Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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  #1   Report Post  
stone
 
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Default using a four jaw chuck on a lathe

Is there any great technique for using this sort of beast?

My four jaw chuck has each jaw adjusted separately.
(maybe they're all this way)

But, what I did was turn each jaw out until I thought
they were flush; then I adjusted each jaw symetrically.

Then I spun the thing(by hand), and gauged how close the piece was
to a tool bit, and tweeked from there until it was pretty
much in the center of the jaw.

Is this it?

Or is there a much better way?


Thanks.

  #2   Report Post  
Paul T.
 
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"stone" wrote in message
oups.com...
Is there any great technique for using this sort of beast?

My four jaw chuck has each jaw adjusted separately.
(maybe they're all this way)


Generally when you say "four jaw chuck" you mean a chuck with fully
independent jaws like yours. This allows you to either chuck round pieces
with zero runout, to chuck square workpieces on center and to chuck round
and square workpieces with an intentional offset, for example to bore and
offset hole in a workpiece.

However, there is such a thing as a scrolling four jaw chuck where all the
jaws move together. This is a special chuck that is only good for chucking
square work pieces on center, you wouldn't want one as your only four jaw
chuck.


But, what I did was turn each jaw out until I thought
they were flush; then I adjusted each jaw symetrically.

Then I spun the thing(by hand), and gauged how close the piece was
to a tool bit, and tweeked from there until it was pretty
much in the center of the jaw.


That's pretty much the way its done, the only thing I'd add is if you need
best accuracy use a dial indicator instead of your eyeball. As you use the
chuck more you'll get faster at chucking things on center. However, if you
need to chuck a lot of workpieces on center and don't have a 3 jaw chuck or
a collet setup, I'd consider getting both as you can afford them.


Is this it?

Or is there a much better way?


Let's see if anybody else has a tip for faster centering.

Paul T.


  #3   Report Post  
Gerald Miller
 
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Default

On 19 Apr 2005 18:32:15 -0700, "stone" wrote:

Is there any great technique for using this sort of beast?

My four jaw chuck has each jaw adjusted separately.
(maybe they're all this way)

But, what I did was turn each jaw out until I thought
they were flush; then I adjusted each jaw symetrically.

Then I spun the thing(by hand), and gauged how close the piece was
to a tool bit, and tweeked from there until it was pretty
much in the center of the jaw.

Is this it?

Or is there a much better way?


Thanks.

A dial gauge can refine the "eyeball" measurement considerably,
especially my little 0.0001 unit.
Gerry :-)}
London, Canada
  #4   Report Post  
Grady
 
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A short piece of angle iron with a rod welded to it sticking up works better
than the eye. Angle is face down across the ways, rod sticking straight up.
Keep dialing the jaws and rotating the chuck until you quit moving the rod
and angle, then get out the dial indicator or DTI to finish it off. Always
works for me.


"stone" wrote in message
oups.com...
Is there any great technique for using this sort of beast?

My four jaw chuck has each jaw adjusted separately.
(maybe they're all this way)

But, what I did was turn each jaw out until I thought
they were flush; then I adjusted each jaw symetrically.

Then I spun the thing(by hand), and gauged how close the piece was
to a tool bit, and tweeked from there until it was pretty
much in the center of the jaw.

Is this it?

Or is there a much better way?


Thanks.



  #5   Report Post  
Harold and Susan Vordos
 
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"Paul T." wrote in message
...

snip----

Let's see if anybody else has a tip for faster centering.

Paul T.


That's the procedure, but don't fail to take advantage of the concentric
rings that are cut on the face of the vast majority of 4 jaw chucks.
They're cut for your convenience so you can judge where the jaws are
relative to the centerline of the spindle.

When you're trying to get an object running true, end to end, it's a good
idea to chuck it short (1/2" or so) so it can be tapped about in the chuck.
If your jaws are not dead parallel and you hold parts deep, it's quite hard
to convince them to allow the part to wallow about enough to get both ends
on center, especially if the jaws are finely serrated. When they are, they
tend to dig in, making it difficult for the part to shift. Unless the part
is extremely long, when properly snugged up, the typical 4 jaw has more than
enough holding power to allow you to machine the part once it's running
true, even when it's chucked short.

