Turn, Turn, Turn...

-

 


Well, the chunk of steel I showed you in the lathe yesterday ended up in the form of the above - please ignore the finish: I took the thing a couple of thou too far roughing it out. I decided to try and cut the largest metric thread I've got the tools for - 12 mm - which necessitated turning the end of the stock down to 12 mm: quite a lot of material to remove, but an interesting exercise, as I don't yet really know the limits of this old lathe.

Turning the spigot for the threaded portion proved to be relatively painless: I seemed to have guessed the right chuck-speed and feed-rate to avoid the smokies, unlike yesterday, when I turned the 'bearing' part of the shaft... What I was most chuffed about, though, was hand-cutting the thread, which, I have to admit, is a bit chunky for the tools I have to hand, but a good challenge well met, I think.

I started the thread with the piece in the chuck of the lathe, and the die/wrench supported and held true by the quill of the tailstock. Once the die was starting to cut and engage, I finished the job off in the vice, by hand: a good workout for the arms and shoulders! I then returned the piece to the chuck to cut back the relief behind the thread, which was when I found one of the lathe's limitations. Using a rather admittedly over-butch 12 mm parting-off tool, the piece dug in a couple of times, making the whole machine buck - and there's a lot of mass in the old thing - quite spectacularly before the drive belts slipped.

I finished the relief off with the recently-purchased small TC insert tool and a warding file. The kicker to all of these shenanigans is that I need to turn that lovely thread down to its final dimensions to fit the change-wheel banjo's slots: seems a shame, but there you go... Then I've got to address the problem of the dearth of keys on the majority of the change-wheels... not sure how I deal with that, but I'm sure something will occur to me. The astute among you will notice my apparent lack of engagement with the bear of little brain's political demise here, this week: done with ranting until we know more...
 

Comments

Post a Comment

Popular posts from this blog

Of Feedback & Wobbles

-
Image
Many years ago I came up with an analogy for poorly damped feedback loops. The feedback loop that prompted this frankly tart analogy was indeed a horror. Anyone who remembers shame-faced their first attempts at clutch control resulting in the good old kangaroo launch across the lights only to stall in the middle of the crossroads will have some idea of the kind of data transfer lag involved in said system. The analogy I made was that of a large blancmange. Untouched, a model of stasis and eminently stable and predictable; but prod the bugger and the resultant chaotic behaviour needs a very complex physical model and some very decent computing horsepower to predict its outputs, if at all. The system in question was a large and complex audio-visual display at what eventually became 'The Electric Mountain' in Llanberis. We were ultimately contracted to maintain the thing having been witness to and peripherally involved in its installation. Certainly not involved in its des...
Read more

A Time of Connection

-
Image
I was just reflecting on the vacuum of continuity that's left behind when someone dies: that sudden sense of disjoint, of fracture, in one's personal history that takes one completely by surprise at the oddest moments. These pinch-points in memory can often yield some surprising revelations of fact about periods in one's past. One such occurred to me tonight, tending my rather lazy meal of pizza in its journey from shrink-wrap to mouth via the oven. Al's recent demise still catches me out from time to time: the space he left bounded by forty plus years of friendship. But the thing that struck me tonight was just how much change was happening on a personal and social level in the very early years of our acquaintance. Between moving here from Birmingham in September 1980 and our buying our first proper house eighteen months later, all manner of things occurred that would chart the course of our lives to the present day. At around the time of our meeting Alan & Irene [...
Read more

Sister Ray

-
Image
Ray Keats - aka Ann Key - local artist & family friend, died this morning. She'd been ill for some years, but never let it get in the way of her work or of tending to the massive network of friends, colleagues and fans she had accumulated over the decades. Her house on the High Street of Rachub, just below where we live - a former cockle factory(!) - bought many years ago when she and her late husband Ronald moved here from Manchester to set up home in Yr Achub, is currently still home to her paintings and drawings, and the front window displays her work, including the last drawing she made in hospital, just days before she died. Her good friend Colin has been a diamond in her latter years, looking out for her and just being there when she needed him. She will be much missed by this tiny community of ageing bohemians up here in the hills, but suffice it to say, George, her cat, will be well looked after now she's gone.
Read more