ok, some setup - I have a mill (Abene), I just bought a chinese coaxial
indicator. I got a large Starrett caliper in the mail with some other
stuff - it has a threaded post that is part of a larger (about 3/4 inch)
protrusion that forms part of the friction hinge. The threaded post was
broken off, hence too short. Thinks I, this is an opportunity to learn to
use that coax indicator - I'll just mill the rest of the post off, center
with the indicator and drill and tap a new hole, insert threaded rod (cut
head off screw) and I'm good to to.

Well, I clamp the part to the mill table firmly, mill off the stub, center
with the indicator, insert a center drill in a chuck to drill a little
starting hole, and as I raise the table to the drill, I notice the hole is
at least 1/8 inch away from the center. I repeat this several times, each
time centering so there is less than 1 thousandth movement on the coax
indicator, and each time the hole is not centered. So, I set it by eye,
measure and drill - it's perfect, and all is well

EXCEPT!!! - what the heck went wrong???

well, maybe the table moved - no, I had the gibs locked.
maybe the piece moved (no, it didn't)

well, mabe the indicator is bad - or maybe not.....

I tried the indicator in a 3/8 end mill holder (the shaft is 3/8) - noticed
about a thousanth clearance (well, maybe 2, I didnt' measure it) and I also
tried it in a drill chuck - both ended up with errors - '

maybe the cat 40 taper is bad, or dirty - clean it, it wasn't dirty.

Put 3/8 drill rod into chuck - it sweeps out a cone - waaay to much error -
so there is some angle on the chuck with respect to the spindle - that's not
good.
put 3/8 drill rod into 3/8 end mill holder - about .100 runout at the tip -
not good (note - drill rod about 5 inches long, not bent)
put 3/8 drill rod into Ericksson collet holder - TIR less than .002 ----
that's more like it
Put 1/2 inch drill rod into 1/2 inch end mill holder - no measurable
runout - repeat, mesure .001 - good....

so, I've got at least two problems I figure, maybe 3 -

1. the 3/8 end mill holder may be damaged since it seems to be oversized
2. the chuck is obviously not running true so I'll need to separate it from
the NMTB40 to jacobs taper adapter (it's a name brand adapter, though I
don't remember the name right now) - the runout is more than the chuck
should have - so ????
3. maybe the indicator was defective - how to test?

And, once all this is solved, how can I hold the indicator so I am sure it's
doing it's job and not finding me a hole that is offset from the center?


ok, no politics, this is real on topic stuff

--
bill
to email me, to to my web page, www.wbnoble.com and find my email
or unscramble the following by removing spaces and correcting the obvious
spelling errors

wil lia m_b_n obl e at msn daught com



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A common problem in the mini mills & mill-drills is that the spindle
may not travel parallel to the vertical travel of the mill head or
table. First square the spindle to the table - there is usually a
provison of squaring about one axis but not the other, while on a BP,
you can easily square to both axes by sweeping an indicator across the
table. Now it gets tricky: You set up a square (or a 1-2-3 block) on
the table and indicate on it as you raise the spindle or lower the
table - test in 2 directions, along and across the table long axis -
you may find that the spindle travel isn't parallel to the vertical
axis travel of the table or mill head. If this is the case, you can
indicate the center of a hole, then after vertical travel of the mill
head or table, you are no longer centered. How you fix this dependss
on the mill design.... Joel in Florida

William Noble wrote:
ok, some setup - I have a mill (Abene), I just bought a chinese coaxial
indicator. I got a large Starrett caliper in the mail with some other
stuff - it has a threaded post that is part of a larger (about 3/4 inch)
protrusion that forms part of the friction hinge. The threaded post was
broken off, hence too short. Thinks I, this is an opportunity to learn to
use that coax indicator - I'll just mill the rest of the post off, center
with the indicator and drill and tap a new hole, insert threaded rod (cut
head off screw) and I'm good to to.

