[Cydrome Leader]

I've tried to look this up and found no real answers so far.

Is there any sort of standard for cutting the chamfer on a thread lead-in?

Say I'm just threading the end of a 1/2" Al rod. The start of the thread
at the end will be jagged and weak. Cutting a 45 (I found 60 does nothing
useful) degree chamfer helps and makes thing far prettier, and for
anything I've done you can just eye-ball this and it really doesn't matter
too much how you do it for my uses.

What's done in the production world for stuff like this where looking
pretty is key? Is there a special angle and distance to cut this chamfer?

Would it be measured as distance into the thread, or the diameter of the
end of the fastner once cut?

Last question- how does one really measure a chamfer anyways? There's no
real surfaces to measure off.

[[email protected]]

On Wed, 22 Jan 2014 21:26:06 +0000 (UTC), Cydrome Leader
wrote:

I've tried to look this up and found no real answers so far.

Is there any sort of standard for cutting the chamfer on a thread lead-in?

Say I'm just threading the end of a 1/2" Al rod. The start of the thread
at the end will be jagged and weak. Cutting a 45 (I found 60 does nothing
useful) degree chamfer helps and makes thing far prettier, and for
anything I've done you can just eye-ball this and it really doesn't matter
too much how you do it for my uses.

What's done in the production world for stuff like this where looking
pretty is key? Is there a special angle and distance to cut this chamfer?

Would it be measured as distance into the thread, or the diameter of the
end of the fastner once cut?

Last question- how does one really measure a chamfer anyways? There's no
real surfaces to measure off.
Typically on a 60 degree thread a 45 degree chamfer will be cut just
beyond the major or minor diameter. Major for internal threads, minor
for external. So, for example, a 1/4-20 tapped hole will be
countersunk 90 degrees included angle to .265 diameter. But on work
that has a large tolerance the countersink may be much larger. When
measuring a chamfer it is fairly easy measure the diameter where the
chamfered surface intersects either the O.D. or I.D. There several
ways. One is to use a magnifier and calipers. This method is good
enough for +or- .003 for someone competent at inspecting machined
parts. Then there are magnifiers with built in reticles with scales
for measuring angles and distances. An optical comparator can be used
as well and then measurements to .001 are easy. Gauges are also
available that have a plunger ground for the specific angle of a
countersink, 100, 90, and 82 degree being the most common ones, that
have a dial indicator that shows either the depth or the diameter of
the countersink. These gauges are used by pressing them into the
countersink until the flat surface that the plunger protrudes from
contacts the work. If you are doing work for yourself then do just
what looks good. I like to finish screws with a rounded end. The
radius used on the end of the screw is much larger than the radius of
the screw, so the end of the screw isn't quite flat. This type of
finishing of screws is common on screws used in high quality
inspection equipment.
ERic

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[[email protected]]

On Wednesday, January 22, 2014 1:26:06 PM UTC-8, Cydrome Leader wrote:
I've tried to look this up and found no real answers so far.



Is there any sort of standard for cutting the chamfer on a thread lead-in?



Say I'm just threading the end of a 1/2" Al rod. The start of the thread

at the end will be jagged and weak. Cutting a 45 (I found 60 does nothing

useful) degree chamfer helps and makes thing far prettier, and for

anything I've done you can just eye-ball this and it really doesn't matter

too much how you do it for my uses.

Cut lead in chamfers slighty smaller than the tap size diameter.

IE 1/2-13 = .421 tap dia. .5-.421= .079 / 2 = .0395 chamfer
so .04 - .045 X 45 chamfer cut on before the threads will be fine.

Same kind of deal for taping. C-sink slighty larger than major thread diameter.






What's done in the production world for stuff like this where looking

pretty is key? Is there a special angle and distance to cut this chamfer?



Would it be measured as distance into the thread, or the diameter of the

end of the fastner once cut?

either way
.040 X 45deg chamfer
or
..42 dia. plus 45 deg.






