From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected to
run perfectly true. Even 3-jaw chucks costing five times more than the one
made for this lathe will have a 0.002" to 0.003" runout. If perfect accuracy
is desired in a particular operation, the use of a 4-jaw chuck or a collet
is recommended. Both are available for your Sherline Lathe."

I don't have a Sherline lathe, but I was considering mounting a small
Sherline chuck on a stepper driven spindle for a fourth axis on one of the
mini CNC mills in the shop.

Bob La Londe wrote:

From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected to
run perfectly true. Even 3-jaw chucks costing five times more than the one
made for this lathe will have a 0.002" to 0.003" runout. If perfect accuracy
is desired in a particular operation, the use of a 4-jaw chuck or a collet
is recommended. Both are available for your Sherline Lathe."

I don't have a Sherline lathe, but I was considering mounting a small
Sherline chuck on a stepper driven spindle for a fourth axis on one of the
mini CNC mills in the shop.

The Adjust-Tru chucks have provisions to allow them to be adjusted to
run true, but I expect that trueness only applies at the particular part
diameter that they are adjusted for.

"Pete C." wrote in message
ster.com...

Bob La Londe wrote:

From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected
to
run perfectly true. Even 3-jaw chucks costing five times more than the
one
made for this lathe will have a 0.002" to 0.003" runout. If perfect
accuracy
is desired in a particular operation, the use of a 4-jaw chuck or a
collet
is recommended. Both are available for your Sherline Lathe."

I don't have a Sherline lathe, but I was considering mounting a small
Sherline chuck on a stepper driven spindle for a fourth axis on one of
the
mini CNC mills in the shop.

The Adjust-Tru chucks have provisions to allow them to be adjusted to
run true, but I expect that trueness only applies at the particular part
diameter that they are adjusted for.

Kinda like polishing the jaws of a chuck? Only works at a particular
diameter?

On 11/12/2010 07:51 AM, Bob La Londe wrote:
From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected
to run perfectly true. Even 3-jaw chucks costing five times more than
the one made for this lathe will have a 0.002" to 0.003" runout. If
perfect accuracy is desired in a particular operation, the use of a
4-jaw chuck or a collet is recommended. Both are available for your
Sherline Lathe."

That's certainly been my understanding of 3-jaw chucks all along -- if
you want perfect accuracy you use a chuck with individually adjustable
jaws, and you run the part in with a dial indicator to establish runout
before you cut.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

On Nov 12, 11:03*am, "Pete C." wrote:
...
The Adjust-Tru chucks have provisions to allow them to be adjusted to
run true, but I expect that trueness only applies at the particular part
diameter that they are adjusted for.

A new, unworn Bison Set-Tru does that. I use the 3-jaw for speed and
convenience, the 4-jaw for accuracy, the Set-Tru feature very rarely
for my one-off type of work.

jsw

In article ,
Tim Wescott wrote:

On 11/12/2010 07:51 AM, Bob La Londe wrote:
From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected
to run perfectly true. Even 3-jaw chucks costing five times more than
the one made for this lathe will have a 0.002" to 0.003" runout. If
perfect accuracy is desired in a particular operation, the use of a
4-jaw chuck or a collet is recommended. Both are available for your
Sherline Lathe."

That's certainly been my understanding of 3-jaw chucks all along -- if
you want perfect accuracy you use a chuck with individually adjustable
jaws, and you run the part in with a dial indicator to establish runout
before you cut.

Or a collet, depending what you are doing and how fast you need to be
doing it (especially if it's over and over again on parts the same size.)

--
Cats, coffee, chocolate...vices to live by

On 11/12/2010 09:01 AM, Ecnerwal wrote:
In ,
Tim wrote:

On 11/12/2010 07:51 AM, Bob La Londe wrote:
From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected
to run perfectly true. Even 3-jaw chucks costing five times more than
the one made for this lathe will have a 0.002" to 0.003" runout. If
perfect accuracy is desired in a particular operation, the use of a
4-jaw chuck or a collet is recommended. Both are available for your
Sherline Lathe."

That's certainly been my understanding of 3-jaw chucks all along -- if
you want perfect accuracy you use a chuck with individually adjustable
jaws, and you run the part in with a dial indicator to establish runout
before you cut.

Or a collet, depending what you are doing and how fast you need to be
doing it (especially if it's over and over again on parts the same size.)

Or you plan your work so that you do it all in one chucking-up operation.