Well, I clamp the part to the mill table firmly, mill off the stub, center
with the indicator, insert a center drill in a chuck to drill a little
starting hole, and as I raise the table to the drill, I notice the hole is
at least 1/8 inch away from the center. I repeat this several times, each
time centering so there is less than 1 thousandth movement on the coax
indicator, and each time the hole is not centered. So, I set it by eye,
measure and drill - it's perfect, and all is well

EXCEPT!!! - what the heck went wrong???

well, maybe the table moved - no, I had the gibs locked.
maybe the piece moved (no, it didn't)

well, mabe the indicator is bad - or maybe not.....

I tried the indicator in a 3/8 end mill holder (the shaft is 3/8) - noticed
about a thousanth clearance (well, maybe 2, I didnt' measure it) and I also
tried it in a drill chuck - both ended up with errors - '

maybe the cat 40 taper is bad, or dirty - clean it, it wasn't dirty.

Put 3/8 drill rod into chuck - it sweeps out a cone - waaay to much error -
so there is some angle on the chuck with respect to the spindle - that's not
good.
put 3/8 drill rod into 3/8 end mill holder - about .100 runout at the tip -
not good (note - drill rod about 5 inches long, not bent)
put 3/8 drill rod into Ericksson collet holder - TIR less than .002 ----
that's more like it
Put 1/2 inch drill rod into 1/2 inch end mill holder - no measurable
runout - repeat, mesure .001 - good....

so, I've got at least two problems I figure, maybe 3 -

1. the 3/8 end mill holder may be damaged since it seems to be oversized
2. the chuck is obviously not running true so I'll need to separate it from
the NMTB40 to jacobs taper adapter (it's a name brand adapter, though I
don't remember the name right now) - the runout is more than the chuck
should have - so ????
3. maybe the indicator was defective - how to test?

And, once all this is solved, how can I hold the indicator so I am sure it's
doing it's job and not finding me a hole that is offset from the center?


ok, no politics, this is real on topic stuff

Head's not square to the table, and the two tools are of different
lengths. Maybe.

Beat up toolholders, another to watch for. A ****beat, used, abused,
US made toolholder, is more suspect than a new cheapo import, but all
deserve a look, with an indicator and some known straight pins. Collets,
too!

Cheers
Trevor Jones

William Noble wrote:
ok, some setup - I have a mill (Abene), I just bought a chinese coaxial

And, once all this is solved, how can I hold the indicator so I am sure it's
doing it's job and not finding me a hole that is offset from the center?
A centering indicator will work best in a collet. An end mill
holder may force it off-center a bit. An Abene has a pretty
fancy articulated head, you need to tram it to make sure it is
perfectly normal to the X-Y plane of table motion. I have a CNC
routine I use, but it can be done on a manual machine. Probably
the easiest way is to take a small end mill (3/8 or 1/2" max)
and plane off the top of a piece of scrap aluminum. Don't use a
fly cutter, you want it to make a sawtooth if the head is out of
tram. Now, put a dial test indicator in the spindle and with
the spindle centered over the scrap, sweep around in a circle,
and see what is high and low. Retram the head to get as
parallel in both front-back and left-right as possible, then
repeat. This time there should be very little sawtooth in the
surface, but recheck with the indicator. You want to get down
into the tenths of a thousandth of an inch over the largest
scrap you have, I use a 7" block.

(The other method is to level a block in the vise by moving the
table and reading the 4 corners with an indicator, then sweep
the indicator in a circle and read and tram as above.)

The idea here is that if the head is not in very good tram, then
any length change in the spindle puts the tool off-center from
where you set up. Only if the tip of the drill bit was at the
same length as the tip of the coax indicator will you be
spot-on. Also, if the head is out of tram and you drill by
raising the knee, you will bend the drill and can't get a
straight hole.

Jon

great suggestion but on my mill (an Abene), there is no vertical travel to
the spindle - though I can rotate it, so it is possible that the vertical
stop isn't exactly at the vertical position - I guess that could do it, I'll
try it.