Last question- how does one really measure a chamfer anyways? There's no

real surfaces to measure off.

chamfers are one time everybody can:
scale & eyeball vernier tips


The real c-sink question is :
Why are Flat Head Screws c-sink at 82 deg? (41 deg / side)
The heads of FHS are 45 deg.?

any takers?

[Miguel[_2_]]

On Wed, 22 Jan 2014 21:26:06 +0000 (UTC), Cydrome Leader
wrote:

I've tried to look this up and found no real answers so far.

Is there any sort of standard for cutting the chamfer on a thread lead-in?

Say I'm just threading the end of a 1/2" Al rod. The start of the thread
at the end will be jagged and weak. Cutting a 45 (I found 60 does nothing
useful) degree chamfer helps and makes thing far prettier, and for
anything I've done you can just eye-ball this and it really doesn't matter
too much how you do it for my uses.

What's done in the production world for stuff like this where looking
pretty is key? Is there a special angle and distance to cut this chamfer?

I just had a look at a number of Grade 8 bolts - all from Caterpillar
Tractor it happens - and none of them has a noticeable chamfer on the
beginning of the threads. Perhaps in the industrial world "pretty" is
not a common requirement.

Would it be measured as distance into the thread, or the diameter of the
end of the fastner once cut?

Last question- how does one really measure a chamfer anyways? There's no
real surfaces to measure off.

Most drawings I've seen call out a chamfer by the angle and the width
of the chamfer
--
Cheers,

Miguel

[Jim Wilkins[_2_]]

wrote in message
...
On Wed, 22 Jan 2014 21:26:06 +0000 (UTC), Cydrome Leader
wrote:

I've tried to look this up and found no real answers so far.

Is there any sort of standard for cutting the chamfer on a thread
lead-in?

...I like to finish screws with a rounded end. The
radius used on the end of the screw is much larger than the radius
of
the screw, so the end of the screw isn't quite flat. This type of
finishing of screws is common on screws used in high quality
inspection equipment.
ERic

The rounded form tool can be a quarter-round concave end mill, or
custom ground on a lathe bit with a conical stone in a die grinder.
The conical stone leaves a smooth and circular (or elliptical) edge
that is relieved all around for cutting clearance. You can measure and
mark the desired finish diameter on the stone.
jsw

[Larry Jaques[_4_]]

On Wed, 22 Jan 2014 15:47:49 -0800 (PST), wrote:

On Wednesday, January 22, 2014 1:26:06 PM UTC-8, Cydrome Leader wrote:
I've tried to look this up and found no real answers so far.



Is there any sort of standard for cutting the chamfer on a thread lead-in?



Say I'm just threading the end of a 1/2" Al rod. The start of the thread

at the end will be jagged and weak. Cutting a 45 (I found 60 does nothing

useful) degree chamfer helps and makes thing far prettier, and for

anything I've done you can just eye-ball this and it really doesn't matter

too much how you do it for my uses.

Cut lead in chamfers slighty smaller than the tap size diameter.

IE 1/2-13 = .421 tap dia. .5-.421= .079 / 2 = .0395 chamfer
so .04 - .045 X 45 chamfer cut on before the threads will be fine.

Same kind of deal for taping. C-sink slighty larger than major thread diameter.






What's done in the production world for stuff like this where looking

pretty is key? Is there a special angle and distance to cut this chamfer?



Would it be measured as distance into the thread, or the diameter of the

end of the fastner once cut?

either way
.040 X 45deg chamfer
or
.42 dia. plus 45 deg.






Last question- how does one really measure a chamfer anyways? There's no

real surfaces to measure off.

chamfers are one time everybody can:
scale & eyeball vernier tips

I'd recommend against using calipers as chamfer cutters, myself.


The real c-sink question is :
Why are Flat Head Screws c-sink at 82 deg? (41 deg / side)
The heads of FHS are 45 deg.?

any takers?

