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@nbleopard.com wrote:

--
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

Nothing is for sale here.

shouldn't the Openscad community be looking for ways to get as many
hobbyists as possible to use Openscad - even if they are not programmers?

I don't know. I would never recommend it to anyone that isn't a programmer,
particularly now that there are good free CAD tools, both open and closed
source. Writing software is a very slow process and so is designing objects
with OpenSCAD. When I see what James Bruton knocks up with Fusion360 I
realise it is much more productive that coding in OpenSCAD.

On Wed, 2 Oct 2019 at 17:50, Matt Maggio mattmaggio19@gmail.com wrote:

nophead wrote

That does not mean that the product should not be marketed - that is, if you
want to widen the user base.

I don't know who James is but I suspect he is very familiar with Fusion360.

I'm thinking of the novice who knows none of the CAD programs and may only
want to build one or two models in a year. For that sort of user a system
that requires very little learning will be very attractive. I think Openscad
can be that system.

...R

--
Sent from: http://forum.openscad.org/

I like math. I like geometry, algebra, trigonometry and even one semester of calculus, but don't ask me to remember any of the latter!
Trying to engage our makerspace members in OpenSCAD hasn't been fruitless, but as soon as numbers come into play, all bets are off. So far, most of them are full GUI users, ala Tinkercad or rarely Onshape, so having to type (no typing skills either) in words and do math and create geometry scares away most.
Recently a new member, with a passing interest in programming became aware of both OpenSCAD and Solvespace. The former you know, the latter is GUI, but parametric and constrained. Useful for a variety of things and a handy tool for the toolbox.
The new member, let's call him John (because it's his name) embraced OpenSCAD with an enthusiasm I've not seen before. He used the same method I enjoy. Look at someone else's work, try something, if it doesn't work, try something else and of course, trouble shoot why the first one didn't cut it.
Every person takes a different approach to a modeling program, and OpenSCAD certainly fits for many people.
The price is hard to beat.

On Wednesday, October 2, 2019, 3:25:11 PM EDT, Robin2 <robin@nbleopard.com> wrote:  

nophead wrote

That does not mean that the product should not be marketed - that is, if you
want to widen the user base.

I don't know who James is but I suspect he is very familiar with Fusion360.

I'm thinking of the novice who knows none of the CAD programs and may only
want to build one or two models in a year. For that sort of user a system
that requires very little learning will be very attractive. I think Openscad
can be that system.

...R

--
Sent from: http://forum.openscad.org/

OpenSCAD mailing list
Discuss@lists.openscad.org
http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org

OpenSCAD mailing list wrote

Same as its competitors - Solvespace and Freecad.

So the competition must be fought with something other than price - such as
an easier learning curve?

...R

--
Sent from: http://forum.openscad.org/

OpenSCAD mailing list wrote

Well, it's not strictly necessary, true, but in some cases, it would be very
handy.

Examples:

When things move around a lot. Think of a robot arm, with several bend
points. Sure, build it part by part and be careful, and you can do it, but
occasionally (for example if you do an anim), you might want to know where
the claw is without having to to do all the math.

Say that you are doing a an axle, with bunches of nuts and washers, passing
through several  other bits. Sure, the math is easy, but if components are
designed as modules, I need to check out how thick a nut or a washer is,
instead of just "stack them".

Making rounded/chamfered corners on parts. If you could just query the item,
it would be pretty simple to just get the needed dimensions and procedurally
add the roundings/chamfers.

--
Sent from: http://forum.openscad.org/

For a complex assembly like a robot arm I would have modules to position
each segment onto the last one. So there would be say
shoulder_upper_arm_position(), upper_arm_forearm_position() and
forearm_wrist_position().

In the arm assembly the hand would be a child of the forearm, placed with
forearm_wrist_position() and the forearm would be a child of the upper arm,
positioned with  upper_arm_forearm_position (), etc.

If I want to say put a ring on a finger it would simply be a matter of
calling the right sequence of positioning modules, no extra maths at all.
something like:

left_shoulder_position()  shoulder_upper_arm_position ()
upper_arm_forearm_position() forearm_wrist_position()
wrist_ring_finger_position()  ...  ring();

The joint positions might be parameters to each positioning module, or
perhaps $variables.

The position of the ring would be a long chain of transformations but that
is hidden. If I wanted it in X,Y,Z coordinates I would put the maths from
the positioning modules into into functions with the same name. Then the
module version would simply be

module  shoulder_upper_arm_position ()
multmatrix(shoulder_upper_arm_position() ) children();

Then I could call the function versions and multiply the matrices together
to get a transformation matrix the goes from the origin of the robot to the
ring. Mulitpling that by [0, 0, 0, 1] gives the coordinate of the ring.

For stacking washer, my washer and nut modules position their children on
top of themselves. So nut(..) washer(..) nut(..) washer(..)  screw(..)
would build a washer kebab.

On Thu, 3 Oct 2019 at 07:34, Troberg troberg.anders@gmail.com wrote:

I express all the properties I need for my objects with functions and
modules. Each parametric object is represented by a list with a set of
accessor functions, so nothing is specified twice and I don't need to query
the geometry. All the important features of an object are built with its
accessor functions. It is a bit clunky as there is a lot of boiler plate to
write but it is very simple code in a simple language, so should be easily
understood.

Syntactic sugar would be object.property instead of
object_property(object). Function literals will allow functions to be
embedded in the property list, so objects can be polymorphic.

On Thu, 3 Oct 2019 at 11:56, Troberg troberg.anders@gmail.com wrote:

What OpenSCAD is missing that traditional cad programs have is the
ability to "snap". two pieces together.

Sure you can keep track of where you put the holes, etc., but
something like intersection() creates new surfaces that may be
difficult to find the edges and surface tangents of, may require
complex trigonometry and/or geometry to calculate...

On Thu, Oct 3, 2019 at 6:56 AM Troberg troberg.anders@gmail.com wrote: