|
Machinist here. Clicking through to the source image shows a much higher resolution and clearly shows to me a very coarse thread or grooving inside the bore, likely what would have been a buttress or trapezoidal thread (very common on large guns because of strength characteristics). The swarf (chips/cuttings) in the bore and on the machine are very similar to what actually results with single-point threading, with large width that's along the axis of the cut and high stiffness that keeps the chip relatively straight. The thread cutting tool tip itself is hidden from view, it would be on the left side of the tool holder in the turret. The controls for feed for threading would be out of view below her right hand, and it is possible that after engaging the cut, she is leaning forward to get a better look at the tool position while it is far away from the end and she doesn't need to disengage the feed for some time still. My verdict is that the description is plausible and accurate. (for reference, I have attached a photo showing how a threading operation chip looks like)
|