For drawings and other information look at:
http://www.cox-internet.com/drspiff/...20flange%20dwg

DeepDiver wrote:

Are there any differences between NT40 and CAT40 spindle tapers? I've also
seen reference to 40 National Taper, 40 National Taper with Drive Flange,
and 40 National Taper with "V" Flange. What are the differences (and why)?
Can anyone provide a reference to the actual design specs for the various
National Tapers?

Finally, why are 40 National Taper spindles so rare in milling machines
sized for the small shop? It seems to be vastly superior (in strength,
concentricity, rigidity, and ability to accommodate larger-sized tooling) to
R8. Yet, even the 10"x54" class milling machines (costing $7,000+) are
fitted with wimpy R8 spindles. Not that I'm ready to buy such a machine...

- Michael

Are there any differences between NT40 and CAT40 spindle tapers? I've also
seen reference to 40 National Taper, 40 National Taper with Drive Flange,
and 40 National Taper with "V" Flange. What are the differences (and why)?
Can anyone provide a reference to the actual design specs for the various
National Tapers?

Finally, why are 40 National Taper spindles so rare in milling machines
sized for the small shop? It seems to be vastly superior (in strength,
concentricity, rigidity, and ability to accommodate larger-sized tooling) to
R8. Yet, even the 10"x54" class milling machines (costing $7,000+) are
fitted with wimpy R8 spindles. Not that I'm ready to buy such a machine...

- Michael

The specs for machine tool tapers are in Machinery's Handbook.
lg
no neat sig line

"DeepDiver" wrote in message
...
Are there any differences between NT40 and CAT40 spindle tapers? I've also
seen reference to 40 National Taper, 40 National Taper with Drive Flange,
and 40 National Taper with "V" Flange. What are the differences (and why)?
Can anyone provide a reference to the actual design specs for the various
National Tapers?

Finally, why are 40 National Taper spindles so rare in milling machines
sized for the small shop? It seems to be vastly superior (in strength,
concentricity, rigidity, and ability to accommodate larger-sized tooling)
to R8. Yet, even the 10"x54" class milling machines (costing $7,000+) are
fitted with wimpy R8 spindles. Not that I'm ready to buy such a machine...

- Michael

I've got NMTB 40 taper on my mill. It uses a threaded draw bar to pull the
tool in tight. The CAT taper has a pull stud on the end. So, they are not
interchangable even though the taper part is identical. I have modified a
few rare CAT 40 holders over to NMTB40. More work than its worth but doable.

The drive flange and V flange are two different ways to keep the holder from
slipping. The V flange also has the drive flange collar so they will
interchange if you use drive flange.

After using taper 40, I will never buy and R8 machine again. So much better.

Karl


"DeepDiver" wrote in message
...
Are there any differences between NT40 and CAT40 spindle tapers? I've also
seen reference to 40 National Taper, 40 National Taper with Drive Flange,
and 40 National Taper with "V" Flange. What are the differences (and why)?
Can anyone provide a reference to the actual design specs for the various
National Tapers?

Finally, why are 40 National Taper spindles so rare in milling machines
sized for the small shop? It seems to be vastly superior (in strength,
concentricity, rigidity, and ability to accommodate larger-sized tooling)
to R8. Yet, even the 10"x54" class milling machines (costing $7,000+) are
fitted with wimpy R8 spindles. Not that I'm ready to buy such a machine...

- Michael

On Mon, 27 Jun 2005 02:59:54 GMT, "Karl Townsend"
remove .NOT to reply wrote:

I've got NMTB 40 taper on my mill. It uses a threaded draw bar to pull the
tool in tight. The CAT taper has a pull stud on the end. So, they are not
interchangable even though the taper part is identical. I have modified a
few rare CAT 40 holders over to NMTB40. More work than its worth but doable.

The drive flange and V flange are two different ways to keep the holder from
slipping. The V flange also has the drive flange collar so they will
interchange if you use drive flange.

After using taper 40, I will never buy and R8 machine again. So much better.

