I hardly ever turn things between centers. I came across a job where it
would have been appropriate. I hit the books but came away with some
unanswered questions:

1) For work between the centers a dead center in the tailstock is said to
yield more accurate results. However, due to friction issues the working
speed is limited. I can find no recommendations regarding maximum speeds for
a dead center. BTW I am interested in mild steel, brass and aluminum.

2) By what magnitude does the accuracy deteriorate if live instead of dead
center is used in the tailstock?

3) What diameter-to-length ratio is allowable before bowing of the piece in
the middle becomes an issue? Given that it is recommended not to turn
anything protruding beyond the chuck jaws by more than 2 to 4 diameters
(this seems to depend on who you ask :-) I would assume that 8 diameters
would be OK. Is this assumption valid?

--
Michael Koblic,
Campbell River, BC

"Michael Koblic" fired this volley in
:

I came across a job where it
would have been appropriate.

Mike, I turn a LOT of tapers in the work I do. Working between centers
is almost automatic.

I use a live center only for quick-n-dirty work that is cylindrical. When
I turn tapers, I always use a dead center. Live centers seldom keep
their accuracy for more than a few years of use at significant loads. A
dead center is as accurate as its finish. Besides, live centers aren't
as well-suited to taking lateral loads as they are axial loads. Turning
taper puts side loads on the bearing. Only one tiny line of contact
exists between the centerbore in the end of the work, and the surface of
the tailstock center with a compensating ring of material bearing on the
opposite surface of the tailstock center where the bore ends in the pilot
hole. The effect is to put significant side-thrust on the bearing.

The maximum speed of the work depends upon lubrication, tailstock force,
and the material. There isn't a fixed figure to quote. In addition to
all those things, as the work expands from the heat of cutting (and
friction on the tailstock center) you'll need to "relax" the tailstock
between cut series, or let the work cool and re-tension the tailstock.

I'd assume about 8 diameters is the maximum for an unsupported cut taking
heavy cuts. You can do MUCH longer work with fine cuts. The best way to
handle the length issue is to use a follower rest. There's no practical
limit to the L/D ratio if you do.

LLoyd

The best way to handle the length issue is to use a follower rest. There's no practical
limit to the L/D ratio if you do.

LLoyd

But how do you handle a taper cut with a follower rest?

cheers
T.Alan

On Tue, 27 Jul 2010 18:21:53 -0700, "Michael Koblic"
wrote:

I hardly ever turn things between centers. I came across a job where it
would have been appropriate. I hit the books but came away with some
unanswered questions:

1) For work between the centers a dead center in the tailstock is said to
yield more accurate results. However, due to friction issues the working
speed is limited. I can find no recommendations regarding maximum speeds for
a dead center. BTW I am interested in mild steel, brass and aluminum.

Lubrication is a must. I like moly disulfide EP chassis
grease. Some people use straight STP. The old books suggest
a blend of grease and graphite and/or white lead.

2) By what magnitude does the accuracy deteriorate if live instead of dead
center is used in the tailstock?
While this may have been true when live centers were first
introduced, it now appears to be an old machinist's tale,
assuming reasonable quality/condition of the live center.

3) What diameter-to-length ratio is allowable before bowing of the piece in
the middle becomes an issue? Given that it is recommended not to turn
anything protruding beyond the chuck jaws by more than 2 to 4 diameters
(this seems to depend on who you ask :-) I would assume that 8 diameters
would be OK. Is this assumption valid?
For straight turning, this is what a traveling steady rest
is for. You can make your own. See
http://mcduffee-associates.us/machining/TRAVEL~1.HTM
===========
One of the old time techniques for turning tapers is to use
what is called a bell center drill.

for examples see
http://www.use-enco.com/CGI/INPDFF?P...PARTPG=INLMK32
{bottom of page
and
http://www.wttool.com/category-exec/category_id/19639

Another possibility, which may require 3 hands to set-up, is
to have a regular 60 degree center in both ends of the part
and the headstock/tailstock supports with a suitable size
ball bearing in between. This will allow for smooth
rotation but you must allow the lathe dog to pivot freely as
the part moves/tilts in relation to the faceplate.

One item that I find handy is that my mill spindle and lathe
tail stock are both 2MT. This allows me to mount the
boring head in the tail stock and use the boring head
adjustment to dial in exactly the taper I want without
disturbing the tail stock alignment (and this will work even
if the tail stock is fixed and can't be set over). Use some
short pieces of drill rod that will fit the holes in the
boring head, and turn both a dead center with a 60 degree
angle, and a short stub with a regular 60 degree center for
use with a ball. For light/occasional use you won't need to
harden, but these will last longer if you do.

