I have a 1960 Bridgeport J head mill I am working on and have a
question. On the right side of the knee (facing the machine) there are
three 3/8-16 tapped holes, which are also spotfaced to accept washers.
What are these holes for? These are not the grease fitting holes, mine
hase nothing there. Just wondering if anyone knows what should be
there.
Thank you,
Craig

Craig Suslosky writes:

I have a 1960 Bridgeport J head mill I am working on and have a
question. On the right side of the knee (facing the machine) there are
three 3/8-16 tapped holes, which are also spotfaced to accept washers.
What are these holes for? These are not the grease fitting holes, mine
hase nothing there. Just wondering if anyone knows what should be
there.

A DRO scale that has been removed.

"Richard J Kinch" wrote in message
. ..
Craig Suslosky writes:

I have a 1960 Bridgeport J head mill I am working on and have a
question. On the right side of the knee (facing the machine) there are
three 3/8-16 tapped holes, which are also spotfaced to accept washers.
What are these holes for? These are not the grease fitting holes, mine
hase nothing there. Just wondering if anyone knows what should be
there.

A DRO scale that has been removed.

Nice try.

Bridgeport mills come with the holes, likely so you can mount a DRO scale.
That there is no scale present is NOT an indication that one has been
removed. It's only an indication that there isn't a scale present.
Probably never had one, ever.

Harold

In article ,
says...

"Richard J Kinch" wrote in message
. ..
Craig Suslosky writes:

I have a 1960 Bridgeport J head mill I am working on and have a
question. On the right side of the knee (facing the machine) there are
three 3/8-16 tapped holes, which are also spotfaced to accept washers.
What are these holes for? These are not the grease fitting holes, mine
hase nothing there. Just wondering if anyone knows what should be
there.

A DRO scale that has been removed.

Nice try.

Bridgeport mills come with the holes, likely so you can mount a DRO scale.

Though I'm sure many DRO scales have been mounted in these
holes, they were originally intended for mounting a trough
to be used with end measuring rods. The x-axis trough
mounted in the t-slot on the front of the table.

Ned Simmons

Ned Simmons writes:

Though I'm sure many DRO scales have been mounted in these
holes, they were originally intended for mounting a trough
to be used with end measuring rods. The x-axis trough
mounted in the t-slot on the front of the table.

That's funny, my 1956 vintage Bridgeport manual shows a diagram of the
holes with "mount digital readout scale here". Heheheh.

On Wed, 25 Aug 2004 14:46:26 -0500, Richard J Kinch wrote:

||Ned Simmons writes:
||
|| Though I'm sure many DRO scales have been mounted in these
|| holes, they were originally intended for mounting a trough
|| to be used with end measuring rods. The x-axis trough
|| mounted in the t-slot on the front of the table.
||
||That's funny, my 1956 vintage Bridgeport manual shows a diagram of the
||holes with "mount digital readout scale here". Heheheh.

Shouldn't that have read "mount analog readout scale here" ?
Texas Parts Guy

In article ,
(Rex B) says...
On Wed, 25 Aug 2004 14:46:26 -0500, Richard J Kinch wrote:

||Ned Simmons writes:
||
|| Though I'm sure many DRO scales have been mounted in these
|| holes, they were originally intended for mounting a trough
|| to be used with end measuring rods. The x-axis trough
|| mounted in the t-slot on the front of the table.
||
||That's funny, my 1956 vintage Bridgeport manual shows a diagram of the
||holes with "mount digital readout scale here". Heheheh.

Shouldn't that have read "mount analog readout scale here" ?
Texas Parts Guy


There was such a thing, an optical readout. I just found a
picture of one in an old BP catalog and the y scale is
mounted in the holes in question. There's a pic here...

http://www.lathes.co.uk/bridgeport/page8.html

I tried using one about 20 years ago, it isn't as easy as
it appears. You have to crane your neck around to get a
good view of the scale; imagine trying to use a microscope
when the eyepiece keeps moving around.

