[OpenSCAD] Difference between modelling with Openscad and Freecad

Matt Maggio mattmaggio19 at gmail.com
Wed Oct 2 12:46:22 EDT 2019


There are ways to keep track of dimensions in openscad using parameters. If
you just type cube([10,2,12]); that doesn't produce a record of what those
dimensions where. If they are important or used multiple places it can
often be a good idea to start the script by stating parameters.

cube_l = 10;
cube_w = 2;
cube_h =12;

cube([10,2,12]);

Now we know the dimension of the object if we need to reference it later
like perhaps to put a mitered piece on it.

Another neat trick is to put a hashtag in front of an object to make it
transparent, this way you know what object in the design that line is
referencing. So if you aren't sure if a cylinder is a cut out for a hole or
part of a different part of an assembly you can pick it out of the design.
Be aware this only applies to the f5 preview and has no effect on the final
render. You can also have your finished design and use a #cube(); function
to find the bounding box by iterating the size of the cube, your precision
is limited but it can be useful to ball park the size of the stock you
would need to make something in a subtractive manufacturing process.

Last thing i'll say is that it can be useful to take your design and
difference it from a cube which you manipulate to form different cutouts.
Obviously only relevant if you have internal features, but can be very
helpful.

Openscad is powerful when you can express the final shape in terms of a
mathmatical relationship between objects, or when some really smart person
made a package which does exactly what you want and you can scale it to
your application.


On Wed, Oct 2, 2019 at 5:35 AM Robin2 <robin at nbleopard.com> wrote:

> I don't mean the user-interface, which is obviously very different between
> Openscad and Freecad. Different people like different interfaces but anyone
> could learn either or both of them if necessary.
>
> It seems to me there is a more fundamental difference. With Freecad (and
> other similar CAD programs) you can define an object and later "ask
> questions" about that object. For example you can select a point that is
> the
> corner of a cube and it will tell you the coordinates in 3D space. And you
> can locate the surface of a face of the cube even though it may have been
> rotated or scaled.
>
> However with Openscad the process of defining a model is mono-directional.
> You define the object (such as a cube) and you can have no further
> interaction with it. You cannot "ask questions".
>
> Is this a fair assessment, or am I completely muddled?
>
> As I see it very many projects can be created with an Openscad approach -
> i.e. without ever needing to be able to "ask questions". But I suspect
> there
> are some projects where the ability to easily locate a point or a surface
> of
> an existing object would be essential. And for those cases Openscad would
> not be an option.
>
> ...R
>
>
>
> --
> Sent from: http://forum.openscad.org/
>
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> Discuss at lists.openscad.org
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>


-- 
Matt Maggio
Senior Research Technologist
Resuscitation Institute (Rm. 1.380)
Department of Medicine
Rosalind Franklin University of Medicine and Science
3333, Green Bay Rd, North Chicago, IL - 60064.
Office: 224-570-7954
Cell: 815-703-2879
"Take chances, make mistakes, and get messy!!" - Mrs. Frizzle, PhD
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