Harold




  #6   Report Post  
Don Young
 
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That's the right idea. It will speed it up if you will work on only two
opposite jaws at a time, turning the work back and forth only 180 degrees
and adjusting out one half the wobble each time.
Don Young
"stone" wrote in message
oups.com...
Is there any great technique for using this sort of beast?

My four jaw chuck has each jaw adjusted separately.
(maybe they're all this way)

But, what I did was turn each jaw out until I thought
they were flush; then I adjusted each jaw symetrically.

Then I spun the thing(by hand), and gauged how close the piece was
to a tool bit, and tweeked from there until it was pretty
much in the center of the jaw.

Is this it?

Or is there a much better way?


Thanks.



  #7   Report Post  
Wooding
 
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stone wrote:
Is there any great technique for using this sort of beast?

My four jaw chuck has each jaw adjusted separately.
(maybe they're all this way)

But, what I did was turn each jaw out until I thought
they were flush; then I adjusted each jaw symetrically.

Then I spun the thing(by hand), and gauged how close the piece was
to a tool bit, and tweeked from there until it was pretty
much in the center of the jaw.

Is this it?

Or is there a much better way?


Thanks.

As others have said, that's the way its done.
I've found the quickest way is to use two chuck keys - each one on
opposite jaws. This allows you to easily keep the jaws in contact with
the work piece at all times. If you don't have a 2nd key, make one. You
won't regret it.

Use the 'eyeball' method to get the piece pretty central, then use a dti
to make it as accurate as you like. Work on the jaws that are
horizontally opposed and use both keys to move the piece to halve the
dti error when you turn the chuck through 180 degrees. You can ignore
any wobble caused by the other 2 jaws. When you are happy with the 1st 2
jaws, turn the chuck through 90 degrees and do the same with the 2nd
two. Repeat until you are happy.

--

Regards, Gary Wooding
(To reply by email, change feet to foot in my address)
  #8   Report Post  
Gunner
 
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On Wed, 20 Apr 2005 08:08:29 +0100, Wooding
wrote:


As others have said, that's the way its done.
I've found the quickest way is to use two chuck keys - each one on
opposite jaws. This allows you to easily keep the jaws in contact with
the work piece at all times. If you don't have a 2nd key, make one. You
won't regret it.



Ayup. Done with two keys, and some practice over time, it can be done
very quickly

Gunner

Rule #35
"That which does not kill you,
has made a huge tactical error"
  #9   Report Post  
Bugs
 
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Your .0001" unit is called an indicator, and is the only way to
accurately center a piece in the chuck. A previously drilled center
drill pilot can be centered with a wiggler attachment too. Stone should
find a good machinist's book to learn all the techniques available.
Bugs

  #10   Report Post  
Lloyd E. Sponenburgh
 
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"Paul T." wrote in message
...

snip----

Let's see if anybody else has a tip for faster centering.

Paul T.

There's a very simple way to get the work within a half-thou without a dial
indicator.

It's not that the indicator isn't easy to use, or more accurate than this
method, but the extra few minutes you might spend setting it up and tearing
it down before machining are often just "lost time" when you don't need that
accuracy. A mag base might make it quicker, but some small vee-bed lathes
don't even have a convenient place for the base-- not even on the
cross-slide.

For round or square work -- Instead of the run-out gauge, just move your
tool as close to the "high" side of the work as you can get it without
touching. Rotate the work 180, adjust by eyeball to eliminate about 1/2 of
the gap. Run the tool in again to whatever has become the high side, and
repeat, halving the error each time. In three or four iterations, you'll
have the tool pulling swarf over two thirds-or-so of the circumference of
the work. By then it's within a thou or less of centered, and ready for any
rough surfacing.

Just quicker... that's all. A bright, narrow-beam work light helps see the
gap.