This particular mill (there's a photo on my web page, wbnoble.com, under
tools/hobbies, but it's not very informative) is much larger than the mini
mills/drills - 6 hp spindle motor, 2 hp traverse motor -

I'll try the test you suggest tomorrow or Saturday

wrote in message
oups.com...
A common problem in the mini mills & mill-drills is that the spindle
may not travel parallel to the vertical travel of the mill head or
table. First square the spindle to the table - there is usually a
provison of squaring about one axis but not the other, while on a BP,
you can easily square to both axes by sweeping an indicator across the
table. Now it gets tricky: You set up a square (or a 1-2-3 block) on
the table and indicate on it as you raise the spindle or lower the
table - test in 2 directions, along and across the table long axis -
you may find that the spindle travel isn't parallel to the vertical
axis travel of the table or mill head. If this is the case, you can
indicate the center of a hole, then after vertical travel of the mill
head or table, you are no longer centered. How you fix this dependss
on the mill design.... Joel in Florida




--
Posted via a free Usenet account from http://www.teranews.com

Jon - this makes sense - I keep forgetting the potential for the head to not
be vertical - but your statement to get it parallel in left right and front
back directions has me puzzled. As you know, on this mill, the head can
rotate from vertical to horizontal by simply loosening a couple of lock
bolts - but there is no adjustment for any other alignment, the only
adjustment is the position of the stop.

So, were you suggesting two adjustments? or were you suggesting two
measurments, one left/right (which I don't see how I can adjust anyway) and
one front/back (which should reveal any out of tram condition of the
head)???

thanks. Slowly getting to the bottom of this puzzle.


more followup - removed drill chuck from 40 taper to 33 JT adapter, measured
1/2 thousandth (or a little less) using a last word indicator, but I didn't
see if the high spot at each vertical position along the JT taper was along
a vertical line - I'll check that tomorrow. The holder is a new Kennametal
holder, so my inclination is that it's probably OK, but it never hurts to
verify.

so now my list of problems seems to have at least three things on it:

drill chuck/taper holder problem (research on that in process)
3/8 end mill holder problem
possible out of tram condition on head - to be checked "soon"




"Jon Elson" wrote in message
...
William Noble wrote:
ok, some setup - I have a mill (Abene), I just bought a chinese coaxial
And, once all this is solved, how can I hold the indicator so I am sure
it's doing it's job and not finding me a hole that is offset from the
center?
A centering indicator will work best in a collet. An end mill holder may
force it off-center a bit. An Abene has a pretty fancy articulated head,
you need to tram it to make sure it is perfectly normal to the X-Y plane
of table motion. I have a CNC routine I use, but it can be done on a
manual machine. Probably the easiest way is to take a small end mill (3/8
or 1/2" max) and plane off the top of a piece of scrap aluminum. Don't
use a fly cutter, you want it to make a sawtooth if the head is out of
tram. Now, put a dial test indicator in the spindle and with the spindle
centered over the scrap, sweep around in a circle, and see what is high
and low. Retram the head to get as parallel in both front-back and
left-right as possible, then repeat. This time there should be very
little sawtooth in the surface, but recheck with the indicator. You want
to get down into the tenths of a thousandth of an inch over the largest
scrap you have, I use a 7" block.

(The other method is to level a block in the vise by moving the table and
reading the 4 corners with an indicator, then sweep the indicator in a
circle and read and tram as above.)

The idea here is that if the head is not in very good tram, then any
length change in the spindle puts the tool off-center from where you set
up. Only if the tip of the drill bit was at the same length as the tip of
the coax indicator will you be spot-on. Also, if the head is out of tram
and you drill by raising the knee, you will bend the drill and can't get a
straight hole.

Jon



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"Jon Elson" wrote in message
...
snip---
A centering indicator will work best in a collet. An end mill holder may
force it off-center a bit.

While being off center isn't the best scenario, it will have little effect
on the outcome (assuming it's not a great deal off). Remember, regardless
of how far off center it may be held, when the center of rotation (the
spindle) is concentric with the hole, the indicator will see the hole
equally, regardless of position, be it on center, or not. What ever error
is generated will be generated equally.

