Here's a question from another newsgroup. Opinions?

[John is in Britain, hence the "Pondian" reference.]


From: John Hatpin
Newsgroups: alt.fan.cecil-adams
Subject: Hey, chuck!
Date: Tue, 28 Feb 2006 23:00:34 +0000
Message-ID:

Frame of reference: you've got an electric drill, or maybe a
hand-drill, and the bit fits into a traditional chuck, tightened
with a key that slots into one of three holes on the chuck and
meshes with a circular, toothed edge at a 90-degree angle. You
know the deal, I'd guess, unless there are major Pondian
differences I'm unaware of.

My father, God bless him, who knows more about tools than I'll
ever comprehend, tightens the chuck by putting the key into each
of the three holes in turn and giving it a final twist from each.
I only tend to do it once in one hole, on the basis that all
you're doing is turning the collar of the chuck, and there's no
difference between doing that with the end of the key in hole 1, 2
or 3.

Assuming I've framed the question adequately, what's your opinion?
Is my lovely old Dad right?

darkon wrote:

My father, God bless him, who knows more about tools than I'll
ever comprehend, tightens the chuck by putting the key into each
of the three holes in turn and giving it a final twist from each.
I only tend to do it once in one hole, on the basis that all
you're doing is turning the collar of the chuck, and there's no
difference between doing that with the end of the key in hole 1, 2
or 3.

Assuming I've framed the question adequately, what's your opinion?
Is my lovely old Dad right?

That's the way I was taught in high
school shop class...

On Wed, 01 Mar 2006 13:36:44 -0800, Jim Stewart wrote:
darkon wrote:

Assuming I've framed the question adequately, what's your opinion?
Is my lovely old Dad right?

That's the way I was taught in high
school shop class...

Well, same here, but they also told us that glass flows over time and a
bunch of other provably wrong stuff. I'm with darkon on this one, I've
heard it, I do it, but I've never understood the reasoning for it.

Put it another way - my 3-jaw on my lathe only has one place to tighten
the chuck...

darkon wrote:

snip

My father, God bless him, who knows more about tools than I'll
ever comprehend, tightens the chuck by putting the key into each
of the three holes in turn and giving it a final twist from each.
I only tend to do it once in one hole, on the basis that all
you're doing is turning the collar of the chuck, and there's no
difference between doing that with the end of the key in hole 1, 2
or 3.

Assuming I've framed the question adequately, what's your opinion?
Is my lovely old Dad right?


In my experience, tightening from all three holes will hold the bit
tighter and, if done properly, make the bit run more true. When
tightened all from one hole, and not snugged a bit in the other two, I
believe the bit is skewed some. Moot point with self tightening chucks,
which I like better.

It's always good practice to tighten all the holes in sucession. It
takes out any possible slop in the the chuck, gives you the best
possible hold. You will commonly find one of the holes seems to tighten
things up better than the other 2.

It's mandatory on a 4 jaw chuck, moving one may unsettle the others. In
that case, you need to tighten sequentionally until you get 4 in a row
that show no signs of movement.

darkon wrote:
Here's a question from another newsgroup. Opinions?

[John is in Britain, hence the "Pondian" reference.]


From: John Hatpin
Newsgroups: alt.fan.cecil-adams
Subject: Hey, chuck!
Date: Tue, 28 Feb 2006 23:00:34 +0000
Message-ID:

Frame of reference: you've got an electric drill, or maybe a
hand-drill, and the bit fits into a traditional chuck, tightened
with a key that slots into one of three holes on the chuck and
meshes with a circular, toothed edge at a 90-degree angle. You
know the deal, I'd guess, unless there are major Pondian
differences I'm unaware of.

My father, God bless him, who knows more about tools than I'll
ever comprehend, tightens the chuck by putting the key into each
of the three holes in turn and giving it a final twist from each.
I only tend to do it once in one hole, on the basis that all
you're doing is turning the collar of the chuck, and there's no
difference between doing that with the end of the key in hole 1, 2
or 3.

