I'm leaning towards the 4 jaw independent. Thoughts.

Wes

--Depends. Heh.

--
"Steamboat Ed" Haas : Imagine what I could do if
Hacking the Trailing Edge! : I knew what I was doing...
www.nmpproducts.com
---Decks a-wash in a sea of words---

My first chuck was a 4 jaw. I thought "It's more useful - it'll hold
anything." True enough, but the diddling around with 4 adjustments
every time got tiresome. Especially since 95% or more times it's round
stock that I'm turning. I now have a 3 jaw also & I wouldn't be without
it. I.e., I'd give up the 4 jaw 1st.

BTW, they are both Bisons & the 3-jaw centers to .001, IIRC.

Bob

On Wed, 13 May 2009 19:24:16 -0400, Wes wrote:

I'm leaning towards the 4 jaw independent. Thoughts.

Wes

How about an adapter so you can use your lathe chucks?

--
Ned Simmons

Wes fired this volley in news:BEIOl.390676
:

I'm leaning towards the 4 jaw independent. Thoughts.

Wes

It's the only rational choice. What if you have to chuck up odd-leg
parts?

It takes a few "lessons" to learn to quickly true up the work in a 4-
jaw independent chuck, but you can work to much better tolerances with
it than with a self-centering type.

LLoyd

On May 14, 9:24 am, Wes wrote:
I'm leaning towards the 4 jaw independent. Thoughts.

Wes

3jaw, if you want to get anything done without spending huge amounts
of time in setting up.

reasons?
a)using it as a rotary table, you will centre it under the mill
spindle with the x-y mill controls. so it doesn't matter if its out a
bit in the chuck.
b)using it horizontally as an indexing head, the major fixed
adjustment is determined by your tailstock - you adjust the other end
to this, and check levels/eccentricity. There is adjustment in the
divider head to get it really close.

And unless your machinery is in absolute, first class, no wear,
calibrated condition - slop in othere areas is going to be the
limiting factor, not the 3 or 4 jaw chuck.

(the above I learnt at trade school, in 'Basic Milling")

Andrew VK3BFA.

On Wed, 13 May 2009 19:24:16 -0400, Wes wrote:

I'm leaning towards the 4 jaw independent. Thoughts.

Wes

A 4-jaw will enable more precise centering and is more versatile,
3-jaw is quicker and more convenient. With a bit of practice it only
takes a minute or two to get something centered in a 4J to under a
thou.

You know what accuracy you seek. In my case, I have a 3J on my
indexing head and have a 4J for it that I've never used.

On Wed, 13 May 2009 19:38:14 -0700 (PDT), wrote:


a)using it as a rotary table, you will centre it under the mill
spindle with the x-y mill controls. so it doesn't matter if its out a
bit in the chuck.

True only if you don't rotate the rotary table.

The mill's x-y controls can't take out centering error in the chuck
because the x-y position of the mill table remains constant while the
x-offset and y-offset of the piece in the chuck vary with the
rotational angle.

"Ned Simmons" wrote in message
...
On Wed, 13 May 2009 19:24:16 -0400, Wes wrote:

I'm leaning towards the 4 jaw independent. Thoughts.

Wes

How about an adapter so you can use your lathe chucks?

--
Ned Simmons

Exactly what I made to use my rotary table as a dividing head.


Steve R.

Don Foreman wrote in
:

A 4-jaw will enable more precise centering and is more versatile,
3-jaw is quicker and more convenient. With a bit of practice it only
takes a minute or two to get something centered in a 4J to under a
thou.

Time spent indicating work in a four jaw chuck on a dividing head will be
quite a bit longer than on a lathe. 40:1 turns ratio makes for 20 handle
turns every time you adjust a jaw and check with an indicator. Repeat a
few, maybe three times for jaws one and three, three more for jaws two and
four.