Karl

30 Taper is about the smallest that I consider to be solid enough for
production work...ie big cuts.

My Gorton Mastermill uses the 30T

Gunner



"DeepDiver" wrote in message
...
Are there any differences between NT40 and CAT40 spindle tapers? I've also
seen reference to 40 National Taper, 40 National Taper with Drive Flange,
and 40 National Taper with "V" Flange. What are the differences (and why)?
Can anyone provide a reference to the actual design specs for the various
National Tapers?

Finally, why are 40 National Taper spindles so rare in milling machines
sized for the small shop? It seems to be vastly superior (in strength,
concentricity, rigidity, and ability to accommodate larger-sized tooling)
to R8. Yet, even the 10"x54" class milling machines (costing $7,000+) are
fitted with wimpy R8 spindles. Not that I'm ready to buy such a machine...

- Michael



"Considering the events of recent years,
the world has a long way to go to regain
its credibility and reputation with the US."
unknown

DeepDiver writes:

Finally, why are 40 National Taper spindles so rare in milling machines
sized for the small shop?

Historical standards tend by nature to self-propagate long after they are
obsolete. Especially with tooling.

I muse about this during every tedious R8 tool change.

In article . net,
Karl Townsend remove .NOT to reply wrote:
"DeepDiver" wrote in message
...
Are there any differences between NT40 and CAT40 spindle tapers? I've also
seen reference to 40 National Taper, 40 National Taper with Drive Flange,
and 40 National Taper with "V" Flange. What are the differences (and why)?
Can anyone provide a reference to the actual design specs for the various
National Tapers?

I've got NMTB 40 taper on my mill. It uses a threaded draw bar to pull the
tool in tight. The CAT taper has a pull stud on the end. So, they are not
interchangable even though the taper part is identical. I have modified a
few rare CAT 40 holders over to NMTB40. More work than its worth but doable.

It depends on the particular taper you are adapting *to*.

I've got both NMTB 30 taper (Bridgeport Boss-3 CNC mill), and
generic 40 taper (Nichols horizontal mill, plus vertical head to use the
same tooling).

Converting a CAT-40 to the Nichols mill (which only needs the
threads for the drawbar and (optionally) the notches) involves:

1) Heating the ball-pull to debond the Loctite so you can unscrew
the ball pull.

2) Turning an adaptor which threads into the original threads for
the ball pull in the back of te taper, and which provides the
orientation collar and the female threads to match the drawbar.
(You could make an alternative drawbar which fits through the
spindle, is a bit longer, and threads directly into the CAT-40
threads for the ball pull.

3) Loctiting that adaptor into the CAT-40 to keep from
experiencing the adaptor unscrewing from the CAT-40 while stuck
on the drawbar, thus trapping the drawbar. (My really old
Nichols has too small a spindle bore to allow the alternative
design, and I *really* did not want to have to try cutting off
the drawbar to get the parts out.

However -- converting a CAT-30 (or similar) to fit into the
Erickson quick-change head for NMTB-30 tools) requires turning the
flange down to a precise thickness so the quick-change lock will work on
the flange. (The BOSS-3 has no drawbar.)

The drive flange and V flange are two different ways to keep the holder from
slipping. The V flange also has the drive flange collar so they will
interchange if you use drive flange.

You mean for a tool turret to automatically change tools on a
running machine? The 'V' is for the gripping part of the tool turret.

After using taper 40, I will never buy and R8 machine again. So much better.

And interesting thing is that the taper of an R8 and a 30-taper
is identical, as is the larger diameter end of the taper. An R8 taper
stops sooner, at a larger minimum diameter. But, with a drawbar, you
can hold a 30-taper into an R8 spindle. Unfortunately, you lack the
keys to prevent spinning -- both under cutting load and when trying to
unscrew the drawbar.

Finally, why are 40 National Taper spindles so rare in milling machines
sized for the small shop? It seems to be vastly superior (in strength,
concentricity, rigidity, and ability to accommodate larger-sized tooling)
to R8. Yet, even the 10"x54" class milling machines (costing $7,000+) are
fitted with wimpy R8 spindles. Not that I'm ready to buy such a machine...