Assuming I've framed the question adequately, what's your opinion?
Is my lovely old Dad right?

darkon wrote:

Here's a question from another newsgroup. Opinions?

[John is in Britain, hence the "Pondian" reference.]


From: John Hatpin
Newsgroups: alt.fan.cecil-adams
Subject: Hey, chuck!
Date: Tue, 28 Feb 2006 23:00:34 +0000
Message-ID:

Frame of reference: you've got an electric drill, or maybe a
hand-drill, and the bit fits into a traditional chuck, tightened
with a key that slots into one of three holes on the chuck and
meshes with a circular, toothed edge at a 90-degree angle. You
know the deal, I'd guess, unless there are major Pondian
differences I'm unaware of.

My father, God bless him, who knows more about tools than I'll
ever comprehend, tightens the chuck by putting the key into each
of the three holes in turn and giving it a final twist from each.
I only tend to do it once in one hole, on the basis that all
you're doing is turning the collar of the chuck, and there's no
difference between doing that with the end of the key in hole 1, 2
or 3.

Assuming I've framed the question adequately, what's your opinion?
Is my lovely old Dad right?

You may get away with single-hole tightening on a quality chuck in new
condition, but I *always* tighten all 3. You will too as soon as you feel the
scroll move more.

GWE

On Wed, 01 Mar 2006 22:30:51 GMT, RoyJ wrote:
It's always good practice to tighten all the holes in sucession. It
takes out any possible slop in the the chuck,

How can it? The two parts you're exerting force on, are the same parts
in each of the 3 locations.

gives you the best
possible hold. You will commonly find one of the holes seems to tighten
things up better than the other 2.

Well, yeah, the first one seems to have more effect

"Dave Hinz" wrote in message
...
On Wed, 01 Mar 2006 22:30:51 GMT, RoyJ wrote:
It's always good practice to tighten all the holes in sucession. It
takes out any possible slop in the the chuck,

How can it? The two parts you're exerting force on, are the same parts
in each of the 3 locations.


Hi dave

Could it be that the teeth on the key have a different leverage on the
chuck teeth while in one hole than they do when in another hole??
I always thought the guys who designed the "gear ratio" had it figured out
so the teeth engaged differently from each of the three holes.

Jerry

In article M8qNf.53363$3W5.39831@trnddc02,
says...

"Dave Hinz" wrote in message
...
On Wed, 01 Mar 2006 22:30:51 GMT, RoyJ wrote:
It's always good practice to tighten all the holes in sucession. It
takes out any possible slop in the the chuck,

How can it? The two parts you're exerting force on, are the same parts
in each of the 3 locations.


Hi dave

Could it be that the teeth on the key have a different leverage on the
chuck teeth while in one hole than they do when in another hole??
I always thought the guys who designed the "gear ratio" had it figured out
so the teeth engaged differently from each of the three holes.


I think it has to do with the fact that the ring with the teeth is not a
perfect fit on the chuck body. Tightening the chuck tends to cock the
ring a bit so it doesn't turn as freely. Moving the key to a different
hole pushes on a different point on the ring and frees it up.

Ned Simmons

"Grant Erwin" wrote: You may get away with single-hole tightening on a
quality chuck in new condition, but I *always* tighten all 3. (clip)
^^^^^^^^^^^^^^^^
I think Grant has put his finger on it. When you tighten a chuck in one
hole, you rotate the geared sleeve, but you also push all the clearance to
one side. If the chuck is new and in good condition, this will be minimal,
but there will always be some. So, as the chuck tightens, the same friction
that holds it closed will hold the jaws slightly off center. Applying the
chuck key to each of the holes in succession keeps pushing the jaws closer
to perfect concentricity.

"Ned Simmons" wrote in message
...
In article M8qNf.53363$3W5.39831@trnddc02,
says...

