BRIDGEPORT MILL, TYPES OF SPINDLES

[mango]

Hello guys, I recently acquired a used Bridgeport mill ( my first encounter) a
friend had outdoors . I managed to get all the parts freed up, even the motor
works. But i've encountered one road-block, the R8 collet i tried in the
spindle seems to be too long. _*_What other type of collet does the Bridgeport
use?_*_ I think this is a J series, here is the serial # J163607 stamped on
the head. A plate attached to the head has drive serial #2J40289. **

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[Howard Beal]

"mango" <0f8503901d844703ee...@example.com> wrote in message
news:56acc$56b9222a$43de0cc0$14...@news.flashnewsgroups.com...

Could be a 2MT, i remember some of the old bridgeports had that taper.

Best Regards
Tom.

[Martin Eastburn]

Have you rotated the R8 ? there is likely a pin that goes into a slot
on the R8.

Where did you get the R8 with the mill ? more of them ?? options ??
Is there an insert already there ?

Martin

[Steve W.]

mango wrote:
> Hello guys, I recently acquired a used Bridgeport mill ( my first encounter) a
> friend had outdoors . I managed to get all the parts freed up, even the motor
> works. But i've encountered one road-block, the R8 collet i tried in the
> spindle seems to be too long. _*_What other type of collet does the Bridgeport
> use?_*_ I think this is a J series, here is the serial # J163607 stamped on
> the head. A plate attached to the head has drive serial #2J40289. **
>

A 2J head spindle is either an R8 or Erickson QC30 There were also some
with KwickSwitch 300 (which if that is what you have, plan on replacing
the spindle because those are RARE...

--
Steve W.

[DoN. Nichols]

On 2016-02-08, mango <0f8503901d844703ee...@example.com> wrote:
> Hello guys, I recently acquired a used Bridgeport mill ( my first encounter) a
> friend had outdoors . I managed to get all the parts freed up, even the motor
> works. But i've encountered one road-block, the R8 collet i tried in the
> spindle seems to be too long.

You know that there is a keying pin in the spindle to engage a
groove in the R8 collet? You have to rotate the collet until the pin
engages the groove so you can push the collet up into the spindle. The
purpose of the pin is *not* for drive torque, but rather to allow you to
turn the drawbar at the top of the head without having to hold the
collet after the first turn or two to engage the drawbar threads.

Some people don't like this, and have removed the keying pin,
but if I were using R8 collets, *I* would want to keep the keying pin
installed. I have helped a friend replace a sheared off one.

> _*_What other type of collet does the Bridgeport
> use?_*_ I think this is a J series, here is the serial # J163607 stamped on
> the head. A plate attached to the head has drive serial #2J40289. **

Is it *possible* that you have a machine which started life as a
CNC machine? Bridgeport had a number of machines with a spindle for the
NTMB 30 mill holders. That one has a knurled collar on the bottom of
the spindle with some holes for a pin spanner wrench. It turns
something like a half turn or so and rotates a pair of fingers which
passed through slots in the flange of the NTMB 30 so they are now over
the flange, and then clamps the fingers down to hold the flange in
place, and the mill holder (which *may* use certain collets) firmly in
place. This short rotation allows quick switching of tools -- *and*
retains the projection of the tool between insertions, unlike an R8
collet, which has a different projection every time you swap the end
mill.

The normal R8 spindle has no such collar, so you may simply be
encountering the keying pin.

Enjoy,
DoN.

--
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--- Black Holes are where God is dividing by zero ---

[DoN. Nichols]

On 2016-02-09, Howard Beal <H...@network.com> wrote:
>
> "mango" <0f8503901d844703ee...@example.com> wrote in message
> news:56acc$56b9222a$43de0cc0$14...@news.flashnewsgroups.com...
>> Hello guys, I recently acquired a used Bridgeport mill ( my first
>> encounter) a
>> friend had outdoors . I managed to get all the parts freed up, even the
>> motor
>> works. But i've encountered one road-block, the R8 collet i tried in the
>> spindle seems to be too long. _*_What other type of collet does the
>> Bridgeport
>> use?_*_ I think this is a J series, here is the serial # J163607 stamped
>> on
>> the head. A plate attached to the head has drive serial #2J40289. **

[ ... ]

> Could be a 2MT, i remember some of the old bridgeports had that taper.

