I noticed that too! I suppose he was a starving actor reading the
script provided, as stranslated to english, by the engineer back in the
Kinda interesting, but understandable for the most part.
seems fairly simple. It's just a giant flycutter, with the rotation
synchronised so that the work moves the necessary number of degrees i
the period when the cutting bit isn't there.
if you rotate the cutter twice as fast as the work, the first strik
would be on one side of the work and the second on the face 180 degree
from the first. Or rotate work and tool at the same speed and have th
same number of arms as you want flats, a tool with six arms woul
produce six flats.
It's exactly the same principle as walking a pair of compasses roun
the circumference of a circle.
You should be able to demonstrate the effect simply by mounting
cutter in a powered toolholder on the crosslide and the work in th
headstock with a calculated, controlled RPM.
But I still have trouble visualizing the actions of a wobble broach
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A bit off-topic, but one of the tests when I was learning was to make a
1" cube from a 1.25" length of off-square-cut 1.5" round bar - on a
lathe. All sides, and squarenesses, had to be within one thou, and
within a few tenths was better.
You could make a 0.900" cube if you messed up, or an 0.800" cube, and so
-- Peter Fairbrother
The polygon turning? Search YouTube. I am almost certain that there is
a company video on there with a slow-mo animation showing the process.
It is simply the coordination of the lathe spindle speed, and the
cutter tip passing by. (Simply. There's a misuse of the word!)
A few years ago there were similar vertical milling attachments to do things
like hexagons on bolt heads.
A tipped cutter with a splined shaft through it went down to a gearbox on
the table via a universal joint. This drove an offset collet head which held
All obsolete now though. These type of things eat up carbide inserts though
due to the intermittent cutting action.
wrote:> >Try this for size:> >http://video.google.com/videoplay?docid=-7831550688320827327 > --Thanks! Makes more sense than my easily-fooled intuition! :-) I> had convinced myself that sort of motion would produce crescent-shaped
As a service engineer on machine tools in the 80's I worked for a company in
the UK who sold lathes that could turn external shapes better than it could
machine round, the process was developed by a German company called WERA
whose built machines to manufacture screwdriver, posidrive and philips hand
tools but found a market outside of their world. We used to install machines
in companies who used high speed sheet metal punching machines. The
principal is actually very simple and you all did it at school in maths,
take two gears of say 2:1 ratio and on the small mount the work piece, on
the larger gear mount two cutters at 180 deg apart, spin the work piece and
see what occurs. A square will appear. Under a precision measuring machine
the flats have a very slight radius but to our eyes no problem.
The video shows servo motors instead of gearing, it just needs to be timed
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