I've found that I can mark the piece and my chuck, take it out, and put
it back in so the marks line up, and get decent repeatability -- so far.
I certainly wouldn't count on that, though.

We both forgot to mention turning between centers.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" was written for you.
See details at http://www.wescottdesign.com/actfes/actfes.html

There aren't many adjustable workholding chucks that are perfectly true to
the center axis.
The more moving parts, the less accuracy.. generally.

Variations in the overall (in)accuracies of individual parts will dictate
the accuracy of a chuck (lathe, drill, etc).

Collets are generally considered to be much more accurate than adjustable
chucks. The adjustability feature of chucks is more for convenience.

Turning a simple part such as a bushing with a shoulder, will most likely be
most accurately machined/turned, when the bushing dimensions are cut to
desired sizes, then the part is cut off.
This is a common practice for very good/excellent concentricity.

Having chucks with soft replaceable jaws allows the user to bore an
axis-concentric hole/bore in the jaws for a particular sized workpiece, and
re-bored for a different size for best accuracy.

The jaws themselves, the guides that position the jaws and a scroll that
engages the jaws for adjustment, are all involved in the overall accuracy of
adjustable lathe or drill chucks.

The jaws typically aren't identical in adjustable chucks (the gear-type
teeth that engage the scroll differ from jaw 1, 2, 3 etc), so it's not as if
one could build a very accurate chuck with only a couple of sets of jaws.

The big difference in accuracy between chucks, is cost. Accuracy and quality
control are more expensive.
China and India typically make consumer grade products that looky-like a
real item, but quality control and accuracy generally aren't priorities..
just filling up the cargo containers for the next shipment is what matters.

Accuracy of chucks from other locations will vary, depending upon the cost
and the intended application that they were manufactured for.

--
WB
..........


"Bob La Londe" wrote in message
...
From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected
to run perfectly true. Even 3-jaw chucks costing five times more than the
one made for this lathe will have a 0.002" to 0.003" runout. If perfect
accuracy is desired in a particular operation, the use of a 4-jaw chuck or
a collet is recommended. Both are available for your Sherline Lathe."

I don't have a Sherline lathe, but I was considering mounting a small
Sherline chuck on a stepper driven spindle for a fourth axis on one of the
mini CNC mills in the shop.

--I've got a 6-jaw Buck Adjust-tru chuck on a Myford Super 7B and I
can dial it to within .0001" if I have to. If you're needing accuracy that's
what you need to do. I don't often have something so kattywompus that I have
to mess with the chuck tho; it's repeatable accuracy is less than .001" fer
sure. If Sherline can't maintain that sort of accuracy it sounds like a
badly designed spindle assembly, not a chuck problem. There's a reason the
Sherline is inexpensive and that's gotta be one of 'em..

--
"Steamboat Ed" Haas : Time flies like an arrow
Hacking the Trailing Edge! : Fruit flies like a banana
www.nmpproducts.com
---Decks a-wash in a sea of words---

Bob,
I don't know where you got your accuracy numbers, but all of my 3 jaws are accurate to less than .001". Keep them clean and oiled
and don't over torque them and they are accurate enough for 90%+ of your work.
Steve

"Bob La Londe" wrote in message ...
From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected to run perfectly true. Even 3-jaw chucks costing five
times more than the one made for this lathe will have a 0.002" to 0.003" runout. If perfect accuracy is desired in a particular
operation, the use of a 4-jaw chuck or a collet is recommended. Both are available for your Sherline Lathe."

I don't have a Sherline lathe, but I was considering mounting a small Sherline chuck on a stepper driven spindle for a fourth
axis on one of the mini CNC mills in the shop.

"Steve Lusardi" wrote in message
...
Bob,
I don't know where you got your accuracy numbers,


From the Sherline website. LOL. That was their claim.


but all of my 3 jaws are accurate to less than .001". Keep them clean and
oiled and don't over torque them and they are accurate enough for 90%+ of
your work.
Steve

"Bob La Londe" wrote in message
...
From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected
to run perfectly true. Even 3-jaw chucks costing five times more than the
one made for this lathe will have a 0.002" to 0.003" runout. If perfect
accuracy is desired in a particular operation, the use of a 4-jaw chuck
or a collet is recommended. Both are available for your Sherline Lathe."

I don't have a Sherline lathe, but I was considering mounting a small
Sherline chuck on a stepper driven spindle for a fourth axis on one of
the mini CNC mills in the shop.