When I was in QA in the '70s, I inspected some FHSs which were 82,
while others were cut at 100 degs. I guess the former were US
standards while the latter was aviation.

Oops, these guys show a larger array of angles for countersinks.
http://en.wikipedia.org/wiki/Countersink


Are you in MetricLand? 90 would be the norm, giving you your fave 45
number.

--
Sound character provides the power with which a person may ride
the emergencies of life instead of being overwhelmed by them.
Failure is... the highway to success.
--Og Mandino

[PrecisionmachinisT]

"Cydrome Leader" wrote in message
...
I've tried to look this up and found no real answers so far.

Is there any sort of standard for cutting the chamfer on a thread lead-in?

Say I'm just threading the end of a 1/2" Al rod. The start of the thread
at the end will be jagged and weak. Cutting a 45 (I found 60 does nothing
useful) degree chamfer helps and makes thing far prettier, and for
anything I've done you can just eye-ball this and it really doesn't matter
too much how you do it for my uses.

What's done in the production world for stuff like this where looking
pretty is key? Is there a special angle and distance to cut this chamfer?


No reason to chamfer beyond the root diameter.

Would it be measured as distance into the thread, or the diameter of the
end of the fastner once cut?

Diameter after cut, or depth below theoretical major, take your pick...

Last question- how does one really measure a chamfer anyways? There's no
real surfaces to measure off.

Optical comparators work really well for this.

[PrecisionmachinisT]

"Miguel" wrote in message
...
On Wed, 22 Jan 2014 21:26:06 +0000 (UTC), Cydrome Leader
wrote:

I've tried to look this up and found no real answers so far.

Is there any sort of standard for cutting the chamfer on a thread lead-in?

Say I'm just threading the end of a 1/2" Al rod. The start of the thread
at the end will be jagged and weak. Cutting a 45 (I found 60 does nothing
useful) degree chamfer helps and makes thing far prettier, and for
anything I've done you can just eye-ball this and it really doesn't matter
too much how you do it for my uses.

What's done in the production world for stuff like this where looking
pretty is key? Is there a special angle and distance to cut this chamfer?

I just had a look at a number of Grade 8 bolts - all from Caterpillar
Tractor it happens - and none of them has a noticeable chamfer on the
beginning of the threads. Perhaps in the industrial world "pretty" is
not a common requirement.

Those probably are rolled threads.


Would it be measured as distance into the thread, or the diameter of the
end of the fastner once cut?

Last question- how does one really measure a chamfer anyways? There's no
real surfaces to measure off.

Most drawings I've seen call out a chamfer by the angle and the width
of the chamfer
--
Cheers,

Miguel

[Miguel[_2_]]

On Wed, 22 Jan 2014 20:06:01 -0800, "PrecisionmachinisT"
wrote:


"Miguel" wrote in message
.. .
On Wed, 22 Jan 2014 21:26:06 +0000 (UTC), Cydrome Leader
wrote:

I've tried to look this up and found no real answers so far.

Is there any sort of standard for cutting the chamfer on a thread lead-in?

Say I'm just threading the end of a 1/2" Al rod. The start of the thread
at the end will be jagged and weak. Cutting a 45 (I found 60 does nothing
useful) degree chamfer helps and makes thing far prettier, and for
anything I've done you can just eye-ball this and it really doesn't matter
too much how you do it for my uses.

What's done in the production world for stuff like this where looking
pretty is key? Is there a special angle and distance to cut this chamfer?

I just had a look at a number of Grade 8 bolts - all from Caterpillar
Tractor it happens - and none of them has a noticeable chamfer on the
beginning of the threads. Perhaps in the industrial world "pretty" is
not a common requirement.

Those probably are rolled threads.

If it was it was pretty sneaky as the o.d. of the threads and the bolt
was identical :-)



Would it be measured as distance into the thread, or the diameter of the
end of the fastner once cut?

