Awl --

I got a hardware-store eye-bolt, 1/4-20, garden variety, not welded or cast.

The thread measures .246 -- no pro'leng.
But the part of the rod that forms the eye measures .210-.215.... !!

Shouldn't the eyebolt measure .246 *everywhere*?

Or did they form-thread .215 rod, with the threads now deformed out to
..246?
I figger that's gotta be the explanation?
I know about form tapping, just never heard of form-threading, which I
assume must exist.

--
EA

Existential Angst wrote:
Awl --

I got a hardware-store eye-bolt, 1/4-20, garden variety, not welded or cast.

The thread measures .246 -- no pro'leng.
But the part of the rod that forms the eye measures .210-.215.... !!

Shouldn't the eyebolt measure .246 *everywhere*?

Or did they form-thread .215 rod, with the threads now deformed out to
.246?
I figger that's gotta be the explanation?
I know about form tapping, just never heard of form-threading, which I
assume must exist.


Standard procedure just look up thread rolling. You can get tools to do
it on a normal lathe. Have a look at youtube for videos of the process.
Things like the splined drive shafts on many vehicles have been formed
in a similar manner for decades. It's a cold forming process.

"Existential Angst" fired this volley in
:

I figger that's gotta be the explanation?
I know about form tapping, just never heard of form-threading, which I
assume must exist.


Assuming the threads were cut, they'd have to begin with a blank that had
the thread area larger than the rest.

But that's not the standard way "screw machine" equipment works on cheap
fasteners. Not only does roll forming exist, it is the standard way by
which its done in mass-production.

They don't even use a "forming die", they use flat forming plates between
two of which the stock is rolled under extreme pressure to create the
threads.

LLoyd

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"Existential Angst" fired this volley in
:

I figger that's gotta be the explanation?
I know about form tapping, just never heard of form-threading, which I
assume must exist.


Assuming the threads were cut, they'd have to begin with a blank that had
the thread area larger than the rest.

But that's not the standard way "screw machine" equipment works on cheap
fasteners. Not only does roll forming exist, it is the standard way by
which its done in mass-production.

They don't even use a "forming die", they use flat forming plates between
two of which the stock is rolled under extreme pressure to create the
threads.

Mystery solved!
Heh, but boy, the threads sure do *look* like cut threads!

So much for traditional machining, eh?
--
EA


LLoyd

On Jan 6, 3:00*pm, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:
"Existential Angst" fired this volley :

I figger that's gotta be the explanation?
I know about form tapping, just never heard of form-threading, which I
assume must exist.

Assuming the threads were cut, they'd have to begin with a blank that had
the thread area larger than the rest. *

But that's not the standard way "screw machine" equipment works on cheap
fasteners. *Not only does roll forming exist, it is the standard way by
which its done in mass-production.

They don't even use a "forming die", they use flat forming plates between
two of which the stock is rolled under extreme pressure to create the
threads.

LLoyd

Not just cheap fasteners, though?
I thought roll-formed threads were stronger than cut.

Dave

"Dave__67" wrote in message
...
On Jan 6, 3:00 pm, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:
"Existential Angst" fired this volley
:

I figger that's gotta be the explanation?
I know about form tapping, just never heard of form-threading, which I
assume must exist.

Assuming the threads were cut, they'd have to begin with a blank that had
the thread area larger than the rest.

But that's not the standard way "screw machine" equipment works on cheap
fasteners. Not only does roll forming exist, it is the standard way by
which its done in mass-production.

They don't even use a "forming die", they use flat forming plates between
two of which the stock is rolled under extreme pressure to create the
threads.

LLoyd

Not just cheap fasteners, though?
I thought roll-formed threads were stronger than cut.

Dave

They are.

--
Ed Huntress

On Wed, 06 Jan 2010 19:57:44 +0000, David Billington
wrote:

Existential Angst wrote:
Awl --

I got a hardware-store eye-bolt, 1/4-20, garden variety, not welded or cast.

The thread measures .246 -- no pro'leng.
But the part of the rod that forms the eye measures .210-.215.... !!

Shouldn't the eyebolt measure .246 *everywhere*?

Or did they form-thread .215 rod, with the threads now deformed out to
.246?
I figger that's gotta be the explanation?
I know about form tapping, just never heard of form-threading, which I
assume must exist.


Standard procedure just look up thread rolling. You can get tools to do
it on a normal lathe. Have a look at youtube for videos of the process.
Things like the splined drive shafts on many vehicles have been formed
in a similar manner for decades. It's a cold forming process.
Back in the good old days (prior to '82) when I worked from an on site
office rather than in the regional cube farm, whenever I came up with
a bright idea, be it work related or personal, I just went to the
maintenance shop and did my thing with available materials. One day I
grabbed a handful of 1/4-20x1 cap screws and, after trying for some
time to start the nut on one, took a closer look. The nicely formed
threads looked great except for the fact that they were half way
between RH and LH, i.e. they were just ridges around the shaft!
Apparently, the blank hit the rolls at the wrong angle.
Gerry :-)}
London, Canada

On Wed, 6 Jan 2010 16:21:39 -0500, "Existential Angst"
wrote:

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
.3.70...
"Existential Angst" fired this volley in
:

I figger that's gotta be the explanation?
I know about form tapping, just never heard of form-threading, which I
assume must exist.


Assuming the threads were cut, they'd have to begin with a blank that had
the thread area larger than the rest.

But that's not the standard way "screw machine" equipment works on cheap
fasteners. Not only does roll forming exist, it is the standard way by
which its done in mass-production.

They don't even use a "forming die", they use flat forming plates between
two of which the stock is rolled under extreme pressure to create the
threads.

Mystery solved!
Heh, but boy, the threads sure do *look* like cut threads!

Not only that but the fastener is supposedly stronger than if the
threads were die cut.
Gerry :-)}
London, Canada

On Wed, 6 Jan 2010 14:42:16 -0500, "Existential Angst"
wrote:

Awl --

I got a hardware-store eye-bolt, 1/4-20, garden variety, not welded or cast.

The thread measures .246 -- no pro'leng.
But the part of the rod that forms the eye measures .210-.215.... !!

Shouldn't the eyebolt measure .246 *everywhere*?

Or did they form-thread .215 rod, with the threads now deformed out to
.246?
I figger that's gotta be the explanation?
I know about form tapping, just never heard of form-threading, which I
assume must exist.
==============
see
http://video.google.com/videosearch?...ed=0CDUQqwQwCQ
http://www.efunda.com/processes/meta...ad_rolling.cfm


The only problems are cosmetic in that the crests of the thread
may not not be perfect, but the crests don't effect the
functionality of the thread.
Unka George

(George McDuffee)

The past is a foreign country;
they do things differently there.
L. P. Hartley (1895-1972), British author.
The Go-Between, Prologue (1953).