Hi all,

I'm going to get a live center (only have dead ones now).
Is there any reason to not get a live center with a
CNC spindle type point for a manual lathe?
What's the difference between than an a normal live center?

Thanks,
Wayne D.

Wayne wrote:

Hi all,

I'm going to get a live center (only have dead ones now).
Is there any reason to not get a live center with a
CNC spindle type point for a manual lathe?
What's the difference between than an a normal live center?

Thanks,
Wayne D.

The cnc type with the extended smaller point is a little less rigid but
unless you are doing heavy cutting on steel, probably won't notice the
difference.

"Wayne" wrote in message
news
Hi all,

I'm going to get a live center (only have dead ones now).
Is there any reason to not get a live center with a
CNC spindle type point for a manual lathe?
What's the difference between than an a normal live center?

Thanks,
Wayne D.

Wayne, this doesn't answer your question, and I don't want to add to
confusion, but...

You mention manual lathe. If you're like most of us here and have old
instruction books and handbooks about turning, note that a "live center" in
the old books refers to a center that's rotated under power, in the
headstock. A dead center is one that isn't directly driven and which is used
in the tailstock, whether it's a plain, non-rotating type, or a ball-bearing
type that rotates.

Today, the common terminology has done a transformation and the
rotating-type tailstock centers often are called "live centers." But the
purists (like me g) will still call that type of center a "dead center,"
because it only idles at the tailstock end and isn't directly driven.

This is mostly for any beginners who may be confused by the change in
terminology.

--
Ed Huntress

In article ,
Wayne wrote:
Hi all,

I'm going to get a live center (only have dead ones now).
Is there any reason to not get a live center with a
CNC spindle type point for a manual lathe?

If the ones which you are talking about are the ones with a
steep taper between the 60 degree taper at the tip and the bearing
housing -- there are reasons to get it, and reasons to not get it.

Not get:

1) The longer tip puts more leverage on the tailstock ram,
possibly producing more offset under heavy turning loads.

2) Usually significantly more expensive.

To get:

1) The longer taper gives you more clearance for the toolpost
and toolholder, allowing you to work with smaller diameters at
the very end while keeping a shorter tool extension, so the
chance for chatter is reduced. I find this most useful when
threading at the end of a shaft, as that requires more reach
towards the center than the turning just prior to that does.

2) Probably better (and more) bearings, so it is more rigid within
itself.

3) Bragging rights? :-)

What's the difference between than an a normal live center?

1) Based mostly on what I have seen in the catalog pages, it will
have more rows of bearings, so it handles a load better.
(Whether the tailstock ram will do so remains to be seen.)

2) The longer taper, to get the bearing housing out of the way of
your work. More necessary with a tool turret in a CNC lathe,
but useful also with a big fat toolpost.

3) Maybe a difference in the shank. Some of them may have
cylindrical shanks instead of Morse taper shanks.


Note that the one which I have (with a MT-1 shank), made by
Royal, is an interesting style. The profile looks more like this:

/\
/ \ ---- 60 degrees
| | --- straight
| |
/ \ --- 60 degrees
/ \
/ \
/ \
| | -- straight
| |
| |
+-----| |-----+ --- everything from this line up rotates
| | ---- Morse taper within the limits of
|| ASCII graphics
||

This means that not only is it an extended taper for close turning, but
it also is a bull-nose taper for turning pipes and tubing.

If you get a CNC live center, you will probably also need at
least a bull-nose taper sometime, and an interchangeable point one can
be quite useful at times, too.

I hope that this helps,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In news:Wayne typed:
Hi all,

I'm going to get a live center (only have dead ones now).
Is there any reason to not get a live center with a
CNC spindle type point for a manual lathe?

I use mine for facing off material between centers that has a #5 center
drilled hole in it. That means I can face off all the way across the face
without having to bump a bigger live center. Having it really protects my
tooling, some of which has a .005" radius which would for sure get broken if
it jammed into a normal live center.
--
Ted Harris
http://www.tedharris.com

On 24 Jan 2005 00:44:18 -0500, (DoN. Nichols)
wrote:

In article ,
Wayne wrote:
Hi all,

I'm going to get a live center (only have dead ones now).
Is there any reason to not get a live center with a
CNC spindle type point for a manual lathe?

If the ones which you are talking about are the ones with a
steep taper between the 60 degree taper at the tip and the bearing
housing -- there are reasons to get it, and reasons to not get it.

snip

Note that the one which I have (with a MT-1 shank), made by
Royal, is an interesting style. The profile looks more like this:

/\
/ \ ---- 60 degrees
| | --- straight
| |
/ \ --- 60 degrees
/ \
/ \
/ \
| | -- straight
| |
| |
+-----| |-----+ --- everything from this line up rotates
| | ---- Morse taper within the limits of
|| ASCII graphics
||

This means that not only is it an extended taper for close turning, but
it also is a bull-nose taper for turning pipes and tubing.

If you get a CNC live center, you will probably also need at
least a bull-nose taper sometime, and an interchangeable point one can
be quite useful at times, too.