Ned Simmons

In article ,
(Rex B) says...
On Wed, 25 Aug 2004 14:46:26 -0500, Richard J Kinch wrote:

||Ned Simmons writes:
||
|| Though I'm sure many DRO scales have been mounted in these
|| holes, they were originally intended for mounting a trough
|| to be used with end measuring rods. The x-axis trough
|| mounted in the t-slot on the front of the table.
||
||That's funny, my 1956 vintage Bridgeport manual shows a diagram of the
||holes with "mount digital readout scale here". Heheheh.

Shouldn't that have read "mount analog readout scale here" ?
Texas Parts Guy


There was such a thing, an optical readout. I just found a
picture of one in an old BP catalog and the y scale is
mounted in the holes in question. There's a pic here...

http://www.lathes.co.uk/bridgeport/page8.html

I tried using one about 20 years ago, it isn't as easy as
it appears. You have to crane your neck around to get a
good view of the scale; imagine trying to use a microscope
when the eyepiece keeps moving around.

Ned Simmons

Ned Simmons wrote:

In article ,
(Rex B) says...


On Wed, 25 Aug 2004 14:46:26 -0500, Richard J Kinch wrote:

||Ned Simmons writes:
||
|| Though I'm sure many DRO scales have been mounted in these
|| holes, they were originally intended for mounting a trough
|| to be used with end measuring rods. The x-axis trough
|| mounted in the t-slot on the front of the table.
||
||That's funny, my 1956 vintage Bridgeport manual shows a diagram of the
||holes with "mount digital readout scale here". Heheheh.

Shouldn't that have read "mount analog readout scale here" ?
Texas Parts Guy




There was such a thing, an optical readout. I just found a
picture of one in an old BP catalog and the y scale is
mounted in the holes in question. There's a pic here...

http://www.lathes.co.uk/bridgeport/page8.html

I tried using one about 20 years ago, it isn't as easy as
it appears. You have to crane your neck around to get a
good view of the scale; imagine trying to use a microscope
when the eyepiece keeps moving around.


They actually are not too bad, and a GREAT improvement over the
measuring rod system (which had a dial indicator and a bunch of
precise rods in 1" lengths, like micrometer standards). There was a
readout window that showed a magnified view of the glass scale,
where you could read inches and hundredths. Then there was a
dial you could turn that was a bit like a vernier, it moved the
marks on the glass window, and had numbers from 00 to 99,
which was your thousandths and ten thousandths.

The one big drawback froman electronic DRO was that the scale was
numbered in one direction only. So, you couldn't have the numbers
run the other way from zero without subtracting.

I found one in a scrapyard and used it for a couple years before I got my
CNC system running.

Jon

Ned Simmons wrote in message ...
In article ,
says...

"Richard J Kinch" wrote in message
. ..
Craig Suslosky writes:

I have a 1960 Bridgeport J head mill I am working on and have a
question. On the right side of the knee (facing the machine) there are
three 3/8-16 tapped holes, which are also spotfaced to accept washers.
What are these holes for? These are not the grease fitting holes, mine
hase nothing there. Just wondering if anyone knows what should be
there.

A DRO scale that has been removed.

Nice try.

Bridgeport mills come with the holes, likely so you can mount a DRO scale.

Though I'm sure many DRO scales have been mounted in these
holes, they were originally intended for mounting a trough
to be used with end measuring rods. The x-axis trough
mounted in the t-slot on the front of the table.

Ned Simmons

Thanks everyone, can I just put bolts in them to close the holes? It
did not look like anything was ever there, I wanted to make sure
something wasnt missing that was supposed to be there.
Thanks again,
Craig

On Wed, 25 Aug 2004 12:03:43 -0500, Richard J Kinch
wrote:

Craig Suslosky writes:

I have a 1960 Bridgeport J head mill I am working on and have a
question. On the right side of the knee (facing the machine) there are
three 3/8-16 tapped holes, which are also spotfaced to accept washers.
What are these holes for? These are not the grease fitting holes, mine
hase nothing there. Just wondering if anyone knows what should be
there.

A DRO scale that has been removed.

WHOA!!! Some DRO to need 3/8 bolts. Maybe you meant optical reader
or Trav-A-dial.

Ned Simmons writes:

There was such a thing, an optical readout. I just found a
picture of one in an old BP catalog and the y scale is
mounted in the holes in question.

The early Bridgeport BOSS stepper-motor CNC system had odometer type
readouts geared to the ballscrews.