Ruby Loftus Screwing A Breach-Ring

[Khandro]

I have been looking at the famous war-time painting named above, by Dame Laura Knight; http://www.google.co.uk/imgres?hl=en&biw=1344&bih=701&tbm=isch&tbnid=wYbd3saQXrOFeM:&imgrefurl=http://www.iwm.org.uk/collections/item/object/15504&docid=DFl-_QeWSzY_BM&imgurl=http://media.iwm.org.uk/iwm/mediaLib/146/media-146374/large.jpg&w=800&;h=679&ei=2b6xUrzUBImVtAbauYGwCg&zoom=1&iact=rc&;page=1&tbnh=128&tbnw=144&start=0&;ndsp=32&ved=1t:429,r:0,s:0,i:83&tx=103&ty=65
and she seems to be intently not doing anything. Can anyone with knowledge of lathe operating explain what she is doing. Also, isn't the lady in the background using a grinding wheel rather dangerously?

[LazyGun]

I thought this was going to be some salacious ditty about a woman with links to QPR getting jiggy with a breach ring, whatever one of those is :) Imagine my disappointment...

[Baldric]

"Your call is important to us, H & S will be with you shortly!"

[dustypuss]

See if you can wade through this lot!

http://www.patentgenius.com/patent/7159502.html

[EDDIE51]

No eye protection ,very dangerous.

[Graham-W]

She is machining a thread to the breach (opening) of a large gun so that after the shell has been inserted, the breach can be securely closed before firing.

[Graham-W]

Having had another look, as above but it is the actual closure to the breach she is machining a thread to.

[dustypuss]

[The Builder]

To answer your question on why she doesn't appear to be doing anything, Khandro........... probably automatic feed. You set it up, then let the motor feed the cutter into the work.

The machine does the job... but you have to be there :o)))

[Khandro]

LG; Would I be so bold?
Baldric; :-)
Builder; Thanks, but if it is all automatic, I wonder why she appears so attentive? I think her leaning is probably to do with accentuating the top-right to bottom-left composition.
Thanks for the link dusty and graham for observations.

[heathfield]

Incidentally, for a gun, it's "breech"

[Barks]

Usually in the breech lock you have what is known as an interrupted thread whereby sections are machined out of the serrated section so you can open and close it quickly without having to screw the breech plug in or out like you would on a coffee jar lid for instance
When you cut a thread you have to control the pitch, ie the distance between the points, the actual profile of the thread and what is known as the effective diameter or the pitch diameter which is a measurement taken in the "vee" of thr profile.
Pitch is controlled by the machine as stated but it has to be set correctly by the operator; the profile is ground on the tool but will wear over time and the effective diameter is controlled by the cross-slide, which is the block with the handle that her left hand is on
Too close to her and it's oversize and scrap; too far the other way and it's undersize and will need reworking which ties up a machine and operator that could be making another gun for the war effort.
Also when using automatic feed, particularly in blind holes like a breech, you have to be careful disengage before you hit the bottom, wrecking the workpiece and probably badly damaging the lathe
That's probably why she is concentrating on the job

[Khandro]

Barks; Superb answer!