Re: building full scale car body ???

From: Brock Hinzmann (
Date: Wed Jul 07 1999 - 02:41:13 EEST

I was curious to see recently how a group of people in the 1920s and
1930s used a pointing technology to build very large scale objects. They would
first build a small-scale model and then hang a pointing device with a
string across the front of it to make inch-by-inch measurements. They then
built a full-scale version of the pointer and hung it on top of the build
material (granite), onto which they would make scaled-up markings. Then
they drilled holes into the granite, which they filled with dynamite. They
got so they could blast within an inch of tolerance and could then finish to
spec. Then final result was called Mount Rushmore. It took 400 people 14
years to build, but you can still see it today.

Fusioneng wrote:
>In a message dated 7/2/99 5:35:09 PM Central Daylight Time,
><< 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,
> 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
> 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
> Good luck! I'd like to see what other suggestions come up...
> Bill Richards >>
>Bill is correct. In the old days we used to draw (or plot) all the
>of the final product on paper. Then we would glue the paper onto 1/8 or
>masonite. We would then cut and sand the profiles to the pencil lines.
>whole construction is then assembled onto a spine with a cross section
>half or 1 inch. The whole thing is then filled with plaster and sanded.
>know you have the contour when you see the masonite. This method is
>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
>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
>using a high pressure stream of water. Thats what Charles Thomas uses at
>University of Utah. His is particularly nice because it 5 axis. (saves
>finishing time). Now days most people would take the cross sections and
>lofted surfaces from them and cut the model in a high speed CNC its much
>labour intensive. If you break the car into assembled sections most CNC
>can cut them for you. Just my 2 cents (again)
>Bob Morton
>Fusion Engineering
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