I was trying to make two rings from copper pipes, 1.625" OD (wall
thickness 0.061") and 2.125" OD (wall thickness 0.035") respectively.
The length of the ring was to be 0.75".

I cut the pipe oversize on my bandsaw. As expected the cut was not
exactly square. I clamped the first ring initially on the inside in my
3-jaw chuck trying to make sure that the sides of the piece were at
right angles to the body of the chuck as determined by a square.

I faced off the first side and deburred it. I reversed the ring and
clamped it the same way with the faced-off part flat against the jaws
base. I faced off the other end to the required dimension. Everything
looked good.

However, when I checked the final product with a square it was obvious
that neither plane of the ring was square to the sides. I did an
additional check with a height gauge with the ring on a flat (well, as
flat as I could get) surface. There was a difference of 0.017" in
height of the ring around the circumference.

I tried a second ring of the same diameter, this time clamping on the
outside. I checked the position with the square in three different
spots. The interesting part was that the fit was square in two of them
but not in the third.

Anyway, the result was almost identical and I got the same result with
the larger ring.

Although the result is adequate for my purposes I would like to know
why I was unable to make the rings properly. Was I not following the
correct procedure? Where in the procedure could the error have
occurred? I have never before had a problem with facing-off being out
of square with the sides.

Thanks.

Michael Koblic,
Campbell River, BC

wrote in message
...
I was trying to make two rings from copper pipes, 1.625" OD (wall
thickness 0.061") and 2.125" OD (wall thickness 0.035")
respectively.
The length of the ring was to be 0.75".
...
However, when I checked the final product with a square it was
obvious
that neither plane of the ring was square to the sides. I did an
additional check with a height gauge with the ring on a flat (well,
as
flat as I could get) surface. There was a difference of 0.017" in
height of the ring around the circumference.

Michael Koblic,
Campbell River, BC

I can't make good rings that way either. I'd turn a wooden mandrel and
slide the pipe onto it, then part off the rings.

You can turn a shallow parting groove and use it to guide the bandsaw
blade. Saw a shallow cut, then rotate the work a little in the blade
travel direction so the flexible incoming blade rubs on and is guided
by the wall of the turned groove. Saw in a little and advance again.
Unless the blade is new and sharp it won't dig into the wall of the
groove much. Once the saw cut extends all around the blade should cut
the piece off squarely, or if not you can see it deflect.

The same trick can cut under the hard shell of a scrap hydraulic
cylinder rod with a tool you can easily sharpen rather than the
expensive sawblade.
jsw

"BQ340" wrote in message
...
On 8/5/2013 9:02 PM, wrote:
I was trying to make two rings from copper pipes, 1.625" OD (wall
thickness 0.061") and 2.125" OD (wall thickness 0.035") respectively.
The length of the ring was to be 0.75".

I cut the pipe oversize on my bandsaw. As expected the cut was not
exactly square. I clamped the first ring initially on the inside in my
3-jaw chuck trying to make sure that the sides of the piece were at
right angles to the body of the chuck as determined by a square.

I faced off the first side and deburred it. I reversed the ring and
clamped it the same way with the faced-off part flat against the jaws
base. I faced off the other end to the required dimension. Everything
looked good.

However, when I checked the final product with a square it was obvious
that neither plane of the ring was square to the sides. I did an
additional check with a height gauge with the ring on a flat (well, as
flat as I could get) surface. There was a difference of 0.017" in
height of the ring around the circumference.

I tried a second ring of the same diameter, this time clamping on the
outside. I checked the position with the square in three different
spots. The interesting part was that the fit was square in two of them
but not in the third.

Anyway, the result was almost identical and I got the same result with
the larger ring.

Although the result is adequate for my purposes I would like to know
why I was unable to make the rings properly. Was I not following the
correct procedure? Where in the procedure could the error have
occurred? I have never before had a problem with facing-off being out
of square with the sides.

Thanks.

Michael Koblic,
Campbell River, BC


Copper as you know, is very soft. You can't clamp it very hard before it
distorts & also it will move in the chuck unless you take very light cuts.
You did not say but I assume you deburred it before chucking in the lathe?

Maybe check it with the square after you faced one end but before you
unclamp it to see if it had moved in the chuck during facing?

