When I was tightening up some bolts that used an Allen key, I started to
wonder: how do they make the hexagonal hole in the top of the bolt that the
key fits into ?

I imagine they drill a pilot hole and then enlarge it with a milling
machine, but the corners of the hexagon are angular, not rounded as you'd
expect a milling machine to make. Or do they finish it off with a very small
diameter milling tool so the corners, although still rounded, have a very
small radius or curvature and so look to be a sharp-cornered hexagon?

NY wrote:
When I was tightening up some bolts that used an Allen key, I started to
wonder: how do they make the hexagonal hole in the top of the bolt that the
key fits into ?

I imagine they drill a pilot hole and then enlarge it with a milling
machine, but the corners of the hexagon are angular, not rounded as you'd
expect a milling machine to make. Or do they finish it off with a very small
diameter milling tool so the corners, although still rounded, have a very
small radius or curvature and so look to be a sharp-cornered hexagon?



I've always assumed they start with a round hole and then crimp the head
around a hex former. Can't see how else you would do it.

Tim

NY wrote:
When I was tightening up some bolts that used an Allen key, I started to
wonder: how do they make the hexagonal hole in the top of the bolt that
the key fits into ?

I imagine they drill a pilot hole and then enlarge it with a milling
machine, but the corners of the hexagon are angular, not rounded as
you'd expect a milling machine to make. Or do they finish it off with a
very small diameter milling tool so the corners, although still rounded,
have a very small radius or curvature and so look to be a sharp-cornered
hexagon?
I think you imagine wrongly, Probably stamped with a die or forged,
there would be other methods but not as easy.

On 19/04/2016 09:43, NY wrote:
When I was tightening up some bolts that used an Allen key, I started to
wonder: how do they make the hexagonal hole in the top of the bolt that
the key fits into ?

I imagine they drill a pilot hole and then enlarge it with a milling
machine, but the corners of the hexagon are angular, not rounded as
you'd expect a milling machine to make. Or do they finish it off with a
very small diameter milling tool so the corners, although still rounded,
have a very small radius or curvature and so look to be a sharp-cornered
hexagon?

https://www.youtube.com/watch?v=3kxcw08p_oY

Doesn't show the hex head, but it'll just be a different set of dies.
Dice? Dunno.

Cheers
--
Syd

On 4/19/2016 9:51 AM, F Murtz wrote:
NY wrote:
When I was tightening up some bolts that used an Allen key, I started to
wonder: how do they make the hexagonal hole in the top of the bolt that
the key fits into ?

I imagine they drill a pilot hole and then enlarge it with a milling
machine, but the corners of the hexagon are angular, not rounded as
you'd expect a milling machine to make. Or do they finish it off with a
very small diameter milling tool so the corners, although still rounded,
have a very small radius or curvature and so look to be a sharp-cornered
hexagon?
I think you imagine wrongly, Probably stamped with a die or forged,
there would be other methods but not as easy.

I'm pretty sure they will be hot forged.

NY wrote:
When I was tightening up some bolts that used an Allen key, I started to
wonder: how do they make the hexagonal hole in the top of the bolt that
the key fits into ?

I imagine they drill a pilot hole and then enlarge it with a milling
machine, but the corners of the hexagon are angular, not rounded as
you'd expect a milling machine to make. Or do they finish it off with a
very small diameter milling tool so the corners, although still rounded,
have a very small radius or curvature and so look to be a sharp-cornered
hexagon?
There is an article in the latest Model Engineers Workshop magazine on
an amateur rotary broaching technique that will make sharp cornered
polyagonal holes on either a lathe or a mill.
Quite an interesting read but certainly not the way socket cap screws
will be made commercially.

Bob

"NY" wrote in message
o.uk...

When I was tightening up some bolts that used an Allen key, I started to
wonder: how do they make the hexagonal hole in the top of the bolt that the
key fits into ?

I imagine they drill a pilot hole and then enlarge it with a milling
machine, but the corners of the hexagon are angular, not rounded as you'd
expect a milling machine to make. Or do they finish it off with a very
small diameter milling tool so the corners, although still rounded, have a
very small radius or curvature and so look to be a sharp-cornered hexagon?


They will be hot stamped or rotary broached in quantity, but this is how I
did a 'one off' :


http://madmodder.net/index.php/topic...html#msg103240


Andrew

On 19/04/2016 09:43, NY wrote:
When I was tightening up some bolts that used an Allen key, I started to
wonder: how do they make the hexagonal hole in the top of the bolt that
the key fits into ?

I imagine they drill a pilot hole and then enlarge it with a milling
machine, but the corners of the hexagon are angular, not rounded as
you'd expect a milling machine to make. Or do they finish it off with a
very small diameter milling tool so the corners, although still rounded,
have a very small radius or curvature and so look to be a sharp-cornered
hexagon?

If it's been custom machined, you can often see the metal from where
they drilled a hole then pushed a tool down to make the corners. There
are six little tails all squashed down at the bottom.

For regular bolts, I'd imagine it would be pressed/stamped in some way.