"Bob La Londe" wrote:

The Adjust-Tru chucks have provisions to allow them to be adjusted to
run true, but I expect that trueness only applies at the particular part
diameter that they are adjusted for.

Kinda like polishing the jaws of a chuck? Only works at a particular
diameter?

No, there are 4 adjustment screws on the mounting plate that allow you to after loosening
the clamping bolts to center the chuck body on the base plate then secure the clamping
bolts.

All the eaze of a 3 jaw with the accuracy of a 4 jaw independent. Very nice setup, I use
one at work from time to time.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

Wes wrote:

No, there are 4 adjustment screws on the mounting plate that allow you to after loosening
the clamping bolts to center the chuck body on the base plate then secure the clamping
bolts.

All the eaze of a 3 jaw with the accuracy of a 4 jaw independent. Very nice setup, I use
one at work from time to time.

You may not get perfect repeatablity on a single diameter but you can dial in any chucked
up part to your level of perfection.

Wes

Bob La Londe wrote:
From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be
expected to run perfectly true. Even 3-jaw chucks costing five times
more than the one made for this lathe will have a 0.002" to 0.003"
runout. If perfect accuracy is desired in a particular operation, the
use of a 4-jaw chuck or a collet is recommended. Both are available
for your Sherline Lathe."

I don't have a Sherline lathe, but I was considering mounting a small
Sherline chuck on a stepper driven spindle for a fourth axis on one of
the mini CNC mills in the shop.
My understanding is that good 3 jaw chucks are marked with a master
tightening socket, marked 0 in all the cases I've seen, and that socket
when used to tighten the new chuck gives the minimum runout. IIRC this
is intentional and due to necessary internal clearances as the scroll
and the diameter it bears against are made so that the thrust from the
master socket pinion take up the internal clearances to provide the most
true running.

I have a couple of Bison 3 jaw chucks and a TOS 3 jaw chuck and that
holds true. The last Bison chuck I bought about 6 years ago was a bog
standard accuracy chuck and had 0.01mm TIR runout on a 1" diameter test
bar at the chuck after mounting on the backplate, The back plate
mounting procedure being which has been mentioned on RCM before with a
slight interference fit register machined on the mounted backplate to
suit the chuck register diameter and no adjust-tru provison on the
chuck. Due to its accuracy class I wouldn't expect that to hold
throughout the clamping range or that the runout away from the chuck was
great but it's way better than some Chinese chucks I've seen, and has
always been more than sufficient for the vast majority of the work I do.

"Wild_Bill" wrote in message
...
There aren't many adjustable workholding chucks that are perfectly true to
the center axis.
The more moving parts, the less accuracy.. generally.

Variations in the overall (in)accuracies of individual parts will dictate
the accuracy of a chuck (lathe, drill, etc).

Collets are generally considered to be much more accurate than adjustable
chucks. The adjustability feature of chucks is more for convenience.

Turning a simple part such as a bushing with a shoulder, will most likely
be most accurately machined/turned, when the bushing dimensions are cut to
desired sizes, then the part is cut off.
This is a common practice for very good/excellent concentricity.

Having chucks with soft replaceable jaws allows the user to bore an
axis-concentric hole/bore in the jaws for a particular sized workpiece,
and re-bored for a different size for best accuracy.

The jaws themselves, the guides that position the jaws and a scroll that
engages the jaws for adjustment, are all involved in the overall accuracy
of adjustable lathe or drill chucks.

The jaws typically aren't identical in adjustable chucks (the gear-type
teeth that engage the scroll differ from jaw 1, 2, 3 etc), so it's not as
if one could build a very accurate chuck with only a couple of sets of
jaws.

The big difference in accuracy between chucks, is cost. Accuracy and
quality control are more expensive.
China and India typically make consumer grade products that looky-like a
real item, but quality control and accuracy generally aren't priorities..
just filling up the cargo containers for the next shipment is what
matters.

Accuracy of chucks from other locations will vary, depending upon the cost
and the intended application that they were manufactured for.

--
WB
.........


"Bob La Londe" wrote in message
...
From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected
to run perfectly true. Even 3-jaw chucks costing five times more than the
one made for this lathe will have a 0.002" to 0.003" runout. If perfect
accuracy is desired in a particular operation, the use of a 4-jaw chuck
or a collet is recommended. Both are available for your Sherline Lathe."

