Re: [CAD_CAM_EDM_DRO] Re: Expectations, bridgeport

>One none cnc question, what is engine turning?

Hi John,

Engine turning is the fancy engraving you see on the back of old powder
compacts, watches and under the enamelling of various bits of old jewellery
etc. It is a fascinating subject. The majority of this work was done by
'gentlemen' as a hobby and the best lathes by such as Holtzappfel were
really beautiful pieces of equipment - all brass and polished mahogany.
The principle is fairly simple, the headstock of the lathe is pivoted along
its length and, where the pulleys normally are, it has a set of large fancy
brass cams - i.e cams with a repeating pattern around their periphery. The
whole headstock is pressed to one side by a strong spring so that one of
these cams rests on a fixed arm with a roller on its end. Then the headstock
spindle is turned slowly, usually by a handwheel, so that the action of the
cam passing by the fixed arm makes the whole headstock rock backwards and
forwards. A tool is pressed by hand against the work which is held in the
chuck or on a faceplate and so this makes wavy lines - much like a
spirograph. There are many combinations of cams, tools and cutting frames
which revolve eccentric cutters against the work and the number of patterns
which can be made is almost infinite. Of course, on the odd occasion that
engraved work of this type is needed now, it is more likely to be done with
a cnc engraving machine and a program like Art Cam.
There are good books on the sublect of engine turning by Holtappfel, Martin
Matthews and Bergeron and you will also find some stuff on the web,
including links to the 'Society of Ornamental Turners'.
HTH.


Ian
--
Ian W. Wright
Sheffield UK
www.iw63.freeserve.co.uk