My past experience has been that a three jaw is adequate for the class of
work done on items that require plain indexing cuts. For more complex and
higher tolerance dividing work like cutting gears the job was placed
between centers and driven with a dog. I've not had a project that
required the hold of a four jaw or accuracy exceeding a 3 jaw with a bit of
shim to correct chuck runout.

I'd vote for a 3 jaw for starters. Get the 4 jaw later if you have a
project that can't be gripped in the 3 jaw.

On May 14, 1:29*am, "Steve R." wrote:
"Ned Simmons" wrote in message

How about an adapter so you can use your lathe chucks?
Ned Simmons

Exactly what I made to use my rotary table as a dividing head.
Steve R.

Mine arrived yesterday. It looks well made and turns smoothly without
roughness or tight spots, but a neighbor needed help cutting up and
hauling some trees so I didn't get to check it out further.

I previously made a 1-1/2 - 8 adapter to hold a Jacobs 58B lathe chuck
in a 1" 5C collet. I think I could make back plates for borrowed lathe
chucks and center the work on it in the lathe first. As others have
noted, centering in a 40 turn indexer is very slow and tedious. I made
a non-plunger handle for my small rotary table to speed it up some.

The center taper is Morse 2, not B&S 7.

The Jacobs lathe chuck looked too good to pass up but I haven't found
much use for it. I leave a 1/2" chuck on the 1/2-20 spindle of my
small lathe to use for polishing, since the jaws aren't as dangerous.

jsw

My vote is to go for the advantages of both. Get an "adjust true" three jaw
chuck. I got one for my lathe and I'm plumb spoilt.

If you haven't seen one, this chuck has an extra plate that can be loosened
and then four set screws to adjust the part right on center.

Karl

On May 14, 8:48*am, Charles U Farley wrote:

Time spent indicating work in a four jaw chuck on a dividing head will be
quite a bit longer than on a lathe. *40:1 turns ratio makes for 20 handle
turns every time you adjust a jaw and check with an indicator. *Repeat a
few, maybe three times for jaws one and three, three more for jaws two and
four.


Couldn't you use one of those indicator holders that mount on the mill
spindle, and first indicate on the chuck body. So you get the spindle
directly over the dividing head center of rotation.

And then indicate on the part so you get the part centered.

That would be twice the number of times one has to indicate, so twice
the chance for error. But I would think one would usually need to
get the mill spindle directly in line with the center of the dividing
head anyway at some point.

Well I think that would work when using the dividing head horizontal.
Or you could center with the head horizontal and then rotate it to
vertical.

Dan

On Wed, 13 May 2009 21:07:23 -0400, Ned Simmons
wrote:

How about an adapter so you can use your lathe chucks?

My smallest chuck is too big.

Wes

On May 14, 8:25*am, " wrote:

Well I think that would work when using the dividing head horizontal.
Or you could center with the head horizontal and then rotate it to
vertical.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *Dan

The BS-0 could be aligned with a 1/2" rod in its MT2 center hole. If
your collet springs open a center finder point is convenient, it also
works with 5C collet blocks. But they are difficult to remove from
tight collets.

jsw

On 2009-05-14, Charles U Farley wrote:
Don Foreman wrote in
:

A 4-jaw will enable more precise centering and is more versatile,
3-jaw is quicker and more convenient. With a bit of practice it only
takes a minute or two to get something centered in a 4J to under a
thou.

Time spent indicating work in a four jaw chuck on a dividing head will be
quite a bit longer than on a lathe. 40:1 turns ratio makes for 20 handle
turns every time you adjust a jaw and check with an indicator. Repeat a
few, maybe three times for jaws one and three, three more for jaws two and
four.

I don't know about your dividing head, but mine had a knurled
thumbscrew which will disengage the worm from the spindle, allowing you
to turn the chuck much more quickly by hand. It also has a ring behind
the chuck with a lever-controlled pin for simple dividing
(2/3/4/6/8/etc) so you don't even need the plate for simple dividing.

