The job went well. It would have been a breeze with a CNC mill! I used a
3/4" center cutting endmill plunged into the center then did a "X" and "Y"
feed close to the OD and a square pattern using the DRO. After doing this
to all 35 pockets I finished the ODs with a boring bar in a boring head.
This job would have been hell without the DRO.

It would be nice to have a CNC mill but I do so very few jobs that a CNC
would shine that I just can't justify it. Besides, doesn't a CNC setup make
it difficult to use the mill in manual mode?

It would be nice to have a CNC mill but I do so very few jobs that a CNC
would shine that I just can't justify it. Besides, doesn't a CNC setup make
it difficult to use the mill in manual mode?

Not necessarily. I set my CNC up with handwheels. you can just turn
the servo off and turning by hand, the servo encoder still works so
you have a DRO.

I must say for several years i haven't used this feature. I have a
great manual mill that uses the same tooling. Its even more rigid than
my CNC with power feed on all axis. There are a lot of jobs that are
easier on a manual mill.

Karl

On 2012-03-17, Tom Gardner wrote:

[ ... ]

It would be nice to have a CNC mill but I do so very few jobs that a CNC
would shine that I just can't justify it. Besides, doesn't a CNC setup make
it difficult to use the mill in manual mode?

It depends. The first CNC mill which I encountered -- a
Taiwanese clone of a Bridgeport retrofitted by Anilim to CNC had Dished
handwheels with spring-loaded folding crank handles whose balance was
such that the handle would stay folded in at high speeds. (This was a
servo conversion, not a stepper one, FWIW, and the rapid motion was
scary. :-) Anyway -- stop the CNC control, and you have just enough
current through the servos to avoid self-feeding of the ball screws, and
you can easily use the handwheels to feed it -- with proper dials still
present.

However, my Bridgeport BOSS-3 (being converted to servos) is
quite different.

The X-axis ball leadscrew is rigidly mounted to the right end of
the table, and the ball nut is mounted between a pair of opposed tapered
bearings with the proper preload to minimize backlash). That ball nut
is rotated via a stepper (or servo) mounted well below the table on the
right side of the knee. No access by hand to the timing belts used to
connect them.

The Y-axis ball leadscrew is rotated, but by a timing belt from
a stepper below it which is recessed into the knee, and it is all
covered. (There is a Veeder-Root counter to display the X and Y axis
positions.) But there is no access for a handwheel.

The Z-axis is actually a hollow ball screw which surrounds the
quill, so the feed is truly on axis (the Anilam conversion above used a
ball screw in place of the feed stop screw, so it is pressing off center
and would hasten wear of the quill in the headstock.) However, again
the ball nut is mounted in bearings and turned via a timing belt and a
motor off to the left of the headstock. The original stop screw is used
to actuate the feed limit switches instead, and can't be used to read
the position. There is a dial on the bottom of the pulley so you can
tell where in a rotation the motor (and ball screw) are, but not which
rotation.

The control, when the CNC is stopped, has jog modes which allow
motion of 0.001", 0.010" 0.100" and 1.000" -- rotate a switch to point
to the desired size of the jog, and then push in the switch (which is
also a pushbutton) to cause the motion. I've actually done a little
machining with this, but it was a serious pain. :-)

So -- all in all, I would have to say that this one was not
suited for manual machining, and that the Anilam conversion (or some
other custom conversion of a manual mill) would be the better choice,
with the folding handle handwheels, so you don't get whacked by the
handle when you stand too close just when it is going into a rapid
motion. :-)

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 ---

"DoN. Nichols" wrote:

On 2012-03-17, Tom Gardner wrote:

[ ... ]

It would be nice to have a CNC mill but I do so very few jobs that a CNC
would shine that I just can't justify it. Besides, doesn't a CNC setup make
it difficult to use the mill in manual mode?

It depends. The first CNC mill which I encountered -- a
Taiwanese clone of a Bridgeport retrofitted by Anilim to CNC had Dished
handwheels with spring-loaded folding crank handles whose balance was
such that the handle would stay folded in at high speeds. (This was a
servo conversion, not a stepper one, FWIW, and the rapid motion was
scary. :-) Anyway -- stop the CNC control, and you have just enough
current through the servos to avoid self-feeding of the ball screws, and
you can easily use the handwheels to feed it -- with proper dials still
present.

However, my Bridgeport BOSS-3 (being converted to servos) is
quite different.

The X-axis ball leadscrew is rigidly mounted to the right end of
the table, and the ball nut is mounted between a pair of opposed tapered
bearings with the proper preload to minimize backlash). That ball nut
is rotated via a stepper (or servo) mounted well below the table on the
right side of the knee. No access by hand to the timing belts used to
connect them.

The Y-axis ball leadscrew is rotated, but by a timing belt from
a stepper below it which is recessed into the knee, and it is all
covered. (There is a Veeder-Root counter to display the X and Y axis
positions.) But there is no access for a handwheel.