But the Bridgeport BOSS-3 (and later) were often fitted with
NMTB-30 taper with an Erickson quick-change head in the spindle.

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 ---

"larry g" wrote in message
...
"DeepDiver" wrote in message
...
Are there any differences between NT40 and CAT40 spindle tapers? I've
also seen reference to 40 National Taper, 40 National Taper with Drive
Flange, and 40 National Taper with "V" Flange. What are the differences
(and why)? Can anyone provide a reference to the actual design specs for
the various National Tapers?

The specs for machine tool tapers are in Machinery's Handbook.
lg

Thanks Larry. I remember looking for the R8 specs in Machinery's Handbook a
few years ago and not finding them. So it didn't occur to me to look for the
NT specs now. My oversight.

- Michael

"Richard J Kinch" wrote in message
. ..
DeepDiver writes:

Finally, why are 40 National Taper spindles so rare in milling machines
sized for the small shop?

Historical standards tend by nature to self-propagate long after they are
obsolete. Especially with tooling.

Hmmm... I was under the impression that NMTB predated R8. Perhaps I'm wrong.

- Michael

"DeepDiver" wrote in message
...
Are there any differences between NT40 and CAT40 spindle tapers? I've also
seen reference to 40 National Taper, 40 National Taper with Drive Flange,
and 40 National Taper with "V" Flange. What are the differences (and why)?
Can anyone provide a reference to the actual design specs for the various
National Tapers?

Ok, so I think I understand the differences now, thanks primarily to J
Gold's excellent link:

http://www.cox-internet.com/drspiff/...ets/tapers.htm

The most obvious difference is that the NMTB tapers have a pilot extension
at the small end of the taper, while the CAT tapers do not (in order to
accomodate a pull stud). The CAT tapers also have a grooved flange (which I
assume is for an automated tool changer).

One thing that's still not clear: in my Machinery Handbook, it shows that
the drawbar for NMTB tapers have two threaded portions at the toolholder
end: a larger threaded portion (what they call the "Large End"), followed by
a smaller threaded portion (what they call the "Small End"). Why is the
drawbar stepped in this fashion and how does it work with the NMTB taper
toolholder?

- Michael

On Tue, 28 Jun 2005 10:39:48 GMT, "DeepDiver"
wrote:

"DeepDiver" wrote in message
...
Are there any differences between NT40 and CAT40 spindle tapers? I've also
seen reference to 40 National Taper, 40 National Taper with Drive Flange,
and 40 National Taper with "V" Flange. What are the differences (and why)?
Can anyone provide a reference to the actual design specs for the various
National Tapers?

Ok, so I think I understand the differences now, thanks primarily to J
Gold's excellent link:

http://www.cox-internet.com/drspiff/...ets/tapers.htm

The most obvious difference is that the NMTB tapers have a pilot extension
at the small end of the taper, while the CAT tapers do not (in order to
accomodate a pull stud). The CAT tapers also have a grooved flange (which I
assume is for an automated tool changer).

One thing that's still not clear: in my Machinery Handbook, it shows that
the drawbar for NMTB tapers have two threaded portions at the toolholder
end: a larger threaded portion (what they call the "Large End"), followed by
a smaller threaded portion (what they call the "Small End"). Why is the
drawbar stepped in this fashion and how does it work with the NMTB taper
toolholder?


Because not all tool holders have the same size threads. I ran into
this on the Cinci #3 I ran at previous employment. The collection of
tool holders there was very old and some of them used the large thread
while others used the small one.

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook

In article ,
Wayne Cook wrote:
On Tue, 28 Jun 2005 10:39:48 GMT, "DeepDiver"
wrote:

[ ... ]

One thing that's still not clear: in my Machinery Handbook, it shows that
the drawbar for NMTB tapers have two threaded portions at the toolholder
end: a larger threaded portion (what they call the "Large End"), followed by
a smaller threaded portion (what they call the "Small End"). Why is the
drawbar stepped in this fashion and how does it work with the NMTB taper
toolholder?