You would probably need to put it on a mandrel for perfect accuracy.

MikeB

--
Email is valid

Yup , mandrel . Bolt in the end with a rubber washer under a regular steel
washer I'd machine the steel with the mandrel , trim the rubber with a
knife/sandpaper . Tighten the bolt , rubber expands and grips the sleeve .
Take light cuts ...
--
Snag

On 6/08/2013 10:09 AM, Terry Coombs wrote:
"BQ340" wrote in message
...
On 8/5/2013 9:02 PM, wrote:
I was trying to make two rings from copper pipes, 1.625" OD (wall
thickness 0.061") and 2.125" OD (wall thickness 0.035") respectively.
The length of the ring was to be 0.75".

I cut the pipe oversize on my bandsaw. As expected the cut was not
exactly square. I clamped the first ring initially on the inside in my
3-jaw chuck trying to make sure that the sides of the piece were at
right angles to the body of the chuck as determined by a square.

I faced off the first side and deburred it. I reversed the ring and
clamped it the same way with the faced-off part flat against the jaws
base. I faced off the other end to the required dimension. Everything
looked good.

However, when I checked the final product with a square it was obvious
that neither plane of the ring was square to the sides. I did an
additional check with a height gauge with the ring on a flat (well, as
flat as I could get) surface. There was a difference of 0.017" in
height of the ring around the circumference.

I tried a second ring of the same diameter, this time clamping on the
outside. I checked the position with the square in three different
spots. The interesting part was that the fit was square in two of them
but not in the third.

Anyway, the result was almost identical and I got the same result with
the larger ring.

Although the result is adequate for my purposes I would like to know
why I was unable to make the rings properly. Was I not following the
correct procedure? Where in the procedure could the error have
occurred? I have never before had a problem with facing-off being out
of square with the sides.

Thanks.

Michael Koblic,
Campbell River, BC


Copper as you know, is very soft. You can't clamp it very hard before it
distorts & also it will move in the chuck unless you take very light cuts.
You did not say but I assume you deburred it before chucking in the lathe?

Maybe check it with the square after you faced one end but before you
unclamp it to see if it had moved in the chuck during facing?

You would probably need to put it on a mandrel for perfect accuracy.

MikeB

--
Email is valid

Yup , mandrel . Bolt in the end with a rubber washer under a regular steel
washer I'd machine the steel with the mandrel , trim the rubber with a
knife/sandpaper . Tighten the bolt , rubber expands and grips the sleeve .
Take light cuts ...



I tried a similar thing but to make the mandrel I used a bar just under
the ID of the tube I wanted to machine. I then put pieces of thin wall
tube over the mandrel with O rings spaced along in between. When it was
tightened down the O rings expanded outward holding the tube in place.

===============TUBING TO BE MACHINED==================
|tube O tube O tube O tube O tube O tube O|
================================================== ====|
mandrel BOLT
================================================== ====|
|tube O tube O tube O tube O tube O tube O|
===============TUBING TO BE MACHINED==================

wrote in message
...
I was trying to make two rings from copper pipes, 1.625" OD (wall
thickness 0.061") and 2.125" OD (wall thickness 0.035") respectively.
The length of the ring was to be 0.75".

I cut the pipe oversize on my bandsaw. As expected the cut was not
exactly square. I clamped the first ring initially on the inside in my
3-jaw chuck trying to make sure that the sides of the piece were at
right angles to the body of the chuck as determined by a square.

I faced off the first side and deburred it. I reversed the ring and
clamped it the same way with the faced-off part flat against the jaws
base. I faced off the other end to the required dimension. Everything
looked good.

However, when I checked the final product with a square it was obvious
that neither plane of the ring was square to the sides. I did an
additional check with a height gauge with the ring on a flat (well, as
flat as I could get) surface. There was a difference of 0.017" in
height of the ring around the circumference.

I tried a second ring of the same diameter, this time clamping on the
outside. I checked the position with the square in three different
spots. The interesting part was that the fit was square in two of them
but not in the third.

Anyway, the result was almost identical and I got the same result with
the larger ring.

