I am milling a part I want to fit reasonably closely to something (close
slip fit, ideally). Something like -0.000"/+0.001". I have it clamped in
my mill vise, and I have a stop set to locate one end. I'm milling out a
small pocket, and the best I can do for measuring the width & length is a
digital caliper. The thing it fits on is too big to try in place.

Thus far, I haven't taken it out of the mill. I few more passes, and it
should be done. My question is whether I have a prayer of taking it out &
returning it with adequate precision if it ends up a bit tight? I was
figuring that if it doesn't quite fit, I could count on it not locating
exactly the same. That way another pass with the same settings should open
it up a hair.

My experience says that I should (barring chips getting in the way) be able
to relocate the part within 0.001", but I'm not sure how much better than
that I can count on. Depth isn't as critical, so a little "vice lift"
won't kill me.

Comments? Suggestions?

Thanks!

Doug White

On Oct 9, 7:36*am, Doug White wrote:
I am milling a part I want to fit reasonably closely to something (close
slip fit, ideally). *Something like -0.000"/+0.001". *I have it clamped in
my mill vise, and I have a stop set to locate one end. *I'm milling out a
small pocket, and the best I can do for measuring the width & length is a
digital caliper. *The thing it fits on is too big to try in place.

Thus far, I haven't taken it out of the mill. *I few more passes, and it
should be done. *My question is whether I have a prayer of taking it out &
returning it with adequate precision if it ends up a bit tight? *I was
figuring that if it doesn't quite fit, I could count on it not locating
exactly the same. *That way another pass with the same settings should open
it up a hair.

My experience says that I should (barring chips getting in the way) be able
to relocate the part within 0.001", but I'm not sure how much better than
that I can count on. *Depth isn't as critical, so a little "vice lift"
won't kill me.

Comments? Suggestions?

Thanks!

Doug White

If you are only making one part and it turns out too tight, then get
out your files and make it fit. If you are making many of the item,
you might invest in DRO for your mill.

Paul

On Oct 9, 10:36*am, Doug White wrote:
I am milling a part I want to fit reasonably closely to something (close
slip fit, ideally). *Something like -0.000"/+0.001". *I have it clamped in
my mill vise, and I have a stop set to locate one end. *I'm milling out a
small pocket, and the best I can do for measuring the width & length is a
digital caliper. *The thing it fits on is too big to try in place.

Thus far, I haven't taken it out of the mill. *I few more passes, and it
should be done. *My question is whether I have a prayer of taking it out &
returning it with adequate precision if it ends up a bit tight? *I was
figuring that if it doesn't quite fit, I could count on it not locating
exactly the same. *That way another pass with the same settings should open
it up a hair.

My experience says that I should (barring chips getting in the way) be able
to relocate the part within 0.001", but I'm not sure how much better than
that I can count on. *Depth isn't as critical, so a little "vice lift"
won't kill me.

Doug White

With power off, back off the cutter a little and advance it until it
barely pinches a strip of paper. After you check the fit you can see
if it still pinches at the same dial setting.

If you blacken the cut surface with a marker you can detect very light
contact with the spinning cutter.

jsw

On Sat, 09 Oct 2010 14:36:44 GMT, Doug White
wrote:

I am milling a part I want to fit reasonably closely to something (close
slip fit, ideally). Something like -0.000"/+0.001". I have it clamped in
my mill vise, and I have a stop set to locate one end. I'm milling out a
small pocket, and the best I can do for measuring the width & length is a
digital caliper. The thing it fits on is too big to try in place.

Thus far, I haven't taken it out of the mill. I few more passes, and it
should be done. My question is whether I have a prayer of taking it out &
returning it with adequate precision if it ends up a bit tight? I was
figuring that if it doesn't quite fit, I could count on it not locating
exactly the same. That way another pass with the same settings should open
it up a hair.

My experience says that I should (barring chips getting in the way) be able
to relocate the part within 0.001", but I'm not sure how much better than
that I can count on. Depth isn't as critical, so a little "vice lift"
won't kill me.

Comments? Suggestions?

Thanks!

Doug White

You should be able to locate an edge to within half a thou with one of
these:
http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3

Doug White writes:

The thing it fits on is too big to try in place.

Then you must make a gage. Shop-made gages, jigs, and fixtures are a
critical part of competent metalworking. You are very limited if you only
work with what you can buy from a catalog.

Doug White wrote:
I am milling a part I want to fit reasonably closely to something (close
slip fit, ideally). Something like -0.000"/+0.001". I have it clamped in
my mill vise, and I have a stop set to locate one end. I'm milling out a
small pocket, and the best I can do for measuring the width & length is a
digital caliper. The thing it fits on is too big to try in place.

