I bought the one from Enco many years ago and use it often. The stated
accuracy is 0.0001, but is more like 0.001. But I still find it useful
where edge finders, wigglers, and the like are useless. I do cast
injection molds which might need some machining or changes after
casting. With the scope I can alien the mill spindle with an edge of a
small cavity or the tangent of a hole. Using contact devises could
easily damage the mold and most features would be too small to use an
edge finder anyway. I do have 3 axis DRO to help position the cutter. I
use collets for the scope and cutter. The run out of the collet also
effects the accuracy. Using the scope effectively will require a lot of
time and practice, and twisting your head around to see through the eye
piece is frustrating. There are much more accurate scopes available but
they are also 10 times the price. If you are only trying to locate over
a mark on the workpiece, setting up the scope will take a lot longer
than the other methods.
--
Billy Hiebert
HIEBERT SCULPTURE WORKS
Small Part Injection Molding
http://www.hieberts.com

Joseph Gwinn wrote:
I've seen an optical tool intended for centering the spindle of a mill
over a crosshair or mark on a workpiece, one that doesn't require such
good vision as many do not have.

Enco has it as item 240-0404 for $170:
http://www.use-enco.com/CGI/INSRIT?PMAKA=240-0404.

MSC has what appears to be the same thing, with more description and a
higher price:
http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1758752&PMT4NO=25857782.
The long description is in the printed catalog, not the website.

Travers also has it as item 57-101-650, for $237! Well, they used to -
it no longer appears on their website. In the 2007 paper catalog, it
appears on page 805 as a TTC Fine Centering Scope. But it probably
didn't sell well.

I did find this thread from 2006:
http://www.cnczone.com/forums/archive/index.php/t-26230.html.

And this one
http://www.artsoftcontrols.com/forum/index.php?topic=1563.10.

And this user's website (about halfway down):
http://homepage2.nifty.com/modelicengine/c05062.htm.


In any event, even at $170 it's kind of expensive for what it does, and
I wonder if anybody has any experience with it or anything like it.
Also, does anyone know the actual make and model? It seems to start
with SKO.


Thanks,

Joe Gwinn

In article ,
Billy Hiebert wrote:

I bought the one from Enco many years ago and use it often. The stated
accuracy is 0.0001, but is more like 0.001.

One cannot do better than the runout and angular error of the spindle
(and collet) of the mill in question, so I won't do better than 0.001"
either.

I assume that the 0.0001" Enco guarantees is measured in a far better
machine than I will own any time soon.


But I still find it useful
where edge finders, wigglers, and the like are useless. I do cast
injection molds which might need some machining or changes after
casting. With the scope I can align the mill spindle with an edge of a
small cavity or the tangent of a hole. Using contact devices could
easily damage the mold and most features would be too small to use an
edge finder anyway.

Very good point.


I do have 3 axis DRO to help position the cutter. I
use collets for the scope and cutter. The run out of the collet also
affects the accuracy. Using the scope effectively will require a lot of
time and practice, and twisting your head around to see through the eye
piece is frustrating.

Why is getting eye to scope harder than getting eye positioned to see
the scribed marks and wiggler needle, with bad lighting and the bulk of
the mill in the way?

Does the eyepiece arm of the scope interfere with the mill? It looks
like it wants to interfere with the quill.


There are much more accurate scopes available but
they are also 10 times the price.

Flexbar has one for
$425:http://store.flexbar.com/merchant2/m...n=PROD_MT&Stor
e_Code=FLX&Product_Code=17272&Category_Code=MT-Tool-Setters. This is
only 2.5 times. What other makes and models do you know of?

Google yielded http://www.titantoolsupply.com/store.asp?pid=11554,
which is ~$1,000. And Deckel makes a really good, but pricey one.

I think it would be best to put the money into a better mill first.


If you are only trying to locate over
a mark on the workpiece, setting up the scope will take a lot longer
than the other methods.

Really? I find the other methods (wiggler over scribed marks) very slow
and fiddly. And error-prone. But I haven't used a scope either.
Please expand a bit.

The bottom line remains that you do use it a lot, and this is
encouraging.

Thanks,

Joe Gwinn


--
Billy Hiebert
HIEBERT SCULPTURE WORKS
Small Part Injection Molding
http://www.hieberts.com

Joseph Gwinn wrote:
I've seen an optical tool intended for centering the spindle of a mill
over a crosshair or mark on a workpiece, one that doesn't require such
good vision as many do not have.

Enco has it as item 240-0404 for $170:
http://www.use-enco.com/CGI/INSRIT?PMAKA=240-0404.

MSC has what appears to be the same thing, with more description and a
higher price:
http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1758752&PMT4NO=25857782.
The long description is in the printed catalog, not the website.

Travers also has it as item 57-101-650, for $237! Well, they used to -
it no longer appears on their website. In the 2007 paper catalog, it
appears on page 805 as a TTC Fine Centering Scope. But it probably
didn't sell well.

I did find this thread from 2006:
http://www.cnczone.com/forums/archive/index.php/t-26230.html.

And this one
http://www.artsoftcontrols.com/forum/index.php?topic=1563.10.

And this user's website (about halfway down):
http://homepage2.nifty.com/modelicengine/c05062.htm.


In any event, even at $170 it's kind of expensive for what it does, and
I wonder if anybody has any experience with it or anything like it.
Also, does anyone know the actual make and model? It seems to start
with SKO.


Thanks,

Joe Gwinn

Joseph Gwinn wrote:
In article ,
Billy Hiebert wrote:

I do have 3 axis DRO to help position the cutter. I
use collets for the scope and cutter. The run out of the collet also
affects the accuracy. Using the scope effectively will require a lot of
time and practice, and twisting your head around to see through the eye
piece is frustrating.


Why is getting eye to scope harder than getting eye positioned to see
the scribed marks and wiggler needle, with bad lighting and the bulk of
the mill in the way?

Does the eyepiece arm of the scope interfere with the mill? It looks
like it wants to interfere with the quill.

Here's the problem. You may notice a black knurled sleeve just above the
lower lens housing; you turn this to move the image in the lens along
the same axis as the eye piece barrel. This is because the cross hair is
not automatically centered with the spindle. It must be adjusted when
after you put it in the collet. Because you can't get your head between
the mill column and the table, you swing the eye piece in line with the
x axis of the table, find a y edge, then adjust the swing until the now
y hair is on the edge, swing the scope 180, if the hair is not on the
edge, turn the sleeve 1/2 the distance, move the table to line up,
swing to the other side, if not lined up, repeat until both sides line
up. The other hair will not necessarily be centered, there is backlash
in the thing, and you have to remember to turn backward then forward
just like a mill table. I usually just use the one hair and zero both x
and y. The scope will turn freely 360 on my Bridgeport, it just misses
the DRO Z scale. Sorry about this description, but it's the best I can
do from memory. I would hope that the more expensive scopes would not
have this problem.

There are much more accurate scopes available but
they are also 10 times the price.


Flexbar has one for
$425:http://store.flexbar.com/merchant2/m...n=PROD_MT&Stor
e_Code=FLX&Product_Code=17272&Category_Code=MT-Tool-Setters. This is
only 2.5 times. What other makes and models do you know of?

Google yielded http://www.titantoolsupply.com/store.asp?pid=11554,
which is ~$1,000. And Deckel makes a really good, but pricey one.

I think it would be best to put the money into a better mill first.



If you are only trying to locate over
a mark on the workpiece, setting up the scope will take a lot longer
than the other methods.


Really? I find the other methods (wiggler over scribed marks) very slow
and fiddly. And error-prone. But I haven't used a scope either.
Please expand a bit.

If I only need to find the edge of a block of material, I use the
standard edge finder. For a center punched mark, I would use the pointed
end edge finder. They would be faster than the scope.

The bottom line remains that you do use it a lot, and this is
encouraging.

Maybe because of the type of machining I do, trying to locate odd
features. There may be other methods I'm not aware of but the fact that
the scope is non-contact is a big plus when you need to locate off an
existing, delicate feature on a cast mold. On a machined mold, you would
have provided locaters when you began the mold so it could always be set
up without touching the untouchables.


Thanks,

Joe Gwinn

--
Billy Hiebert
HIEBERT SCULPTURE WORKS
Small Part Injection Molding
http://www.hieberts.com

In article ,
Billy Hiebert wrote:

Joseph Gwinn wrote:
In article ,
Billy Hiebert wrote:

I do have 3 axis DRO to help position the cutter. I
use collets for the scope and cutter. The run out of the collet also
affects the accuracy. Using the scope effectively will require a lot of
time and practice, and twisting your head around to see through the eye
piece is frustrating.


Why is getting eye to scope harder than getting eye positioned to see
the scribed marks and wiggler needle, with bad lighting and the bulk of
the mill in the way?

Does the eyepiece arm of the scope interfere with the mill? It looks
like it wants to interfere with the quill.

Here's the problem. You may notice a black knurled sleeve just above the
lower lens housing; you turn this to move the image in the lens along
the same axis as the eye piece barrel. This is because the cross hair is
not automatically centered with the spindle. It must be adjusted when
after you put it in the collet. Because you can't get your head between
the mill column and the table, you swing the eye piece in line with the
x axis of the table, find a y edge, then adjust the swing until the now
y hair is on the edge, swing the scope 180, if the hair is not on the
edge, turn the sleeve 1/2 the distance, move the table to line up,
swing to the other side, if not lined up, repeat until both sides line
up. The other hair will not necessarily be centered, there is backlash
in the thing, and you have to remember to turn backward then forward
just like a mill table. I usually just use the one hair and zero both x
and y. The scope will turn freely 360 on my Bridgeport, it just misses
the DRO Z scale. Sorry about this description, but it's the best I can
do from memory.

Ouch. Sounds like a crucial design flaw. This is just as fiddly to use
as the wiggler.


I would hope that the more expensive scopes would not
have this problem.

Yes. This goes in the checklist for sure.


There are much more accurate scopes available but
they are also 10 times the price.


Flexbar has one for
$425:http://store.flexbar.com/merchant2/m...n=PROD_MT&Stor
e_Code=FLX&Product_Code=17272&Category_Code=MT-Tool-Setters. This is
only 2.5 times. What other makes and models do you know of?

Google yielded http://www.titantoolsupply.com/store.asp?pid=11554,
which is ~$1,000. And Deckel makes a really good, but pricey one.

I think it would be best to put the money into a better mill first.



If you are only trying to locate over
a mark on the workpiece, setting up the scope will take a lot longer
than the other methods.


Really? I find the other methods (wiggler over scribed marks) very slow
and fiddly. And error-prone. But I haven't used a scope either.
Please expand a bit.

If I only need to find the edge of a block of material, I use the
standard edge finder. For a center punched mark, I would use the pointed
end edge finder. They would be faster than the scope.

The bottom line remains that you do use it a lot, and this is
encouraging.

