Re: [CAD_CAM_EDM_DRO] Watch finishes, by CNC

To program a spiral tool path it is easy to do this manually with a simple
spreadsheet program. using polar coordinates makes the functional
relationship between 'r' and 'theta' trivial and you can convert to 'x' and
'y' Cartesian coordinates by x=rcos(theta) and y=rsin(theta). The spiral
function in polar coordinates is simply r=theta, just do step increments in
theta (it is easy if you use degrees and then convert to radians for the 'x'
and 'y' conversion formula). If you run theta from 0 to 360 degrees you
will get a single loop spiral, if you go to 720 degrees, you get two loops,
etc. You will then have to scale the output with a simple scaling factor on
both axes.

If you want more instructions on this, just ask.

Daniel J. Statman, Statman Designs
www.statmandesigns.com
dan.statman@...

----- Original Message -----
From: "Chuck Knight" <chuckknight@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Sunday, November 30, 2003 10:51 PM
Subject: [CAD_CAM_EDM_DRO] Watch finishes, by CNC


>
>
> http://mywebpages.comcast.net/timconnor/ham922/ham922_07.jpg
>
> I want to do this type of finishing to a watch movement, just as an
> experiment...isn't it pretty? This style of decoration is done by using
> a rotating emery disc, and a watchmaker's lathe...lots of tedious
> handwork. I'm thinking of attaching an emery disc onto the end of a
> dowel, and chucking it into a router. Needless to say, there is no
> pressure involved, but only light contact and a precise and slightly
> overlapped toolpath. Given a small, reasonably accurate CNC router,
> this should be simple to achieve. FYI: This watch is from the turn of
> the last century -- one with this level of decoration would cost a
> minimum of $2500, and most are closer to $4000, in today's market. This
> one cost >$100, 100 years ago...this is one of the super-accurate
> railroad watches that kept the trains on time.
>
> Back to CNC. As I see it, once I have a tool made, it should simply be
> a matter of programming the toolpath. Does anyone have a program that
> would automatically generate a spiral, concentric circles, straight
> parallel lines (cotes de geneve) and other simple "filler" patterns
> which I could use for this purpose? I don't want to "reinvent the
> wheel" if I don't have to. I already know that the dust generated will
> require me to clean the movement afterwards, but for the purpose of this
> experiment, I'll happily do it. I could probably do it myself, but I've
> never programmed in G-Code.
>
> I know there are simple "pocketing" programs floating around...what
> types of paths do they generate?
>
> -- Chuck Knight
>
>
>
>
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