Thus far, I haven't taken it out of the mill. I few more passes, and it
should be done. My question is whether I have a prayer of taking it out &
returning it with adequate precision if it ends up a bit tight? I was
figuring that if it doesn't quite fit, I could count on it not locating
exactly the same. That way another pass with the same settings should open
it up a hair.

My experience says that I should (barring chips getting in the way) be able
to relocate the part within 0.001", but I'm not sure how much better than
that I can count on. Depth isn't as critical, so a little "vice lift"
won't kill me.

Comments? Suggestions?

Thanks!

Doug White


Usually the back edge of your mill vise is not going to move on you.

You will get a bit of lift when you tighten the vice but a little tap
with a mallet will unually bring your part snug against the paralells.

The position against the stop is usually consistant so yo should not
have too much trouble there.

Also since it is a slot, can you use a pin to measure the width of the
slot? That might be easier than your calipers. Also a pin that is a
few thou under size can be used a feeler gauge to measure.

Hope this helps.

Roger Shoaf

On 2010-10-09, Doug White wrote:
I am milling a part I want to fit reasonably closely to something (close
slip fit, ideally). Something like -0.000"/+0.001". I have it clamped in
my mill vise, and I have a stop set to locate one end. I'm milling out a
small pocket, and the best I can do for measuring the width & length is a
digital caliper. The thing it fits on is too big to try in place.

Thus far, I haven't taken it out of the mill.

[ ... ]

Comments? Suggestions?

I would suggest that you take a set of fine adjust inside and
outside calipers (spring hinge and a knurled nut on a fine screw) and
use that to transfer the fit from the workpiece pocket to the part which
it fits. It takes a bit of "feel" but that should be better than the
digital calipers overall. That is how machinists made things to fit in
the old days. If you have two pair of each style, you can set the
outside calipers to fit both dimensions on the thing you are fitting,
and then transfer to the inside calipers for both dimensions and use
those to check the fit.

Good Luck,
DoN.

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On 2010-10-09, Jim Wilkins wrote:
On Oct 9, 10:36*am, Doug White wrote:
I am milling a part I want to fit reasonably closely to something (close
slip fit, ideally). *Something like -0.000"/+0.001". *I have it clamped in
my mill vise, and I have a stop set to locate one end. *I'm milling out a
small pocket, and the best I can do for measuring the width & length is a
digital caliper. *The thing it fits on is too big to try in place.

Thus far, I haven't taken it out of the mill. *I few more passes, and it
should be done. *My question is whether I have a prayer of taking it out &

[ ... ]

My experience says that I should (barring chips getting in the way) be able
to relocate the part within 0.001", but I'm not sure how much better than
that I can count on. *Depth isn't as critical, so a little "vice lift"
won't kill me.

Doug White

With power off, back off the cutter a little and advance it until it
barely pinches a strip of paper. After you check the fit you can see
if it still pinches at the same dial setting.

What is good for that is rolling papers. They are quite thin (I
think 0.001" but double check with a micrometer first) and you can wet
one before sticking it in place, then advance carefully until it moves
from where it was stuck.

If you blacken the cut surface with a marker you can detect very light
contact with the spinning cutter.

Indeed so.

Enjoy,
DoN.

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On 2010-10-09, Don Foreman wrote:
On Sat, 09 Oct 2010 14:36:44 GMT, Doug White
wrote:

I am milling a part I want to fit reasonably closely to something (close
slip fit, ideally). Something like -0.000"/+0.001". I have it clamped in
my mill vise, and I have a stop set to locate one end.

[ ... ]

My experience says that I should (barring chips getting in the way) be able
to relocate the part within 0.001", but I'm not sure how much better than
that I can count on. Depth isn't as critical, so a little "vice lift"
won't kill me.

[ ... ]

You should be able to locate an edge to within half a thou with one of
these:
http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3

Yes -- and the final question is -- what is the actual size of
the end mill, once you have set things with the edge finder. You know
that the edge finder is 3/8" or 0.200" diameter (these) or I have an
older one which is 0.500" -- but if the mills have been resharpened, you
need to take that size into account.

The prices on those edge finders look pretty good.

Enjoy,
DoN.

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"DoN. Nichols" wrote in message
...
On 2010-10-09, Doug White wrote:
I am milling a part I want to fit reasonably closely to something (close
slip fit, ideally). Something like -0.000"/+0.001". I have it clamped
in
my mill vise, and I have a stop set to locate one end. I'm milling out a
small pocket, and the best I can do for measuring the width & length is a
digital caliper. The thing it fits on is too big to try in place.