"Dave Hinz" wrote in message
...
On Wed, 01 Mar 2006 22:30:51 GMT, RoyJ wrote:
It's always good practice to tighten all the holes in sucession. It
takes out any possible slop in the the chuck,

How can it? The two parts you're exerting force on, are the same parts
in each of the 3 locations.


Hi dave

Could it be that the teeth on the key have a different leverage on the
chuck teeth while in one hole than they do when in another hole??
I always thought the guys who designed the "gear ratio" had it figured
out
so the teeth engaged differently from each of the three holes.


I think it has to do with the fact that the ring with the teeth is not a
perfect fit on the chuck body. Tightening the chuck tends to cock the
ring a bit so it doesn't turn as freely. Moving the key to a different
hole pushes on a different point on the ring and frees it up.

Ned Simmons

Hi Ned

I'd bet you have the right idea. That even makes sense.

Jerry

Yeah I'll jump in here.

I was taught to use all three holes on a jacobs chuck...
I agree with the 'coller gets torqued differently' theory...


As for the 3 Jaw lathe chuck, I was taught that since the actuation
mechinisim is totaly differet than on a jacobs chuck that it was
unnecessary, since the scroll is doing the work not pushers behing the
coller...

and yeah, if I'm really worried on the lathe.. I use all three....

I say.... Dad was right.....

--.- Dave


"darkon" wrote in message
...
Here's a question from another newsgroup. Opinions?

[John is in Britain, hence the "Pondian" reference.]


From: John Hatpin
Newsgroups: alt.fan.cecil-adams
Subject: Hey, chuck!
Date: Tue, 28 Feb 2006 23:00:34 +0000
Message-ID:

Frame of reference: you've got an electric drill, or maybe a
hand-drill, and the bit fits into a traditional chuck, tightened
with a key that slots into one of three holes on the chuck and
meshes with a circular, toothed edge at a 90-degree angle. You
know the deal, I'd guess, unless there are major Pondian
differences I'm unaware of.

My father, God bless him, who knows more about tools than I'll
ever comprehend, tightens the chuck by putting the key into each
of the three holes in turn and giving it a final twist from each.
I only tend to do it once in one hole, on the basis that all
you're doing is turning the collar of the chuck, and there's no
difference between doing that with the end of the key in hole 1, 2
or 3.

Assuming I've framed the question adequately, what's your opinion?
Is my lovely old Dad right?

Accuracy is kept with the triple tightening.
My Dad told me in the 50's.
He got it from three professional (USAF) Machinists who in their spare time
built Trains that they could sit in not on.

They worked on the B-36's and other prop machines - later they moved to Jets and
one to a not named department that has a bunch of very large antennas..... :-)

Martin

Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH & Endowment Member
NRA Second Amendment Task Force Charter Founder



darkon wrote:
Here's a question from another newsgroup. Opinions?

[John is in Britain, hence the "Pondian" reference.]


From: John Hatpin
Newsgroups: alt.fan.cecil-adams
Subject: Hey, chuck!
Date: Tue, 28 Feb 2006 23:00:34 +0000
Message-ID:

Frame of reference: you've got an electric drill, or maybe a
hand-drill, and the bit fits into a traditional chuck, tightened
with a key that slots into one of three holes on the chuck and
meshes with a circular, toothed edge at a 90-degree angle. You
know the deal, I'd guess, unless there are major Pondian
differences I'm unaware of.

My father, God bless him, who knows more about tools than I'll
ever comprehend, tightens the chuck by putting the key into each
of the three holes in turn and giving it a final twist from each.
I only tend to do it once in one hole, on the basis that all
you're doing is turning the collar of the chuck, and there's no
difference between doing that with the end of the key in hole 1, 2
or 3.

Assuming I've framed the question adequately, what's your opinion?
Is my lovely old Dad right?