The Z-axis is actually a hollow ball screw which surrounds the
quill, so the feed is truly on axis (the Anilam conversion above used a
ball screw in place of the feed stop screw, so it is pressing off center
and would hasten wear of the quill in the headstock.) However, again
the ball nut is mounted in bearings and turned via a timing belt and a
motor off to the left of the headstock. The original stop screw is used
to actuate the feed limit switches instead, and can't be used to read
the position. There is a dial on the bottom of the pulley so you can
tell where in a rotation the motor (and ball screw) are, but not which
rotation.

The control, when the CNC is stopped, has jog modes which allow
motion of 0.001", 0.010" 0.100" and 1.000" -- rotate a switch to point
to the desired size of the jog, and then push in the switch (which is
also a pushbutton) to cause the motion. I've actually done a little
machining with this, but it was a serious pain. :-)

So -- all in all, I would have to say that this one was not
suited for manual machining, and that the Anilam conversion (or some
other custom conversion of a manual mill) would be the better choice,
with the folding handle handwheels, so you don't get whacked by the
handle when you stand too close just when it is going into a rapid
motion. :-)

Most any CNC mill can be used manually if it has an MPG. Just select the
axis and a suitable step rate and crank away. I can't really see why you
would want to though when you can just "manually" machine one line of G
code at a time in MDI mode.

On 2012-03-18, Pete C. wrote:

"DoN. Nichols" wrote:

On 2012-03-17, Tom Gardner wrote:

[ ... ]

It would be nice to have a CNC mill but I do so very few jobs that a CNC
would shine that I just can't justify it. Besides, doesn't a CNC setup make
it difficult to use the mill in manual mode?

It depends. The first CNC mill which I encountered -- a
Taiwanese clone of a Bridgeport retrofitted by Anilim to CNC had Dished

[ ... ]

However, my Bridgeport BOSS-3 (being converted to servos) is
quite different.

[ ... ]

So -- all in all, I would have to say that this one was not
suited for manual machining, and that the Anilam conversion (or some
other custom conversion of a manual mill) would be the better choice,
with the folding handle handwheels, so you don't get whacked by the
handle when you stand too close just when it is going into a rapid
motion. :-)

Most any CNC mill can be used manually if it has an MPG. Just select the
axis and a suitable step rate and crank away. I can't really see why you
would want to though when you can just "manually" machine one line of G
code at a time in MDI mode.

By MPG I presume you mean Manual Pulse Generator. The
Bridgeport did not have that, and while there were complete schematics,
the CPU was a DEC LSI-11, and there was no source code for it to allow
adding such things to it. (Not to mention that it was limited to 64K
bytes (32K words) of memory -- both the G-code program memory, and the
machine language code (in ROMs) which translated the G-codes into actual
motion. This was in the early days of CNC. Bridgeport's BOSS-3 was the
first model to escape form the factory (nobody seems to know what
happened to the BOSS-1 and BOSS-2 -- presumably died of too many bugs to
be released. :-) They stayed with the stepper motors up through the
BOSS-6, and I'm pretty sure that the BOSS-8 was servos, but I don't know
whether the BOSS-7 was similarly invisible or not. :-)

Nobody ever released a version of EMC/LinuxCNC for the LSI-11,
and I doubt that anyone would bother with the limitations of memory.
(Back then, they even measured the memory in "feet" (feet of punched
paper tape, at 10 bytes per inch. That whole address space would only
hold 546.1333 feet of tape -- even if no space were being used for the
code in ROM. :-) This is one reason why they came fitted with a punched
tape reader. If you set your program up right, you could load almost as
much as memory was available for, then run that part, and when it was
done, it would automatically read the next chunk of tape to proceed with
the program. Then, you were only limited by how much tape you could get
on a reel. (Or maybe even more, if you could swap tapes while it was
running the last chuck which would fit on one tape -- but that required
being a bit more alert than CNC made common.

Why not three MPGs -- one per axis, so you could crank two axes
at once -- or even three if you put one in reach of your knee. :-)

Obviously, as I convert it to servos, a MPG is a nice feature to
add for positioning and for testing layouts with the system serving as a
DRO.

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 ---

"DoN. Nichols" wrote:

On 2012-03-18, Pete C. wrote:


trimmed


Most any CNC mill can be used manually if it has an MPG. Just select the
axis and a suitable step rate and crank away. I can't really see why you
would want to though when you can just "manually" machine one line of G
code at a time in MDI mode.

By MPG I presume you mean Manual Pulse Generator. The
Bridgeport did not have that, and while there were complete schematics,
the CPU was a DEC LSI-11, and there was no source code for it to allow
adding such things to it. (Not to mention that it was limited to 64K
bytes (32K words) of memory -- both the G-code program memory, and the
machine language code (in ROMs) which translated the G-codes into actual
motion. This was in the early days of CNC. Bridgeport's BOSS-3 was the
first model to escape form the factory (nobody seems to know what
happened to the BOSS-1 and BOSS-2 -- presumably died of too many bugs to
be released. :-) They stayed with the stepper motors up through the
BOSS-6, and I'm pretty sure that the BOSS-8 was servos, but I don't know
whether the BOSS-7 was similarly invisible or not. :-)

Nobody ever released a version of EMC/LinuxCNC for the LSI-11,
and I doubt that anyone would bother with the limitations of memory.
(Back then, they even measured the memory in "feet" (feet of punched
paper tape, at 10 bytes per inch. That whole address space would only
hold 546.1333 feet of tape -- even if no space were being used for the
code in ROM. :-) This is one reason why they came fitted with a punched
tape reader. If you set your program up right, you could load almost as
much as memory was available for, then run that part, and when it was
done, it would automatically read the next chunk of tape to proceed with
the program. Then, you were only limited by how much tape you could get
on a reel. (Or maybe even more, if you could swap tapes while it was
running the last chuck which would fit on one tape -- but that required
being a bit more alert than CNC made common.

