"D MacPherson" ) writes:

..My observation is that the unwrapping is
based on a geodesic approach (i.e., attached triangles), not a developable
surface (i.e., unwrapped conic sections).

yes, I made a silly mistake in my first attempt at this boat of having the
lowest point midships adn the widest point somewhat further aft, a shape
to which plywood would not confrom. Neither the BluePeter nor the Carlson
program complained. I knew better but was not thinking. So then I made the
carboard model the old fashioned way to check before keying the offsets
into the two programs to do the calculations and get the unfolded plotting
points for the panels.

I know designers use computers to calculate the shape of unfolded plywood
panels and transfer the points to a computer controlled cutting board.
I've seen advertisments on the Internet from companies like Chesepeak(?)
Ligth Craft who sell kayak kits made this way. Since Greg Carlson sells
cutter/plotters and his program produces a file for his cutter/plotters
then I figure there should be some way I can get the program to produce
accurate plotting points.


Having
said that, I've never seen more than a small gap at the stem.

I've given myself the challenge of attempting a constant bevel which is
making the stem a bit tricky on the small scale drawing on the computer
screen.

We usually
plot these via the DXF - have you tried comparing plots from the nesting and
DXF through a CAD program?

oh no, I have to learn how to use anoother computer program?

BHW: I've found it easier to use the Patterns/Nesting output because all
the files have negative values for plotting points which I haven't been
able to figure out.

One other FYI - the DXF format exported by this program is not compatible
with all CAD programs. I've had good success with TurboCAD, Rhino and the
Voloview Express viewer. I'm sure there are others.

I can display the DXF images with the program that came with the flat bed
scanner I use. They look okay, just like the images displayed by the
program itself. Havent' figured out yet how those images relate to the
problems I've had with the plotting points.

I tried again last night producign a new file of plotting points, drawign
and cutting the panels, and taping them together. I still have more work
to do on this. I could use teh old fashioned way but am determined to
learn how to do it on the computer.

BTW2: I make the panels pretty quickly by taping 2 letter sized sheets of
paper together which gives 16" for the 16' of two sheets of plywood,
plotting and joing the points (straight lines with a ruler is okay for
this), putting duct tape over the back of ach panel outline for some
stiffness, then cutting out the panel with scissors, and taping
teh panels together on the duct tape side with small pieces of cello tape.
The duct tape makes it easier to move the cello tape, no tearing of paper.

Thanks to everyone for the advice.
I'll keep at it.
--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
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Try printing onto trimmed manila folders. They give enough stiffness and
bend nicely. It helps to have a straight-feed printer, though. (The students
use a Laserjet for this.)

Regards,

Don

Donald M. MacPherson
VP Technical Director
HydroComp, Inc.
http://www.hydrocompinc.com
tel (603)868-3344
fax (603)868-3366

2004 Propeller Seminar - January 16th in Tampa, Florida.
http://www.hydrocompinc.com/support/...lerSeminar.htm



"William R. Watt" wrote in message
...
"D MacPherson" ) writes:

snip...


BTW2: I make the panels pretty quickly by taping 2 letter sized sheets of
paper together which gives 16" for the 16' of two sheets of plywood

Card stock is a lot cheaper to buy and has the stiffness that is easy to
work with.

Brian