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----

"Ned Simmons" wrote in message
...
In article M8qNf.53363$3W5.39831@trnddc02,
says...

"Dave Hinz" wrote in message
...
On Wed, 01 Mar 2006 22:30:51 GMT, RoyJ wrote:


I think it has to do with the fact that the ring with the teeth is not a
perfect fit on the chuck body. Tightening the chuck tends to cock the
ring a bit so it doesn't turn as freely. Moving the key to a different
hole pushes on a different point on the ring and frees it up.

Ned Simmons


You are on the right track. The fit between the chuck and scroll can wear
with use. When you tighten one hole it forces the scroll off center, so by
tightening all three you have equalized the forces on the 3 holes. Bringing
it back to center. Mostly noticeable on older worn chucks. I have seen one
chuck so bad the only way it would center up right was to use a torque
wrench on each hole.
Those who have older worn chucks know that the fit between the scroll and
chuck body is bad, and can lightly tap on the chuck jaw and dial in a part
in a 3 jaw with an indicator. Then start cutting. As long as you don't do
any heavy roughing it will continue to run true. This is a way to get a 3
jaw chuck with only 1 tightening hole in it to run true.
This is a different problem from having worn the jaws bell mouth. Which
is corrected by grinding the chuck jaws true.

On the day of Wed, 1 Mar 2006 19:06:18 -0500...
Ned Simmons
typed these letters:


I think it has to do with the fact that the ring with the teeth is not a
perfect fit on the chuck body. Tightening the chuck tends to cock the
ring a bit so it doesn't turn as freely. Moving the key to a different
hole pushes on a different point on the ring and frees it up.

Ned Simmons


Sounds reasonable to me. I've drilled quite a bit of stainless steel
on a Delta 16" drill press were I used to work. At times I was
drilling 1/2 " or larger holes in 1/4" to 1/2" thick stainless flat
stock. Occasionally I would have the bit lock up and the chuck would
keep spinning as the bit broke through the bottom of the steel.
Someone I was working with recommended that I tighten the chuck at all
3 holes. Sounded silly to me at the time but it worked.

Devonshire

In article ,
says...

"Ned Simmons" wrote in message
...



I think it has to do with the fact that the ring with the teeth is not a
perfect fit on the chuck body. Tightening the chuck tends to cock the
ring a bit so it doesn't turn as freely. Moving the key to a different
hole pushes on a different point on the ring and frees it up.

Ned Simmons


You are on the right track. The fit between the chuck and scroll can wear
with use.

I was talking about a Jacobs type drill chuck, which I think was the
subject of the original post, not a lathe chuck.

Ned Simmons

Ok, listen up...you're ALL wrong! I drill up to 300,000 holes a DAY! If a
drill moves, we make crap or something else breaks. If a drill wobbles a
little, it's toast in an hour, and we make crap. We use 4" breaker bars on
chuck keys and blow the teeth off the keys often, we buy 100 keys at a
time...it's worth it. Tighten a chuck in hole one until snug, tighten in
hole two a bit more, tighten in hole three a bit more yet, then tighten in
hole one again just short of busting the teeth off the key. Any procedure
other than this and the drill WILL move on us. Surprisingly, chucks last 5
to 10 years.

I didn't see Joe's word yet but THAT would be the final word.

"darkon" wrote in message
...
Here's a question from another newsgroup. Opinions?

[John is in Britain, hence the "Pondian" reference.]


From: John Hatpin
Newsgroups: alt.fan.cecil-adams
Subject: Hey, chuck!
Date: Tue, 28 Feb 2006 23:00:34 +0000
Message-ID:

Frame of reference: you've got an electric drill, or maybe a
hand-drill, and the bit fits into a traditional chuck, tightened
with a key that slots into one of three holes on the chuck and
meshes with a circular, toothed edge at a 90-degree angle. You
know the deal, I'd guess, unless there are major Pondian
differences I'm unaware of.