On 19/04/2016 10:12, Syd Rumpo wrote:

https://www.youtube.com/watch?v=3kxcw08p_oY

Doesn't show the hex head, but it'll just be a different set of dies.
Dice? Dunno.

Cheers

Cheers. I enjoyed that video. Those automatic machines are impressive.

On 20/04/2016 09:42, GB wrote:
On 19/04/2016 10:12, Syd Rumpo wrote:

https://www.youtube.com/watch?v=3kxcw08p_oY

Doesn't show the hex head, but it'll just be a different set of dies.
Dice? Dunno.

Cheers

Cheers. I enjoyed that video. Those automatic machines are impressive.

I liked the thread forming best, I was expecting some sort of 'normal'
rotating die.

Cheers
--
Syd

On Wed, 20 Apr 2016 09:42:11 +0100, GB wrote:

On 19/04/2016 10:12, Syd Rumpo wrote:

https://www.youtube.com/watch?v=3kxcw08p_oY

Doesn't show the hex head, but it'll just be a different set of dies.
Dice? Dunno.

Cheers

Cheers. I enjoyed that video. Those automatic machines are impressive.

I can watch 'How It's Made' (when it's on, usually Quest) for hours.

In message , GB
writes
On 19/04/2016 10:12, Syd Rumpo wrote:

https://www.youtube.com/watch?v=3kxcw08p_oY

Doesn't show the hex head, but it'll just be a different set of dies.

Cheers. I enjoyed that video. Those automatic machines are impressive.

Extremely. Not knowing anything about these processes, I wonder why the
bolts are cold forged, but the nuts require heat.

--
Graeme

On 20/04/2016 11:01, News wrote:
In message , GB
writes
On 19/04/2016 10:12, Syd Rumpo wrote:

https://www.youtube.com/watch?v=3kxcw08p_oY

Doesn't show the hex head, but it'll just be a different set of dies.

Cheers. I enjoyed that video. Those automatic machines are impressive.

Extremely. Not knowing anything about these processes, I wonder why the
bolts are cold forged, but the nuts require heat.

I would guess that the bolts are cold forged because there are several
stages and it would be difficult to clamp them firmly enough while hot
and keep them hot through the stages.

The nuts are made in a single motion with no need to hold them other
than with the hex forming die. The threads are cut cold. Also, the nuts
don't have to be as strong.

Pure speculation.

Cheers
--
Syd

On Tue, 19 Apr 2016 14:32:29 +0100, Clive George wrote:

On 19/04/2016 09:43, NY wrote:
When I was tightening up some bolts that used an Allen key, I started to
wonder: how do they make the hexagonal hole in the top of the bolt that
the key fits into ?

I imagine they drill a pilot hole and then enlarge it with a milling
machine, but the corners of the hexagon are angular, not rounded as
you'd expect a milling machine to make. Or do they finish it off with a
very small diameter milling tool so the corners, although still rounded,
have a very small radius or curvature and so look to be a sharp-cornered
hexagon?

If it's been custom machined, you can often see the metal from where
they drilled a hole then pushed a tool down to make the corners. There
are six little tails all squashed down at the bottom.

For regular bolts, I'd imagine it would be pressed/stamped in some way.

ISTR, from many, many Fortnights ago, the term "cold-heading", i.e.
wham-bang-goodbye mam.
--
Peter.
The gods will stay away
whilst religions hold sway

On 20/04/2016 10:03, Syd Rumpo wrote:
On 20/04/2016 09:42, GB wrote:
On 19/04/2016 10:12, Syd Rumpo wrote:

https://www.youtube.com/watch?v=3kxcw08p_oY

Doesn't show the hex head, but it'll just be a different set of dies.
Dice? Dunno.

Cheers

Cheers. I enjoyed that video. Those automatic machines are impressive.

I liked the thread forming best, I was expecting some sort of 'normal'
rotating die.

Cheers

I am pretty sure that rolling threads is both faster and results in a
stronger bolt or screw.

On 22/04/2016 09:55, Steve Walker wrote:
On 20/04/2016 10:03, Syd Rumpo wrote:
On 20/04/2016 09:42, GB wrote:
On 19/04/2016 10:12, Syd Rumpo wrote:

https://www.youtube.com/watch?v=3kxcw08p_oY

Doesn't show the hex head, but it'll just be a different set of dies.
Dice? Dunno.

Cheers

Cheers. I enjoyed that video. Those automatic machines are impressive.

I liked the thread forming best, I was expecting some sort of 'normal'
rotating die.

Cheers

I am pretty sure that rolling threads is both faster and results in a
stronger bolt or screw.

I'm impressed that it lines up perfectly all the way round, and there's
no join.

"NY" wrote in message
o.uk...
When I was tightening up some bolts that used an Allen key, I started to
wonder: how do they make the hexagonal hole in the top of the bolt that
the key fits into ?

I imagine they drill a pilot hole and then enlarge it with a milling
machine, but the corners of the hexagon are angular, not rounded as you'd
expect a milling machine to make. Or do they finish it off with a very
small diameter milling tool so the corners, although still rounded, have a
very small radius or curvature and so look to be a sharp-cornered hexagon?

It's forged that way.