Subject: Re: How do you remove the chuck from lathe?

From: Roy Robinson <[email-masked]>
Date: Sun, 12 May 1996 08:22:26 -0600

Paolo Zini wrote:
> 
> I have a Mayford Ml7 lathe, when the chuck has been in place for
> some week it is very difficult to unscrew it.
> I have spent a lot of time to true the chuck and I do not like to
> use the hammer...
> I have solved the problem using the chain tool used for can shaped oil
> filters of cars; one on the bull gear another on the chuck.
> This avoids the risk of breaking one tooth of the gear and the risk of
> damaging or untrueing (correct?) the chuck; but ... question:
> It must exist one "standard metod" valid also if you must remove one
> backplate (perfectly round, no holes... etc)...
> Can someone explain the "correct" or "traditional" method to me?
> The chuck and the spindle are perfectly round, no holes, pins, special
> tool...and no
> 
> Paolo
> 
>                             _______
>                             TTTTTTT
>                             | | | |
>                           ===========
> Paolo Zini                TTTTTTTTT
> CNUCE institute of CNR    | | | | |
> Pisa ITALY               ===========
> [email-masked]      TTTTTTTTT
>                          | | | | |
>                         ===========
>                         TTTTTTTTT
>                         | | | | |
>                        ===========
> Had the same problem.  It was caused by the shoulder on the spindle of 
the lathe.  It had a "dent" which had raised some metal and caused the 
back plate to hang up.  I removed the chuck and took a very light face 
cut on the lathe spindle shoulder.  Never had trouble since.  BTW, I 
broke a tooth on the back gear while removing chuck.

---

From: Charles Lamont <[email-masked]>
Date: Sun, 12 May 1996 23:55:56 +0100

David William Jenkins writes
> 
>In article <[email-masked]>, Paolo Zini ([email-masked]) 
>writes:
><snip>
>I was taught to put a piece of wood in the jaws of the chuck
>(sideways) to give a lever. Lock up the mandrel by any means at
>your disposal (I put mine into back gear AND leave the "direct"
>connection engaged).  Bang the end of the wood with a fist. 
>Usually works!
>
>The wood is about 25mm x 50mm, 500mm long - use something tough,
>like beech.
>
>
I agree.  This should be all that is necessary.  However, you must make
sure than the spindle nose and chuck bore are really clean, and you
should put a bit of light oil on the spindle before mounting the chuck.
You should not need to screw it on very tightly either.  Screw it gently
until it is almost home, undo it a quarter of a turn, and then screw it
back up sharply, gripping the chuck with both hands, so that the chuck
is seated firmly by its own inertia.    

-- 
Charles

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From: [email-masked] (Paolo Zini)
Date: 13 May 1996 09:19:48 GMT

>is seated firmly by its own inertia.    

I think that my solution is still better: no risk of broken teeth on the
bull gear (I have broken one..), the chain tool are cheap (about 4$ each)
and distribute the stress all around the chuck and the gear then you
don't have uneven stress on chuck and jaws, the operation is smoot even
if the chuck is hardly loked and more you can gently remove a chuck
holding a partially machined piece without untrueing it.

Really this is the story:
I have got a russian 3 jaws 4" chuck for 70 $ (NEW!) and i was in the 
process of buildig the backplate for it, to true the mounting face of
the backplate it must be screwed on the spindle and turned and after 
unscrewed to make holes for bolts.
At this point the problem arises, the backplate was solidly locked and
perfectly round....
I have imagined the chain tool solution to solve this problem, but this 
works also for the chuck. 
After trueing work the final result is:

I have placed a ROUND bar in the chuck and it is true +- 0.01 mm or
+- 0.0005" near the jaws and +- 0.03 (+- 0.0015") four inch from jaws;
I think that is a good result for a RUSSIAN 70$ chuck......