LLoyd




  #11   Report Post  
jim rozen
 
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In article . net, Lloyd E.
Sponenburgh says...


Just quicker... that's all. A bright, narrow-beam work light helps see the
gap.


And a white 3x5 card on the cross slide, under the work, makes it
easy too. Shine the light on the card, which is then viewed through
the gap.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================
  #12   Report Post  
Bob Engelhardt
 
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stone wrote:

Is there any great technique for using this sort of beast?

....

The Master had this to say about centering in a 4-jaw:

begin quote
Quick tip for setting work true in a 4 jaw in two revolutions!

(I learned this, setting up roll turning lathes with 108" swing and a
jogging speed of two to four MINUTES per revolution.)

1. Revolve the work through one revolution..noting the TOTAL swing of
the indicator needle. Bring the spindle to a halt at the MIDPOINT of the
swing and ZERO the dial to the needle.

2. Revolve spindle to bring jaw one to be "on the plunger". Adjust jaw
one and jaw three to ZERO the needle again.

3 Rotate 1/4 turn and adjust jaws two and four to re-zero needle.

Job is done!

Robert Bastow
end quote
  #13   Report Post  
stone
 
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I should have added, that my piece is square bar
that I want to make round on one end.

It won't move, but something will pivot on the round end.

So, since it, itself wouldn't be spinning, I wasn't too
concerned with great accuracy.

Thanks, everyone.

Is it possible to use a 3 jaw chuck for this job? Safely?

  #14   Report Post  
Tim Wescott
 
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Default

stone wrote:

Is there any great technique for using this sort of beast?

My four jaw chuck has each jaw adjusted separately.
(maybe they're all this way)

But, what I did was turn each jaw out until I thought
they were flush; then I adjusted each jaw symetrically.

Then I spun the thing(by hand), and gauged how close the piece was
to a tool bit, and tweeked from there until it was pretty
much in the center of the jaw.

Is this it?

Or is there a much better way?


Thanks.

Something implicit in all of the replies so far is that a 3-jaw chuck is
for automatically centering round or hexagonal work -- but they
generally only center to a few thousandths (mine are more like 5-10
thou, but they're cheap Chinese stuff).

A collet will center much more accurately and will be, if anything,
quicker than a 3-jaw but will only fit a small range of work sizes, and
will generally only fit round work. I can't quote an accuracy figure
for you 'cause I've never had the $$$ to buy a collet set.

A 4-jaw will let you center things to the limits of your skill and
patience. It will let you center just about any straight-sided profile:
round, square, hexagonal, pentagonal, elliptical, extruded aluminum in
Bill Clinton's profile -- anything. It takes more time to set up, but
you only need to get one of it, and it'll do for many, many tasks.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
  #15   Report Post  
WillR
 
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stone wrote:
Is there any great technique for using this sort of beast?
=20
My four jaw chuck has each jaw adjusted separately.
(maybe they're all this way)
=20
But, what I did was turn each jaw out until I thought
they were flush; then I adjusted each jaw symetrically.
=20
Then I spun the thing(by hand), and gauged how close the piece was
to a tool bit, and tweeked from there until it was pretty
much in the center of the jaw.
=20
Is this it?
=20
Or is there a much better way?
=20
=20
Thanks.
=20


Thanks to all who answered this thread.

I have a PITA 4 jaw for my wood lathe. your tips have assisted greatly.

:-)

--=20
Will R.
Jewel Boxes and Wood Art
http://woodwork.pmccl.com
The power of accurate observation is commonly called cynicism by those=20
who have not got it.=94 George Bernard Shaw


  #16   Report Post  
Rick
 
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"Ignoramus14555" wrote
in message ...
I think that I have the same chuck on my clausing lathe,

four jaws and
foud adjustment points. Very strange. Why would they even

want to make
them like that.



You'll find out : )


  #17   Report Post  
Harold and Susan Vordos
 
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"Tim Wescott" wrote in message
...
snip-----

and will generally only fit round work


Not necessarily true. Hex and square collets are readily available, and
soft collets as well. For production runs, it's not uncommon to machine a
profile in a soft collet so irregular parts can be routinely held with
precision and speed. You are, of course, limited to size by the collet,
but for large diameter short pieces, step chucks (collets) are available.