My father, God bless him, who knows more about tools than I'll
ever comprehend, tightens the chuck by putting the key into each
of the three holes in turn and giving it a final twist from each.
I only tend to do it once in one hole, on the basis that all
you're doing is turning the collar of the chuck, and there's no
difference between doing that with the end of the key in hole 1, 2
or 3.

Assuming I've framed the question adequately, what's your opinion?
Is my lovely old Dad right?

Yes.

"Tom Gardner" wrote in message
. com...
Ok, listen up...you're ALL wrong! I drill up to 300,000 holes a DAY! If a
drill moves, we make crap or something else breaks. If a drill wobbles a
little, it's toast in an hour, and we make crap. We use 4" breaker bars
on chuck keys and blow the teeth off the keys often, we buy 100 keys at a
time...it's worth it. Tighten a chuck in hole one until snug, tighten in
hole two a bit more, tighten in hole three a bit more yet, then tighten in
hole one again just short of busting the teeth off the key. Any procedure
other than this and the drill WILL move on us. Surprisingly, chucks last
5 to 10 years.

You should consider collets instead of chucks if you're drilling 300,000
holes/day. Chucks are a compromise at best.

Regards,

Robin

On Thu, 02 Mar 2006 00:40:46 GMT, Jerry Martes wrote:

"Ned Simmons" wrote in message
...

I think it has to do with the fact that the ring with the teeth is not a
perfect fit on the chuck body. Tightening the chuck tends to cock the
ring a bit so it doesn't turn as freely. Moving the key to a different
hole pushes on a different point on the ring and frees it up.

I'd bet you have the right idea. That even makes sense.

Yeah, that does have a "ring" to it. We tend to forget that metal does
distort when we're using it. Got a great lesson in that last night with
a 1/8" endmill.

Wow, now that was hardcore !... heheheh.
As so many have said, including Dad, tighten at least once in each
hole. You don't need to break the teeth on the key, rather apply
lighter pressure when drilling if that's the case. In case you're using
a handheld drill, a small deviation won't be noticeable compared to the
imprecision of the method, but if you're using a drill press it's
absolutely necessary to have the bit trued properly.

No room, and we need a multitude of sizes. Each hole is 1/2" deep in hard
Beech at 20,000 rpm in 100 milliseconds. We get two long twisty chips that
are HOT that get sucked into an impeller that chops them up and scoots them
into the collector. (What's a handheld drill...sounds like work?)

darkon wrote:
Here's a question from another newsgroup. Opinions?

[John is in Britain, hence the "Pondian" reference.]


From: John Hatpin
Newsgroups: alt.fan.cecil-adams
Subject: Hey, chuck!
Date: Tue, 28 Feb 2006 23:00:34 +0000
Message-ID:

Frame of reference: you've got an electric drill, or maybe a
hand-drill, and the bit fits into a traditional chuck, tightened
with a key that slots into one of three holes on the chuck and
meshes with a circular, toothed edge at a 90-degree angle. You
know the deal, I'd guess, unless there are major Pondian
differences I'm unaware of.

My father, God bless him, who knows more about tools than I'll
ever comprehend, tightens the chuck by putting the key into each
of the three holes in turn and giving it a final twist from each.
I only tend to do it once in one hole, on the basis that all
you're doing is turning the collar of the chuck, and there's no
difference between doing that with the end of the key in hole 1, 2
or 3.

Assuming I've framed the question adequately, what's your opinion?
Is my lovely old Dad right?

That's how I've always done it. I often wiggle the drill after
hand-tightening, to make sure that it is properly centred, before using
the chuck key.

Leon

Ned Simmons wrote:

In article ,
says...

"Ned Simmons" wrote in message
...

I think it has to do with the fact that the ring with the
teeth is not a perfect fit on the chuck body. Tightening the
chuck tends to cock the ring a bit so it doesn't turn as
freely. Moving the key to a different hole pushes on a
different point on the ring and frees it up.

