screw a bolt through that into the newly threaded hole. That bolt will draw the tapered stub out with almost no torque on the wrench. It is even more cost effective when you salvage an Albrecht chuck this way. Leigh at MarMachine
Reply to
CATRUCKMAN
I'm beginning to think I may not win this battle either. I don't have a press to try.
I'm in the process of trying Bob's idea of side pressure.
Reply to
xray
Thanks. It's worth a double check, but it is a Jocobs 14N chuck. As far as I know, that means 3JT taper mount.
Reply to
xray
This idea sounded good to me.
I put some 1/2 inch rod in the chuck and tightened it hard. Put the extending rod in my lathe chuck with the two chucks jaws-to-jaws. Clamped some hardwood in my tool holder and pressed it hard against the far end of the MT-2 arbor. A bit of waxy lube between the wood and metal. Slow speed on the lathe.
I can see the whole assmebly flexing as I crank in the cross slide. Ran it this way for several minutes with no success yet. I just put the chuck back in the oven and will try again after a bake.
I haven't given up yet.
Reply to
xray
I would have thought the Jacobs arbor would be too hard for boring and tapping. So that's not true in your experience?
Might give this a shot as last resort. I'm debating about just polishing up the existing MT-2 taper and pretending it doesn't bother me.
Reply to
xray
Thanks for all the ideas. Maybe some of the things like Bob's idea of side pressure and my application of several heat(400f)/cool cycles may have helped break it loose.
The final solution was brute force. I drilled the hole through the center of the chuck a little bigger so I could fit a bigger punch to the arbor and then used a big hammer.
There was no galling inside the chuck mount taper, so it was just simple metal to metal contact working better than I expected.
A long battle to finish exactly the way I started.
Reply to
xray
Unless you are trying to salvage the MT arbor you can machine/file slots for the wedges and heat the assembly. Be aware that some people assemble their chuck/arbor with loctite.
Unka George (George McDuffee)
There is something to be said for government by a great aristocracy which has furnished leaders to the nation in peace and war for generations; even a democrat like myself must admit this. But there is absolutely nothing to be said for government by a plutocracy, for government by men very powerful in certain lines and gifted with the "money touch," but with ideals which in their essence are merely those of so many glorified pawnbrokers.
Theodore Roosevelt (1858-1919), U.S. Republican (later Progressive) politician, president. Letter, 15 Nov. 1913.
Reply to
F. George McDuffee
All us "cheap screws" out here appreciate this tip.
Thanks
Unka George (George McDuffee)
There is something to be said for government by a great aristocracy which has furnished leaders to the nation in peace and war for generations; even a democrat like myself must admit this. But there is absolutely nothing to be said for government by a plutocracy, for government by men very powerful in certain lines and gifted with the "money touch," but with ideals which in their essence are merely those of so many glorified pawnbrokers.
Theodore Roosevelt (1858-1919), U.S. Republican (later Progressive) politician, president. Letter, 15 Nov. 1913.
Reply to
F. George McDuffee
Glad you got it off okay. Another method is to fit a sturdy pipe, a little longer than the arbor, loosely around the arbor. Then, with the chuck at the top, slam the pipe end as hard as you can against a solid steel surface. The inertia of the arbor will often pull it out. Don Young
Reply to
Don Young
According to :
A good one. And another related one, which starts the same has you installing a Zerk fitting into the threaded hole, and pumping in grease to pop it free. (Of course, that would not work with this one, because I remember mention of it having a hole in the body which reaches through to the arbor, so the grease would simply fill the chuck -- unless you could also tap that hole and put in a screw to plug the hole.
I'm going to be trying the Zerk and grease trick on an arbor which a friend got from eBay with the wrong sized arbor for his lathe. It also has too small a shoulder for the wedges to work. And if the grease fails, there is already that threaded hole made for the Zerk to try your trick on -- complete with nicely grease-lubricated threads to help the process. :-)
Enjoy, DoN.
Reply to
DoN. Nichols

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