Let the group know how things work out for you, and good
luck.
-- Unka George (George McDuffee)
...............................
The past is a foreign country;
they do things differently there.
L. P. Hartley (1895-1972), British author.
The Go-Between, Prologue (1953).

On 2010-07-28, Michael Koblic wrote:
I hardly ever turn things between centers. I came across a job where it
would have been appropriate. I hit the books but came away with some
unanswered questions:

Of course. :-)

1) For work between the centers a dead center in the tailstock is said to
yield more accurate results. However, due to friction issues the working
speed is limited. I can find no recommendations regarding maximum speeds for
a dead center. BTW I am interested in mild steel, brass and aluminum.

Each material would have a different speed -- in part a function
of the diameter of the workpiece, and in part a function of the maximum
diameter of the center hole you were using. (Think of the SFM (Surface
Feet per Minute) at the OD of the center contact.

And what lubricant would you be using where the workpiece
contacts the center? You need something with a high film strength.
What *used* to be used was white lead (lead oxide PbO -- not Pb3O4 which
is "red lead") -- but given the current level of hysteria over all forms
of lead, that will probably be very difficult to find.

2) By what magnitude does the accuracy deteriorate if live instead of dead
center is used in the tailstock?

Proably not enough to matter for you -- and I could see a
greater inaccuracy using a fixed center in soft aluminum than with a
live center.

And with a high dollar live center, I doubt that you could match
it with a hardened "dead" one on your machine.

(BTW -- at one time, when non bearing centers were used at both
ends, the one in the tailstock was called "dead" because it did not
turn, and the one in the headstock was called "live" because it turned
with the spindle.

3) What diameter-to-length ratio is allowable before bowing of the piece in
the middle becomes an issue? Given that it is recommended not to turn
anything protruding beyond the chuck jaws by more than 2 to 4 diameters
(this seems to depend on who you ask :-) I would assume that 8 diameters
would be OK. Is this assumption valid?

Again -- this depends on the material. I know that I would not
machine Delrin with a 4:1 stickout (without tailstock support). It
bends too easily.

I would be uncertain about some aluminum alloys. A good 360L
brass I would feel fairly happy with, and with pretty much any steel, i
would be happy -- with reasonably conservative depth of cut.

If you want a way to *measure* things -- put a dial indicator
with a broad point above the workpiece where the tool cuts. Zero it at
the tailstock end and watch it as you cut. While 0.001" of lift (alone,
ignoring bowing back from the cutter) does not equal 0.001" of change in
diameter -- the smaller the diameter the more effect it does have. I
think that the lift will likely be greater than the bowing back.

Assuming workpieces on the order of 1/2" -- I would suggest that
if you see 0.002" of lift, you should either reduce the depth of cut, or
set up a traveling steady (follower rest). The smaller you turn it, the
worse the lift will get, until it finally climbs on top of the cutting
tool.

Now -- if you are intending to make decorative curved turning
(like table legs or similar) you will not be able to use a steady rest
of any sort.

Good Luck,
DoN.

--
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Email: | Voice (all times): (703) 938-4564
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On Tue, 27 Jul 2010 20:37:30 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

"Michael Koblic" fired this volley in
:

I came across a job where it
would have been appropriate.

Mike, I turn a LOT of tapers in the work I do. Working between centers
is almost automatic.

I use a live center only for quick-n-dirty work that is cylindrical. When
I turn tapers, I always use a dead center. Live centers seldom keep
their accuracy for more than a few years of use at significant loads. A
dead center is as accurate as its finish. Besides, live centers aren't
as well-suited to taking lateral loads as they are axial loads. Turning
taper puts side loads on the bearing. Only one tiny line of contact
exists between the centerbore in the end of the work, and the surface of
the tailstock center with a compensating ring of material bearing on the
opposite surface of the tailstock center where the bore ends in the pilot
hole. The effect is to put significant side-thrust on the bearing.

The maximum speed of the work depends upon lubrication, tailstock force,
and the material. There isn't a fixed figure to quote. In addition to
all those things, as the work expands from the heat of cutting (and
friction on the tailstock center) you'll need to "relax" the tailstock
between cut series, or let the work cool and re-tension the tailstock.

