So how do they machine that?
 

I was looking at a steel pulley block the a while ago (the type that
fits onto the end of a crank shaft on an engine and drives the belts)...

It was apparently machined from solid. The hole though the centre of the
approx 3" thick pulley was perhaps 1/2" diameter. The through hole had a
square cut slot (approx 5mm deep and wide) machined into its
circumference for a woodruff key. I was struggling to visualise how you
could machine that, anyone know?

(just occurred to me it may have started life as a casting with the key
slot already cast in place - perhaps it was just drilled and trimmed up
after)




--
Cheers,

John.

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| Internode Ltd - http://www.internode.co.uk |
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| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

It was apparently machined from solid. The hole though the centre of the
approx 3" thick pulley was perhaps 1/2" diameter. The through hole had a
square cut slot (approx 5mm deep and wide) machined into its circumference
for a woodruff key. I was struggling to visualise how you could machine
that, anyone know?

Broached maybe?

Phil

"John Rumm" wrote in message
...
I was looking at a steel pulley block the a while ago (the type that fits
onto the end of a crank shaft on an engine and drives the belts)...

It was apparently machined from solid. The hole though the centre of the
approx 3" thick pulley was perhaps 1/2" diameter. The through hole had a
square cut slot (approx 5mm deep and wide) machined into its circumference
for a woodruff key. I was struggling to visualise how you could machine
that, anyone know?

A broach would be the usual way to make an odd-shaped hole.

http://www.culvertool.com/Products.htm

shows some of the shapes you can make with a broach.

Colin Bignell

nightjar nightjar@ wrote:

A broach would be the usual way to make an odd-shaped hole.

http://www.culvertool.com/Products.htm

shows some of the shapes you can make with a broach.

Yup that looks like the job... in fact the wikipedia entry
(http://en.wikipedia.org/wiki/Broach) explicitly cites making keyways
and splines on gear wheels etc.

Not a technique I had come across before though - Hence why I was having
difficulty working out how you would get an end mill in there ;-)

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Wed, 22 Jun 2005 16:41:24 +0100, John Rumm
wrote:

The through hole had a
square cut slot (approx 5mm deep and wide) machined into its
circumference for a woodruff key.

Usually cut with a slotting machine, rather than a broach. This is like
a shaper, but skinny and with a long reach - they were the original form
of shaper and one of the first specialised machines tools. (A shaper is
a single point tool like a lathe tool, oscillating back and forth whilst
the work moves sideways beneath it.)

Internal splines are usually broached, but broach tooling is expensive,
and needs an expensive press to operate it. So if you're just doing a
single keyway slot, a slotting machine is simpler.

On Wed, 22 Jun 2005 20:38:21 +0100, Andy Dingley
wrote:

On Wed, 22 Jun 2005 16:41:24 +0100, John Rumm
wrote:

The through hole had a
square cut slot (approx 5mm deep and wide) machined into its
circumference for a woodruff key.

Usually cut with a slotting machine, rather than a broach. This is like
a shaper, but skinny and with a long reach - they were the original form
of shaper and one of the first specialised machines tools. (A shaper is
a single point tool like a lathe tool, oscillating back and forth whilst
the work moves sideways beneath it.)

As opposed to a planer, where the work moves back and forth and the
tool (with it's clapper box) stays still; the whole shebang being
hand-driven.

....Memories of room W5 at school some 40-mumble years ago.

That was a wonderful metalwork room. A couple of Harrison screwcutting
lathes, two or three shaft-driven ones, forges and anvils, brazing
hearths, pedestal drills, shaper, planer, power hacksaw, grinders,
polishers. surface plates, metal beating/riveting benches, guillotine,
moulding benches, and of course "Archie" Campbell the teacher, deaf as
a post, who wore proper metalworkers glasses with springy hooks to go
around the ears. He had a slogan written in gold leaf above the
blackboard "Be accurate", which somebody modified to "Be a curate".

I'm allowed to reminisce - it's my birthday today ....

--
Frank Erskine
Sunderland

Hi John
Not a technique I had come across before though - Hence why I was having
difficulty working out how you would get an end mill in there ;-)

Hence the old engineering expression "I don't know if I'm punched, reamed,
broached or bored".

No, I don't know what it means either :-)

Dave

On Wed, 22 Jun 2005 22:50:05 UTC, "David Lang"
wrote:

Hi John
Not a technique I had come across before though - Hence why I was having
difficulty working out how you would get an end mill in there ;-)

Hence the old engineering expression "I don't know if I'm punched, reamed,
broached or bored".

No, I don't know what it means either :-)

Sounds like something the actress would have said to the bishop...