Ned Simmons


You are on the right track. The fit between the chuck and
scroll can wear with use.

I was talking about a Jacobs type drill chuck, which I think was
the subject of the original post, not a lathe chuck.

Yes, a Jacobs chuck was the subject in the OP. But I would have
been surprised if the thread didn't drift at all*. That's partly
why I copied the question to this newsgroup: to see where the
conversation would lead.

(* It occurs to me that in a metalworking group, "thread" and
"drift" are easily misconstrued. I was referring to the tendency
of a conversation to wander away from the original subject. g)

Dave August wrote:

Yeah I'll jump in here.

I was taught to use all three holes on a jacobs chuck...
I agree with the 'coller gets torqued differently' theory...



I bought a new import 3 jaw lathe chuck a couple of years ago and it
came with a final inspection chart.

I noticed that in the section of that chart where the runout of a test
rod clamped in the chuck was recorded, there was one data line for
"master pinion" and another for "any pinion".

The runout written on the line for "master pinion" was less than the one
for "any pinions".

Looking at the chuck, one of the three pinion tightening holes had an
"M" stamped on the chuck body next to it.

I checked it myself after the chuck was mounted, and the inspection
chart was correct. Tightening the "M" pinion gave less runout than
tightening either of the other two pinions.

I checked another 3 jaw of mine and found a similar runout difference
when tightening different pinions, so I stamped an "M" next to the one
which gave the lowest runout.

Course now that I just finished writing this, it occurs to me that might
only hold for tightening the jaws on a piece with a specific diameter,
and that tolerances and wear on the chuck scroll may well make one of
the other pinions become the "master pinion" when smaller or larger
diameter test rods are grabbed.

Oh well, it was a nice theory anyway...and I still paint a witness mark
on the chuck and what's in it if I have to remove and replace the workpiece.

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

"Ned Simmons" wrote in message
...
In article ,
says...

"Ned Simmons" wrote in message
...



I think it has to do with the fact that the ring with the teeth is not
a
perfect fit on the chuck body. Tightening the chuck tends to cock the
ring a bit so it doesn't turn as freely. Moving the key to a different
hole pushes on a different point on the ring and frees it up.

Ned Simmons

I was talking about a Jacobs type drill chuck, which I think was the
subject of the original post, not a lathe chuck.

Ned Simmons

Right you are. Some how I got off track and was thinking about a lathe
chuck.

On the day of Thu, 02 Mar 2006 04:02:06 GMT...
(Devonshire)
typed these letters:


Sounds reasonable to me. I've drilled quite a bit of stainless steel
on a Delta 16" drill press were I used to work. At times I was
drilling 1/2 " or larger holes in 1/4" to 1/2" thick stainless flat
stock. Occasionally I would have the bit lock up and the chuck would
keep spinning as the bit broke through the bottom of the steel.
Someone I was working with recommended that I tighten the chuck at all
3 holes. Sounded silly to me at the time but it worked.

Devonshire

I forgot to mention... the chuck on this delta drill was a "ball
bearing Jacobs chuck"

Devonshire

"Dave Hinz" wrote in message
...
On Wed, 01 Mar 2006 22:30:51 GMT, RoyJ wrote:
It's always good practice to tighten all the holes in sucession. It
takes out any possible slop in the the chuck,

How can it? The two parts you're exerting force on, are the same parts
in each of the 3 locations.

Simple. Due to inherent clearances of components, the outer member is skewed
by the tightening force, so you benefit by tightening each of the positions,
offsetting the deflection, with a result of a tighter grip. You usually
gain better concentricity in the bargain. If the device was perfect, with
no slop, and no friction, that likely wouldn't be true

Harold

On Thu, 2 Mar 2006 23:51:37 -0800, Harold and Susan Vordos wrote:

"Dave Hinz" wrote in message
...

How can it? The two parts you're exerting force on, are the same parts
in each of the 3 locations.

