draft analysis for STL export / 3D printing

[big_red_frog]

Having been tuning designs a lot recently to minimize support implications for 3d printing I am aware of how massive a difference this tweaking can make to reduction in the support material / time / reliability of print / surface finish impact.

A little effort makes a night and day difference to all these factors.

What would make this so much easier, and something I don't think I have seen elsewhere is the combination of these two workflows.

1. Make it possible to export STL at the body level using any construction plane as the reference plane for down. Presently to force the orientation of parts for STL export so that my flat model face I wish to have down is aligned to a origin axis, I have to export the part out of the main design, where it may be in a complex orientation to a separate design. Host it in a new component within that design, draw a circle on the origin plane via a sketch, then using a joint defined on the "down" face of the body, joint the body to the sketch. Then I have to export from the root of the design, or it doesn't observe the intent of the orientation. If you could simply define an arbitrary plane as the "down" during the STL export of the body at the node in the browser, it would make export in place with easy orientation so easy. This is important to ensure you get absolute alignment of the down face in the slicer package you may use, Makerware for example, if you have to manually tweak you can be sure your face will not be perfectly aligned, and this means poor finish. It also empowers point 2 below.

2. Add an analysis feature that, colorizes the body faces according to angle from the selected "down" plane. Using this and a parameter that represents your printers capability to build overhangs without support, lets say 45 degrees for the purposes of this description, you can color faces that are up in relation to the down plane as "passive", faces that are down but shallow enough to not require support as "healthy", and those approaching the angle where support is required to those where it is definitely required to varying shades of "needs attention" with a good contrast where that boundary angle is crossed.

You can then work directly in fusion to prep your model, where angles can be adjusted or down face chosen differently without compromising your design.

This would be so much faster / convenient than the current workflow of exporting STL and examining in various external packages that visualize support output.

If this already exists in fusion then please point me at it.

I assume it should be similar to draft angle analysis for molded parts.

Yours in hope.

[Helmi74]

I totally second both request - they would definitely be useful for 3D print preparation. I do lots of this for different printers but that would help with all of them.

The orientation stuff could probably also be on component level at least alternatively. Maybe this could also sit somewhere in the origin section - having a chance to choose one of the planes there as "down for export" would help really much.

[samenor]

Totally agree - the orientation stuff (1) is huge - especially for FDM printing. Currently we export .stl then import it into Netfab to repair the models and rotate to the right plane (both are generally trivial but necessary extra steps).

It'd be great if when you export a body / component as STL there was some autosensing to suggest one or more possible planes (though with the option to free-hand them). Shouldn't be too hard just something like

1) identify the convex hull of the body

2) identify the largest planar surface(s) on the hull surface

3) identify the orientation from (2) with the minimum amount of overhanging faces

Give the user a simple GUI to select among those planes.

A trivial example would be something like an ideal cut diamond. The object itself would be a convex hull with all of the faces identified as possible planes for the user to select, but the largest / top face selected as the default.

One small note - for overhangs (in FDM printing at least), I believe it's not just the angle of a planar surface but of the curvature normal to the vertical axis (or something similar).

An extended version of this could be useful for injection or investment casting mold design. It'd definitely be worth talking with someone who really understands moldmaking because there are a lot of simple properties that should be easy to programmatically identify that can make the difference between using a simple two part mold and needing more or moving parts which will make the molds much more complicated or expensive.

[schneik-adsk]

Autodesk has a great project being developed with 3D print companies called the 3D print utility.

It can automatically decided the part orientation that requires the least support materials and adjust the stl position on the print bed accordingly.

It also can:

• Autorepair men common stl problems
• Detect walls that are too thin
• Hollow out models to reduce print time
• Copy and scale models
• Preview the print bed and material preview for different model printers.

The results can be sent directly to printer driver software or saved to an STL for latter printing.

