topic Re: STL Output is Miniscule in Fusion Support Forum

STL Output is Miniscule

jtevisD9ACH — Wed, 17 Jan 2018 17:27:15 GMT

I have a simple model in Fusion 360 that measures approximately 2"W x 1"H x .5"D. When I export this model as an STL file and import into my slicer software (Cura or ideaMaker), the model is miniscule and requires scaling on the order of 100,000% to get the original size. Am I doing something wrong? Thanks.

Re: STL Output is Miniscule

James.Youmatz — Wed, 17 Jan 2018 18:10:04 GMT

Hi @jtevisD9ACH,

Welcome to the Fusion 360 Community!

I am curious if this is related to the import on Cura's side, or the export on Fusion's side. Try this - take the output STL file and then open a new Fusion design and hit Insert->Mesh (don't upload to the data panel). Make sure to select Inch as your units.

Use the measure tool to see if it is the correct dimensions. If it is, I would be curious to see why Cura is shrinking the model so much.

Thanks,

Re: STL Output is Miniscule

jtevisD9ACH — Wed, 17 Jan 2018 21:11:31 GMT

For this test, I created a simple cylinder that measured 2 inches in diameter and 1 inch high (2" diameter circle extruded 1"). Cura doesn't support inches (one reason why I prefer ideaMaker), but here is how the slicers imported the cylinder:

ideaMkaer - 0.157" x 0.157" x -.039" (which is 4mm x 4mm x 1mm)
Cura - 4mm x 4mm x 1mm

I further imported the cylinder mesh into Fusion and it came in with the correct dimensions. From looking at the results above, it seems that Fusion exports the object in millimeters even if the units are set to inches in Fusion. I would think this would be a bug.

Re: STL Output is Miniscule

HughesTooling — Wed, 17 Jan 2018 23:43:50 GMT

One question, is the cylinder 2" diameter or radius. The reason I ask is you say the size exported is 1x4x4, this looks like a 4" diameter 1" long and fusion is exporting your stl as 4 units in diameter and 1 unit long. STL files are unitless so both programs need to work in the same units and from tests and from all the other posts with this problem Fusion exports 1" as 1 unit and it seems like most slicers expect MMs so you see 1mm instead of 25.4mm(1").

One option is expand the document settings in the browser and set to mm, export then set back to inches. The other is on the STL export dialog select Send to 3d print utility then select custom then select your slicer. Exporting this way seems to scale the model correctly. So your 4" diameter will export as 101.6 units by 25.4 units.

Mark

Re: STL Output is Miniscule

jtevisD9ACH — Thu, 18 Jan 2018 01:18:20 GMT

Hi Mark,

Sorry about the diameter error; I meant to say radius, so 2" radius and 4" diameter.

Your explanation makes sense as far as describing what I would call a bug, either in Fusion or gcode. If I can set Fusion measurements to be inches, and I have ideaMaker units set to inches, when I import the test cylinder, ideaMaker shouldn't tell the model is too small and ask if it should it switch to millimeters. Because in either case, I have to scale the imported model back up to the original size.

Cura doesn't support Imperial measurements, so it just imports the model in millimeters with the same results.

But you have directed me to the solution. I was unaware that the slicer app could be defined in the Send to 3D Printer process. I had just been sending to no printer, which saves the STL file, then loading that into ideaMaker. After using your "custom" option and specifying ideaMaker as the destination, the model exported directly to ideaMaker with the correct model dimensions in inches. So why the STL files would exhibit such shrinkage and direct export would not is still a mystery.

Thanks!!

Re: STL Output is Miniscule

HughesTooling — Thu, 18 Jan 2018 08:23:11 GMT

The direct export is not in mm it is unitless so 4x4x1 units your slicer is expecting mm so it opens as 4x4x1 mm, Fusion is not doing anything wrong. I think the export direct to the slicer assumes all slicers expect an stl file in mm so it scales the file. If I export an inch stl to Rhino3d and open in a inch template the file imports correctly, the slicer software has been kept simple for people with no real knowledge of cad so it looks like they've been dumbed down so everything is in mm.

Mark