Re: [CAD_CAM_EDM_DRO] Re: 4-AXIS FOAM CUTTER

Its been a while since I did any RC model plane stuff, and even when I
did I only tried some crude experiments with foam cutting, so perhaps
what I'm about to say is overlooking something.

Anyway, assuming the procedure for cutting a tapered wing involves
either constant ratio moves along the two chords (both wire ends are
at 90% of their respective chord at the same time) or perhaps constant
ratio moves along the arc length, then writing software to convert two
curves to 4 axis instructions should not be very hard.

If the curves are sampled rather than functions, then the first thing
needed will be a procedure to interpolate between the points.

Then you calculate a series of equally spaced points along the chord
at each end and calculate the appropriate thickness of the airfoil at
that point from the function or interpolator. Space them close enough
that you can use straight lines instead of circular interpolation, for
simplicity. Use some formatted output statements to make it look like
G code, and dump it to a file you can feed to any four axis capable
controller.

Doing constant surface speed along the arc length requires a bit
more work, but it is still no big deal. With todays computer speeds,
its perfectly fine to numerically intergrate along the arc length once
to determine its total, then again to space off waypoints at
appropriate fractions.

IMHO, everyone should take a stab some time at writing a simple
program to generate G-code. It's trivial - use whatever you are
comfortable with: Basic, C, even some spreadsheets!

Chris

PS - postscript (a language many laser printers understand) is a lot
like G code - different syntax, but if you want to generate fairly
accurate 1:1 hardcopy output from some program, writing raw postscript
is pretty easy too.

--
Christopher C. Stratton, stratton@...
Instrument Maker, Horn Player & Engineer
22 Adrian Street, Somerville, MA 02143
http://www.mdc.net/~stratton
NEW PHONE NUMBER: (617) 628-1062 home, 253-2606 MIT