Could be --- but unlikely in a J-head mill. The keying pin, or
the alternative NTMB-30 quick-switch spindle are the most likely, here.
I described both in an article just posted before this one.

[Gunner Asch]

On Mon, 8 Feb 2016 17:23:04 -0800, "Howard Beal" <H...@network.com>
wrote:

>J163607

Thats a 1974 machine..so its probably NOT anything other than an R8
Take a good look up into the spindle and see if the alignment screw
hasnt been moved too far out into the bore and is blocking the hole.
Ive seen this happen several times, generally with machines that were
fussed with by second owners.....unless..unless you have one with the
Ericson QC-30 spindle noses. I have (2) spindles with that on them.

http://www.practicalmachinist.com/vb/general/please-identify-bridgeport-spindle-177124/

Gunner, who rebuilds BPs on the side.

[mango]

replying to Martin Eastburn, mango wrote:
The collet aligning screw is broken off, i plan to replace it. When i slammed
the R8 collet in the spindle it didn't go all the way in. I measured the
distance from the shoulder inside the spindle to the end of the spindle,
compared to the R8, it was shorter by 1-1/8". I had the R8 prior to the mill.
There is no insert in the spindle.

[mango]

replying to Steve W., mango wrote:
So far i've heard about the 2MT, the NTMB30 and the EricksonQC30
spindles/collets. I copied the taper in the spindle on a piece of wood, it
MATCHES the taper on the R8. Only difference is the length of the straight
portion of the R8, which is 3", compared to the 2'' straight portion inside
the spindle. Which one of those spindles mentioned measures 2" from the end
opp. the taper to the start of taper?

[mango]

replying to DoN. Nichols, mango wrote:
Now that you described the NTMB30 i know it's not one of those. I've used a
JET mill, and the spindle looks similar, that's why i tried the R8 collet,
which fits the Jet. That leaves the 2MT and ERICKSON QC 30. Which one of
those two measures 2" from the end to where the taper starts, has the same
taper as the R8, and has total length of approx. 3"?

[Gunner Asch]

On Fri, 12 Feb 2016 12:33:22 -0800, Gunner Asch <gunne...@gmail.com>
wrote:

Here are ALL the tapers/holders that BP ever produced.

http://www.lathes.co.uk/bridgeport/page3.html

Get a good photo , taken UP the spindle, with the draw bar removed and
lets see what we can determine the critter is.

Gunner

[DoN. Nichols]

On 2016-02-12, mango <0f8503901d844703ee...@example.com> wrote:
> replying to Steve W., mango wrote:
> So far i've heard about the 2MT, the NTMB30 and the EricksonQC30

The latter two are the same thing. Just Erickson is one maker
of those -- and makes the Quick-Change spindle chuck for them.

> spindles/collets. I copied the taper in the spindle on a piece of wood, it
> MATCHES the taper on the R8. Only difference is the length of the straight
> portion of the R8, which is 3", compared to the 2'' straight portion inside
> the spindle. Which one of those spindles mentioned measures 2" from the end
> opp. the taper to the start of taper?

The 30 taper (NTMB or Erickson) is actually the same taper as
the tapered part of an R8 collet. It goes down to a smaller diameter,
and longer in general in the tapered part. But that part is not
critical, as a drawbar engages the threads in the tool holder, and pulls
the larger diameter part of the taper of the holder firmly against the
female taper of the spindle. (Or the QC chuck pulls the male taper of
the holder firmly against the female taper of the spindle.)

Exactly what the clearance back there will actually be remains
to be seen.

Do you have a copy of _Machinery's Handbook_? It will include
drawings for the NTMB 30 (and other tapers of different sizes but the
same basic design.) Beware that I often transpose letters in the NTMB
(maybe NMTB instead), so look under both. You will only find one of the
two. :-)

Other things like the CAT-30 taper tool holders will be the same
taper, but instead of accepting a drawbar, will have a projecting ball
which is gripped by a set of expanding fingers -- and *that* might need
the larger diameter. Usually, that sort of thing will be found with an
automatic tool changer on the mill.

Oh yes -- the CAT-30 will have a thicker flange, with a V-groove
in the edge for the automatic changer to handle it.

Good Luck,