Re: [CAD_CAM_EDM_DRO] Re: Expectations, bridgeport

I just happen to have a book called "The Principiles & Practice of
Ornamental or Complex Turning" by John Jacob Holtzapffel. It's fantanstic
what that guy ccould do with one of those specialty lathes.

The tool in most cases is also rotating. Based on some of the accessories
used for some of the projects shown in the book, it would be pretty
difficult to duplicate the work using CNC. You'd need several axis that
aren't normally found on a CNC machine.

The only CNC machine I can think of that even comes close would be the
DreamMachines I have been working on.
Reproduction Holtzaffel lathes are available if you have the bucks.

Smoke

>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