Harold


  #18   Report Post  
Harold and Susan Vordos
 
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"Ignoramus14555" wrote in message
...
I think that I have the same chuck on my clausing lathe, four jaws and
foud adjustment points. Very strange. Why would they even want to make
them like that.


Could be that in wood working it makes little sense, but when machining
metals, it makes all the sense in the world. A 4 jaw chuck is the most
precise of all holding devices *because* it allows for independent
adjustment. The level of precision is up to the operator, unlike the
typical universal chuck (typically a scroll type device that adjusts all
jaws simultaneously). With such a chuck, you're at the mercy of the level
of precision inherent in its manufacture, plus the results of use and abuse.
Because all the jaws work together, you can't make adjustments when they're
off, although there are three jaw and six jaw chucks on the market with an
adjustable body. If one had but one choice for a lathe, it would have
to be an independent 4 jaw, otherwise many jobs would be impossible to hold.
They are often slower, but very flexible.

Harold


  #19   Report Post  
Harold and Susan Vordos
 
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"Harold and Susan Vordos" wrote in message
...

"Ignoramus14555" wrote in message
...
I think that I have the same chuck on my clausing lathe, four jaws and
foud adjustment points. Very strange. Why would they even want to make
them like that.


Could be that in wood working it makes little sense, but when machining
metals, it makes all the sense in the world. A 4 jaw chuck is the most
precise of all holding devices *because* it allows for independent
adjustment. The level of precision is up to the operator, unlike the
typical universal chuck (typically a scroll type device that adjusts all
jaws simultaneously). With such a chuck, you're at the mercy of the

level
of precision inherent in its manufacture, plus the results of use and

abuse.
Because all the jaws work together, you can't make adjustments when

they're
off, although there are three jaw and six jaw chucks on the market with an
adjustable body. If one had but one choice for a lathe, it would

have
to be an independent 4 jaw, otherwise many jobs would be impossible to

hold.
They are often slower, but very flexible.


Don't overlook the fact that irregular items can be held as well, and parts
can be held such that diameters can be turned eccentric with one another.
Very important if you're trying to build a crank shaft or eccentric device.

Harold




  #20   Report Post  
Dave Hinz
 
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On 20 Apr 2005 18:53:36 GMT, Ignoramus14555 wrote:
On Wed, 20 Apr 2005 11:40:43 -0700, Harold and Susan Vordos wrote:

If one had but one choice for a lathe, it would have
to be an independent 4 jaw, otherwise many jobs would be impossible to hold.
They are often slower, but very flexible.


Wouldn't that mean, though, that every time I insert something into
the jaws, I need to perform a complicated centering operation??? That
seems rather painful.


Correct on both counts. But useful when you need something non-concentric.


  #21   Report Post  
Chuck Sherwood
 
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Wouldn't that mean, though, that every time I insert something into
the jaws, I need to perform a complicated centering operation??? That
seems rather painful.


Depends on how accurate you need to be. If your stock is oversized,
you don't have to center very accurately. Frequently you can do that
by looking at the marks on the chuck and using a tool bit to show
which side is high. If you need better accuracy, you will need
to use an indicator. Using an indicator you can get as good as your
indicator will allow, which is much better than any scroll chuck.

Lathe chucks are accessories. The more you have the better!
I have 3 jaw, 6 jaw, 4 jaw (both independent and dependent)
for some of my lathes. Choose the right tool for the job!

chuck

chuck

  #22   Report Post  
Dave Hinz
 
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On 20 Apr 2005 19:33:23 GMT, Ignoramus14555 wrote:
On 20 Apr 2005 19:04:50 GMT, Chuck Sherwood wrote:
Lathe chucks are accessories. The more you have the better!
I have 3 jaw, 6 jaw, 4 jaw (both independent and dependent)
for some of my lathes. Choose the right tool for the job!