Simple. Due to inherent clearances of components, the outer member is skewed
by the tightening force, so you benefit by tightening each of the positions,
offsetting the deflection, with a result of a tighter grip. You usually
gain better concentricity in the bargain. If the device was perfect, with
no slop, and no friction, that likely wouldn't be true

Right. Makes perfect sense. I tested it last night on my drillpress
and a fairly tight Jacobs chuck, seemed to behave as expected. If I was
going to engineer something to check the torque at which it spins, well,
then I wouldn't be making stuff. I'm sure someone has done that
already.

"Jeff Wisnia" wrote in message
...
snip-----

The runout written on the line for "master pinion" was less than the one
for "any pinions".

Those of us that work with soft jaws are well acquainted with that. Using
anything but the same socket when tightening the chuck will generally cost
you the .0005" concentricity that is almost guaranteed with soft jaws that
are properly machined. Truth is, with soft jaws, it makes no difference
which socket is selected, so long as the same one is used at all times with
the particular setup.

Some three jaws have a single line next to the "best" socket. Others have
nothing, and some have but one socket.

Harold

"Dave August" wrote in message
. net...
Yeah I'll jump in here.

I was taught to use all three holes on a jacobs chuck...
I agree with the 'coller gets torqued differently' theory...


As for the 3 Jaw lathe chuck, I was taught that since the actuation
mechinisim is totaly differet than on a jacobs chuck that it was
unnecessary, since the scroll is doing the work not pushers behing the
coller...

That's not necessarily true. You'll find that any scroll type chuck will
benefit from tightening each of the holes, but with a three jaw with which
you are seeking concentricity, the socket selected will have a profound
affect on how the chuck grips. The scroll has clearance on the bushing upon
which it mounts, so it moves side to side with each socket. You can see
that for yourself if you work with soft jaws, or you can chuck a ground
piece of material that is straight and round. Each socket will provide
different results almost without fail.

Harold

"Richard W." wrote in message
...

"Ned Simmons" wrote in message
...
In article M8qNf.53363$3W5.39831@trnddc02,
says...

"Dave Hinz" wrote in message
...
On Wed, 01 Mar 2006 22:30:51 GMT, RoyJ
wrote:


I think it has to do with the fact that the ring with the teeth is not a
perfect fit on the chuck body. Tightening the chuck tends to cock the
ring a bit so it doesn't turn as freely. Moving the key to a different
hole pushes on a different point on the ring and frees it up.

Ned Simmons


You are on the right track. The fit between the chuck and scroll can
wear
with use. When you tighten one hole it forces the scroll off center, so by
tightening all three you have equalized the forces on the 3 holes.
Bringing
it back to center. Mostly noticeable on older worn chucks. I have seen one
chuck so bad the only way it would center up right was to use a torque
wrench on each hole.
Those who have older worn chucks know that the fit between the scroll
and
chuck body is bad, and can lightly tap on the chuck jaw and dial in a part
in a 3 jaw with an indicator. Then start cutting. As long as you don't do
any heavy roughing it will continue to run true. This is a way to get a 3
jaw chuck with only 1 tightening hole in it to run true.
This is a different problem from having worn the jaws bell mouth.
Which
is corrected by grinding the chuck jaws true.



Yep! That's the voice of experience.

Harold

"Ned Simmons" wrote in message
...
In article ,
says...

"Ned Simmons" wrote in message
...



I think it has to do with the fact that the ring with the teeth is not
a
perfect fit on the chuck body. Tightening the chuck tends to cock the
ring a bit so it doesn't turn as freely. Moving the key to a different
hole pushes on a different point on the ring and frees it up.

Ned Simmons


You are on the right track. The fit between the chuck and scroll can
wear
with use.

I was talking about a Jacobs type drill chuck, which I think was the
subject of the original post, not a lathe chuck.

Ned Simmons

Different chucks, same problems, however.

Harold