Openscad measurements

When I make an object, for example, a rectangle - cube(size = [40,30,30]);
the measurements are not 40 mm by 30 mm by 30 mm, they are about 75% smaller. I have to design objects, see how they print, and then adjust the numbers to compensate and get the correct size. Is there a way to input real dimensions into Openscad?
My printer is set up correctly, and if I print the 40mm test cube, it comes out 40mm.
I looked in Openscads preferences, but there is no settings for this.

The Openscad dimensions are always 1:1 with the STL. I don't know how your getting 75%. Have you tried measuring the STL with something like NetFabb Studio?

---

[www.hydraraptor.blogspot.com]

they are real dimensions in MM,

did you hit F6 then export the stl file? also it's good practice to hit the "design" -> "flush caches" bit in the menu everytime before you export and stl file,

---

-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-

nophead Wrote:
-------------------------------------------------------
> The Openscad dimensions are always 1:1 with the
> STL. I don't know how your getting 75%. Have you
> tried measuring the STL with something like
> NetFabb Studio?

I have been running everything I do through Netfabb and I just checked and the dimensions are correct. I'm wondering now if the test cube I downloaded was wrong. I will create my own 40mm cube in Openscad and test/calibrate to that.

Thanks for confirming that Openscad is accurate. I thought that maybe it was set to inches or something and that i was looking for millimeters.

Openscad is unit less and so are STL files. It is the slicer and the firmware that decides one unit is 1mm

---

[www.hydraraptor.blogspot.com]

nophead Wrote:
-------------------------------------------------------
> Openscad is unit less and so are STL files. It is
> the slicer and the firmware that decides one unit
> is 1mm

thats pretty much the standard thing across just about every bit of cam software out there,

---

-=( blog )=- -=( thingiverse )=- -=( 3Dindustries )=- -=( Aluhotend - mostly metal hotend)=--=( Facebook )=-

... before exporting STL's from different CAD programs I can set the internal units in the CAM so (and rescale the 3D-object), that the STL-units will be common -- imperial with US origined, metric with other CAM's.

In my old Lightwave the basic units are in microns, so I have to recalculate this (25.4mm per inch) for programs interpreting the STL units as inches ...

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

The only reference to units in the OpenSCAD documentation is in linear_extrude, where it states that the height of the extrusion is in mm. It may be that everything else is unitless, but it is not very helpful to have some of the program be unitless while another portion is not unitless. When I create a polygon and then do the linear extrusion, the height of the extrusion is clearly incompatible with the dimensions of the underlying polygon. I'm not sure how to work around this.

angle_offset = 44; // distance from bottom of opener to bottom of angle
angle_height = 26; // length of angle
angle_top_thick = 6.3; // the uncurved part
angle_radius = 50; // radius of the curved part

module AnglePart() {
ao = angle_offset;
ah = angle_height;
at = angle_top_thick;
aw = (max_ID - min_ID) / 2;
linear_extrude(heighth = at, center = true, convexity = 10, twist = 0)
polygon([[0, ao], [0, ao + ah], [aw, ao + ah], [aw, (ao + ah) / 2]]);
}

openSCAD won't recognize "heighth" as a parameter. The work around is to spell it correctly.

The documentation is wrong if it says mm. All openscad dimensions are unit less and only become mm because slicers interpret STL units as mm.

---

[www.hydraraptor.blogspot.com]

I don't know how that statement got in to the linear_extrude() description, I am pretty sure it is wrong too.

I have updated the wiki [www.openscad.org] and also updated some other stuff on DXF extrusion.

The section on "STL Import and Export" needs more work...