I'd assume about 8 diameters is the maximum for an unsupported cut taking
heavy cuts. You can do MUCH longer work with fine cuts. The best way to
handle the length issue is to use a follower rest. There's no practical
limit to the L/D ratio if you do.

LLoyd

Not to disagree with Lloyd at all, I haven't used a tailstock dead
center in a decade. Live center works just fine for me -- but Lloyd
probably turns more than I do and probably has higher standards for
accuracy. Getting to within a thou is close enough for about
everything I do.

I like the live center because then I don't need to mess with lube. I
did use dead centers decades ago, with white lead for lube. Waiting
for someone to chime in to say that this may explain a few things G

On Tue, 27 Jul 2010 18:21:53 -0700, "Michael Koblic"
wrote:

I hardly ever turn things between centers. I came across a job where it
would have been appropriate. I hit the books but came away with some
unanswered questions:

1) For work between the centers a dead center in the tailstock is said to
yield more accurate results. However, due to friction issues the working
speed is limited. I can find no recommendations regarding maximum speeds for
a dead center. BTW I am interested in mild steel, brass and aluminum.

2) By what magnitude does the accuracy deteriorate if live instead of dead
center is used in the tailstock?

That really depends on the quality and condition of the live center.
Most of my working centers, with good bearings, will have TIR (total
indicated runout) of less than .0001. One tenthousandth of an inch. And
mine are not by any standards....minty.


3) What diameter-to-length ratio is allowable before bowing of the piece in
the middle becomes an issue? Given that it is recommended not to turn
anything protruding beyond the chuck jaws by more than 2 to 4 diameters
(this seems to depend on who you ask :-) I would assume that 8 diameters
would be OK. Is this assumption valid?

Good question. I regularly profile 10-14" lengths of 1" material between
centers. But it does to be sure, depend on the material and the type of
insert/cutter one uses. When cutting long, I generally use a postive
rake HSS tool, sharpened well, or a postive rake carbide tool and save
the last pass for .005 - .010ish..depending on the material.
Brass...one can turn a very long length without issue.
Inconel......thats another story.

Lathe used is a Hardinge HLV-H.....shrug

Gunner

One could not be a successful Leftwinger without realizing that,
in contrast to the popular conception supported by newspapers
and mothers of Leftwingers, a goodly number of Leftwingers are
not only narrow-minded and dull, but also just stupid.
Gunner Asch

On Jul 27, 9:21*pm, "Michael Koblic" wrote:
I hardly ever turn things between centers. I came across a job where it
would have been appropriate. I hit the books but came away with some
unanswered questions:

1) For work between the centers a dead center in the tailstock is said to
yield more accurate results. However, due to friction issues the working
speed is limited. I can find no recommendations regarding maximum speeds for
a dead center. BTW I am interested in mild steel, brass and aluminum.

2) By what magnitude does the accuracy deteriorate if live instead of dead
center is used in the tailstock?

3) What diameter-to-length ratio is allowable before bowing of the piece in
the middle becomes an issue? Given that it is recommended not to turn
anything protruding beyond the chuck jaws by more than 2 to 4 diameters
(this seems to depend on who you ask :-) I would assume that 8 diameters
would be OK. Is this assumption valid?

--
Michael Koblic,
Campbell River, BC

In my experience the way the tool point is ground has the largest
effect. I usually rough to about 0.010 oversize with a live center and
bits that cut freely but don't leave a smooth finish because the tip
width is narrower than the feed, to minimize radial pressure. Then I
resharpen and change to a dead center to finish to size. I have an old
tube of graphite dead center grease but way oil works well enough for
light cuts.

Deflection of a long piece is easily measured as taper after a
practice finish cut, which also calibrates the feed dials to the part
diameter. It is reduced by a sharper point and a slower feed. I've had
good luck with a point like the bow of a warship or a TT221 insert.

I've made stainless steel #0-80 screws over an inch long this way.

jsw

"T.Alan Kraus" fired this volley in news:4c4f95c7$0
:

But how do you handle a taper cut with a follower rest?

You can't actually cut a taper with it, but if you need to do any spot work
(like, say cutting a groove) somewhere along its length, then it's the
proper support to use.

If the L/D ratio of a taper is too long to prevent springing, you need to
take finer cuts and mind carefully your cutter geometry and surface speeds.

LLoyd

Don Foreman fired this volley in
:

I like the live center because then I don't need to mess with lube. I
did use dead centers decades ago, with white lead for lube. Waiting
for someone to chime in to say that this may explain a few things G

Don, I have 'em and use 'em. If I'm not turning to tenths, then that's the
way to go, for sure.