Last question- how does one really measure a chamfer anyways? There's no
real surfaces to measure off.

Most drawings I've seen call out a chamfer by the angle and the width
of the chamfer
--
Cheers,

Miguel

--
Cheers,

Miguel

[Jim Wilkins[_2_]]

"Miguel" wrote in message
...
On Wed, 22 Jan 2014 20:06:01 -0800, "PrecisionmachinisT"
wrote:


Those probably are rolled threads.

If it was it was pretty sneaky as the o.d. of the threads and the
bolt
was identical :-)

Even micrometer threads are rolled. Look closely at how the metal
extruded at the end, amd measure the ODs of the threads and the
unthreaded shank.
jsw

[Miguel[_2_]]

On Thu, 23 Jan 2014 09:15:14 -0500, "Jim Wilkins"
wrote:

"Miguel" wrote in message
.. .
On Wed, 22 Jan 2014 20:06:01 -0800, "PrecisionmachinisT"
wrote:


Those probably are rolled threads.

If it was it was pretty sneaky as the o.d. of the threads and the
bolt
was identical :-)

Even micrometer threads are rolled. Look closely at how the metal
extruded at the end, amd measure the ODs of the threads and the
unthreaded shank.
jsw

I did, and I just said that the O.D. of both the unthreaded shank and
the threads was identical.
--
Cheers,

Miguel

[[email protected]]

On Fri, 24 Jan 2014 06:41:34 +0700, Miguel wrote:

On Thu, 23 Jan 2014 09:15:14 -0500, "Jim Wilkins"
wrote:

"Miguel" wrote in message
. ..
On Wed, 22 Jan 2014 20:06:01 -0800, "PrecisionmachinisT"
wrote:


Those probably are rolled threads.

If it was it was pretty sneaky as the o.d. of the threads and the
bolt
was identical :-)

Even micrometer threads are rolled. Look closely at how the metal
extruded at the end, amd measure the ODs of the threads and the
unthreaded shank.
jsw

I did, and I just said that the O.D. of both the unthreaded shank and
the threads was identical.
Greetings Miguel,
I just measured the threads on several grade 8 capscrews. All the
screws have rolled threads. I was surprised to find the the O.D. of
the threads and the shanks were the same diameter within .001". This
implies some pretty tight tolerances on the screw shanks before the
threads were rolled. But why not? It really makes sense. Thread
rolling requires accurate sizing, too big and the rolls can break or
chip, too small and the thread comes out way undersize. A rolled
thread screw is easy to identify with just a casual inspection.
Between where the thread stops and the shank begins is a taper that
goes from the shank O.D. to the diameter of the screw before rolling.
You can aslo plainly see that the thread diminishes to nothing on this
taper. A cut thread will have 4 terminations where the 4 dies in the
die head stop cutting when they pull away from the work. I haven't
seen a cut thread machine screw in some time.
Cheers,
Eric

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[Cydrome Leader]

Gunner Asch wrote:
On Wed, 22 Jan 2014 15:40:25 -0800, wrote:

On Wed, 22 Jan 2014 21:26:06 +0000 (UTC), Cydrome Leader
wrote:

I've tried to look this up and found no real answers so far.

Is there any sort of standard for cutting the chamfer on a thread lead-in?

Say I'm just threading the end of a 1/2" Al rod. The start of the thread
at the end will be jagged and weak. Cutting a 45 (I found 60 does nothing
useful) degree chamfer helps and makes thing far prettier, and for
anything I've done you can just eye-ball this and it really doesn't matter
too much how you do it for my uses.

What's done in the production world for stuff like this where looking
pretty is key? Is there a special angle and distance to cut this chamfer?

Would it be measured as distance into the thread, or the diameter of the
end of the fastner once cut?