Harold

"William Noble" wrote in message
.. .
Jon - this makes sense - I keep forgetting the potential for the head to
not be vertical - but your statement to get it parallel in left right and
front back directions has me puzzled. As you know, on this mill, the head
can rotate from vertical to horizontal by simply loosening a couple of
lock bolts - but there is no adjustment for any other alignment, the only
adjustment is the position of the stop.

Make things real easy on yourself. Place a rod, bent @ 90 degrees, in the
spindle, be it in a collet, end mill holder or drill chuck. Makes no
difference. The rod should accommodate a DTI of sorts. Mount it such
that when you turn the spindle (which should be out of gear, so it turns
easily), that the pointer of the indicator trails off the slots, so it won't
hit them from the side of the contact. Set the indicator so it is just
barely in contact with the table (a thou or two) and sweep an arc that is
only slightly smaller in diameter than the table is deep, front to back.
That will give you the best level of precision possible. When you sweep
the table with the indicator, you should find it equal in all positions,
NSE&W. If it can be adjusted and is out, do so, then reset the permanent
stop, assuming it's out in that direction. It's always a good idea to
sweep the head once it's been moved, even when you have a stop.

Be aware, if your gib on the knee is worn, or very loose, the entire knee
assembly may be tilting away from the mill, or even sagging side to side as
the load move across the saddle. Adjust the gib so it's snug before you
do the head adjustment. That will insure that you don't set the head to a
sagging knee, which will be a repeat of the same problem you find now.

How about a report on what you find? Could be your machine needs some
attention beyond adjusting.

Harold

According to William Noble :
Jon - this makes sense - I keep forgetting the potential for the head to not
be vertical - but your statement to get it parallel in left right and front
back directions has me puzzled. As you know, on this mill, the head can
rotate from vertical to horizontal by simply loosening a couple of lock
bolts - but there is no adjustment for any other alignment, the only
adjustment is the position of the stop.

Is this a Bridgeport, or some other brand?

I know that there are two separate adjustments on *some*
Bridgeports, while others (some of the Series I machines and probably of
the Series II as well) have a rigid head.

Those that do have the adjustments have the loosening of the two
nuts which then allow the head to be rotated clockwise/counterclockwise
as viewed from the front. Note that some (such as for sure the Series I
which I have) include a hex projecting to the right and down which turns
a worm gear to rotate the head. When nearly vertical, there is enough
slop to make it difficult to get the adjustments correct. On these
heads (and perhaps on the ones without the worm gear as well) there are
pins to keep it from rotating too far to the left or right, and these
have to be pulled to allow inverting the head for moving.

But aside from this, there is a knuckle on the end of the ram
(I'm presuming a machine new enough to have a dovetailed ram instead of
a round ram, and I'm not sure what is present with the round ram.)
Anyway -- this has three bolts which can be slacked which allows the
head to "nod" so it points more towards the column, or away from it.
This is where you adjust the other tilt.

But some Series I machines lack both of these adjustments, and
simply have the head bolted onto the end of the ram, set *once* to be
right, and then drilled and reamed for taper pins to allow it to be
replaced in that specific position if it ever has to be removed for
whatever work.

Harold has already given you a description of how to make a tool
for checking how far out it is in each direction.

Good Luck,
DoN.


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

top posted --

Don - this is an Abene VHF-3 mill (made in 1970) , info on it is here if you
are curious http://www.lathes.co.uk/abene/page4.html - mine does not have
the quill downfeed lever, so any vertical motion is via the table - it is
very different from a bridgeport.

so, today I spent some time and set the head properly vertical - it was off
by a couple of degrees - I've set it pretty close - if I sweep out a 4 inch
circle, there is two thousandths total difference between the back and
front - to do this, I tilted the head, removed the stop, set the head
vertical (and dialed it in), moved the stop back to the head, lossened and
rotated the head so I could tightendown the stop (can't reach the bolt with
head in vertical position), and then rotated head back to stop - if I want
it better than the .002, I can disengage the stop and dial it in more
carefully.

so, now I have the mill in alignment, and I've tested that the Co-Ax
indicator is not defective - that leaves me with two problems:

2. my 3/8 end mill holder needs to be replaced - the entry into the holder
is oversized by about a thousandth, though it does neck down to close to
proper tolerance about 1/2 inch into the holder. the only solution I see is
to replace it, which I will do in due time

3. the drill chuck wobble problem is under investigation - the chuck is
mounted on a Kennametal arbor (40 taper to JT33 taper) - I measured the
runout of the JT taper - top, and bottom - I measured .001 at each place,
but the high spot was at opposite sites of the taper - this could throw the
chuck off a little - but I'm more suspicious of the chuck body itself - this
remains a homework assignment.

Meanwhile, the next issue with this mill is tightening of the traverse drive
belt - I'll start a new thread on that subject since it is probably of more
general interest.....

thanks to all



"DoN. Nichols" wrote in message
...
According to William Noble :
Jon - this makes sense - I keep forgetting the potential for the head to
not
be vertical - but your statement to get it parallel in left right and
front
back directions has me puzzled. As you know, on this mill, the head can
rotate from vertical to horizontal by simply loosening a couple of lock
bolts - but there is no adjustment for any other alignment, the only
adjustment is the position of the stop.

Is this a Bridgeport, or some other brand?

I know that there are two separate adjustments on *some*
Bridgeports, while others (some of the Series I machines and probably of
the Series II as well) have a rigid head.

Those that do have the adjustments have the loosening of the two
nuts which then allow the head to be rotated clockwise/counterclockwise
as viewed from the front. Note that some (such as for sure the Series I
which I have) include a hex projecting to the right and down which turns
a worm gear to rotate the head. When nearly vertical, there is enough
slop to make it difficult to get the adjustments correct. On these
heads (and perhaps on the ones without the worm gear as well) there are
pins to keep it from rotating too far to the left or right, and these
have to be pulled to allow inverting the head for moving.

But aside from this, there is a knuckle on the end of the ram
(I'm presuming a machine new enough to have a dovetailed ram instead of
a round ram, and I'm not sure what is present with the round ram.)
Anyway -- this has three bolts which can be slacked which allows the
head to "nod" so it points more towards the column, or away from it.
This is where you adjust the other tilt.

But some Series I machines lack both of these adjustments, and
simply have the head bolted onto the end of the ram, set *once* to be
right, and then drilled and reamed for taper pins to allow it to be
replaced in that specific position if it ever has to be removed for
whatever work.

Harold has already given you a description of how to make a tool
for checking how far out it is in each direction.

Good Luck,
DoN.


--
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Posted via a free Usenet account from http://www.teranews.com

On 28 Oct 2007 02:24:17 GMT, (DoN. Nichols)
wrote:

According to William Noble :
Jon - this makes sense - I keep forgetting the potential for the head to not
be vertical - but your statement to get it parallel in left right and front
back directions has me puzzled. As you know, on this mill, the head can
rotate from vertical to horizontal by simply loosening a couple of lock
bolts - but there is no adjustment for any other alignment, the only
adjustment is the position of the stop.

Is this a Bridgeport, or some other brand?

http://wbnoble.com/tools/PICT0107.JPG

"[L]iberals are afraid to state what they truly believe in, for to do so
would result in even less votes than they currently receive. Their
methodology is to lie about their real agenda in the hopes of regaining
power, at which point they will do whatever they damn well please. The
problem is they have concealed and obfuscated for so long that, as a group,
they themselves are no longer sure of their goals. They are a collection of
wild-eyed splinter groups, all holding a grab-bag of dreams and wishes. Some
want a Socialist, secular-humanist state, others the repeal of the Second
Amendment. Some want same sex/different species marriage, others want voting
rights for trees, fish, coal and bugs. Some want cradle to grave care and
complete subservience to the government nanny state, others want a culture
that walks in lockstep and speaks only with intonations of political
correctness. I view the American liberals in much the same way I view the
competing factions of Islamic
fundamentalists. The latter hate each other to the core, and only join
forces to attack the US or Israel. The former hate themselves to the core,
and only join forces to attack George Bush and conservatives." --Ron Marr

According to William Noble :
top posted --

Don - this is an Abene VHF-3 mill (made in 1970) , info on it is here if you
are curious http://www.lathes.co.uk/abene/page4.html - mine does not have
the quill downfeed lever, so any vertical motion is via the table - it is
very different from a bridgeport.

