Hi All,
I’m new to Rhino but have been 3D resin printing for some time.
When I export a ring I designed in rhino 7 mac to an stl, all units in mm, and then import into Chitubox for resin printing, the print is substantially larger than the original ring diameter.
I checked all units and they are in mm. What am I doing wrong?
Thank you in advance.
Gunter
stl as a file format does not have a unit (mm, inches, …) by default.
My guess it s some setting in Chitubox.
did you check their forum
maybe make a very simple test:
draw a 20x30x40mm big box in rhino, expert as .stl.
_box 0 20 30 40
_mesh
→ export selected (the mesh)
post the .3dm file here (including the box and the mesh)
export and post the .stl here
if something went wrong with the export this forum can help you.
you can also export the stl with the ASCII option and open the .stl in a texteditor…
if something is wrong on the import maybe you get better support from Chitubox.
hope this helps - kind regards - tom
Tom, thank you very much for your answer.
I checked Chitubox and the parameters and units seem fine and the “scale to fit” option is unticked.
I exported the box in stl as you recommended but I’m unclear how to export the mesh? I work on
a mac and there doesn’t seem to be an option for that. I took 2 screenshots of the export process so you could see how I’m exporting it.
I also tried the Ascii option and the size is closer but still not accurate.
Attached is the stl file.
Box 0 20 30 40.stl (684 Bytes)
Thank you in advance for your help!
Gunter
Hi Gunter - stl is a mesh format - if the object is not a mesh in Rhino and can be converted, that happens on export as your second image shows.
-Pascal
you box dimensions look right to me
opening in rhino and measure the diagonal with _distance returns
dx = 20.000 dy = 30.000 dz = 40.000
I think it s an import problem
The file you uploaded also imports into PrusaSlicer and Blender with the correct dimensions X=20, Y=30, Z=40
Strange that Binary and ASCII files don’t import into Chitubox with the same dimensions. They produce the same (correct) result when importing into Rhino, Blender, or PrusaSlicer.
What dimensions are you seeing in Chitubox?
You can look at ASCII stl files with any text editor. Here you can see that the vertices of your 20x30x40 cube have X-positions of 0 or 20, Y-positions of 0 or 30 and Z-Positions of 0 or 40
solid OBJECT
facet normal -0 -1 0
outer loop
vertex 0 0 0
vertex 20 0 0
vertex 20 0 40
endloop
endfacet
facet normal 0 -1 0
outer loop
vertex 0 0 0
vertex 20 0 40
vertex 0 0 40
endloop
endfacet
facet normal 1 0 -0
outer loop
vertex 20 0 0
vertex 20 30 0
vertex 20 30 40
endloop
endfacet
facet normal 1 -0 0
outer loop
vertex 20 0 0
vertex 20 30 40
vertex 20 0 40
endloop
endfacet
facet normal -0 1 -0
outer loop
vertex 20 30 0
vertex 0 30 0
vertex 0 30 40
endloop
endfacet
facet normal 0 1 0
outer loop
vertex 20 30 0
vertex 0 30 40
vertex 20 30 40
endloop
endfacet
facet normal -1 0 0
outer loop
vertex 0 30 0
vertex 0 0 0
vertex 0 0 40
endloop
endfacet
facet normal -1 -0 0
outer loop
vertex 0 30 0
vertex 0 0 40
vertex 0 30 40
endloop
endfacet
facet normal 0 0 -1
outer loop
vertex 20 0 0
vertex 0 0 0
vertex 0 30 0
endloop
endfacet
facet normal -0 -0 -1
outer loop
vertex 0 30 0
vertex 20 30 0
vertex 20 0 0
endloop
endfacet
facet normal -0 -0 1
outer loop
vertex 20 0 40
vertex 0 30 40
vertex 0 0 40
endloop
endfacet
facet normal 0 0 1
outer loop
vertex 0 30 40
vertex 20 0 40
vertex 20 30 40
endloop
endfacet
endsolid OBJECT
This all points to the fact that the problem is with Chitubox. Seems like there must be a setting relating to units or scaling that needs to be changed.
-Kevin
I using chitubox too and have too problems with exported stl files form rhino but not that hard. I need to resize all objects by a fix % value (0,07%) to match real size.
But i think this is normal by all printers of this type. Many materials are shrinking an expanding while getting exposed to sunlight and washed in alcohol.
Are you measure the object after printing or are you check the sizes inside chitubox?
By me the site in Chitubox is correct but the printing is to small without my fix value added.
@Gunter511
Perhaps try to bring your model as .obj. much more pleasant file format and better for keeping dimensions
Chitubox loves .obj
.stl is an old format, not necessary anymore for printing.
Thanks Akash. I’d like to try that. When I export selected to obj I get this pop up:
I work on a mac so which of the top 3 options do I choose please?
Also in the Geometry tab, I’m guessing I should choose Polygon Mesh Objects and not Nurbs, is that right?
Many thanks,
Gunter
Hi
it seems to be the same on my side, so this is good
Leave the Windows formate as is.
the significant Digit is what control the level of precision of the mesh, 17 [rhino default] is very high and it makes the mesh larger then how it would be saved by some other apps.
it’s not an issue unless you need lighter file size…?
in the mesh tab, this is how it is on my side.
you can always experiment to see what gives you the result you like.
I like to have the mesh welded.
And by the way, not sure if you know…? but you don’t have to boolean all the parts, if they intersect, then the printer will see them as one solid, but the parts need to be closed volumes.
Then you have the mesh setting, it depends on the level of details you have.
but up to 1 mil poly should not be a problem to the printer.
HTH
Akash
Brilliant, thank you very much for your detailed explanation Akash, that really helps!
Best,
Gunter