                            _______
                            TTTTTTT  
                            | | | | 
                          ===========
Paolo Zini                TTTTTTTTT

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From: Steve Wellcome <[email-masked]>
Date: 13 May 1996 12:49:22 GMT

First, if you are having a great deal of difficulty getting a
chuck to unscrew, you may want to see if you can find the cause.
THOROUGHLY clean the screw thread in the back of the chuck to
be sure there are no chips, and be sure there are no chips on
the spindle thread.

Then, when screwing on the chuck, do so gently.  Don't wind it
on so it bottoms out with a "thunk."

Typically, I find that I can unscrew my lathe chucks by putting
the lathe in back gear without pulling the bull gear pin (to 
lock the spindle), then putting the chuck key in a hole and
pulling on it.  If it takes more than a moderate tug, it generally
means there's a chip jammed in the screw thread that I neglected
to clean out before putting on the chuck.

In that case I've used a strap wrench, as you have.

One can also clamp a longish bar crosswise in the chuck jaws and
use is as a lever.

A last-distch-effort approach, suggested by Guy Lautard in one 
of his "Bedside Reader" books, is to start the lathe in slowest 
back gear, then slip a block of wood between the lathe bed and 
a chuck jaw as the jaw comes around.

---

From: [email-masked] (Steve Rayner)
Date: Mon, 13 May 1996 10:45:54 GMT

Even after some 26 years the 4 jaw chuck for my ML7 is tight on the spindle.
I lock it in back gear, and use a bronze bar as a lever, and just pull.  
This avoids shock damage to the gears.  Remember, lathe gears are ofen 
cast iron, or semi steel.

-- 
************************************************************************
     MY SECRET IS OIL OF HARLEY DAVIDSON !      Steve Rayner
************************************************************************

---

From: "Kay R. Fisher" <[email-masked]>
Date: Mon, 13 May 1996 16:14:34 -0400

...
> some week it is very difficult to unscrew it.
...
> Paolo
...

The chuck end is easy.  I keep an old broom handle around and just
open up the jaws and put the wood dowel(broom handle) in it and gently
pull - it usually doesn't take much of a tug.

The mandrel might be harder.  I have a Myford Super 7 and there
is a pin on the left rear of the lathe that you can set to freeze
the mandrel.  I guess the ML-7 doesn't have this.  Check to be sure.
If not what most folks due is engage the back gear without engaging
the spindle (hope I'm not butchering up the terminology too bad).

This locks the mandrel.  But if you really get on the chuck it would
be possible to break a gear!  If your worried about that you can
try just wacking the chuck with the broom handle and having only 
the enertia of the mandrel as resistance - same way as you would
take lug nuts off the front wheel of a car if it was already jacked up
and you had no helper to step on the break.

Clear?

Just looked in my manual (which also covers the ML-7).
To lock up the mandrel put in the back gear lock key to lock the
bull wheel to the cone pulley pinion AND lift up the lever on
the right side of the headstock to engage the back gear.

Bye
Kay R. Fisher

---

From: [email-masked] (David William Jenkins)
Date: Mon, 13 May 1996 22:02:51 GMT

In article <[email-masked]>, Paolo Zini ([email-masked]) writes:

<good stuff deleted> 

Paolo,

I forgot to mention, when describing my method of inserting a piece
of wood and banging it, that the first thing you should do is try
pulling the end of the wood - the leverage may be enough to shift
it.

If you have to thump it, use no more than your fist - not very
hard.  No harder than thumping your hand on a desk to emphasise a
point!  The advantage is that you will stop before you break
anything on the lathe, because it hurts if you get too heavy handed.

DON'T USE ANY TOOLS TO HIT IT! EVER!

The other contributors' point about making sure that the mandrel
nose and chuck threads are as clean as possible is VERY true.  Also
helps to keep the work running true.

David Jenkins              -- aka --             Lathyrus Computers Ltd
***********************************************************************
* All incorrect spelling and grammar is intentional.  Corrections are *
* superfluous and will be ignored.  So there.                         *

---

From: [email-masked]
Date: 13 May 1996 22:37:43 GMT

>on so it bottoms out with a "thunk."

Perhaps the single *most* important advise given on this subject.
If the chuck is "snapped" onto the spindle, it will almost always
be a problem to undo.

