The other day I changed the boot on my car's CV joint, and while I
had the thing apart I began to wonder how they go about making it.
For anyone who hasn't had one apart, it's an outer housing with a
spherical cavity with six grooves around the inside. There's a ball
cage that's about six millimeters thick, spherical outside and inside,
with six oblong holes around it. Two a little longer so you can wiggle
the cage into the housing. It's a very snug fit. Inside that, a
six-sided vaguely star shaped piece. Spherical, again, on the outside,
and also a snug fit. The six grooves rounded bottom, for six ball
bearings to fit into.
The part I'm curious about, how do they setup to grind an internal
spherical surface, and how to measure it? Then the grooves cut in the
star and housing, they were rounded-bottom, to hug the bearings. But
there's also a gradient. As a ball rolls toward one end of the housing,
it moves slightly out of the cage, so the housing groove is deeper. But
as it rolls to the other end, the opposite is true, the groove in the
star has to be deeper. Again, how would you set up for that kind of
cut, and how to measure it when done?
I know the factories use CNC machines, but is it practically possible
to make such a shape with only manual machines and mechanical linkages?

--
B.B. --I am not a goat! thegoat4 at airmail dot net

On Fri, 19 May 2006 13:56:29 -0500, "B.B."
u wrote:

The other day I changed the boot on my car's CV joint, and while I
had the thing apart I began to wonder how they go about making it.
For anyone who hasn't had one apart, it's an outer housing with a
spherical cavity with six grooves around the inside. There's a ball
cage that's about six millimeters thick, spherical outside and inside,
with six oblong holes around it. Two a little longer so you can wiggle
the cage into the housing. It's a very snug fit. Inside that, a
six-sided vaguely star shaped piece. Spherical, again, on the outside,
and also a snug fit. The six grooves rounded bottom, for six ball
bearings to fit into.
The part I'm curious about, how do they setup to grind an internal
spherical surface, and how to measure it? Then the grooves cut in the
star and housing, they were rounded-bottom, to hug the bearings. But
there's also a gradient. As a ball rolls toward one end of the housing,
it moves slightly out of the cage, so the housing groove is deeper. But
as it rolls to the other end, the opposite is true, the groove in the
star has to be deeper. Again, how would you set up for that kind of
cut, and how to measure it when done?
I know the factories use CNC machines, but is it practically possible
to make such a shape with only manual machines and mechanical linkages?


Practically impossible just about sises it up.

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

"B.B." u wrote in message
news
The other day I changed the boot on my car's CV joint, and while I
had the thing apart I began to wonder how they go about making it.
For anyone who hasn't had one apart, it's an outer housing with a
spherical cavity with six grooves around the inside. There's a ball
cage that's about six millimeters thick, spherical outside and inside,
with six oblong holes around it. Two a little longer so you can wiggle
the cage into the housing. It's a very snug fit. Inside that, a
six-sided vaguely star shaped piece. Spherical, again, on the outside,
and also a snug fit. The six grooves rounded bottom, for six ball
bearings to fit into.
The part I'm curious about, how do they setup to grind an internal
spherical surface, and how to measure it? Then the grooves cut in the
star and housing, they were rounded-bottom, to hug the bearings. But
there's also a gradient. As a ball rolls toward one end of the housing,
it moves slightly out of the cage, so the housing groove is deeper. But
as it rolls to the other end, the opposite is true, the groove in the
star has to be deeper. Again, how would you set up for that kind of
cut, and how to measure it when done?
I know the factories use CNC machines, but is it practically possible
to make such a shape with only manual machines and mechanical linkages?

--
B.B. --I am not a goat! thegoat4 at airmail dot net
My recollection is these were once known as "Rzeppa" joints or something
like that and certainly predate any CNC machining. I believe the Cord FWD
automobiles from 1929 to 1938 might have used them. I have no idea how they
were made then. Research on "constant velocity universal joint" might bring
something to light.

Don Young

Don Young

Don Young wrote:

"B.B." u wrote in message
news
The other day I changed the boot on my car's CV joint, and while I
had the thing apart I began to wonder how they go about making it.
For anyone who hasn't had one apart, it's an outer housing with a
spherical cavity with six grooves around the inside. There's a ball
cage that's about six millimeters thick, spherical outside and inside,
with six oblong holes around it. Two a little longer so you can wiggle
the cage into the housing. It's a very snug fit. Inside that, a
six-sided vaguely star shaped piece. Spherical, again, on the outside,
and also a snug fit. The six grooves rounded bottom, for six ball
bearings to fit into.
The part I'm curious about, how do they setup to grind an internal
spherical surface, and how to measure it? Then the grooves cut in the
star and housing, they were rounded-bottom, to hug the bearings. But
there's also a gradient. As a ball rolls toward one end of the housing,
it moves slightly out of the cage, so the housing groove is deeper. But
as it rolls to the other end, the opposite is true, the groove in the
star has to be deeper. Again, how would you set up for that kind of
cut, and how to measure it when done?
I know the factories use CNC machines, but is it practically possible
to make such a shape with only manual machines and mechanical linkages?

--
B.B. --I am not a goat! thegoat4 at airmail dot net
My recollection is these were once known as "Rzeppa" joints or something
like that and certainly predate any CNC machining. I believe the Cord FWD
automobiles from 1929 to 1938 might have used them. I have no idea how they
were made then. Research on "constant velocity universal joint" might bring
something to light.

Don Young

Don Young

The early Cords used back to back cross type joints, the later Cord
810 & 812s used Bendix-Weiss Ball CV joints. The Rzeppa joint was a
later
joint that once the lube problems were overcome, has become the
prevalent cv joint of the industry.

Jim

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

From Google:

"A type of CV joint invented and introduced in 1926 by Alfred H. Rzeppa. It
uses six balls, and an inner and outer race to provide constant velocity
torque..."

Not so new.


"Jim" wrote in message ...
Don Young wrote:

"B.B." u wrote in
message

news
The other day I changed the boot on my car's CV joint, and while I
had the thing apart I began to wonder how they go about making it.
For anyone who hasn't had one apart, it's an outer housing with a
spherical cavity with six grooves around the inside. There's a ball
cage that's about six millimeters thick, spherical outside and inside,
with six oblong holes around it. Two a little longer so you can
wiggle
the cage into the housing. It's a very snug fit. Inside that, a
six-sided vaguely star shaped piece. Spherical, again, on the
outside,
and also a snug fit. The six grooves rounded bottom, for six ball
bearings to fit into.
The part I'm curious about, how do they setup to grind an internal
spherical surface, and how to measure it? Then the grooves cut in the
star and housing, they were rounded-bottom, to hug the bearings. But
there's also a gradient. As a ball rolls toward one end of the
housing,
it moves slightly out of the cage, so the housing groove is deeper.
But
as it rolls to the other end, the opposite is true, the groove in the
star has to be deeper. Again, how would you set up for that kind of
cut, and how to measure it when done?
I know the factories use CNC machines, but is it practically
possible
to make such a shape with only manual machines and mechanical
linkages?

--
B.B. --I am not a goat! thegoat4 at airmail dot net
My recollection is these were once known as "Rzeppa" joints or something
like that and certainly predate any CNC machining. I believe the Cord
FWD
automobiles from 1929 to 1938 might have used them. I have no idea how
they
were made then. Research on "constant velocity universal joint" might
bring
something to light.

Don Young

Don Young

The early Cords used back to back cross type joints, the later Cord
810 & 812s used Bendix-Weiss Ball CV joints. The Rzeppa joint was a
later
joint that once the lube problems were overcome, has become the
prevalent cv joint of the industry.

Jim

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

"Don Young" wrote in message
...

"B.B." u wrote in
message
news
The other day I changed the boot on my car's CV joint, and while I
had the thing apart I began to wonder how they go about making it.
For anyone who hasn't had one apart, it's an outer housing with a
spherical cavity with six grooves around the inside. There's a ball
cage that's about six millimeters thick, spherical outside and inside,
with six oblong holes around it. Two a little longer so you can wiggle
the cage into the housing. It's a very snug fit. Inside that, a
six-sided vaguely star shaped piece. Spherical, again, on the outside,
and also a snug fit. The six grooves rounded bottom, for six ball
bearings to fit into.
The part I'm curious about, how do they setup to grind an internal
spherical surface, and how to measure it? Then the grooves cut in the
star and housing, they were rounded-bottom, to hug the bearings. But
there's also a gradient. As a ball rolls toward one end of the housing,
it moves slightly out of the cage, so the housing groove is deeper. But
as it rolls to the other end, the opposite is true, the groove in the
star has to be deeper. Again, how would you set up for that kind of
cut, and how to measure it when done?
I know the factories use CNC machines, but is it practically possible
to make such a shape with only manual machines and mechanical linkages?

--
B.B. --I am not a goat! thegoat4 at airmail dot net
My recollection is these were once known as "Rzeppa" joints or something
like that and certainly predate any CNC machining. I believe the Cord FWD
automobiles from 1929 to 1938 might have used them. I have no idea how
they were made then. Research on "constant velocity universal joint" might
bring something to light.

Don Young

Don Young


Rzeppa joint were commonly used in heavy equipment front end loader
applications when they still used a steering axle before the idea of
articulation was in common use. They seemed to work well until one applied
max power when the wheels were turned. Althought that breakage might have
been a sign of the joint being worn out.
Steve