Agreed -- very different. They can switch between being a
vertical and a horizontal mill -- and do a proper job of each. While
I've never seen one in person, a distant friend has one, and I've
admired it in photos.

so, today I spent some time and set the head properly vertical - it was off
by a couple of degrees - I've set it pretty close - if I sweep out a 4 inch
circle, there is two thousandths total difference between the back and
front - to do this, I tilted the head, removed the stop, set the head
vertical (and dialed it in), moved the stop back to the head, lossened and
rotated the head so I could tightendown the stop (can't reach the bolt with
head in vertical position), and then rotated head back to stop - if I want
it better than the .002, I can disengage the stop and dial it in more
carefully.

O.K. And this machine has *only* the "nodding" adjustment, not
from side to side as far as I know.

so, now I have the mill in alignment, and I've tested that the Co-Ax
indicator is not defective - that leaves me with two problems:

Good!

2. my 3/8 end mill holder needs to be replaced - the entry into the holder
is oversized by about a thousandth, though it does neck down to close to
proper tolerance about 1/2 inch into the holder. the only solution I see is
to replace it, which I will do in due time

Agreed -- that was probably abused at sometime in the past.

3. the drill chuck wobble problem is under investigation - the chuck is
mounted on a Kennametal arbor (40 taper to JT33 taper) - I measured the
runout of the JT taper - top, and bottom - I measured .001 at each place,
but the high spot was at opposite sites of the taper - this could throw the
chuck off a little - but I'm more suspicious of the chuck body itself - this
remains a homework assignment.

While the body *may* also have problems, 0.001" opposed from top
to bottom would make a significant runout at the end of the chuck.
Remember that those two points are not that far apart, and by the time
you reach the drill's flutes you are up to significant runout. I
suspect that that arbor has been crashed sometime -- with that, or
another chuck in place, so I think that it should be replaced, too.

I actually use 40 taper tooling too -- in my Nichols horizontal
mill -- with a vertical adaptor as part of the set. Also, *my* Series-1
Bridgeport (A CNC -- BOSS-3 one) uses 30-taper tooling in a quick-change
spindle. That tooling also fits the Nichols with a 30-taper to 40-taper
adaptor.

Meanwhile, the next issue with this mill is tightening of the traverse drive
belt - I'll start a new thread on that subject since it is probably of more
general interest.....

O.K.

Good Luck,
DoN.

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continuing follow up on this drill chuck
friend with lots of tooling and measuring stuff - took the chuck - mounted
it on an accurate arbor with no measurable runout, in his lathe. Measured
less than .001 runout at the chuck body, but with a 1/2 inch drill blank in
the chuck, measured .020 runout (repeatable, no matter which hole used for
tightening) at the far end of the rod - so for sure the chuck is a problem -
The arbor is Kennametal, and looked new when I got it (cheaply via ebay),
and I haven't crashed it. so, will try a better chuck and report results.
I'm learning, I guess....

snip ----------------
"
3. the drill chuck wobble problem is under investigation - the chuck is
mounted on a Kennametal arbor (40 taper to JT33 taper) - I measured the
runout of the JT taper - top, and bottom - I measured .001 at each place,
but the high spot was at opposite sites of the taper - this could throw
the
chuck off a little - but I'm more suspicious of the chuck body itself -
this
remains a homework assignment.

While the body *may* also have problems, 0.001" opposed from top
to bottom would make a significant runout at the end of the chuck.
Remember that those two points are not that far apart, and by the time
you reach the drill's flutes you are up to significant runout. I
suspect that that arbor has been crashed sometime -- with that, or
another chuck in place, so I think that it should be replaced, too.

snip ------------------

Good Luck,
DoN.



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