Why not three MPGs -- one per axis, so you could crank two axes
at once -- or even three if you put one in reach of your knee. :-)

Obviously, as I convert it to servos, a MPG is a nice feature to
add for positioning and for testing layouts with the system serving as a
DRO.

It's kinda fun sitting on the table of a large gantry machining center,
MPG pod in hand, dialing around the table you're sitting on (X) as well
as the gantry (Y) and head (Z) as you reinstall the spindle cartridge
after rebuilding it.

On 18 Mar 2012 04:25:12 GMT, "DoN. Nichols"
wrote:

On 2012-03-18, Pete C. wrote:

"DoN. Nichols" wrote:

On 2012-03-17, Tom Gardner wrote:

[ ... ]

It would be nice to have a CNC mill but I do so very few jobs that a CNC
would shine that I just can't justify it. Besides, doesn't a CNC setup make
it difficult to use the mill in manual mode?

It depends. The first CNC mill which I encountered -- a
Taiwanese clone of a Bridgeport retrofitted by Anilim to CNC had Dished

[ ... ]

However, my Bridgeport BOSS-3 (being converted to servos) is
quite different.

[ ... ]

So -- all in all, I would have to say that this one was not
suited for manual machining, and that the Anilam conversion (or some
other custom conversion of a manual mill) would be the better choice,
with the folding handle handwheels, so you don't get whacked by the
handle when you stand too close just when it is going into a rapid
motion. :-)

Most any CNC mill can be used manually if it has an MPG. Just select the
axis and a suitable step rate and crank away. I can't really see why you
would want to though when you can just "manually" machine one line of G
code at a time in MDI mode.

By MPG I presume you mean Manual Pulse Generator. The
Bridgeport did not have that, and while there were complete schematics,
the CPU was a DEC LSI-11, and there was no source code for it to allow
adding such things to it. (Not to mention that it was limited to 64K
bytes (32K words) of memory -- both the G-code program memory, and the
machine language code (in ROMs) which translated the G-codes into actual
motion. This was in the early days of CNC. Bridgeport's BOSS-3 was the
first model to escape form the factory (nobody seems to know what
happened to the BOSS-1 and BOSS-2 -- presumably died of too many bugs to
be released. :-) They stayed with the stepper motors up through the
BOSS-6, and I'm pretty sure that the BOSS-8 was servos, but I don't know
whether the BOSS-7 was similarly invisible or not. :-)

Nobody ever released a version of EMC/LinuxCNC for the LSI-11,
and I doubt that anyone would bother with the limitations of memory.
(Back then, they even measured the memory in "feet" (feet of punched
paper tape, at 10 bytes per inch. That whole address space would only
hold 546.1333 feet of tape -- even if no space were being used for the
code in ROM. :-) This is one reason why they came fitted with a punched
tape reader. If you set your program up right, you could load almost as
much as memory was available for, then run that part, and when it was
done, it would automatically read the next chunk of tape to proceed with
the program. Then, you were only limited by how much tape you could get
on a reel. (Or maybe even more, if you could swap tapes while it was
running the last chuck which would fit on one tape -- but that required
being a bit more alert than CNC made common.

Why not three MPGs -- one per axis, so you could crank two axes
at once -- or even three if you put one in reach of your knee. :-)

Obviously, as I convert it to servos, a MPG is a nice feature to
add for positioning and for testing layouts with the system serving as a
DRO.

Enjoy,
DoN.

FWIW, even the latest Fanuc CNCs drip-feed large programs to the
control's memory from a remote DNC computer. It only has 8 Mb, I
think, and it's all a special flash memory that's designed to last for
25 years.

Fanuc is obsessive about reliability and will not put a hard drive in
their controls -- they say hard drives have no place on a factory
floor.

--
Ed Huntress

"DoN. Nichols" wrote in message
...
On 2012-03-17, Tom Gardner wrote:

[ ... ]

It would be nice to have a CNC mill but I do so very few jobs that
a CNC
would shine that I just can't justify it. Besides, doesn't a CNC
setup make
it difficult to use the mill in manual mode?

I've used a Bridgeport ProtoTRAK mostly in manual mode with the jog
dial. It's a little less convenient in some ways than turning the
handwheels, but I didn't have to reach as far. It was good enough for
one-off prototype jobs that often included milling a casting to a
scribed line or drilling at transfer punch marks.

jsw