>One can also clamp a longish bar crosswise in the chuck jaws and

Or my occasional court of last resort:  my largest adjustable 
crescent wrench - placed on one of the jaws.  (gentle here!
don't want to spring the chuck!)

>a chuck jaw as the jaw comes around.  

Hmm!  Sounds dangerous.

===========================================================

 1959 BMW R50                                           Jim Rozen              
 1969 BMW R60US                                (JRR0 @ watson.ibm.com)                 
 1975 BMW R75/6    (The "new" one)        

===========================================================

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From: [email-masked] (Honor� de Gronckel)
Date: 15 May 1996 16:31:33 GMT

In article <[email-masked]>, [email-masked] says...

>I think that is a good result for a RUSSIAN 70$ chuck......
Just being curious, but where did you get that russian chuck? Around here 
russian stuff is vented by polish people at fleamarkets. Do they make it 
to Italy too?
Regards, Honoré.

---

From: [email-masked] (Edk4)
Date: 14 May 1996 07:13:42 -0400

I recall seeing, I think in HS, several years ago, an article describing
what I 
think the author called a "Banjo Chuck Wrench", or something like that.

It was shaped like a ping-pong paddle, made of plywood, and had an
equalatteral
"Y" shaped cutout in the center of the paddle part.

The "Y" was shaped to fit snuggly over *all three jaws", so that when
torsion was
applied, all of the jaws shared the stress, more or less equally. He
reported that it
worked very well.

------------------
Ed Kingsley

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From: Charlie Greenman <[email-masked]>
Date: 16 May 1996 12:53:23 GMT

I'd like to argue against the 1/4 turn "bump the chuck"
method. That's what will lock the sucker on tight from
jamming it. There is no reason to do this.

What has not been mentioned yet (I think anyway) is to
be sure the register on the chuck is good. You can use
Dykems blue, remove all oil from the spindle, put a VERY
light amount of blue on the chuck register, and lightly
screw the chuck home on the spindle. Unscrew the chuck
and see if there is evidence that the chuck register (the
rear of the chuck that sits against the spindle flat)
is touching the spindle all the way around. If it isn't,
then when you screw it down (and lord knows bump it),
you'll cock it a bit and make it harder to remove. And
of course throw the jaws out of concentricity with the
lathe spindle!

If the chuck register is good, and the spindle nose is
clean and the chuck threads are clean, and you lightly
oil the spindle, you should be able to (with 2 hands)
just screw it home, without bumping it. 

My .02

/Charlie

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From: David W Hoskin <[email-masked]>
Date: Thu, 16 May 1996 08:40:15 +0100

Nobody seems to have mentioned yet the method I find simplest and
safest.
I have a piece (two pieces actually as I am always loosing one among the
swarf...) -anyway, as I was saying: I have a piece of hardwood about an
inch and a half square (old chair leg) and just long enough when stood
vertically on the rear slideway to allow one of the chuck jaws to rest
on top in a horizontal position. I then turn the mandrel in the reverse
direction by giving the drive belt a tug.  If backgear is selected the
mechanical advantage is such that only a gentle pull on the belt frees
the chuck in a completely controlled way. Often, if the chuck is not too
firmly wedged I don't find it necessary even to engage backgear.
I thought everyone did it that way! 
--                    
Regards,              **************************************************
David Hoskin          The business of finding fault is very easy: that
East Yorkshire, UK    of doing better, very difficult.(Francis de Sales)
                      **************************************************

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From: [email-masked] (Steve Rayner)
Date: Fri, 17 May 1996 09:53:34 GMT

The information given below is good, if you have a large lathe with heavy 
chucks, and large keys.

With light lathes like a Myford, you could break the key for the 4 jaw chuck,
as it is quite small, and not up to the stress.  Due to the small size of 
some chucks, a piece of wood will break under moderate force, because you 
can't get a big enough piece between the jaws.  That's why I use a bronze 
bar.  The bar is also used to " Bif " out the morse tapers, no hammer, 
just the inertia of a sharp push on the bar.