Thus far, I haven't taken it out of the mill.

[ ... ]

Comments? Suggestions?

I would suggest that you take a set of fine adjust inside and
outside calipers (spring hinge and a knurled nut on a fine screw) and
use that to transfer the fit from the workpiece pocket to the part which
it fits. It takes a bit of "feel" but that should be better than the
digital calipers overall. That is how machinists made things to fit in
the old days. If you have two pair of each style, you can set the
outside calipers to fit both dimensions on the thing you are fitting,
and then transfer to the inside calipers for both dimensions and use
those to check the fit.


Don, is there any place for using telescopic gauges in this instance?
Personally, I have had limited luck in transferring dimension from outside
to inside calipers and vice versa. I have taken to setting the dimension on
the micrometer (or use the micrometer to measure the male part of the
assembly), set my telescopic gauge to that dimension and then us it to check
the part being machined.

--
Michael Koblic,
Campbell River, BC

" wrote in
:

On Oct 9, 7:36*am, Doug White wrote:
I am milling a part I want to fit reasonably closely to something
(close slip fit, ideally). *Something like -0.000"/+0.001". *I have
it clamp
ed in
my mill vise, and I have a stop set to locate one end. *I'm milling
out
a
small pocket, and the best I can do for measuring the width & length
is a digital caliper. *The thing it fits on is too big to try in
place.

Thus far, I haven't taken it out of the mill. *I few more passes, and
i
t
should be done. *My question is whether I have a prayer of taking it
ou
t &
returning it with adequate precision if it ends up a bit tight? *I
was figuring that if it doesn't quite fit, I could count on it not
locating exactly the same. *That way another pass with the same
settings should
open
it up a hair.

My experience says that I should (barring chips getting in the way)
be ab
le
to relocate the part within 0.001", but I'm not sure how much better
than that I can count on. *Depth isn't as critical, so a little "vice
lift" won't kill me.

Comments? Suggestions?

Thanks!

Doug White

If you are only making one part and it turns out too tight, then get
out your files and make it fit. If you are making many of the item,
you might invest in DRO for your mill.

I ended up cutting the most critical dimension a mil oversized & filing
it to fit. A DRO doesn't really help here. I can read the dials on my
mill to less than half a mil. Knowing where the table is is only part of
the equation. As it turns out, I ended up cutting the slip fit about 1
mil larger than I'd wanted. This was without moving the piece. I
suspect the problem was flex in the mill. It's an old Clausing 8520, and
although I was taking light climb mill cuts, I'd been taking 5 mils off
per pass quite reliably until I got close. Then I tried to take off 2
mils, and it took off ~ half a mil more than I'd expected per side.

Live and learn. The thing works fine, and I know more than when I
started. All in all, a successful project.

Doug White

"Michael Koblic" wrote in
:


"DoN. Nichols" wrote in message
...
On 2010-10-09, Doug White wrote:
I am milling a part I want to fit reasonably closely to something
(close slip fit, ideally). Something like -0.000"/+0.001". I have
it clamped in
my mill vise, and I have a stop set to locate one end. I'm milling
out a small pocket, and the best I can do for measuring the width &
length is a digital caliper. The thing it fits on is too big to try
in place.

Thus far, I haven't taken it out of the mill.

[ ... ]

Comments? Suggestions?

I would suggest that you take a set of fine adjust inside and
outside calipers (spring hinge and a knurled nut on a fine screw) and
use that to transfer the fit from the workpiece pocket to the part
which it fits. It takes a bit of "feel" but that should be better
than the digital calipers overall. That is how machinists made
things to fit in the old days. If you have two pair of each style,
you can set the outside calipers to fit both dimensions on the thing
you are fitting, and then transfer to the inside calipers for both
dimensions and use those to check the fit.


Don, is there any place for using telescopic gauges in this instance?
Personally, I have had limited luck in transferring dimension from
outside to inside calipers and vice versa. I have taken to setting the
dimension on the micrometer (or use the micrometer to measure the male
part of the assembly), set my telescopic gauge to that dimension and
then us it to check the part being machined.

I like the caliper idea. I'm not sure I have one of each, and my
recollection is the one(s?) I have are fairly large. The pocket was
narrow & shallow, so it might have been a bit tricky to fit an inside one
down in the pocket. I've used telescoping gages in the past, but the
pocket was definitely too small in this case.

