In a message dated 7/2/99 5:35:09 PM Central Daylight Time, wdr@virtcon.com
writes:
<< Chris,
It would be possible to use a CNC machine to carve out a foam core.
It's done in homebuilt aircraft fairly often. You can do the in pieces, and
assemble them to create your core.
I would like to hear from my fellow RPer's in the automotive
industry to confirm or deny this, but don't a number of automobile
manufacturers have large-scale CNC machines that can carve out a 1:1 foam
core in one shot?
A more likely -- and less expensive -- route to follow would be to
use a plotter to print up full-scale profiles, and use these as patterns to
cut the foam by hand, and then fill the gaps and hand contour your model.
Good luck! I'd like to see what other suggestions come up...
Bill Richards >>
Chris:
Bill is correct. In the old days we used to draw (or plot) all the sections
of the final product on paper. Then we would glue the paper onto 1/8 or 3/16
masonite. We would then cut and sand the profiles to the pencil lines. The
whole construction is then assembled onto a spine with a cross section every
half or 1 inch. The whole thing is then filled with plaster and sanded. You
know you have the contour when you see the masonite. This method is pretty
labour intensive but it works well and its inexpensive. (except the labour if
you have to pay someone). Another thought is most major industrial areas have
shops with large format water jets ( I know there is one in Rockford IL
anyway). They can cut aluminum, or wood, or foam profiles pretty inexpensivly
using a high pressure stream of water. Thats what Charles Thomas uses at the
University of Utah. His is particularly nice because it 5 axis. (saves some
finishing time). Now days most people would take the cross sections and build
lofted surfaces from them and cut the model in a high speed CNC its much less
labour intensive. If you break the car into assembled sections most CNC shops
can cut them for you. Just my 2 cents (again)
Bob Morton
Fusion Engineering
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