My past experience has been that a three jaw is adequate for the class of
work done on items that require plain indexing cuts. For more complex and
higher tolerance dividing work like cutting gears the job was placed
between centers and driven with a dog. I've not had a project that
required the hold of a four jaw or accuracy exceeding a 3 jaw with a bit of
shim to correct chuck runout.

And -- you can also set things up on an arbor between centers to
get plenty of accuracy.

I'd vote for a 3 jaw for starters. Get the 4 jaw later if you have a
project that can't be gripped in the 3 jaw.

I don't even (yet) have a 4-jaw for my index head. Between the
3-jaw and the between centers I've been able to do what I need to do.
But a 4-jaw would be nice, and if I stumble across one which fits it,
I'll pick it up.

--
Email: | Voice (all times): (703) 938-4564
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--- Black Holes are where God is dividing by zero ---

On May 14, 11:22*pm, "DoN. Nichols" wrote:
On 2009-05-14, Charles U Farley wrote:
Don Foreman wrote in
...
I don't know about your dividing head, but mine had a knurled
thumbscrew which will disengage the worm from the spindle, allowing you
to turn the chuck much more quickly by hand. It also has a ring behind
the chuck with a lever-controlled pin for simple dividing
(2/3/4/6/8/etc) so you don't even need the plate for simple dividing.

The exploded drawing shows a screw behind the index plate that may
lock the eccentric worm engagement.

My past experience has been that a three jaw is adequate for the class of
work done on items that require plain indexing cuts. For more complex and
higher tolerance dividing work like cutting gears the job was placed
between centers and driven with a dog. I've not had a project that
required the hold of a four jaw or accuracy exceeding a 3 jaw with a bit of
shim to correct chuck runout. ...

Personnally I've mostly done either lengthwise grooves or flats on a
shaft, between centers or in a collet, or cuts on or near the OD of a
disk which was centered on a mandrel and clamped to a faceplate. Two
examples are the tractor steering gear and a circular tee slot. I've
made a number of long adjusting screws by milling a hex on threaded
rod, which doesn't fit collets very well.

I bought some 5C-mount lathe chucks to index a turned part accurately
and found that they didn't hold securely enough unless I took very
light cuts. I didn't want to overtighten and damage them. The
instructions for the Sherline chuck warn that it's for light duty
only. If the shaft rotates while cutting flats one side jams into the
end mill. Then the belt slips and I weld up the gouge and regrind the
tool, but that would be expensive on a geared-head mill.

Some commercial jobs I've worked on were more difficult, the most
complex was a rotating ink jet print head somewhat like the crankcase
of a radial engine. I think the machinist made a fixture with
centering plugs to locate both sides.

If you use a faceplate you can clamp all around the edges and remove
each one to cut under it. You could center the work on a rod in the
center collet by making a cone that slides on it, or a slightly
tapered bushing for more precision.

jsw

On May 13, 7:24*pm, Wes wrote:
I'm leaning towards the 4 jaw independent. *Thoughts.

Wes

4 jaw, definitely - unless you spend so much time using the dividing
head that dialing in the 4 jaw gets to be a drag. In which case,
you'll probably be using collets anyway.

You can do things with a 4 jaw chuck that you simply can't do with a 3
jaw. I can't think of anything that the 3 jaw can do that the 4 jaw
can't. Holding hex stock comes the closest, but the 4 jaw will do
even that with some patience. If holding hex stock is your primary
objective with the dividing head chuck though, I'd opt for the 3 jaw.
Or hex collets.

Assuming that your dividing head allows for disengaging the worm gear,
dialing in the 4 jaw is quick. As others have already mentioned.

John Martin

wrote:

Assuming that your dividing head allows for disengaging the worm gear,
dialing in the 4 jaw is quick. As others have already mentioned.

I've looked at the drawings and the unit and determined that it doesn't. If it was able
to disengage, I'd buy the 4 jaw. My lathe sports a 4 jaw, dialing it in has not been that
big a deal. The lathe has a smaller 3 jaw that is too big for the dividing head, I've
never actually used the 3 jaw chuck on the lathe. Usually turns into, how long, how much
effort to change chuck vs, how long to indicate in the 4 jaw.