Maybe because of the type of machining I do, trying to locate odd
features. There may be other methods I'm not aware of but the fact that
the scope is non-contact is a big plus when you need to locate off an
existing, delicate feature on a cast mold. On a machined mold, you would
have provided locaters when you began the mold so it could always be set
up without touching the untouchables.

I don't yet have this problem. Nothing I make is untouchable. Or
untouched.

Maybe the better solution for me is the laser dot generator a number of
people have suggested. Cheaper, too. Here is one:

http://littlemachineshop.com/product...ductID=2604&ca
tegory.

Any opinions, anybody?



Joe Gwinn

According to Joseph Gwinn :

[ ... ]

There are much more accurate scopes available but
they are also 10 times the price.

Flexbar has one for
$425:http://store.flexbar.com/merchant2/m...n=PROD_MT&Stor
e_Code=FLX&Product_Code=17272&Category_Code=MT-Tool-Setters. This is
only 2.5 times. What other makes and models do you know of?

O.K. One difference between this and the earlier ones is that
it has an adjustment for the particular spindle in which you are
mounting it. Put it in the spindle, move it up or down until you have a
sharp image of a scribed line under it, crank the table until the line
matches the hairline in the scope, then rotate the spindle 180 degrees,
and check whether the hairline is still on the scribed line. If it is
not, adjust it half-way to meet the line, and repeat the test. Once you
can rotate the spindle 180 degrees with no obvious change, it is
calibrated to that spindle and collet, and you have the center of
rotation directly over the scribed line. So zero the dial on that axis,
then rotate it 90 degrees, and zero the other axis to a scribed line at
right angles to the first.

Of course -- this does not correct for any errors in
concentricity when you remove the scope and install the milling cutter,
which may exhibit runout of its own, thus changing the width of the cut.
But you are at least zeroed to the axis of rotation of the spindle.

Oh yes -- the "focal length 5/8" part of the specs shows that
you have to add 5/8" to the length extending beyond the collet. At a
rough guess, that would be about 3-1/2 inches if the shank is fully
inside the collet.

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 ---

According to Joseph Gwinn :
In article ,
Billy Hiebert wrote:

[ ... ]

Here's the problem. You may notice a black knurled sleeve just above the
lower lens housing; you turn this to move the image in the lens along
the same axis as the eye piece barrel. This is because the cross hair is
not automatically centered with the spindle. It must be adjusted when
after you put it in the collet.

[ ... ]

Ouch. Sounds like a crucial design flaw. This is just as fiddly to use
as the wiggler.

This is to adjust out any lack of concentricity in the collet,
so it will indicate the true point around which the spindle rotates.
(You can still have runouts introduced by the collet and burs or chips
in the spindle, but at least you know that you are centered over the
spindle's true rotation axis if you have the adjustable type and take
the time to adjust it.)

With a truly good spindle nose and collet, you would not need
the adjustment.


I would hope that the more expensive scopes would not
have this problem.

Yes. This goes in the checklist for sure.

Don't count this against the scope. I think that the more
expensive ones are *more* likely to have that, since they are also
likely to have greater magnification, so the spindle errors are easier
to spot.

[ ... ]

Maybe the better solution for me is the laser dot generator a number of
people have suggested. Cheaper, too. Here is one:

http://littlemachineshop.com/product...ductID=2604&ca
tegory.

Any opinions, anybody?

I don't think that would be as accurate as the kind which was
just discussed with the knob to adjust the centering to be truly on.

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 ---

In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
Billy Hiebert wrote:

[ ... ]

Here's the problem. You may notice a black knurled sleeve just above the
lower lens housing; you turn this to move the image in the lens along
the same axis as the eye piece barrel. This is because the cross hair is
not automatically centered with the spindle. It must be adjusted when
after you put it in the collet.

Ouch. Sounds like a crucial design flaw. This is just as fiddly to use
as the wiggler.

This is to adjust out any lack of concentricity in the collet,
so it will indicate the true point around which the spindle rotates.
(You can still have runouts introduced by the collet and burs or chips
in the spindle, but at least you know that you are centered over the
spindle's true rotation axis if you have the adjustable type and take
the time to adjust it.)

With a truly good spindle nose and collet, you would not need
the adjustment.


I would hope that the more expensive scopes would not
have this problem.

Yes. This goes in the checklist for sure.

Don't count this against the scope. I think that the more
expensive ones are *more* likely to have that, since they are also
likely to have greater magnification, so the spindle errors are easier
to spot.

OK. I see why one would do this, but what escapes me is that if the
fine centering scope isn't a whole lot better at something than a
wiggler, why would anyone buy a scope? I guess what's emerging is that
the advantage is accuracy (and reliability), but not speed. And I was
hoping for all three.


Maybe the better solution for me is the laser dot generator a number of
people have suggested. Cheaper, too. Here is one:

http://littlemachineshop.com/product...ductID=2604&ca
tegory.

Any opinions, anybody?

I don't think that would be as accurate as the kind which was
just discussed with the knob to adjust the centering to be truly on.

I imagine that you are right. The question is if it's good enough, and
sufficiently faster to use to be worthwhile. Does anyone have
experience? I recall one poster reported that it was good enough for
his non-stringent purposes.


Joe Gwinn

In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :

[ ... ]

There are much more accurate scopes available but
they are also 10 times the price.

Flexbar has one for
$425:http://store.flexbar.com/merchant2/m...n=PROD_MT&Stor
e_Code=FLX&Product_Code=17272&Category_Code=MT-Tool-Setters. This is
only 2.5 times. What other makes and models do you know of?