LLoyd

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"T.Alan Kraus" fired this volley in news:4c4f95c7$0
:

But how do you handle a taper cut with a follower rest?

You can't actually cut a taper with it, but if you need to do any spot
work
(like, say cutting a groove) somewhere along its length, then it's the
proper support to use.

If the L/D ratio of a taper is too long to prevent springing, you need to
take finer cuts and mind carefully your cutter geometry and surface
speeds.

LLoyd

And it is possible to at least rig a steady rest near the midpoint of the
length, and then re-set it on the other side to turn past that point.
Tedious, but it's been done, according to some very old machining books.

--
Ed Huntress

"Ed Huntress" fired this volley in
:


And it is possible to at least rig a steady rest near the midpoint of
the length, and then re-set it on the other side to turn past that
point. Tedious, but it's been done, according to some very old
machining books.


There is another type of rest I've seen in a demo film that looks for all
the world like a wood-turner's gouge rest turned backwards, except, it's
got an angle-iron (or, in the case of the one I saw, a rabetted ledge)
inverted so one leg supports the back of the work, and the other leg the
top. It could be, I guess, as long as the work, but it might not be
necessary to support any but (say) the middle third of a spindle.

It's clamped to the bed _somehow_ to clear the slide, and still support
the work. I never noticed how it was mounted, but envision something
like how a taper jig is set up. It would have to be independently
adjustable in height and fore-aft position at both ends.

During taper turning, it's adjusted to clear the back and top of the work
by a scosh (cigarette paper's thickness?). If (when) the work springs
away from the tool, the "rail" prevents it from springing. Obviously, it
would have to be re-adjusted after every cut.

It might be worth making one custom for a large manual production job of
thin tapers.

I think on CNC, it would be better just to take lighter, faster cuts.

LLoyd

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"Michael Koblic" fired this volley in
:

I came across a job where it
would have been appropriate.

Mike, I turn a LOT of tapers in the work I do. Working between centers
is almost automatic.

I use a live center only for quick-n-dirty work that is cylindrical. When
I turn tapers, I always use a dead center. Live centers seldom keep
their accuracy for more than a few years of use at significant loads. A
dead center is as accurate as its finish. Besides, live centers aren't
as well-suited to taking lateral loads as they are axial loads. Turning
taper puts side loads on the bearing. Only one tiny line of contact
exists between the centerbore in the end of the work, and the surface of
the tailstock center with a compensating ring of material bearing on the
opposite surface of the tailstock center where the bore ends in the pilot
hole. The effect is to put significant side-thrust on the bearing.

The maximum speed of the work depends upon lubrication, tailstock force,
and the material. There isn't a fixed figure to quote. In addition to
all those things, as the work expands from the heat of cutting (and
friction on the tailstock center) you'll need to "relax" the tailstock
between cut series, or let the work cool and re-tension the tailstock.

I'd assume about 8 diameters is the maximum for an unsupported cut taking
heavy cuts. You can do MUCH longer work with fine cuts. The best way to
handle the length issue is to use a follower rest. There's no practical
limit to the L/D ratio if you do.


Thank you and all the others.

I have tried the dead center with oil up to 1000 rpm on steel. I keep
feeling the end and there seems to be no appreciable heating. I take it that
I am well within the acceptable range.

I'd better learn how to use the follower rest (soon as I find where I put
it).

--
Michael Koblic,
Campbell River, BC

"Michael Koblic" fired this volley in
:

I'd better learn how to use the follower rest (soon as I find where I
put it).

Well, again, remember that a follower rest can't be used to actually cut
the taper, just to support it for heavier work near the center.

You might consider the "angle iron" type rest I discussed earlier, if you
need to turn really long, thin spindles. I've never built one, just saw it
in a film; but it looked like "the right stuff" for that application.


LLoyd

On Jul 29, 8:03*am, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:
"Michael Koblic" fired this volley :

I'd better learn how to use the follower rest (soon as I find where I
put it).

Well, again, remember that a follower rest can't be used to actually cut
the taper, just to support it for heavier work near the center.

You might consider the "angle iron" type rest I discussed earlier, if you
need to turn really long, thin spindles. *I've never built one, just saw it
in a film; but it looked like "the right stuff" for that application.