I'll go for a 3 jaw, the trueset types are too pricey for my blood in this application. We
have a 3 jaw on a Leblond at work with the trueset feature, that lathe has a 4 jaw that
has never been mounted since I've worked there Critical work, you chuck the part,
center the chuck. Sweet.


Wes

On 2009-05-15, Jim Wilkins wrote:
On May 14, 11:22*pm, "DoN. Nichols" wrote:
On 2009-05-14, Charles U Farley wrote:
Don Foreman wrote in
...
I don't know about your dividing head, but mine had a knurled
thumbscrew which will disengage the worm from the spindle, allowing you
to turn the chuck much more quickly by hand. It also has a ring behind
the chuck with a lever-controlled pin for simple dividing
(2/3/4/6/8/etc) so you don't even need the plate for simple dividing.

The exploded drawing shows a screw behind the index plate that may
lock the eccentric worm engagement.

That could be it -- but IIRC, it is near the other end of the
worm screw from the hand crank and index plate. It both allows the
screw to be disengaged (it is in a bearing which is pivoted near the
index plate), and to be adjusted for minimum backlash when it is
engaged.

My past experience has been that a three jaw is adequate for the class of
work done on items that require plain indexing cuts. For more complex and
higher tolerance dividing work like cutting gears the job was placed
between centers and driven with a dog. I've not had a project that
required the hold of a four jaw or accuracy exceeding a 3 jaw with a bit of
shim to correct chuck runout. ...

Personnally I've mostly done either lengthwise grooves or flats on a
shaft, between centers or in a collet, or cuts on or near the OD of a
disk which was centered on a mandrel and clamped to a faceplate. Two
examples are the tractor steering gear and a circular tee slot. I've
made a number of long adjusting screws by milling a hex on threaded
rod, which doesn't fit collets very well.

Hmm ... I've made some by using a hex collet and hex stock,
turning the OD down using a box tool (in a bed turret) and threading
using a Geometric die head, then parting off. Very quick if you need to
make more than one -- slow to set up for the first one.

I bought some 5C-mount lathe chucks to index a turned part accurately
and found that they didn't hold securely enough unless I took very
light cuts. I didn't want to overtighten and damage them. The
instructions for the Sherline chuck warn that it's for light duty
only. If the shaft rotates while cutting flats one side jams into the
end mill. Then the belt slips and I weld up the gouge and regrind the
tool, but that would be expensive on a geared-head mill.

Yep. My dividing head has a center with a T-bar just behind the
point. The T-bar is slotted parallel to the axis on each end, and
drilled and tapped for a square headed setscrew on each end. You set up
the work between centers, clamp a dog (also using the same style of
square headed setscrews) around the arbor or some direct part of the
workpiece, and then tighten one setscrew in the T-bar against the tail
of the dog so there is no give in the connection of dog tail to T-bar.

It also has a hefty three-jaw chuck which screws onto a 1-1/2x8
(or something similar -- I really need to check that again and make a
mount for the smaller 4-jaw chuck which I used to use on the old 2-1/4x8
spindle for the Clausing before I converted it to L-00 spindle nose.)

Some commercial jobs I've worked on were more difficult, the most
complex was a rotating ink jet print head somewhat like the crankcase
of a radial engine. I think the machinist made a fixture with
centering plugs to locate both sides.

And, of course, something to prevent rotation of the workpiece
relative to the dividing head.

If you use a faceplate you can clamp all around the edges and remove
each one to cut under it. You could center the work on a rod in the
center collet by making a cone that slides on it, or a slightly
tapered bushing for more precision.

Right -- but I don't have a faceplate for the dividing head.
Perhaps I should make one of those, too. The thread should not be
difficult to turn using the Clausing.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
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--- Black Holes are where God is dividing by zero ---