I don't have a Sherline lathe, but I was considering mounting a small
Sherline chuck on a stepper driven spindle for a fourth axis on one of
the mini CNC mills in the shop.


+1 on the soft jaws! I think it's important to plan a job around the
limitations of your tooling. I only see where the accuracy of a chuck come
into play is on a secondary operation or poor planning. If I have to, I
make soft jaws but I try to avoid the extra work with forethought.

Wes wrote:

"Bob La Londe" wrote:

The Adjust-Tru chucks have provisions to allow them to be adjusted to
run true, but I expect that trueness only applies at the particular part
diameter that they are adjusted for.

Kinda like polishing the jaws of a chuck? Only works at a particular
diameter?

No, there are 4 adjustment screws on the mounting plate that allow you to after loosening
the clamping bolts to center the chuck body on the base plate then secure the clamping
bolts.

All the eaze of a 3 jaw with the accuracy of a 4 jaw independent. Very nice setup, I use
one at work from time to time.

No, it's as I indicated, the adjustment only works at the diameter part
it was adjusted on. If you chuck up a part of a notably different
diameter you'll get runout until you once again adjust the Adjust-Tru.
i.e. it can be accurate with any diameter part, but not at the same
time, it has to be readjusted for a different part diameter.

Wes wrote:
wrote:

No, there are 4 adjustment screws on the mounting plate that allow you to after loosening
the clamping bolts to center the chuck body on the base plate then secure the clamping
bolts.

All the eaze of a 3 jaw with the accuracy of a 4 jaw independent. Very nice setup, I use
one at work from time to time.

You may not get perfect repeatablity on a single diameter but you can dial in any chucked
up part to your level of perfection.

Wes

You have to use the same chuck tightening position or the scroll
position will not repeat position. I mark one of them with a magic
marker so the same one is used every time. It makes a big difference
especially if the chuck scroll is worn.

John

"Bob La Londe" wrote in message
...

From the Sherline website.

"Due to the nature of the design of a 3-jaw chuck, it cannot be expected to
run perfectly true. Even 3-jaw chucks costing five times more than the one
made for this lathe will have a 0.002" to 0.003" runout. If perfect accuracy
is desired in a particular operation, the use of a 4-jaw chuck or a collet
is recommended. Both are available for your Sherline Lathe."

I don't have a Sherline lathe, but I was considering mounting a small
Sherline chuck on a stepper driven spindle for a fourth axis on one of the
mini CNC mills in the shop.


Yes, it's true!



Steve R.

Yep, high precision lathe work was done for generations without such
versatile or specialized tooling.

Expectations of perfect tooling are unrealistic.. especially with all the
low priced accessories available today for home shops.
The premium, high grade tooling doesn't guarantee that the work will be
perfectly accurate anyway.

I agree with the poor planning and forethought comments.

--
WB
..........


"Tom Gardner" wrote in message
...

+1 on the soft jaws! I think it's important to plan a job around the
limitations of your tooling. I only see where the accuracy of a chuck
come into play is on a secondary operation or poor planning. If I have
to, I make soft jaws but I try to avoid the extra work with forethought.

On Fri, 12 Nov 2010 19:59:11 -0500, "Pete C."
wrote:


Wes wrote:

"Bob La Londe" wrote:

The Adjust-Tru chucks have provisions to allow them to be adjusted to
run true, but I expect that trueness only applies at the particular part
diameter that they are adjusted for.

Kinda like polishing the jaws of a chuck? Only works at a particular
diameter?

No, there are 4 adjustment screws on the mounting plate that allow you to after loosening
the clamping bolts to center the chuck body on the base plate then secure the clamping
bolts.

All the eaze of a 3 jaw with the accuracy of a 4 jaw independent. Very nice setup, I use
one at work from time to time.

No, it's as I indicated, the adjustment only works at the diameter part
it was adjusted on. If you chuck up a part of a notably different
diameter you'll get runout until you once again adjust the Adjust-Tru.
i.e. it can be accurate with any diameter part, but not at the same
time, it has to be readjusted for a different part diameter.

Correct

Gunner, with 3 AdjustTrus


--
"Confiscating wealth from those who have earned it, inherited it,
or got lucky is never going to help 'the poor.' Poverty isn't
caused by some people having more money than others, just as obesity
isn't caused by McDonald's serving super-sized orders of French fries
Poverty, like obesity, is caused by the life choices that dictate
results." - John Tucci,