LLoyd

Scroll down to "Box Tool":
http://en.wikipedia.org/wiki/Tool_bit#Box_tool

It's a follower rest built into the tool bit holder. I suppose you
could clamp a bar under the tool post and rig one up on it.

jsw

Jim Wilkins fired this volley in news:168d6196-6857-
:

It's a follower rest built into the tool bit holder. I suppose you
could clamp a bar under the tool post and rig one up on it.

I don't think you understand why that wouldn't work.

"Boxed" or not, a follower rest supports the back and top of the
workpiece at a distance that remains fixed from the tool's cutting point.

Regardless of the tool line when turning tapers, the back and top of the
workpiece grow further away from the tool as the cut progresses toward
the larger end of the taper. A follower cannot work.

The other tool I was discussing is fixed to the bed (in such a way to
allow the slide to move), and aligns to the taper, not to the cutting
tool.

LLoyd

On Jul 29, 10:13*am, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:
Jim Wilkins fired this volley in news:168d6196-6857-
:

It's a follower rest built into the tool bit holder. I suppose you
could clamp a bar under the tool post and rig one up on it.

I don't think you understand why that wouldn't work.

"Boxed" or not, a follower rest supports the back and top of the
workpiece at a distance that remains fixed from the tool's cutting point.

Regardless of the tool line when turning tapers, the back and top of the
workpiece grow further away from the tool as the cut progresses toward
the larger end of the taper. *A follower cannot work.

The other tool I was discussing is fixed to the bed (in such a way to
allow the slide to move), and aligns to the taper, not to the cutting
tool.

LLoyd

The box tool is for cutting unsupported cylinders, and may be easier
to rig up as a follower rest if the lathe wasn't made to take one.
Mine was so I haven't tried the alternatives. OBVIOUSLY it won't work
on a long taper, that's what steady rests are for.

I think I remember cutting a long narrow taper a little at a time with
the compound, extending the work further from the collet for each cut
and matching the diameters by eye and feel, then filing it smooth. The
piece was a mandrel for forging rings and didn't have to be accurate.

Until recently the compound dovetail on my lathe was worn unevenly and
it didn't cut quite straight as the free play changed. I had to
regrind it to cut the taper for a surface grinder spindle adapter.
Each machine fixes the others.

jsw

On 2010-07-29, Jim Wilkins wrote:
On Jul 29, 8:03*am, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:
"Michael Koblic" fired this volley :

I'd better learn how to use the follower rest (soon as I find where I
put it).

Well, again, remember that a follower rest can't be used to actually cut
the taper, just to support it for heavier work near the center.

You might consider the "angle iron" type rest I discussed earlier, if you
need to turn really long, thin spindles. *I've never built one, just saw it
in a film; but it looked like "the right stuff" for that application.

LLoyd

Scroll down to "Box Tool":
http://en.wikipedia.org/wiki/Tool_bit#Box_tool

It's a follower rest built into the tool bit holder. I suppose you
could clamp a bar under the tool post and rig one up on it.

While it is normally used in a turret lathe or an automatic
screw machine, but a box tool *can* be mounted in a boring bar holder in
a quick-change toolpost. The trick is getting it adjusted to both
vertical center and horizontal. Once there, you can use it to turn a
straight diameter as long as the carriage will travel -- or at lest
until you hit the collet or the chuck jaws.

Note, BTW, that the grind of the tool bit is strange. It cuts
with an edge of the end forming a radius to the workpiece instead of
using the top edge to cut, and has a complex set of Vs which feed the
chip away from the tool. If you don't get one with it, you may have
difficulty finding and producing the needed shape.

And, of course, it is useless for cutting a long taper.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
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 ---

On Jul 27, 11:34*pm, "DoN. Nichols" wrote:
On 2010-07-28, Michael Koblic wrote:

I hardly ever turn things between centers. I came across a job where it
would have been appropriate. I hit the books but came away with some
unanswered questions:

* * * * Of course. :-)

+1

You're not joking. I've been reading "Machine Shop Essentials" by
Frank Marlow, and throughout the book I have to stop and do an
internet search or post a forum question because something just
doesn't add up.

1) For work between the centers a dead center in the tailstock is said to
yield more accurate results. However, due to friction issues the working
speed is limited. I can find no recommendations regarding maximum speeds for
a dead center. BTW I am interested in mild steel, brass and aluminum.

* * * * Each material would have a different speed -- in part a function
of the diameter of the workpiece, and in part a function of the maximum
diameter of the center hole you were using. *(Think of the SFM (Surface
Feet per Minute) at the OD of the center contact.

