Machining an STL or OBJ File (Fusion360 Machining)




Introduction: Machining an STL or OBJ File (Fusion360 Machining)

About: Artist, Designer, Engineer, Fabricator, Machinist. 5-Axis CNC owner having a fun time! @daveprecise on Instagram :)

So. Here we are.

You somehow ended up at the crossroads of subtractive and additive. You were so used to clicking the "Make" button that you forgot how the other half lives :)

3D printing has trained our feeble minds into thinking that the making of something is as easy as clicking a button and walking away. Not so fast!

In the middle of the crossroad we must wonder if there are ways to work in harmony with one another.

I tell you now that there is a way.

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Step 1: Thingiverse! Now What?

Someone somewhere uploaded a file which you now possess.

Sharing is caring.

In 3D land (addititive), you work with STL and OBJ files.

In machining land (subtractive), we speak a different language. STP and IGS are pretty common. If you work with Inventor, Fusion360, Solidworks, and the list goes on, some file formats will be able to be natively used in CAM (Computer Aided Manufacturing). If not, the aforementioned will work just fine.

We need to be able to manipulate the model in order to control how the tools we are about to use move around the part. There will be another Instructable on the basics of how to accomplish this. For now, let's just figure out how to make this darn file machinable!

Step 2: Face It, Facets Galore.

Here we have a "Noise Ring".

It's a ring design generated using F3App. Its output is STL and OBJ.

We can 3D print it but not machine it. :(

But we'll be able to soon! :)

We've used Autodesk's MeshMixer software to import the file. What you see here is an analytic tool within MeshMixer to view normal vectors as a visual.

What we're about to do is to reduce the number of facets (this one has over 15,000 and it makes Fusion360 a bit uncomfortable, so we'll need to get a handle on it).

Click Select > Then double click the object > Edit > Reduce (Shift + R)

Play around with the number of facets until you're comfortable with it. We chose something under 10,000.

(Full disclosure: @syedrezaali and @daveprecise are collaborating on a project where we use Reza's F3App to generate forms and shapes and turn them into actual rings machined on Dave's Mazak 5-axis Variaxis CNC machine)

Step 3: Mesh to BRep. Say What?

That's right. Never heard of it before either.

Within Fusion 360, there's a function that will let you take your imported STL and automagically turn it into a usable model for machining.

First. Insert the STL.

Second. Turn off timeline!

Third. Mesh to BRep.


Step 4: Thing!

If the model now looks like that Marvel character "Thing", then you've succeeded.


Now it's time to do the stuff that makes machining a wee bit more challenging that pressing that "Make" button...

Step 5: And... STL Machining!

We won't go into how to use the CAM features within Fusion360, but you basically change from Model mode to CAM mode and "Bob's your uncle!".

That's it! Wasn't that easy?

Have a groovy day! :)

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    4 Discussions


    3 years ago

    Is this workflow still accurate for Fusion 360 as of Feb 2017? When I try to convert an STL model made-up of only triangles, Fusion will not convert it.


    Reply 2 years ago

    Hi - yeah, I'm looking into it now. But I heard them say you can now machine directly from the mesh file somehow. Gonna check it out and update this Instructable. Thanks!

    DIY Hacks and How Tos

    That looks really nice. I love the unique geometry.


    Reply 3 years ago

    Thanks! We agree! :)