Fusion 360 in September will support this new utility so when you export a body as STL you can send it directly to the print utility which will be available to download on Mac and Windows from our exchange app store free.

An example Fusion 360 model:

The STL export preview:

The print preview in the utility:

We have some exciting plans to make this process easier and more integrated early next year, but I think the improvements coming soon will help tremendously. 

These suggestion on overhang, support, pre analysis are great ideas and will factor into our plans.

[big_red_frog]

Unfortunately Autodesks 3D print utility is exactly what I don't want.

I want to be able to work the implications of 3D printing directly in fusion, with the results of each modification implied by the live colorisation, not export it to an external pipeline, and have to guess how to project those changes back into my original model.

I have tried the existing autodesk 3D print utility, and was deeply frustrated with the current UI, and aghast that the application changed the orientation of the STL file, which in this case had a well aligned face to the down, but once processed through this utility had moved it off that orientation by 10 degrees or more, so what arrived in makerware had no chance of being flat on the baseplate. Put me off it completely. Always willing to be surprised in a new version, but this request is all about a tight workflow.

[schneik-adsk]

Got it. Then I think the plans we have post September are going to address your needs. 

I'll be sure to post here and have you look at those planes in detail. I understand you needs and concerns. 

[big_red_frog]

Thanks, and appreciated, another way to summarise would be, I understand the place for a toolset to post process and fix bad STL models, and I use them right now, via netfabb, just as a sanity step, before I commit to a 12 hour print, but specifically I want to make good models in the first place...

[lure23]

Frog's suggestion from Nov (having a reference plane for STL export) surfaced again today on the Hangout.

| using any construction plane as the reference plane for down

[deyop]

You should find the support you need for analyzing overhang support in Meshmixer which we provide as an alternative output for Save to STL. However we would like to integrate that capability in Fusion where the UI would be consistent. These are planned for future releases. You could get some idea of the Meshmixer capability here: https://www.youtube.com/watch?v=HcqH7pc1CbA

[thehans]

At the very least I wish I could just see a toggle on export menu for switching between "Y axis is up" (how Autodesk exports), and "Z axis is up" (how every 3d printing slicing application expects the STL to be oriented)

It is annoying to have to reorient every single export.

[mad.macs]

This is still something that would be handy to have, and I'm sad to see it not implemented yet. It is very difficult if you have an component that is in the design at an odd angle (30° off X and 3 off Y ex.) It would seem to be easy enough. -Make a copy, and align the component or body to  one of the XYZ planes, and Export the copy as STL. That's a lot of work, and does not reliably work. Occasionally the imported STL is a few degrees off Axis, and won't lay flat on the platen.

It would seem a much more reliable export option would be to have the option to define a face of the component at the time of export, or be able to save the orientation for future exports.

[s10blazed]

I've been running into this problem with a design I've been working on lately.  Exporting the model to STL seems to give random orientations.  Even if I export the same one 2 times in a row! Manually rotating the model after the first failed export has worked on occasion.  But then again, sometimes I rotate it one way and it exports some entirely new orientation.  It would be so nice to be able to choose a "bottom face" or "print bed face" while exporting.  I don't use Meshmixer and prefer not to add in more programs to my workflow. Fusion should be able to do this.

[michaeleleung]

Are there any current hacks around this issue? Or just cross your fingers that the stl gets exported in the proper orientation for 3d printing?

[P.Donon]

Is this feature still under consideration? Being able to export STL files in the correct orientation would be great!

[roy.o.miller]

This appears to have been implemented (kinda) but it's not obvious. 

Ideally, we could define a unique "Up" for each part in an assembly. Instead, Fusion 360 has an option in the "Preferences --> General --> Default Modeling Orientation" . The default value for this is the non-intuitive "Y-Axis" which makes the back of the model "up". Changing this value to "Z-Axis" appears to make Top equal "up" in the STL file. 

Once configured then you need to rotate your bodies around so that the desired down side is facing the bottom of the navigation cube.