I'll have to add a matching pair of small calipers to my Xmas list. My
wife is always beating up on me because she doesn't know what to get me.
If I decide I really need/want something, I usually just go & buy the
damn thing. The less expensive it is, the more likely I'll snag one
within a day or two of identifying a need. That makes it tricky when
folks are trying to buy gifts with any sort of lead time.

When I was a kid growing up in New Mexico, there was a two week delay
built into almost every project, and it used to drive me nuts. I'd send
out an order via the mail, and wait for the postman to bring the order
back, hopefully correct & complete. Now, I can fire off an order to MSC
and expect it to be delivered in one day. Amazon Prime gets stuff here
in 2 days with no shipping charges. If I'm impatient (who, me?) I can
track every step of it's progress with on-line tracking. I am SO
spoiled.

"The problem with instant gratification is that it takes too long..."

Doug White

On Oct 10, 9:18*am, Doug White wrote:
" wrote :





On Oct 9, 7:36*am, Doug White wrote:
I am milling a part I want to fit reasonably closely to something
(close slip fit, ideally). *Something like -0.000"/+0.001". *I have
it clamp
ed in
my mill vise, and I have a stop set to locate one end. *I'm milling
out
*a
small pocket, and the best I can do for measuring the width & length
is a digital caliper. *The thing it fits on is too big to try in
place.

Thus far, I haven't taken it out of the mill. *I few more passes, and
i
t
should be done. *My question is whether I have a prayer of taking it
ou
t &
returning it with adequate precision if it ends up a bit tight? *I
was figuring that if it doesn't quite fit, I could count on it not
locating exactly the same. *That way another pass with the same
settings should
open
it up a hair.

My experience says that I should (barring chips getting in the way)
be ab
le
to relocate the part within 0.001", but I'm not sure how much better
than that I can count on. *Depth isn't as critical, so a little "vice
lift" won't kill me.

Comments? Suggestions?

Thanks!

Doug White

If you are only making one part and it turns out too tight, then get
out your files and make it fit. If you are making many of the item,
you might invest in DRO for your mill.

I ended up cutting the most critical dimension a mil oversized & filing
it to fit. *A DRO doesn't really help here. *I can read the dials on my
mill to less than half a mil. *Knowing where the table is is only part of
the equation. *As it turns out, I ended up cutting the slip fit about 1
mil larger than I'd wanted. *This was without moving the piece. *I
suspect the problem was flex in the mill. *It's an old Clausing 8520, and
although I was taking light climb mill cuts, I'd been taking 5 mils off
per pass quite reliably until I got close. *Then I tried to take off 2
mils, and it took off ~ half a mil more than I'd expected per side.

Live and learn. *The thing works fine, and I know more than when I
started. *All in all, a successful project.

Doug White

My 8525 misbehaves that way sometimes. I have better luck when I
surface-grind the reference faces of the block after milling, and pad
the moving jaw with wood. It's more precise if I tighten the knee and
quill locks.

jsw

"Doug White" wrote in message
. ..
[...]


I like the caliper idea. I'm not sure I have one of each, and my
recollection is the one(s?) I have are fairly large. The pocket was
narrow & shallow, so it might have been a bit tricky to fit an inside one
down in the pocket. I've used telescoping gages in the past, but the
pocket was definitely too small in this case.

Would even these be too small?

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

I'll have to add a matching pair of small calipers to my Xmas list. My
wife is always beating up on me because she doesn't know what to get me.
If I decide I really need/want something, I usually just go & buy the
damn thing. The less expensive it is, the more likely I'll snag one
within a day or two of identifying a need. That makes it tricky when
folks are trying to buy gifts with any sort of lead time.

Best thing ever is to teach people not to get hung up on this Christmas
thing. Here it is routine to get Christmas presents in September or March.
The September ones are often accompanied by some suitable statement such as
"we thought you looked a bit ill and were not sure you would last..."

When I was a kid growing up in New Mexico, there was a two week delay
built into almost every project, and it used to drive me nuts. I'd send
out an order via the mail, and wait for the postman to bring the order
back, hopefully correct & complete. Now, I can fire off an order to MSC
and expect it to be delivered in one day. Amazon Prime gets stuff here
in 2 days with no shipping charges. If I'm impatient (who, me?) I can
track every step of it's progress with on-line tracking. I am SO
spoiled.

What planet is this?

--
Michael Koblic,
Campbell River, BC

On 2010-10-10, Michael Koblic wrote:

"DoN. Nichols" wrote in message
...

[ ... ]

I would suggest that you take a set of fine adjust inside and
outside calipers (spring hinge and a knurled nut on a fine screw) and
use that to transfer the fit from the workpiece pocket to the part which
it fits. It takes a bit of "feel" but that should be better than the
digital calipers overall. That is how machinists made things to fit in
the old days. If you have two pair of each style, you can set the
outside calipers to fit both dimensions on the thing you are fitting,
and then transfer to the inside calipers for both dimensions and use
those to check the fit.


Don, is there any place for using telescopic gauges in this instance?

If you have them -- and can get them to work well for you --
*and* if they fit where you need to measure -- sure.

Personally, I have had limited luck in transferring dimension from outside
to inside calipers and vice versa.

There are people who have trouble getting repeatable
measurements with telescoping gauge, too.

With both -- it is a matter of developing the right feel to get
repeatable measurements or dimension transfers.

Granted -- something which gives you numbers makes it easier to
figure out how much to advance the cutter for the next pass. (But with
the standard calipers, you can get similar information (in a
non-numeric form) by the angle of the clipers when you start feeling
contact with both sides. (Of course, this will change with the size of
the dimension you are measuring.)

I have taken to setting the dimension on
the micrometer (or use the micrometer to measure the male part of the
assembly), set my telescopic gauge to that dimension and then us it to check
the part being machined.

Hmm ... another way to do this is to use some adjustable
parallels -- find one which fits reasonably in the pocket, adjust it out
to make firm contact with the walls of the pocket, and measure the part
which is projecting from the pocket using your micrometer. (Do I
remember you asking what adjustable parallels are for in an earlier
exchange?)

Here is a web site showing the use of adjustable parallels to
measure an internal dimension:

http://www.wttool.com/product-exec/product_id/16863?utm_medium=cpc&utm_source=froog

Anyway -- there are always multiple ways to accomplish something
in machining -- and in many other things as well. The trick is to find
one which works for you.

Enjoy,
DoN.

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

"Michael Koblic" wrote in
:


"Doug White" wrote in message
. ..
[...]


I like the caliper idea. I'm not sure I have one of each, and my
recollection is the one(s?) I have are fairly large. The pocket was
narrow & shallow, so it might have been a bit tricky to fit an inside
one down in the pocket. I've used telescoping gages in the past, but
the pocket was definitely too small in this case.

Would even these be too small?

http://www.use-enco.com/CGI/INSRIT?P...950942&PARTPG=
INLMK3

The smallest of these might just work, and I'd forgotten that I had a
similar set. Thanks for the reminder!

Doug White

On 2010-10-12, Doug White wrote:
"Michael Koblic" wrote in
:


"Doug White" wrote in message
. ..

[ ... ]

I like the caliper idea. I'm not sure I have one of each, and my
recollection is the one(s?) I have are fairly large. The pocket was
narrow & shallow, so it might have been a bit tricky to fit an inside
one down in the pocket. I've used telescoping gages in the past, but
the pocket was definitely too small in this case.

Would even these be too small?

http://www.use-enco.com/CGI/INSRIT?P...950942&PARTPG=
INLMK3

The smallest of these might just work, and I'd forgotten that I had a
similar set. Thanks for the reminder!

I prefer the ones which are flat bottomed starting at the
equator. Easier to measure shallow grooves. The best ones I have
are an old Lufkin set. Everyone else has more meat on the underside of
the equator.

And you never actually said how small the pocket needed to be.
That might have changed quite a few of the answers. If it was too small
for the telescoping gauges, but would likely work with the smallest of
the small hole gauges, it is pretty small, and I would likely not have
suggested the calipers.

Enjoy,
DoN.

--
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Email: | Voice (all times): (703) 938-4564
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"DoN. Nichols" wrote in
:

snip
Would even these be too small?

http://www.use-enco.com/CGI/INSRIT?P...&PMPXNO=950942
&PARTPG=
INLMK3

The smallest of these might just work, and I'd forgotten that I had a
similar set. Thanks for the reminder!

I prefer the ones which are flat bottomed starting at the
equator. Easier to measure shallow grooves. The best ones I have
are an old Lufkin set. Everyone else has more meat on the underside of
the equator.

And you never actually said how small the pocket needed to be.
That might have changed quite a few of the answers. If it was too
small
for the telescoping gauges, but would likely work with the smallest of
the small hole gauges, it is pretty small, and I would likely not have
suggested the calipers.

The pocket is ~ 0.10" deep, 0.240" wide, and ~ 1.25" long. Too shallow &
too narrow for a typical telescoping gage, but the truncated small hole
gages would probably have worked. The width was the place I wanted a
close fit. The pocket is actually open on one end, and the critical
dimension there was the thickness of the wall on the far end. That I cut
slightly oversized & filed to fit.

Doug White