* * * * And what lubricant would you be using where the workpiece
contacts the center? *You need something with a high film strength.
What *used* to be used was white lead (lead oxide PbO -- not Pb3O4 which
is "red lead") -- but given the current level of hysteria over all forms
of lead, that will probably be very difficult to find.

2) By what magnitude does the accuracy deteriorate if live instead of dead
center is used in the tailstock?

* * * * Proably not enough to matter for you -- and I could see a
greater inaccuracy using a fixed center in soft aluminum than with a
live center.

* * * * And with a high dollar live center, I doubt that you could match
it with a hardened "dead" one on your machine.

* * * * (BTW -- at one time, when non bearing centers were used at both
ends, the one in the tailstock was called "dead" because it did not
turn, and the one in the headstock was called "live" because it turned
with the spindle.

Case in point. In a diagram on page 237 the live center is at the
headstock and the dead center is at the tailstock.

Darren Harris
Staten Island, New York.

"Searcher7" wrote in message
...
On Jul 27, 11:34 pm, "DoN. Nichols" wrote:
On 2010-07-28, Michael Koblic wrote:

I hardly ever turn things between centers. I came across a job where it
would have been appropriate. I hit the books but came away with some
unanswered questions:

Of course. :-)

+1

You're not joking. I've been reading "Machine Shop Essentials" by
Frank Marlow, and throughout the book I have to stop and do an
internet search or post a forum question because something just
doesn't add up.


Beware of that Frank Marlow book - a good friend, who knows a LOT about
machining, from decades of experience on both the engineering and the
production side tried to help Frank proof read it and make corrections - it
was filled with errors, misleading drawings, and bad advise - after working
on it for hundreds of hours, he gave it back, Frank accepted some
suggestions but rejected others because it would affect the book's
pagination, or because it was too hard for his wife to redraw the diagrams,
or ???. So, my friend gave up in disgust. The book he recommends is the
Olivo book "Fundamentals of Machine Technology" - note the exact title -
later editions have a lot of CNC stuff and are less appropriate for hobby
use - look for the exact title - check amazon and you will find them for a
few dollars (used) from time to time, or sometimes they show up on ebay.
There is a second volume, Advanced Machine Technology" - I have both on my
shelf here. I think you will find them much more helpful. And a LOT LOT
LOT cheaper than the Marlow books.

Bill Noble wrote:
... The book he
recommends is the Olivo book "Fundamentals of Machine Technology" ...

I Googled it and found an eBay BIN listing for $1.99, thanks for the
reference. I also did a separate eBay search and found another one (for
$19.99), but that search did not show the 1st one. I've seen this
before on eBay - it's screwy.

Bob

BTW - I did buy the $1.99 one.

"Bill Noble" wrote in message
...


"Searcher7" wrote in message
...
On Jul 27, 11:34 pm, "DoN. Nichols" wrote:
On 2010-07-28, Michael Koblic wrote:

I hardly ever turn things between centers. I came across a job where
it
would have been appropriate. I hit the books but came away with some
unanswered questions:

Of course. :-)

+1

You're not joking. I've been reading "Machine Shop Essentials" by
Frank Marlow, and throughout the book I have to stop and do an
internet search or post a forum question because something just
doesn't add up.


Beware of that Frank Marlow book - a good friend, who knows a LOT about
machining, from decades of experience on both the engineering and the
production side tried to help Frank proof read it and make corrections -
it was filled with errors, misleading drawings, and bad advise - after
working on it for hundreds of hours, he gave it back, Frank accepted some
suggestions but rejected others because it would affect the book's
pagination, or because it was too hard for his wife to redraw the
diagrams, or ???. So, my friend gave up in disgust. The book he
recommends is the Olivo book "Fundamentals of Machine Technology" - note
the exact title - later editions have a lot of CNC stuff and are less
appropriate for hobby use - look for the exact title - check amazon and
you will find them for a few dollars (used) from time to time, or
sometimes they show up on ebay. There is a second volume, Advanced Machine
Technology" - I have both on my shelf here. I think you will find them
much more helpful. And a LOT LOT LOT cheaper than the Marlow books.

As with any subject, one source is never enough. But if you cannot find the
info in 3 or 4 texts it is the time to hit the Google. When that fails, hit
the fora :-). Then you only have to pick out the right answer from 15
contradicting opinions :-)

--
Michael Koblic,
Campbell River, BC