Although the result is adequate for my purposes I would like to know
why I was unable to make the rings properly. Was I not following the
correct procedure? Where in the procedure could the error have
occurred? I have never before had a problem with facing-off being out
of square with the sides.

Thanks.

Michael Koblic,
Campbell River, BC

It is hard to chuck something accurately that is wider than it is long.
You could chuck a long length of the pipe and leave more than 0.75 sticking
out. Clean up the first end, then, with out unchucking, part off the 0.75"
length and deburr by hand.

You could also part off a length that is a little longer, then turn it
around and chuck it using the inside jaws with the flat end resting against
the step in the jaws.

Other folks mentioned making a mandrel, and maybe that is the right way to
do it, but it seems like too much work.

"Gonadicus" wrote in message
. au...
On 6/08/2013 10:09 AM, Terry Coombs wrote:
"BQ340" wrote in message
...
On 8/5/2013 9:02 PM, wrote:
I was trying to make two rings from copper pipes, 1.625" OD (wall
thickness 0.061") and 2.125" OD (wall thickness 0.035") respectively.
The length of the ring was to be 0.75".

I cut the pipe oversize on my bandsaw. As expected the cut was not
exactly square. I clamped the first ring initially on the inside in my
3-jaw chuck trying to make sure that the sides of the piece were at
right angles to the body of the chuck as determined by a square.

I faced off the first side and deburred it. I reversed the ring and
clamped it the same way with the faced-off part flat against the jaws
base. I faced off the other end to the required dimension. Everything
looked good.

However, when I checked the final product with a square it was obvious
that neither plane of the ring was square to the sides. I did an
additional check with a height gauge with the ring on a flat (well, as
flat as I could get) surface. There was a difference of 0.017" in
height of the ring around the circumference.

I tried a second ring of the same diameter, this time clamping on the
outside. I checked the position with the square in three different
spots. The interesting part was that the fit was square in two of them
but not in the third.

Anyway, the result was almost identical and I got the same result with
the larger ring.

Although the result is adequate for my purposes I would like to know
why I was unable to make the rings properly. Was I not following the
correct procedure? Where in the procedure could the error have
occurred? I have never before had a problem with facing-off being out
of square with the sides.

Thanks.

Michael Koblic,
Campbell River, BC


Copper as you know, is very soft. You can't clamp it very hard before it
distorts & also it will move in the chuck unless you take very light
cuts.
You did not say but I assume you deburred it before chucking in the
lathe?

Maybe check it with the square after you faced one end but before you
unclamp it to see if it had moved in the chuck during facing?

You would probably need to put it on a mandrel for perfect accuracy.

MikeB

--
Email is valid

Yup , mandrel . Bolt in the end with a rubber washer under a regular
steel
washer I'd machine the steel with the mandrel , trim the rubber with a
knife/sandpaper . Tighten the bolt , rubber expands and grips the
sleeve .
Take light cuts ...



I tried a similar thing but to make the mandrel I used a bar just under
the ID of the tube I wanted to machine. I then put pieces of thin wall
tube over the mandrel with O rings spaced along in between. When it was
tightened down the O rings expanded outward holding the tube in place.

===============TUBING TO BE MACHINED==================
|tube O tube O tube O tube O tube O tube O|
================================================== ====|
mandrel BOLT
================================================== ====|
|tube O tube O tube O tube O tube O tube O|
===============TUBING TO BE MACHINED==================



How much runout did you get ? Were the pieces of thinwall between the
o-rings a tight slip fit ?
--
Snag

wrote in message
...
I was trying to make two rings from copper pipes, 1.625" OD (wall
thickness 0.061") and 2.125" OD (wall thickness 0.035") respectively.
The length of the ring was to be 0.75".

I cut the pipe oversize on my bandsaw. As expected the cut was not
exactly square. I clamped the first ring initially on the inside in my
3-jaw chuck trying to make sure that the sides of the piece were at
right angles to the body of the chuck as determined by a square.

I faced off the first side and deburred it. I reversed the ring and
clamped it the same way with the faced-off part flat against the jaws
base. I faced off the other end to the required dimension. Everything
looked good.

However, when I checked the final product with a square it was obvious
that neither plane of the ring was square to the sides. I did an
additional check with a height gauge with the ring on a flat (well, as
flat as I could get) surface. There was a difference of 0.017" in
height of the ring around the circumference.

