Hello
Got this as a private mail ?

Anyway, you can include stl in openscad, but as stl (not very efficient)
there's No converter
as stl is a mesh description and scad  geometry....

For a simple design as that one, its easy and fast to redraw natively in
openscad....

Ciao

Bruno Böttcher

35 rue de la république, FR-67270 Schwindratzheim
email: bboett@adlp.org, mobile:bboett@gmail.com
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Dev: Java/Perl/PHP OS:GNU/LINUX, Android

charles meyer reachmeplace@gmail.com schrieb am So., 29. Aug. 2021, 21:41:

This is not possible. You are asking to convert a cake (the .stl file)
into the recipe for making it (the .scad file).

This also is not possible -- and IMHO it /shouldn't/ be. Speaking as a
fellow American, it's way past time that all of us in the US catch up
with the 19th century and learn how to use the metric system. The US is
literally one of only three countries in the world (the other two being
Liberia and Burma) that still use feet and inches, pounds and ounces,
gallons and quarts. All the rest of the world measures things in meters,
kilograms, and liters. And it's costing our economy billions of dollars
every year.

On 8/29/2021 3:44 PM, charles meyer wrote:

I am not sure why you want to change the STL into SCAD format. Do you
want to modify it?  The object is very simple: you can design it
yourself in OpenSCAD fairly easily.

When I need to design something in inches, I create the object in
OpenSCAD and the do a scale(25.4).  Pretty simple

Jon

Hi!

This is... practically impossible.

A .STL is a collection of points and surfaces that makes up an object.

But a .SCAD file is a collection of objects and transformations of those that ends up as a 3D object that you can export a .STL from.

There's no way of 'tracing back' to find out how it was constructed.
The best we could hope for is to generate a big, ugly Polyhedron from it.
And that would be almost as impossible to edit as the .STL itself.
(Curved surfaces or circular ones are made up of very small triangles, so there are thousands on just that chip )

https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Primitive_Solids#polyhedron

I don't know if there's a limit to the number of faces or coordinates in a Polyhedron, but I would expect there to be one.

So, technically possible, but no one is daft enough to try...

Trygve

Den 29. august 2021 kl. 21.44.25 +02.00 skrev charles meyer reachmeplace@gmail.com:

On 8/29/2021 12:44 PM, charles meyer wrote:

OpenSCAD is unitless.  There's nothing that says whether the units are
millimeters, inches, or furlongs.  Similarly, STLs are unitless.

Indeed, most people treat OpenSCAD units and STL units as millimeters,
but that's a matter of how consuming programs use them.

Apparently some people generate STLs where the units are intended to be
inches, because some slicers will detect very small models and suggest
that they might be in inches.

So there are three answers to your question:

1)  Treat OpenSCAD units as millimeters, and wrap a "scale(25.4)" around
your model so that you can design the bulk of it in inches.
2)  Treat OpenSCAD units as inches, and have your slicer scale.
3)  Treat OpenSCAD units as millimeters, and design in millimeters.

I try to design in millimeters, but many years of habits make that
hard.  When I design in inches, I define a variable "inch" with a value
of 25.4, so that I can say, e.g., "12inch".  Why do I do that, instead
of using scale()?  Because the measurements on the printer - layer
height, extrusion width - are in millimeters, and so when I need to do
stuff where the printer's resolution matters I want to be able to drop
into metric.  A lot of my work is on scale models, so I often set "inch"
to 1 for my 1:25.4 scale, and then I can use "3inch" to mean three
scale inches, and use bare numbers where I need to get special effects
down around the printer resolution.

@Charles Meyer, I'm basically echoing what Jordan said:

The top of my OpenScad files tend to look like this:

SCALE=1;	// Global rescale value
inchtoMM=25.4;	// 1 inch equals 25.4mm

main_body_diameter= 4 * inchtoMM * SCALE;
main_body_height= 66 * inchtoMM * SCALE;
bulge_vertical_offset = 100 * SCALE;		// bulge is 100mm up
bulge_diameter_offset = main_body_diameter + 5;	// bulge is body + 5mm
M5_screw_diameter = 5 * SCALE;			// M5 screw is 5 mm diameter

This lets me:
1) specify all measurements at the top of my file
2) Work in either mm or inches, but I also work in meters sometimes
3) Alter the export SCALE to whatever scale I need, depending on
if the target output is for 3d printing, CAD, lasercutting, or import into
a videogame.

Thus Jordan Brown hast written on Mon, Aug 30, 2021 at 03:37:40PM +0000, and, according to prophecy, it shall come to pass that: