On Mon, 02 Oct 2017 10:33:29 -0500, Jon Elson
wrote:

Ignoramus13481 wrote:



I thought that there is a lot of such high production parts needing to be
made.

I hope you don't mind if I pick some nits. d8-)


"Back in the day", when there were carburetors, they had 100 special parts
on each one, needle valves, jets and the screws that held it all together,
that were made by the barrel on screw machines.

Yeah, mostly little Swiss automatics, though, not the big ones. Lots
of fuel-system parts are still made on those machines (Citizen-Cimcom,
Tsugami, etc.) They're basically the same machines, only now they're
CNC instead of cam-controlled.

Lots of other products has
screw machine-produced parts, too. All the threaded plumbing fittings were
made on screw machines.

Hmm...for the past 60 years or so, actually on dial-index transfer
machines.

Well, a lot of that production has moved overseas,
some of those products are made differently (think fuel injection) and a lot
of these parts are molded or cast in some manner now. So, there is less
demand for this. Also, there are rotary transfer machines that are used
to make all sorts of reall high production parts. These can even beat a
screw machine for throughput.

For one thing, screw machines were at one time used to make -- SCREWS!
I suspect that it would be VERY rare to make screws that way, now. Mostly,
they'd be coined

....sort of. Cold-headed, actually.

and have the threads rolled.

Yes.

Nowhere as precise, but
precise enough to hold some gadget together.


Jon

Some specialty screws and bolts are still turned, but the big volumes
are made on ancient, beat-up headers and roll-threaders in countries
where they work in their bare feet.

When I was at Wasino, we turned the big-end con-rod bolts for Cosworth
racing engines on our precision CNC lathes, which would turn to +/- 50
microinches. I think they were $24/each, or possibly $24/pair, when we
were done. d8-)

Do you remember Dobbie Dave, who used to hang out here? I wrote an
article about him and his shop about 15 years ago. Most of his income
was (and maybe still is) from production on his four 1947 B&S,
leather-belt-driven screw machines (known commonly as "Brownies.")

He found himself a niche. He was a sole source, making parts for
lie-detector machines, and a couple of other little hinge pins and
such.

--
Ed Hunttress