I hope that this helps,
DoN.

I got one of those when I needed a bull nose center. Very handy. I
use it whenever I need a center.

Pete Keillor

On Sun, 23 Jan 2005 22:46:21 -0500, Ed Huntress
wrote:

Very interesting tidbit, I wasn't aware.
The name then used to be dependent on where and how
the center was used.

How then was each of the centers called when you went to buy one?
I wonder if that is why the name changed, to be position
independent.

"Wayne" wrote in message
news
Hi all,

I'm going to get a live center (only have dead ones now).
Is there any reason to not get a live center with a
CNC spindle type point for a manual lathe?
What's the difference between than an a normal live center?

Thanks,
Wayne D.

Wayne, this doesn't answer your question, and I don't want to add to
confusion, but...

You mention manual lathe. If you're like most of us here and have old
instruction books and handbooks about turning, note that a "live center"
in
the old books refers to a center that's rotated under power, in the
headstock. A dead center is one that isn't directly driven and which is
used
in the tailstock, whether it's a plain, non-rotating type, or a
ball-bearing
type that rotates.

Today, the common terminology has done a transformation and the
rotating-type tailstock centers often are called "live centers." But the
purists (like me g) will still call that type of center a "dead
center,"
because it only idles at the tailstock end and isn't directly driven.

This is mostly for any beginners who may be confused by the change in
terminology.

--
Ed Huntress

Thanks for all the input.
I ordered one since it seems it will fit my needs.

DoN, you are a very good ascii artist.
I've seen many of your works.

Wayne D.

In article ,
Wayne wrote:
On Sun, 23 Jan 2005 22:46:21 -0500, Ed Huntress
wrote:

Very interesting tidbit, I wasn't aware.
The name then used to be dependent on where and how
the center was used.

How then was each of the centers called when you went to buy one?
I wonder if that is why the name changed, to be position
independent.

Well ... consider that the center in the tailstock is hardened
and ground to final shape to handle the bearing action.

But the headstock center is often mild steel, and turned to true
it optimally just after inserting it.

So -- there is a reason for purchasing differing centers for
headstock and for tailstock. Granted that a ball-bearing center (that
which is now called "live" is even better from the wear point of view,
and does not require a special lubricant (which *used* to be white lead
before the hysteria about lead poisoning came around. :-)

Enjoy,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"Ed Huntress" wrote in message
...
"Wayne" wrote in message
news
Hi all,

I'm going to get a live center (only have dead ones now).
Is there any reason to not get a live center with a
CNC spindle type point for a manual lathe?
What's the difference between than an a normal live center?

Thanks,
Wayne D.

Wayne, this doesn't answer your question, and I don't want to add to
confusion, but...

You mention manual lathe. If you're like most of us here and have old
instruction books and handbooks about turning, note that a "live center"
in
the old books refers to a center that's rotated under power, in the
headstock. A dead center is one that isn't directly driven and which is
used
in the tailstock, whether it's a plain, non-rotating type, or a
ball-bearing
type that rotates.

Today, the common terminology has done a transformation and the
rotating-type tailstock centers often are called "live centers." But the
purists (like me g) will still call that type of center a "dead center,"
because it only idles at the tailstock end and isn't directly driven.

This is mostly for any beginners who may be confused by the change in
terminology.

--
Ed Huntress


Centers in the headstock are often dead in grinding machines. By using a
dead center, there is no chance of generating any eccentricity between the
part and the centers contained within the ends. It is for that reason
ball bearing centers are generally not used on grinders, where tolerance
often is less than the degree of precision of ball bearing centers.

Harold

"Wayne" wrote in message
news
On Sun, 23 Jan 2005 22:46:21 -0500, Ed Huntress
wrote:

Very interesting tidbit, I wasn't aware.
The name then used to be dependent on where and how
the center was used.

How then was each of the centers called when you went to buy one?

Ball-bearing dead center, plain center (hardened for dead; soft for live),
half-point center, rotating- versus plain cup center, etc.

I wonder if that is why the name changed, to be position
independent.

I don't know. Tracking down how words evolve can be tricky business.
Something like "billet wheels," though, is a lot easier. That was a case of
the admen 'got hold of a word that could really sell, by association with
something else.

If there was some profit in finding out, I think you'd find it in the
archives of _American Machinist_ from, say, the 1930s through the 1960s.
They were the gold standard for lots of words used in our business,
including the spelling of "gage" versus "gauge."

--
Ed Huntress

"Harold & Susan Vordos" wrote in message
...


Centers in the headstock are often dead in grinding machines. By using a
dead center, there is no chance of generating any eccentricity between the
part and the centers contained within the ends. It is for that reason
ball bearing centers are generally not used on grinders, where tolerance
often is less than the degree of precision of ball bearing centers.

Harold

Yes, another interesting point (no pun intended g). Another way to look at
it is, under the old terminology, a center was "live" if the shank of it
rotated. It was "dead" if it did not.

Again, this is likely to come up only if you're reading really old machining
books. But a lot of us hobbyists do exactly that.

--
Ed Huntress