Get tiny part when saving file for 3D printing

[steetfidalgo]

I have a simple part that I am saving to print on an Ultimaker 2 via Cura (Ultimake Software).  When I import the STL to Cura, it shows up very small compared to actual size.  A very similar part shows up fine in Cura (cannot measure exact size, but looks about right).   Both parts are made in Fusion 360 via extruding a schetch.

Not sure what controls I have in scale on output from Fusion or how to figure out where the problem is (could be Fusion or Cura), so any tips on what to check would be greatly appreciated!

The part that show too small: http://a360.co/1JA1lUW

Part that shows up the correct size (at least close): http://a360.co/1zNunft

Thanks in advance!

[paul]

I do not think STL files have unit data so it is possible that your file is off by English to metric conversion? Just a thought.

[deyop · Accepted solution]

Paul's suggestion is likely correct.  You may want to take a look at this posting.

STL Export

or this blog which should give you all the details.

Making it Real: Exporting DXF and STL from Fusion 360

Thanks

[dunderhead]

deyop, hi, I have similar issues, one part of it I solved (1), maybe you can help me with (2) below?

(1) The scaling error occurred while importing the STL. I uploaded the file, then dragged it into my design. At that point, Fusion 360 simply thinks your STL units is cm (even when you've chosen mm as the default unit in preferences). To avoid this bug I simply used the insert -> "insert mesh" in "sculpt" mode; then I get a menu asking me for units.

(2) I'm trying to set up a meshmixer + fusion 360 workflow for a poor-and-impatient man's integration of CAD and mesh data operations, that's right along the lines of the intrigueing post of your tantilizing post http://forums.autodesk.com/t5/general-fusion-360-questions/mudbox-meshmixer-or-z-brush/m-p/5432632#M... . This fails because the 'export stl' function applies an affine translation to the data. In other words, the coordinate system is somehow changed!! Is there a way to avoid this? I tried to read up on the view cube, that has been mentioned, but I don't dig why the view should have anything to do with the coordinate system used for export!

(My little project: basically, I want to use the power of T-splines for making changes to an existing complicated solid, a main body, which is a closed STL.  I can easily define bounding boxes and the actual solid changes to the main body in Fusion 360, this part works extremely well with the power of t-splines snapping, pulling, and thickening etc. Then I need to export the solids as meshes into meshmixer and do the Boolean operations there on the main STL before further steps for FEA prepping.  Coordinate system changes on export kill this idea. BTW, I see how meshmixer mode could be very, very neatly integrated into the timeline paradigm of fusion 360)

[steetfidalgo]

Thanks for the very useful comments and links! One thing that was confusing me was that I was getting different results in Cura - sometimes small and sometimes not - still haven't resolved that.

But as far as Fusion360 goes, let me summarize what I've learned for future newbies reading this thread (and please chime in if I've got it wrong!) 

STL files do no contain an indication of the units used, but it seems that Fusion360 will save in the units that you have set for your file.  So a 1x1" box will have coordines [1,1] in the STL if Fusion360 units are inches, and [25.4,25.4] if you switch the units to mm before saving the STL.  It seems Cura (usually!) assumes the units are mm, and so your object will look very small, unless you scale it by 24.5 (which you can easily do with Cura).  So, it might be easier to switch units to mm before saving, and then back to inches afterwards if that's what you are designing in.  I find that less error prone than finding the tiny object and manually scaling in Cura. 

The fact that the units in the STL file are the same as set in Fusion360 cleared up some confusion for me, since some programs always store the same units (usually mm or cm) independent of what you are designing in.