Thanks. I have several chucks (i believe, 3). I will take them out of
my truck tonight and check them out.


You have a chuck truck? What the...heck?

  #23   Report Post  
Dave Hinz
 
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Default

On 20 Apr 2005 20:03:46 GMT, Ignoramus14555 wrote:
On 20 Apr 2005 19:57:34 GMT, Dave Hinz wrote:

You have a chuck truck? What the...heck?


Haha. My truck has quite a few pieces of mill/lathe tooling in it,
such as chucks, collets, indexing head, boring head etc. I brought
home a mill and a lathe yesterday...


Ah, kind of like the trunk of my car, which currently has an 8 and a
12 pound sledge, a Sawzall, a half-full box/roll of 7mil visqueen,
a 40' length of LMR-400 (WiFi) cable, firefighting gear, an EMS kit,
and Windows XP install media.

And that's just this week's projects...
  #24   Report Post  
George
 
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Default

Bob Engelhardt wrote:

stone wrote:

Is there any great technique for using this sort of beast?

...

The Master had this to say about centering in a 4-jaw:

begin quote
Quick tip for setting work true in a 4 jaw in two revolutions!

(I learned this, setting up roll turning lathes with 108" swing and a
jogging speed of two to four MINUTES per revolution.)

1. Revolve the work through one revolution..noting the TOTAL swing of
the indicator needle. Bring the spindle to a halt at the MIDPOINT of the
swing and ZERO the dial to the needle.

2. Revolve spindle to bring jaw one to be "on the plunger". Adjust jaw
one and jaw three to ZERO the needle again.

3 Rotate 1/4 turn and adjust jaws two and four to re-zero needle.

Job is done!

Robert Bastow
end quote


Brilliant!

So in this thread I've learned to use a white index card under the
work to make it easy to see. I've learned that 2 keys are better than
one, I've learned that you only chuck the work up a short distance on
long stock and I've learned how to center in two revolutions.

That's 4 things I didn't know 15 minutes ago.

Off to the shop....
  #25   Report Post  
Harold and Susan Vordos
 
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"jim rozen" wrote in message
...
In article . net, Lloyd

E.
Sponenburgh says...


Just quicker... that's all. A bright, narrow-beam work light helps see

the
gap.


And a white 3x5 card on the cross slide, under the work, makes it
easy too. Shine the light on the card, which is then viewed through
the gap.

Jim


That's the procedure I use (plain paper works fine) for setting threading
tools. You can't see the fit of your tool in the gage nearly as well by
simply looking at it. Slight gaps show up nicely by this method. All I do
is shade the tool and gage, so the only light comes from beneath the part,
off the paper. Works very well.

Harold




  #26   Report Post  
WillR
 
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Default

Ignoramus14555 wrote:
On 20 Apr 2005 21:23:52 GMT, Dave Hinz wrote:
=20
On 20 Apr 2005 20:03:46 GMT, Ignoramus14555 =

5.invalid wrote:

On 20 Apr 2005 19:57:34 GMT, Dave Hinz wrote:

You have a chuck truck? What the...heck?

Haha. My truck has quite a few pieces of mill/lathe tooling in it,
such as chucks, collets, indexing head, boring head etc. I brought
home a mill and a lathe yesterday...


Ah, kind of like the trunk of my car, which currently has an 8 and a
12 pound sledge, a Sawzall, a half-full box/roll of 7mil visqueen,=20
a 40' length of LMR-400 (WiFi) cable, firefighting gear, an EMS kit,
and Windows XP install media.

And that's just this week's projects...

=20
=20
mine has some fishing gear, some boards, some chains, an indexing
head, many tarps, some food (brazil nuts), an entrenching tool/shovel,
and towing gear...
=20
i



I refuse to discuss my F150 with the cap. I don't _like_ being embarrasse=
d.


Again, thanks for all the help and comments guys.


--=20
Will R.
Jewel Boxes and Wood Art
http://woodwork.pmccl.com
The power of accurate observation is commonly called cynicism by those=20
who have not got it.=94 George Bernard Shaw
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