O.K. One difference between this and the earlier ones is that
it has an adjustment for the particular spindle in which you are
mounting it. Put it in the spindle, move it up or down until you have a
sharp image of a scribed line under it, crank the table until the line
matches the hairline in the scope, then rotate the spindle 180 degrees,
and check whether the hairline is still on the scribed line. If it is
not, adjust it half-way to meet the line, and repeat the test. Once you
can rotate the spindle 180 degrees with no obvious change, it is
calibrated to that spindle and collet, and you have the center of
rotation directly over the scribed line. So zero the dial on that axis,
then rotate it 90 degrees, and zero the other axis to a scribed line at
right angles to the first.

If this is what the expensive unit does, what does the $170 unit do? I
thought it used the same 180 degree moves and difference splitting.


Of course -- this does not correct for any errors in
concentricity when you remove the scope and install the milling cutter,
which may exhibit runout of its own, thus changing the width of the cut.
But you are at least zeroed to the axis of rotation of the spindle.

Yep.


Oh yes -- the "focal length 5/8" part of the specs shows that
you have to add 5/8" to the length extending beyond the collet. At a
rough guess, that would be about 3-1/2 inches if the shank is fully
inside the collet.

And the quill travel is 4", so knee motion will be required.


Joe Gwinn

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

[ ... ]

Don't count this against the scope. I think that the more
expensive ones are *more* likely to have that, since they are also
likely to have greater magnification, so the spindle errors are easier
to spot.

OK. I see why one would do this, but what escapes me is that if the
fine centering scope isn't a whole lot better at something than a
wiggler, why would anyone buy a scope?

I consider it a lot better for aligning to scribed lines, and
scribed lines need not be that far from accurate, if you use a stack of
gauge blocks and a rigid scriber sliding along a surface plate to scribe
the lines.

I guess what's emerging is that
the advantage is accuracy (and reliability), but not speed. And I was
hoping for all three.

The speed is not that bad. Normally you look at one position,
adjust the axis to bring the scribed line up to the hairline in the
scope, then rotate it 180 degrees and a quick look tells you that it is
set right -- or occasionally (if the collet is poor or is seated on a
chip or bur) that you need to tweak the setting by turning the knob to
bring the hairline halfway between where it is and the scribed line.
Once you've done this, you can also trust it rotated 90 degrees for
zeroing on the other scribed line. You only need to check the zeroing
of the scope once when you have just put it into the collet, or if you
accidentally hit the knob after it has been zeroed.

And you'll get a feel pretty quickly how often you actually need
to tweak it with *your* spindle and collets. In my case, I would be
using it in a 30 taper end mill holder, since I don't have R8 collets in
my mill.

It is a *lot* easier to see errors with this than with a
wiggler, in part because you don't have to deal with parallax, which you
do when trying to see the point of the wiggler and the scribed line from
an angle. The only way around that is to bring the point down to
*almost* contact, which can be more fiddly than the zeroing of the
scope.

[ ... ]

Any opinions, anybody?

I don't think that would be as accurate as the kind which was
just discussed with the knob to adjust the centering to be truly on.

I imagine that you are right. The question is if it's good enough, and
sufficiently faster to use to be worthwhile. Does anyone have
experience? I recall one poster reported that it was good enough for
his non-stringent purposes.

That could perhaps be the less expensive ones without the
zeroing knob.

I have one (which I had to machine out the old threads for a
broken-off microscope objective and mount one which I had), but I need
to finish the conversion of the mill -- it is no good at the moment with
some stepper motors and some servo motors and a serious case of
electronics Altzheimer's in the original controller. :-)

And my other mill is a horizontal spindle mill, which would be
awkward to use this with.

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 ---

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :

[ ... ]

Flexbar has one for
$425:http://store.flexbar.com/merchant2/m...n=PROD_MT&Stor
e_Code=FLX&Product_Code=17272&Category_Code=MT-Tool-Setters. This is
only 2.5 times. What other makes and models do you know of?

O.K. One difference between this and the earlier ones is that
it has an adjustment for the particular spindle in which you are
mounting it. Put it in the spindle, move it up or down until you have a
sharp image of a scribed line under it, crank the table until the line
matches the hairline in the scope, then rotate the spindle 180 degrees,
and check whether the hairline is still on the scribed line. If it is
not, adjust it half-way to meet the line, and repeat the test. Once you
can rotate the spindle 180 degrees with no obvious change, it is
calibrated to that spindle and collet, and you have the center of
rotation directly over the scribed line. So zero the dial on that axis,
then rotate it 90 degrees, and zero the other axis to a scribed line at
right angles to the first.

If this is what the expensive unit does, what does the $170 unit do? I
thought it used the same 180 degree moves and difference splitting.

The URL for that one is gone, so I can't re-check it, but as I
remember, it did not have the knob which is visible in the flexbar unit
(opposite and a bit above the eyepiece tube's joining point). So, I
think that those cheaper ones do not have this adjustment, and perhaps
also have less magnification, so there is less need for the correction
-- unless you drop it, of course. :-)

[ ... ]

Oh yes -- the "focal length 5/8" part of the specs shows that
you have to add 5/8" to the length extending beyond the collet. At a
rough guess, that would be about 3-1/2 inches if the shank is fully
inside the collet.

And the quill travel is 4", so knee motion will be required.

Unless you are using endmill holders of similar extension
instead of collets..

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 ---

In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :

[ ... ]

Flexbar has one for
$425:http://store.flexbar.com/merchant2/m...en=PROD_MT&Sto
r
e_Code=FLX&Product_Code=17272&Category_Code=MT-Tool-Setters. This is
only 2.5 times. What other makes and models do you know of?

