Shop Note
The Basic's of C.A.D.
Dave M
What is CAD? More commonly now called CADD, Computer
Aided DRAWING, DRAFTING and DESIGN, but in simple
terms it's an electronic drawing board. What you call it is dependent on what you
are using it for. If it's original concept work then its Design, other than that it's
Drawing or Drafting these two being interchangeable.
What can you do with it? Dependent on what type of CAD it is you can do
anything from a simple 2D drawing of an object to a full 3D Solid object with
weight and mass.
The Types of CAD.
| 3D Solid.
| Used principally where there is a need to carry out structural
testing and stress analysis.
|
| 3D Mesh.
| Is used for contour modelling and is the underlying form for 3D
character and object animation.
|
| 3D.
| Very rarely used on it's own. Needs to have faces added before you can
say what it is a representation of.
|
| 2D.
| Your plain piece of paper drawing.
|
What do we need.
For model ship building plans then a relatively good 2D package will full fill
our requirements. I say relative in considering what would be required if you
where using pencil and paper, that is a good Ruler, Protractor, Compasses and a
good set of French Curves. This translates into a CAD package that allows you
to specify a straight line of quoted length and angle from a start point, a
circle of given radius or diameter, a good choice of ways to form curves, like,
Start-Centre-End, Start-Middle-End and the very useful one of 3-point curves.
This is the one that does the work of your French Curves. It should also
hopefully support Spline and Fit curve within its polyline edit options. For
those who don't now, a polyline is a series of straight lines at different
angles that have been joined together to form one entity.
CAD v Paper.
For most people there is very little time saved when using CAD to that of using
a pencil and paper in the production of a drawing. Time is saved however if
you have to correct mistakes, this being quite simple in a CAD package.
Some advantages of CAD are that when making the drawing you work in real size
measurements, that is one foot equals one foot, any scaling that is required is
done when you come to print out the drawing by specifying a print out size
ratio.
Another is that most CAD packages these days support "Layers", that is like
working with a set of transparent sheets with different entity's on different
layers, very useful when around the flat of a hull when the lines run very
close together. This coupled together with being able to plot out the layers
as separate sheets saves a lot of heartache and time.
Printing your finished drawings.
This, surprisingly, is where you are likely to have problems. If you have
access to a proper Plotter you are O K but printers, which are designed with
only text in mind, can have X Y scaling problems. The work around for this is
to always include a scale grid on your drawing, which will then allow you to
check the dimensions of the print out. This also applies when your drawing is
larger than your printer supports and allows you to align the different
sections of the drawing. Again this is something to check with your CAD
package, in that it does allow you to print out parts of a drawing.
What CAD package.
There is no simple answer to this one. If money is no object then it has to be
"AutoCAD". There are cheaper CAD packages such as "AutoCAD Lite", "TurboCAD",
"InteliCAD" and "DesignCAD". A search of the Internet will also produce a
whole range of CAD packages among which will be both Shareware and Freeware
that will do the job, sometimes faster, as they don't have the multiple options
that you will never use that are in professional CAD packages. Try before you
buy is the golden rule here, will it do what you require at a price that suits.
My personal recommendation is Autosketch (ver9 current 2005) at $129 US will
More than do the job. You should also try this
Internet link for other options.
Learning and Training.
Try your local Schools, College's and Universities to see if they offer evening
courses in CAD, many do, particularly if that have links too or have
Engineering or Construction departments. Some local governments and bodies
also offer training options. These will almost certainly be for a specific Cad
package and is likely to be for AutoCAD but it will teach you how to use a CAD
package.
Many of the main CAD suppliers offer training and support (at a cost) and also
tutorial CD's. Check out your local library, there have been a lot of CAD
teaching books written. If you're really stuck then there is always that
little "?" or "HELP" button, some of them are very good.
Finally there's the just sit down and play with it. Read through the help menu.
Check out Yahoo groups, there are quite a few CAD interest groups that will
offer help and guidance.
Just remember that if you're new to CAD and want to really learn to use your
CAD package you're in for a long or steep learning curve.
Enjoy, it's worth it, just don't let it stop that model building.
Dave M
Member AUGI
AutoCAD Academia
Also:
Straight from the AutoCAD News Group International December News letter
Free Scanner Software for AutoCAD and AutoCAD LT (2005)
30 Day trial Scanner Software
Should be worth a look.
In addition, Tim McCoy offered:
... some websites where you can download free, or trial versions
of all kinds of CAD programs:
cadsoftware.htm
cadstd.com [not really
suitable unless you buy the Pro version ($400) as the free one do's not support
partial drawing print out's among other things. - Dave M.]
caddepot.com for advanced
cad users looking for Plug-In's and Lisp programming extentions.
Also, George Levine offered:
You might take a look at the free program, which is specifically for producing a fair hull form.
FREE!ship
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