Stl file yields diameter 1.45mm slicer and imported into rhino is 36mm

Hi,
V5
my object of dia 36mm and plate thickness 1mm,

I export it as .stl

the recipient’s slicer for 3D printing says its very small.
he says:-
I’ve measured the sliced image and I have the following dimensions.
The outer flange is 1 pixel thick or about 0.035mm
The diameter is 1.45mm (41 pixels) with a maximum thickness of 0.175mm (5 pixels)

Are these the dimensions that you were expecting?

reply NO !

1.4173inch 36mm dia (not 1.45mm dia) thickness flange 1mm (not 0.035mm)

import .stl into rhino,

Geometry:
Valid mesh.
Closed double precision polygon mesh: 18758 vertices, 35434 polygons
bounding box: (9.29134,-0.08,1.29134) to (10.7087,0.169053,2.70866)

do maths
and deducting 9.29134 from 10.7087 gives 1.41736 which is the inch diameter so that makes sense,
unless everything is 1:10 scale as Rhino V5 can be, but that’s still 3.6mm if at 1:10 scale, and not 1.45mm

So whats gone wrong, I selected 0.001inch from the 0.01inch in the options box as I have fillets 0.003inch.
went with default settings apart from that.

Steve

Please post the .3dm of just the part in question, plus perhaps the .stl and/or the .stl settings you used.

Hi,
V5
I have to get a signed Non Disclosure Agreement for wherever it gets sent, client rules.
so unable to post it here.

what if I create a disc of same size and export that as stl same settings and get him to see what size that becomes ?

Cheers

Steve

Sure, why not…

A good clue is 25.4 x 1.4173 = 36

STL is a “unitless” file format.
Industry standard practice is to assume millimeters.
If you have modeled in Inches, export to STL with a scale factor of 25.4 to get mm.

1 Like

Hi, V5
attached this test disc, same 36mm x 1mm as the project.
drawn in the same project file, 36mm dia circle solid extrude 1mm.
export as stl. 0.001 in box, rest as default

attached the settings.

have sent to the 3D print company. asking for feedback on size.

and here is the stl file
test stl size disc 36 x 1mm.stl (12.4 KB)

and here is the .3dm file ( same project file stripped bare)
Fastener test stl issue same project file stripped.3dm (68.3 KB)

Steve

As I thought.
Your 3dm file is in Inches units.
If you Import your STL file, choose Inches and it will match up with your surface.

My guess is the way to avoid confusion, if you have modeled in Inches, change units to Millimeters, and scale by 25.4.

Hi,
V5
Methinks simply tell recipient to enter inches as units.
If he/she enters units inches in their slicer then that should work, should it ?

else I have to go to properties and alter units to mm and hit ok.
Then how do I go about resscaling everything , and is that 25.4 x100 = scale factor 2540 ?

where do I do this rescaling of the entire project and what tool and what value to enter ?

Finding rescaling everything a bit scary, I might forget to undo it before saving file.

Steve

Some slicers support mm/inch while others do not.

The only safe way is to only export to STL assuming mm.

To rescale the file, in Options > Units, change from Inches to Millimeters, and Yes to scaling by 25.4.


image

Hi,
Thanks John,
added to my How To compendium now.
Hope I remember.

Best practice is also to place in email some size indicators, incase a print run proceeds without company checking first !

Someone will fall into this trap.

Assuming stl file carries with it project units.

Steve

It does not. STL is a “unitless” file format. Industry practice assumes is it millimeters for convenience.

Madness…

I like to model in Inches as well.
When I send out a file for STL printing, I make a duplicate of the 3DM, open it, change to millimeters and scale it, then export as STL.

Hi,
I have asked company if they can enter inches into their slicer but it has no provision for such.
Hard headed assumption that we all work in inches by slicer company.

Like you I have made a version copy of the 3D file and suffixed it ‘a’. made it mm and ok to 25.4

more duplicates to cope with !

Lets see what happens with that.

stl sending needs this flagging up and advice to say diimension in email sent, else some expensive mistakes could occur.

is .stp better, some prefer .stp ?

Cheers

Steve