O.K. One difference between this and the earlier ones is that
it has an adjustment for the particular spindle in which you are
mounting it. Put it in the spindle, move it up or down until you have a
sharp image of a scribed line under it, crank the table until the line
matches the hairline in the scope, then rotate the spindle 180 degrees,
and check whether the hairline is still on the scribed line. If it is
not, adjust it half-way to meet the line, and repeat the test. Once you
can rotate the spindle 180 degrees with no obvious change, it is
calibrated to that spindle and collet, and you have the center of
rotation directly over the scribed line. So zero the dial on that axis,
then rotate it 90 degrees, and zero the other axis to a scribed line at
right angles to the first.

If this is what the expensive unit does, what does the $170 unit do? I
thought it used the same 180 degree moves and difference splitting.

The URL for that one is gone, so I can't re-check it, but as I
remember, it did not have the knob which is visible in the flexbar unit
(opposite and a bit above the eyepiece tube's joining point). So, I
think that those cheaper ones do not have this adjustment, and perhaps
also have less magnification, so there is less need for the correction
-- unless you drop it, of course. :-)

here it is:
http://www.use-enco.com/CGI/INSRIT?P...822227&PARTPG=
INLMK3.

It's Enco model number 240-0404.

All it has is the knurled rubber knob at the bottom. Now that I think
about it, I think that Billy Hiebert said that this knob moves the
reticle line. I assume that the knurl at the eyepiece does the focusing.

Here is the 20 July 2007 (or the day before) posting:
Billy Hiebert wrote:
[snip]

Here's the problem. You may notice a black knurled sleeve just above the
lower lens housing; you turn this to move the image in the lens along
the same axis as the eye piece barrel. This is because the cross hair is
not automatically centered with the spindle. It must be adjusted when
after you put it in the collet. Because you can't get your head between
the mill column and the table, you swing the eye piece in line with the
x axis of the table, find a y edge, then adjust the swing until the now
y hair is on the edge, swing the scope 180, if the hair is not on the
edge, turn the sleeve 1/2 the distance, move the table to line up,
swing to the other side, if not lined up, repeat until both sides line
up. The other hair will not necessarily be centered, there is backlash
in the thing, and you have to remember to turn backward then forward
just like a mill table. I usually just use the one hair and zero both x
and y. The scope will turn freely 360 on my Bridgeport, it just misses
the DRO Z scale. Sorry about this description, but it's the best I can
do from memory.
End of posting.



Oh yes -- the "focal length 5/8" part of the specs shows that
you have to add 5/8" to the length extending beyond the collet. At a
rough guess, that would be about 3-1/2 inches if the shank is fully
inside the collet.

And the quill travel is 4", so knee motion will be required.

Unless you are using endmill holders of similar extension
instead of collets..

Good point. So far, I've used only R8 collets to hold endmills.


Joe Gwinn

In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

[ ... ]

Don't count this against the scope. I think that the more
expensive ones are *more* likely to have that, since they are also
likely to have greater magnification, so the spindle errors are easier
to spot.

OK. I see why one would do this, but what escapes me is that if the
fine centering scope isn't a whole lot better at something than a
wiggler, why would anyone buy a scope?

I consider it a lot better for aligning to scribed lines, and
scribed lines need not be that far from accurate, if you use a stack of
gauge blocks and a rigid scriber sliding along a surface plate to scribe
the lines.

I guess what's emerging is that
the advantage is accuracy (and reliability), but not speed. And I was
hoping for all three.

The speed is not that bad. Normally you look at one position,
adjust the axis to bring the scribed line up to the hairline in the
scope, then rotate it 180 degrees and a quick look tells you that it is
set right -- or occasionally (if the collet is poor or is seated on a
chip or bur) that you need to tweak the setting by turning the knob to
bring the hairline halfway between where it is and the scribed line.
Once you've done this, you can also trust it rotated 90 degrees for
zeroing on the other scribed line. You only need to check the zeroing
of the scope once when you have just put it into the collet, or if you
accidentally hit the knob after it has been zeroed.

And you'll get a feel pretty quickly how often you actually need
to tweak it with *your* spindle and collets. In my case, I would be
using it in a 30 taper end mill holder, since I don't have R8 collets in
my mill.

It is a *lot* easier to see errors with this than with a
wiggler, in part because you don't have to deal with parallax, which you
do when trying to see the point of the wiggler and the scribed line from
an angle. The only way around that is to bring the point down to
*almost* contact, which can be more fiddly than the zeroing of the
scope.

This is the key for me, I think. The problems with parallax and with
not being able to see the scribed lines well enough really slows things
down, and causes errors. I'm convinced, and will buy the Enco scope.


Any opinions, anybody?

I don't think that would be as accurate as the kind which was
just discussed with the knob to adjust the centering to be truly on.

I imagine that you are right. The question is if it's good enough, and
sufficiently faster to use to be worthwhile. Does anyone have
experience? I recall one poster reported that it was good enough for
his non-stringent purposes.

That could perhaps be the less expensive ones without the
zeroing knob.

I couldn't tell, although the comments were to the effect that
reflections off the workpiece degraded accuracy in practice. In fact,
the description at littlemachineshop.com says just that, and they sell
an accessory (the polarizer) to solve the problem.

Which models have the zeroing knob?

The item at littlemachineshop.com looks like a computer-generated image
of what it ought to look like, not a photograph of what it does look
like. But it does gave holes in the side that look like they give
access to adjusting screws.


I have one (which I had to machine out the old threads for a
broken-off microscope objective and mount one which I had), but I need
to finish the conversion of the mill -- it is no good at the moment with
some stepper motors and some servo motors and a serious case of
electronics Altzheimer's in the original controller. :-)

And my other mill is a horizontal spindle mill, which would be
awkward to use this with.

Would the scope be any better? Sounds like the bulk of the machine
would be in the way. I did see a centering scope sold in the UK where
the arm is perpendicular to the centering axis.

Joe Gwinn

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :

[ ... ]

If this is what the expensive unit does, what does the $170 unit do? I
thought it used the same 180 degree moves and difference splitting.

The URL for that one is gone, so I can't re-check it, but as I
remember, it did not have the knob which is visible in the flexbar unit
(opposite and a bit above the eyepiece tube's joining point). So, I
think that those cheaper ones do not have this adjustment, and perhaps
also have less magnification, so there is less need for the correction
-- unless you drop it, of course. :-)

here it is:
http://www.use-enco.com/CGI/INSRIT?P...822227&PARTPG=
INLMK3.

It's Enco model number 240-0404.

O.K. It is pretty much as I remembered.

All it has is the knurled rubber knob at the bottom. Now that I think
about it, I think that Billy Hiebert said that this knob moves the
reticle line.

"Moves the reticle line" is the same as adjusting the centering
to compensate for slightly off-center collets or spindles. If it does
that, then it does everything that the other does.

I assume that the knurl at the eyepiece does the focusing.

It only does the focusing of your eye to the hairline to make it
good and sharp. Focusing of the image of the scribe line would be done
by Z-axis motion -- either the quill or the knee -- whichever is easier
and gives sufficient range.

I must admit that I had originally though that the bottom
knurled ring (just above the objective lens) was for fine focusing of
the objective, so you don't have to tweak the Z axis as closely.

Here is the 20 July 2007 (or the day before) posting:
Billy Hiebert wrote:
[snip]

Here's the problem. You may notice a black knurled sleeve just above the
lower lens housing; you turn this to move the image in the lens along
the same axis as the eye piece barrel. This is because the cross hair is
not automatically centered with the spindle. It must be adjusted when
after you put it in the collet. Because you can't get your head between
the mill column and the table, you swing the eye piece in line with the
x axis of the table, find a y edge, then adjust the swing until the now
y hair is on the edge, swing the scope 180, if the hair is not on the
edge, turn the sleeve 1/2 the distance, move the table to line up,
swing to the other side, if not lined up, repeat until both sides line
up. The other hair will not necessarily be centered, there is backlash
in the thing, and you have to remember to turn backward then forward
just like a mill table. I usually just use the one hair and zero both x
and y. The scope will turn freely 360 on my Bridgeport, it just misses
the DRO Z scale. Sorry about this description, but it's the best I can
do from memory.

O.K. Though I don't think that there *is* "another hair" -- you
only need one to do what the scope is for. You rotate it 90 degrees to
do the other axis, once you've zeroed it for the axis which lets you
swing the eyepiece both ways. As mentioned above, you can't do the
zeroing with the Y axis because you can't get your head between the
eyepiece and the column -- though one with a TV camera built in and a TV
monitor on a shelf nearby would allow that as well.




Oh yes -- the "focal length 5/8" part of the specs shows that
you have to add 5/8" to the length extending beyond the collet. At a
rough guess, that would be about 3-1/2 inches if the shank is fully
inside the collet.

And the quill travel is 4", so knee motion will be required.

Unless you are using endmill holders of similar extension
instead of collets..

Good point. So far, I've used only R8 collets to hold endmills.

I note that the Enco one says the length is 3" (which I suspect
means from the step at the bottom of the shank to the end of the lens),
and the lens then needs an additional inch to focus (working distance).

It looks to me as though the eyepiece tube on that one is closer
to six inches long, if the end of shank to lens tip is three inches.

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 ---

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

[ ... ]

I consider it a lot better for aligning to scribed lines, and
scribed lines need not be that far from accurate, if you use a stack of
gauge blocks and a rigid scriber sliding along a surface plate to scribe
the lines.

I guess what's emerging is that
the advantage is accuracy (and reliability), but not speed. And I was
hoping for all three.

The speed is not that bad. Normally you look at one position,
adjust the axis to bring the scribed line up to the hairline in the

[ ... ]

It is a *lot* easier to see errors with this than with a
wiggler, in part because you don't have to deal with parallax, which you
do when trying to see the point of the wiggler and the scribed line from
an angle. The only way around that is to bring the point down to
*almost* contact, which can be more fiddly than the zeroing of the
scope.

This is the key for me, I think. The problems with parallax and with
not being able to see the scribed lines well enough really slows things
down, and causes errors. I'm convinced, and will buy the Enco scope.

O.K. It sounds as though it is the thing for you -- especially
if you set to scribed lines often.

[ ... ]

I imagine that you are right. The question is if it's good enough, and
sufficiently faster to use to be worthwhile. Does anyone have
experience? I recall one poster reported that it was good enough for
his non-stringent purposes.

That could perhaps be the less expensive ones without the
zeroing knob.

I couldn't tell, although the comments were to the effect that
reflections off the workpiece degraded accuracy in practice.

Oh -- you were talking about the one with the laser beam
generating a single dot (with the Airy ring surrounding it).

I *think* that the Laser one's knurled ring is for focusing the
dot to the smallest possible -- but I guess that it could be for zeroing
the offset. In that case, I would guess that the easiest way to zero
would be to set the spindle speed at the slowest, and watch the circle
generated by the dot -- and grip and release the knurled ring (if the
design allows that), watching the effect on the circle size until it is
zeroed (stationary even with the spindle rotating). Since I have never
seen one of these, all I can do is to guess.

In fact,
the description at littlemachineshop.com says just that, and they sell
an accessory (the polarizer) to solve the problem.

Which models have the zeroing knob?

I think that none of the Laser diode ones do. And it appears
that the Enco does

The item at littlemachineshop.com looks like a computer-generated image
of what it ought to look like, not a photograph of what it does look
like. But it does gave holes in the side that look like they give
access to adjusting screws.

Those may be for original zeroing at the factory. Though you
might have to tweak it if you drop or bump it hard.

I have one (which I had to machine out the old threads for a
broken-off microscope objective and mount one which I had), but I need
to finish the conversion of the mill -- it is no good at the moment with
some stepper motors and some servo motors and a serious case of
electronics Altzheimer's in the original controller. :-)

And my other mill is a horizontal spindle mill, which would be
awkward to use this with.

Would the scope be any better?

The scope is what I was talking about there -- not the Laser
diode one.

Sounds like the bulk of the machine
would be in the way. I did see a centering scope sold in the UK where
the arm is perpendicular to the centering axis.

That would still be difficult to adjust, because the eyepiece
would probably hit the overarm as you swung from 0 degrees to 180
degrees. (And hit the table, swinging the other way.)

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 ---

In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :

[ ... ]

If this is what the expensive unit does, what does the $170 unit do? I
thought it used the same 180 degree moves and difference splitting.

The URL for that one is gone, so I can't re-check it, but as I
remember, it did not have the knob which is visible in the flexbar unit
(opposite and a bit above the eyepiece tube's joining point). So, I
think that those cheaper ones do not have this adjustment, and perhaps
also have less magnification, so there is less need for the correction
-- unless you drop it, of course. :-)

here it is:
http://www.use-enco.com/CGI/INSRIT?P...822227&PARTPG=
INLMK3.

It's Enco model number 240-0404.

O.K. It is pretty much as I remembered.

All it has is the knurled rubber knob at the bottom. Now that I think
about it, I think that Billy Hiebert said that this knob moves the
reticle line.

"Moves the reticle line" is the same as adjusting the centering
to compensate for slightly off-center collets or spindles. If it does
that, then it does everything that the other does.

So it would appear.


I assume that the knurl at the eyepiece does the focusing.

It only does the focusing of your eye to the hairline to make it
good and sharp. Focusing of the image of the scribe line would be done
by Z-axis motion -- either the quill or the knee -- whichever is easier
and gives sufficient range.

Billy Hiebert said that the lens to target distance needs to be about
1", constant.


I must admit that I had originally though that the bottom
knurled ring (just above the objective lens) was for fine focusing of
the objective, so you don't have to tweak the Z axis as closely.

Here is the 20 July 2007 (or the day before) posting:
Billy Hiebert wrote:
[snip]

Here's the problem. You may notice a black knurled sleeve just above the
lower lens housing; you turn this to move the image in the lens along
the same axis as the eye piece barrel. This is because the cross hair is
not automatically centered with the spindle. It must be adjusted when
after you put it in the collet. Because you can't get your head between
the mill column and the table, you swing the eye piece in line with the
x axis of the table, find a y edge, then adjust the swing until the now
y hair is on the edge, swing the scope 180, if the hair is not on the
edge, turn the sleeve 1/2 the distance, move the table to line up,
swing to the other side, if not lined up, repeat until both sides line
up. The other hair will not necessarily be centered, there is backlash
in the thing, and you have to remember to turn backward then forward
just like a mill table. I usually just use the one hair and zero both x
and y. The scope will turn freely 360 on my Bridgeport, it just misses
the DRO Z scale. Sorry about this description, but it's the best I can
do from memory.

O.K. Though I don't think that there *is* "another hair" -- you
only need one to do what the scope is for. You rotate it 90 degrees to
do the other axis, once you've zeroed it for the axis which lets you
swing the eyepiece both ways. As mentioned above, you can't do the
zeroing with the Y axis because you can't get your head between the
eyepiece and the column -- though one with a TV camera built in and a TV
monitor on a shelf nearby would allow that as well.

I'm hoping for a crosshair.

I read about the calibrated TV cameras. Seemed like far too much
trouble.


Oh yes -- the "focal length 5/8" part of the specs shows that
you have to add 5/8" to the length extending beyond the collet. At a
rough guess, that would be about 3-1/2 inches if the shank is fully
inside the collet.

And the quill travel is 4", so knee motion will be required.

Unless you are using endmill holders of similar extension
instead of collets..

Good point. So far, I've used only R8 collets to hold endmills.

I note that the Enco one says the length is 3" (which I suspect
means from the step at the bottom of the shank to the end of the lens),
and the lens then needs an additional inch to focus (working distance).

It looks to me as though the eyepiece tube on that one is closer
to six inches long, if the end of shank to lens tip is three inches.

Well, I ordered one. When I get it and have used it a bit, I'll post a
report.

Joe Gwinn

In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

It is a *lot* easier to see errors with this than with a
wiggler, in part because you don't have to deal with parallax, which you
do when trying to see the point of the wiggler and the scribed line from
an angle. The only way around that is to bring the point down to
*almost* contact, which can be more fiddly than the zeroing of the
scope.

This is the key for me, I think. The problems with parallax and with
not being able to see the scribed lines well enough really slows things
down, and causes errors. I'm convinced, and will buy the Enco scope.

O.K. It sounds as though it is the thing for you -- especially
if you set to scribed lines often.

We shall see. I've ordered one.


I imagine that you are right. The question is if it's good enough, and
sufficiently faster to use to be worthwhile. Does anyone have
experience? I recall one poster reported that it was good enough for
his non-stringent purposes.

That could perhaps be the less expensive ones without the
zeroing knob.

I couldn't tell, although the comments were to the effect that
reflections off the workpiece degraded accuracy in practice.

Oh -- you were talking about the one with the laser beam
generating a single dot (with the Airy ring surrounding it).

Yes, that's the one, that's the issue.

What I don't understand is why the laser center doesn't have a knob to
vary the intensity. The polarizer sounds like a clumsy workaround for
what should have been simple to fix. It would be far easier to vary the
current through the laser.


I *think* that the Laser one's knurled ring is for focusing the
dot to the smallest possible -- but I guess that it could be for zeroing
the offset. In that case, I would guess that the easiest way to zero
would be to set the spindle speed at the slowest, and watch the circle
generated by the dot -- and grip and release the knurled ring (if the
design allows that), watching the effect on the circle size until it is
zeroed (stationary even with the spindle rotating). Since I have never
seen one of these, all I can do is to guess.

Me too. I have only that copmputer-generated picture.


In fact,
the description at littlemachineshop.com says just that, and they sell
an accessory (the polarizer) to solve the problem.

Which models have the zeroing knob?

I think that none of the Laser diode ones do. And it appears
that the Enco does.

OK. Maybe someday.


The item at littlemachineshop.com looks like a computer-generated image
of what it ought to look like, not a photograph of what it does look
like. But it does gave holes in the side that look like they give
access to adjusting screws.

Those may be for original zeroing at the factory. Though you
might have to tweak it if you drop or bump it hard.

I have one (which I had to machine out the old threads for a
broken-off microscope objective and mount one which I had), but I need
to finish the conversion of the mill -- it is no good at the moment with
some stepper motors and some servo motors and a serious case of
electronics Altzheimer's in the original controller. :-)

And my other mill is a horizontal spindle mill, which would be
awkward to use this with.

Would the scope be any better?

The scope is what I was talking about there -- not the Laser
diode one.

Sounds like the bulk of the machine
would be in the way. I did see a centering scope sold in the UK where
the arm is perpendicular to the centering axis.

That would still be difficult to adjust, because the eyepiece
would probably hit the overarm as you swung from 0 degrees to 180
degrees. (And hit the table, swinging the other way.)

I guess video wins here.

Joe Gwinn

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

[ ... ]

Oh -- you were talking about the one with the laser beam
generating a single dot (with the Airy ring surrounding it).

Yes, that's the one, that's the issue.

What I don't understand is why the laser center doesn't have a knob to
vary the intensity. The polarizer sounds like a clumsy workaround for
what should have been simple to fix. It would be far easier to vary the
current through the laser.

I believe that Laser diodes turn off below a certain current,
unlike LEDs which simply get dimmer. And the "knob to vary the
intensity" would either waste power in a series resistor, or require
active circuitry to control the current (a better but more expensive
solution).

You might be able to reduce the apparent intensity by PWM (Pulse
Width Modulation) -- though I'm not sure that this would eliminate the
appearance of the Airy ring.

[ ... horizontal spindle mill ... ]

Sounds like the bulk of the machine
would be in the way. I did see a centering scope sold in the UK where
the arm is perpendicular to the centering axis.

That would still be difficult to adjust, because the eyepiece
would probably hit the overarm as you swung from 0 degrees to 180
degrees. (And hit the table, swinging the other way.)

I guess video wins here.

I guess so -- except that the camera module would still probably
be put on on a long arm to maintain the maximum sensitivity.

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 ---

In article ,
(DoN. Nichols) wrote:

According to Joseph Gwinn :
In article ,
(DoN. Nichols) wrote:

[ ... ]

Oh -- you were talking about the one with the laser beam
generating a single dot (with the Airy ring surrounding it).

Yes, that's the one, that's the issue.

What I don't understand is why the laser center doesn't have a knob to
vary the intensity. The polarizer sounds like a clumsy workaround for
what should have been simple to fix. It would be far easier to vary the
current through the laser.

I believe that Laser diodes turn off below a certain current,
unlike LEDs which simply get dimmer. And the "knob to vary the
intensity" would either waste power in a series resistor, or require
active circuitry to control the current (a better but more expensive
solution).

True enough, but lasers are linear above threshold, so all that's
necessary is an offset, so zero on the pot is near the lasing threshold,
and max on the pot is at max allowed current. (Or duty cycle, if using
PWM; discussed below.)


You might be able to reduce the apparent intensity by PWM (Pulse
Width Modulation) -- though I'm not sure that this would eliminate the
appearance of the Airy ring.

I think that most laser pointers and modules made today have a little IC
in them, not just a resistor. PWM would certainly work. Perhaps the
ICs already work that way.

The Airy ring disappears simply because it becomes too dim to see with
the unaided eye, especially in a well-lit shop, not because it isn't
there.


[ ... horizontal spindle mill ... ]

Sounds like the bulk of the machine
would be in the way. I did see a centering scope sold in the UK where
the arm is perpendicular to the centering axis.

That would still be difficult to adjust, because the eyepiece
would probably hit the overarm as you swung from 0 degrees to 180
degrees. (And hit the table, swinging the other way.)

I guess video wins here.

I guess so -- except that the camera module would still probably
be put on on a long arm to maintain the maximum sensitivity.

Depends on the camera lens. One would expect that what is being used is
a low-power microscope objective lens.


Joe Gwinn