Because not all tool holders have the same size threads. I ran into
this on the Cinci #3 I ran at previous employment. The collection of
tool holders there was very old and some of them used the large thread
while others used the small one.

Exactly. I have both styles for my Nichols horizontal mill.

Also for the vertical or right-angle head, which has an
interesting drawbar, with a double-ended drawbar and a double-ended nut
on the end, so both are reversed to handle the other size NMTB thread.

To see photos of it in both modes, go to my web page on the
Nichols mill:

http://www2.d-and-d.com/NICHOLS-mill/index.html

click on the link for the vertical head, and go down to images

dsc02290.jpg

and

dsc02300.jpg

I keep being tempted to make a duplicate of that for the
full-length drawbar for the horizontal spindle. As it is, I have one
using the smaller thread which I received with the mill, and another
using the larger thread which I made of allthread.

I hope that this is some help,
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 ---

On Tue, 28 Jun 2005 10:39:48 GMT, "DeepDiver"
wrote:


One thing that's still not clear: in my Machinery Handbook, it shows that
the drawbar for NMTB tapers have two threaded portions at the toolholder
end: a larger threaded portion (what they call the "Large End"), followed by
a smaller threaded portion (what they call the "Small End"). Why is the
drawbar stepped in this fashion and how does it work with the NMTB taper
toolholder?

- Michael


Because there are two different drawbar threads commonly used in both
30 and 40 NMTB. I have a number of 30 taper holders that use 3/8-16
drawbar threads and others that are 5/16-hummm 20 IRRC. Then the Cat
30 tapers use both of those and a third, 1/2-12

I have 3 draw bars hanging from a rack on my Gorton MasterMill, for
this reason.

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

On Wed, 29 Jun 2005 10:35:11 GMT, Gunner
wrote:

On Tue, 28 Jun 2005 10:39:48 GMT, "DeepDiver"
wrote:


One thing that's still not clear: in my Machinery Handbook, it shows that
the drawbar for NMTB tapers have two threaded portions at the toolholder
end: a larger threaded portion (what they call the "Large End"), followed by
a smaller threaded portion (what they call the "Small End"). Why is the
drawbar stepped in this fashion and how does it work with the NMTB taper
toolholder?

- Michael


Because there are two different drawbar threads commonly used in both
30 and 40 NMTB. I have a number of 30 taper holders that use 3/8-16
drawbar threads and others that are 5/16-hummm 20 IRRC. Then the Cat
30 tapers use both of those and a third, 1/2-12

errata...1/2-13

I have 3 draw bars hanging from a rack on my Gorton MasterMill, for
this reason.

Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner

I believe your comment about R8 and 30 taper being the same is
incorrect. 30 taper is 3.5"/ft or 7 in 24 whereas R8is about 3.555"/ft.
I was helping my neighbour make an R8 spindle earlier and had to check
this. The info on the www seems incorrect or misleading, my bridgeport
manual shows the taper as 16 degrees 51 minutes, yet some web pages show
16.51 degrees. 16 degrees 51 minutes works out at a taper of 1 in 3.375
on diameter or 3.555"/ft or 16.85 degrees included. This was checked
against an R8 taper and verified.

DoN. Nichols wrote:

In article . net,
Karl Townsend remove .NOT to reply wrote:

"DeepDiver" wrote in message
...

Are there any differences between NT40 and CAT40 spindle tapers? I've also
seen reference to 40 National Taper, 40 National Taper with Drive Flange,
and 40 National Taper with "V" Flange. What are the differences (and why)?
Can anyone provide a reference to the actual design specs for the various
National Tapers?


I've got NMTB 40 taper on my mill. It uses a threaded draw bar to pull the
tool in tight. The CAT taper has a pull stud on the end. So, they are not
interchangable even though the taper part is identical. I have modified a
few rare CAT 40 holders over to NMTB40. More work than its worth but doable.


It depends on the particular taper you are adapting *to*.

I've got both NMTB 30 taper (Bridgeport Boss-3 CNC mill), and
generic 40 taper (Nichols horizontal mill, plus vertical head to use the
same tooling).

Converting a CAT-40 to the Nichols mill (which only needs the
threads for the drawbar and (optionally) the notches) involves:

1) Heating the ball-pull to debond the Loctite so you can unscrew
the ball pull.

2) Turning an adaptor which threads into the original threads for
the ball pull in the back of te taper, and which provides the
orientation collar and the female threads to match the drawbar.
(You could make an alternative drawbar which fits through the
spindle, is a bit longer, and threads directly into the CAT-40
threads for the ball pull.

3) Loctiting that adaptor into the CAT-40 to keep from
experiencing the adaptor unscrewing from the CAT-40 while stuck
on the drawbar, thus trapping the drawbar. (My really old
Nichols has too small a spindle bore to allow the alternative
design, and I *really* did not want to have to try cutting off
the drawbar to get the parts out.

However -- converting a CAT-30 (or similar) to fit into the
Erickson quick-change head for NMTB-30 tools) requires turning the
flange down to a precise thickness so the quick-change lock will work on
the flange. (The BOSS-3 has no drawbar.)

The drive flange and V flange are two different ways to keep the holder from
slipping. The V flange also has the drive flange collar so they will
interchange if you use drive flange.


You mean for a tool turret to automatically change tools on a
running machine? The 'V' is for the gripping part of the tool turret.

After using taper 40, I will never buy and R8 machine again. So much better.


And interesting thing is that the taper of an R8 and a 30-taper
is identical, as is the larger diameter end of the taper. An R8 taper
stops sooner, at a larger minimum diameter. But, with a drawbar, you
can hold a 30-taper into an R8 spindle. Unfortunately, you lack the
keys to prevent spinning -- both under cutting load and when trying to
unscrew the drawbar.

Finally, why are 40 National Taper spindles so rare in milling machines
sized for the small shop? It seems to be vastly superior (in strength,
concentricity, rigidity, and ability to accommodate larger-sized tooling)
to R8. Yet, even the 10"x54" class milling machines (costing $7,000+) are
fitted with wimpy R8 spindles. Not that I'm ready to buy such a machine...


But the Bridgeport BOSS-3 (and later) were often fitted with
NMTB-30 taper with an Erickson quick-change head in the spindle.

Enjoy,
DoN.

In article ,
David Billington wrote:

DoN. Nichols wrote:

[ ... ]

And interesting thing is that the taper of an R8 and a 30-taper
is identical, as is the larger diameter end of the taper. An R8 taper
stops sooner, at a larger minimum diameter. But, with a drawbar, you
can hold a 30-taper into an R8 spindle. Unfortunately, you lack the
keys to prevent spinning -- both under cutting load and when trying to
unscrew the drawbar.

I believe your comment about R8 and 30 taper being the same is
incorrect. 30 taper is 3.5"/ft or 7 in 24 whereas R8is about 3.555"/ft.
I was helping my neighbour make an R8 spindle earlier and had to check
this.

O.K.

The info on the www seems incorrect or misleading, my bridgeport
manual shows the taper as 16 degrees 51 minutes, yet some web pages show
16.51 degrees. 16 degrees 51 minutes works out at a taper of 1 in 3.375
on diameter or 3.555"/ft or 16.85 degrees included. This was checked
against an R8 taper and verified.

*Which* was verified? The Bridgeport manual's 16 degrees 51
minutes, or the 16.51 degrees? I presume the former.

O.K. I'll accept that, as you have done the measurements. I
had read it some time before, and I simply tried hand-fitting a 30 NMTB
into an R8 spindle. It felt free of rocking, but I did not have
spotting die at the time, so I did not test it beyond that point.

I had received the information from an article here some years
ago, and after a cursory check, took it as valid information. I
obviously need to stop that. :-)

An attempt to use a bevel protractor seemed to come out with the
same figures, but an R8 collet is a rather springy thing to try to
measure.

While _Machinery's Handbook_ has the precise taper of the 30
taper (and the rest of that family) documented, the set of drawings and
tables for the R8 (and similar) spring collets does not bother to
document the precise taper -- at least in either the 24th edition or the
25th edition.

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 ---