I tried a second ring of the same diameter, this time clamping on the
outside. I checked the position with the square in three different
spots. The interesting part was that the fit was square in two of them
but not in the third.

Anyway, the result was almost identical and I got the same result with
the larger ring.

Although the result is adequate for my purposes I would like to know
why I was unable to make the rings properly. Was I not following the
correct procedure? Where in the procedure could the error have
occurred? I have never before had a problem with facing-off being out
of square with the sides.

Thanks.

Michael Koblic,
Campbell River, BC

Are you familiar with soft jaws? They are the answer to your problem.

Harold

On 6/08/2013 11:38 AM, Terry Coombs wrote:
"Gonadicus" wrote in message
. au...
On 6/08/2013 10:09 AM, Terry Coombs wrote:
"BQ340" wrote in message
...
On 8/5/2013 9:02 PM, wrote:
I was trying to make two rings from copper pipes, 1.625" OD (wall
thickness 0.061") and 2.125" OD (wall thickness 0.035") respectively.
The length of the ring was to be 0.75".

I cut the pipe oversize on my bandsaw. As expected the cut was not
exactly square. I clamped the first ring initially on the inside in my
3-jaw chuck trying to make sure that the sides of the piece were at
right angles to the body of the chuck as determined by a square.

I faced off the first side and deburred it. I reversed the ring and
clamped it the same way with the faced-off part flat against the jaws
base. I faced off the other end to the required dimension. Everything
looked good.

However, when I checked the final product with a square it was obvious
that neither plane of the ring was square to the sides. I did an
additional check with a height gauge with the ring on a flat (well, as
flat as I could get) surface. There was a difference of 0.017" in
height of the ring around the circumference.

I tried a second ring of the same diameter, this time clamping on the
outside. I checked the position with the square in three different
spots. The interesting part was that the fit was square in two of them
but not in the third.

Anyway, the result was almost identical and I got the same result with
the larger ring.

Although the result is adequate for my purposes I would like to know
why I was unable to make the rings properly. Was I not following the
correct procedure? Where in the procedure could the error have
occurred? I have never before had a problem with facing-off being out
of square with the sides.

Thanks.

Michael Koblic,
Campbell River, BC


Copper as you know, is very soft. You can't clamp it very hard before it
distorts & also it will move in the chuck unless you take very light
cuts.
You did not say but I assume you deburred it before chucking in the
lathe?

Maybe check it with the square after you faced one end but before you
unclamp it to see if it had moved in the chuck during facing?

You would probably need to put it on a mandrel for perfect accuracy.

MikeB

--
Email is valid

Yup , mandrel . Bolt in the end with a rubber washer under a regular
steel
washer I'd machine the steel with the mandrel , trim the rubber with a
knife/sandpaper . Tighten the bolt , rubber expands and grips the
sleeve .
Take light cuts ...



I tried a similar thing but to make the mandrel I used a bar just under
the ID of the tube I wanted to machine. I then put pieces of thin wall
tube over the mandrel with O rings spaced along in between. When it was
tightened down the O rings expanded outward holding the tube in place.

===============TUBING TO BE MACHINED==================
|tube O tube O tube O tube O tube O tube O|
================================================== ====|
mandrel BOLT
================================================== ====|
|tube O tube O tube O tube O tube O tube O|
===============TUBING TO BE MACHINED==================



How much runout did you get ? Were the pieces of thinwall between the
o-rings a tight slip fit ?



I was actually using the setup to cleanup the outer surface of some
plastic pipe - more aesthetics than anything else, so I don't have any
measurements.

The thin-wall tube was just a neat sliding fit on the mandrel part
(again, no measurements - I just used what I had on hand & could make work).

This was for 16mm ID PVC tube.

I got the idea from seeing those well-nut fasteners & some expanding
pipe bungs at the local truck parts store.

http://www.google.com/search?q=pipe+bungs+expanding&source=lnms&tbm=isch &sa=X&ei=HKwAUt6rN8qskgX2nIC4Dg&ved=0CAkQ_AUoAQ&bi w=1347&bih=564

On Mon, 05 Aug 2013 21:28:22 -0400, BQ340
wrote:

On 8/5/2013 9:02 PM, wrote:
I was trying to make two rings from copper pipes, 1.625" OD (wall
thickness 0.061") and 2.125" OD (wall thickness 0.035") respectively.
The length of the ring was to be 0.75".