Last question- how does one really measure a chamfer anyways? There's no
real surfaces to measure off.
Typically on a 60 degree thread a 45 degree chamfer will be cut just
beyond the major or minor diameter. Major for internal threads, minor
for external. So, for example, a 1/4-20 tapped hole will be
countersunk 90 degrees included angle to .265 diameter. But on work
that has a large tolerance the countersink may be much larger. When
measuring a chamfer it is fairly easy measure the diameter where the
chamfered surface intersects either the O.D. or I.D. There several
ways. One is to use a magnifier and calipers. This method is good
enough for +or- .003 for someone competent at inspecting machined
parts. Then there are magnifiers with built in reticles with scales
for measuring angles and distances. An optical comparator can be used
as well and then measurements to .001 are easy. Gauges are also
available that have a plunger ground for the specific angle of a
countersink, 100, 90, and 82 degree being the most common ones, that
have a dial indicator that shows either the depth or the diameter of
the countersink. These gauges are used by pressing them into the
countersink until the flat surface that the plunger protrudes from
contacts the work. If you are doing work for yourself then do just
what looks good. I like to finish screws with a rounded end. The
radius used on the end of the screw is much larger than the radius of
the screw, so the end of the screw isn't quite flat. This type of
finishing of screws is common on screws used in high quality
inspection equipment.
ERic

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And most of those are indeed done on an optical comparator, sometimes
with additional magnification. Its the fastest and easiest way to
check. Yeah..you can use all manner of nifty indicators and gauges
and whatnot..but with an OC..you turn on the light, focus and turn the
screen to the angle section.

What about for cutting the parts?

I use a sherline, so the compound slide cuts from the "back" of the lathe
with upside down toolbits. I've just been touching the end of the work
with the cutter tip and then doing the math and making the cuts. I touch
off on the end of the work piece as if I prick it and mess up the surface,
it doesn't matter as that side gets cut off anyways. I can't think if any
tricks to make this easier, but I'm all ears if there are tips for this.

[Jim Wilkins[_2_]]

"Cydrome Leader" wrote in message
...

What about for cutting the parts?

I use a sherline, so the compound slide cuts from the "back" of the
lathe
with upside down toolbits. I've just been touching the end of the
work
with the cutter tip and then doing the math and making the cuts. I
touch
off on the end of the work piece as if I prick it and mess up the
surface,
it doesn't matter as that side gets cut off anyways. I can't think
if any
tricks to make this easier, but I'm all ears if there are tips for
this.

Your question is unclear. Are you asking how to cut-off to a specific
length?

I normally measure from the cutoff blade to the end of the work with a
ruler, which is good to about 0.01". For closer accuracy the end rod
on a 4" dial caliper serves well.

[Cydrome Leader]

Jim Wilkins wrote:
"Cydrome Leader" wrote in message
...

What about for cutting the parts?

I use a sherline, so the compound slide cuts from the "back" of the
lathe
with upside down toolbits. I've just been touching the end of the
work
with the cutter tip and then doing the math and making the cuts. I
touch
off on the end of the work piece as if I prick it and mess up the
surface,
it doesn't matter as that side gets cut off anyways. I can't think
if any
tricks to make this easier, but I'm all ears if there are tips for
this.

Your question is unclear. Are you asking how to cut-off to a specific
length?

I normally measure from the cutoff blade to the end of the work with a
ruler, which is good to about 0.01". For closer accuracy the end rod
on a 4" dial caliper serves well.

I mean to cut a chamfer, where the size matters, say for a 45 degree
compression fitting.

I had to make a few of these, and in theory the distance from the OD or
the end of the rod to where the cut starts is the same for 45 degrees.

The parts I made will work fine, but I noticed there's not a really good
way to measure them just to be sure. There's nothing for calipers to catch
on so it's an issue of make the cuts and just hope it's right.

[[email protected]]

On Mon, 27 Jan 2014 22:50:53 +0000 (UTC), Cydrome Leader
wrote:

Jim Wilkins wrote:
"Cydrome Leader" wrote in message
...

What about for cutting the parts?

I use a sherline, so the compound slide cuts from the "back" of the
lathe
with upside down toolbits. I've just been touching the end of the
work
with the cutter tip and then doing the math and making the cuts. I
touch
off on the end of the work piece as if I prick it and mess up the
surface,
it doesn't matter as that side gets cut off anyways. I can't think
if any
tricks to make this easier, but I'm all ears if there are tips for
this.

Your question is unclear. Are you asking how to cut-off to a specific
length?

I normally measure from the cutoff blade to the end of the work with a
ruler, which is good to about 0.01". For closer accuracy the end rod
on a 4" dial caliper serves well.

I mean to cut a chamfer, where the size matters, say for a 45 degree
compression fitting.

I had to make a few of these, and in theory the distance from the OD or
the end of the rod to where the cut starts is the same for 45 degrees.

The parts I made will work fine, but I noticed there's not a really good
way to measure them just to be sure. There's nothing for calipers to catch
on so it's an issue of make the cuts and just hope it's right.
If you have a good loupe, at least 7x, then you can indeed use
calipers to measure the chamfer. You just compare the chamfer to the
open calipers. If you open the calipers .003" at a time it will be
easy to see the difference. You can also grind a tool to the correct
angle and just plunge cut the chamfer.
Eric

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[Jim Wilkins[_2_]]

"Cydrome Leader" wrote in message
...
Jim Wilkins wrote:

I mean to cut a chamfer, where the size matters, say for a 45 degree
compression fitting.

I had to make a few of these, and in theory the distance from the OD
or
the end of the rod to where the cut starts is the same for 45
degrees.

The parts I made will work fine, but I noticed there's not a really
good
way to measure them just to be sure. There's nothing for calipers to
catch
on so it's an issue of make the cuts and just hope it's right.


I use one of these, bought used for much less, to measure features
where calipers have nothing to catch on:
http://www.2spi.com/catalog/magnifiers/mag8.php

The smallest division is 0.0025" which is fine for my home projects.

You could make a gauge from a solid rod and a sleeve that fits over
it, hobby brass tubing works well, and calculate the distance the
sleeve should slide over the rod onto the chamfer, at the sleeve's
inner diameter.

For example if the flat on the end of the chamfer is 0.3" in diameter
and the ID of the tube is 0.5" it should slide in 0.1".

If you clamp the sleeve and rod together and machine their ends flush
(actual length doesn't matter) you can measure the offset directly
with the step on a caliper.
jsw

[Cydrome Leader]

Jim Wilkins wrote:
"Cydrome Leader" wrote in message
...
Jim Wilkins wrote:

I mean to cut a chamfer, where the size matters, say for a 45 degree
compression fitting.

I had to make a few of these, and in theory the distance from the OD
or
the end of the rod to where the cut starts is the same for 45
degrees.

The parts I made will work fine, but I noticed there's not a really
good
way to measure them just to be sure. There's nothing for calipers to
catch
on so it's an issue of make the cuts and just hope it's right.


I use one of these, bought used for much less, to measure features
where calipers have nothing to catch on:
http://www.2spi.com/catalog/magnifiers/mag8.php

The smallest division is 0.0025" which is fine for my home projects.

Interesting tool there, I'll have to pick one up.

You could make a gauge from a solid rod and a sleeve that fits over
it, hobby brass tubing works well, and calculate the distance the
sleeve should slide over the rod onto the chamfer, at the sleeve's
inner diameter.

For example if the flat on the end of the chamfer is 0.3" in diameter
and the ID of the tube is 0.5" it should slide in 0.1".

If you clamp the sleeve and rod together and machine their ends flush
(actual length doesn't matter) you can measure the offset directly
with the step on a caliper.
jsw

good idea. As much as folks complain about off topic stuff, there's lots
of good answers around here.