I cut the pipe oversize on my bandsaw. As expected the cut was not
exactly square. I clamped the first ring initially on the inside in my
3-jaw chuck trying to make sure that the sides of the piece were at
right angles to the body of the chuck as determined by a square.

I faced off the first side and deburred it. I reversed the ring and
clamped it the same way with the faced-off part flat against the jaws
base. I faced off the other end to the required dimension. Everything
looked good.

However, when I checked the final product with a square it was obvious
that neither plane of the ring was square to the sides. I did an
additional check with a height gauge with the ring on a flat (well, as
flat as I could get) surface. There was a difference of 0.017" in
height of the ring around the circumference.

I tried a second ring of the same diameter, this time clamping on the
outside. I checked the position with the square in three different
spots. The interesting part was that the fit was square in two of them
but not in the third.

Anyway, the result was almost identical and I got the same result with
the larger ring.

Although the result is adequate for my purposes I would like to know
why I was unable to make the rings properly. Was I not following the
correct procedure? Where in the procedure could the error have
occurred? I have never before had a problem with facing-off being out
of square with the sides.

Thanks.

Michael Koblic,
Campbell River, BC


Copper as you know, is very soft. You can't clamp it very hard before it
distorts & also it will move in the chuck unless you take very light
cuts. You did not say but I assume you deburred it before chucking in
the lathe?

Maybe check it with the square after you faced one end but before you
unclamp it to see if it had moved in the chuck during facing?

You would probably need to put it on a mandrel for perfect accuracy.

MikeB

Well stated!! Bravo!!

Copper moves like a freaking snake in a 3 jaw chuck. Its not easy to
work with in a proper collet with a bottom in it either.


--
""Almost all liberal behavioral tropes track the impotent rage of small
children. Thus, for example, there is also the popular tactic of
repeating some stupid, meaningless phrase a billion times" Arms for
hostages, arms for hostages, arms for hostages, it's just about sex, just
about sex, just about sex, dumb,dumb, money in politics,money in
politics, Enron, Enron, Enron. Nothing repeated with mind-numbing
frequency in all major news outlets will not be believed by some members
of the populace. It is the permanence of evil; you can't stop it." (Ann
Coulter)

"anorton" wrote in message
m...


Other folks mentioned making a mandrel, and maybe that is the right
way to do it, but it seems like too much work.

The mandrel can be an easy fit except for an inch or two beneath the
rings at the tailstock end. The chuck will squeeze the tube against it
to drive it. A short plug mandrel at each end might work.

On Mon, 5 Aug 2013 21:49:12 -0400, "Jim Wilkins"
wrote:

...

I can't make good rings that way either. I'd turn a wooden mandrel and
slide the pipe onto it, then part off the rings.

You can turn a shallow parting groove and use it to guide the bandsaw
blade. Saw a shallow cut, then rotate the work a little in the blade
travel direction so the flexible incoming blade rubs on and is guided
by the wall of the turned groove. Saw in a little and advance again.
Unless the blade is new and sharp it won't dig into the wall of the
groove much. Once the saw cut extends all around the blade should cut
the piece off squarely, or if not you can see it deflect.

The same trick can cut under the hard shell of a scrap hydraulic
cylinder rod with a tool you can easily sharpen rather than the
expensive sawblade.
jsw


After reading all this I am surprised the rings turned out as good as
they did :-)

I will remember the mandrel trick for next time it matters.

Thanks to all,

Michael Koblic,
Campbell River, BC

fired this volley in
:

I will remember the mandrel trick for next time it matters.

If one has a slitting saw and some time, you can make an "Expandrel" that
will fit tight in any size pipe you want to name, and can be CUT INTO in
order to part rings or to o.d.-surface thinwall tubing. I've seen
versions that will clamp to the outside of a tube to allow i.d.
finishing... but those are a bit of work to make (clinching rings, and
all that).

It depends on the value of the job. An hour or two making a disposable
fixture might be worth the time.

Lloyd