Getting off the ground: printing a rocket

Hobbes · July 17, 2011, 08:50:10 AM

I've been trying to learn how to draw in 3D. I usually pick up new applications fairly quickly, but this time I'm

I'm kind of used to Adobe Illustrator for 2D drawing. Every 3D app I've tried works differently. This means that simple tasks like drawing a line become counterintuitive. Then there's the 3D aspect. I find it difficult to control where my objects end up in the 3D space. Then there are the ideosyncrasies of the applications I've tried: in SketchUp there are things I can't define as a coordinate set (for instance the center of a circle), this means that creating an exact drawing is impossible.
Blender I gave up on because the UI is a nightmare.

I have a few items [1] that I'd really like to draw in 3D in order to have them printed as 3D parts by Shapeways. These are simple shapes: I could draw each of them in 2D in a couple of minutes, using the exact sizes that I need. These could be converted to 3D by rotating the drawing along one of the axes.
I'm close to giving up on this. What can I do to prevent that?

1: I want to build a model of the SpaceX Falcon 9. The nose cone, engines and the bottom of the payload fairing are good candidates for 3D printing.

frank2056 · July 17, 2011, 11:00:06 AM

Quote from: Hobbes on July 17, 2011, 08:50:10 AMin SketchUp there are things I can't define as a coordinate set (for instance the center of a circle), this means that creating an exact drawing is impossible.
Blender I gave up on because the UI is a nightmare.

You're right. The big Sketchup "lie" is that it's easy to use. It isn't; it's fine if you want to make boxes and spheres, but if you want to make and place objects precisely, then you're in for a lot of frustration. The less said about Blender, the better. This is a family oriented board after all.

QuoteI have a few items [1] that I'd really like to draw in 3D in order to have them printed as 3D parts by Shapeways. These are simple shapes: I could draw each of them in 2D in a couple of minutes, using the exact sizes that I need. These could be converted to 3D by rotating the drawing along one of the axes.
I'm close to giving up on this. What can I do to prevent that?

I was on the same path as you a few years ago. The best option I've found is Rhino3D (http://www.rhino3d.com/). It still has a steep learning curve (and price) but I was making objects with confidence after about 4 or so hours. Their STL output is good, but you want an STL viewer/checker/repairer. The best (and free!) is Netfabb Studio (http://www.netfabb.com/).

Mastering a 3D program and learning how to fix STL outputs is honestly about 20-30% of the effort. The rest is dealing with Shapeways insanely tight (and often seemingly arbitrary) design rules. In about 3 years I've gone from sitting down with Rhino one afternoon and learning how to use it to having a part I made (the reverse engineered engines from the AMT Leif Ericson) appear in an injection kit.

To recap:
Tools:
Rhino3D (http://www.rhino3d.com/) The demo has a 25 save limit. You may be able to buy it cheaper if you're a student/staff/faculty at a University. They have fair and generous upgrade options to new versions.
Netfabb Studio (http://www.netfabb.com/)
Patience.

rickshaw · July 18, 2011, 07:12:47 AM

Inventor 3d is actually quite easy to learn. Damn expensive to purchase though. Interfaces with AutoCAD quite well (not surprising as they are both owned by the same studio).

frank2056 · July 18, 2011, 08:54:15 AM

Another free option (at least for now) is Autodesk123D beta (http://www.123dapp.com/). I downloaded it at it seemed slow even on an i7 machine with 12GB of RAM...

Hobbes · July 18, 2011, 11:55:23 AM

Thanks guys. For now I'm investigating a few CAD programs that are available for the Mac; if that fails I'll try Rhino on my work PC.

frank2056 · July 18, 2011, 03:13:08 PM

Quote from: Hobbes on July 18, 2011, 11:55:23 AM
Thanks guys. For now I'm investigating a few CAD programs that are available for the Mac; if that fails I'll try Rhino on my work PC.

There's a Rhino beta for the Mac. (http://mac.rhino3d.com/) It's been in beta for a while now, and it's comparable (if not identical to) the PC version.

Hobbes · August 09, 2011, 03:36:34 AM

Things are moving along nicely now. Thanks to Frank's assistance and advice I've created a few parts that are ready for 3D printing.

The goal is to create a 1:144 scale model of the SpaceX Falcon 9 rocket:

I've started with the parts for the payload fairing:

The parts could be printed in this state, but I want to refine the design a bit more.

There's at least one more part to create: the engine cluster. This is a bit more complex. My initial plan was to create a single engine and print 9 copies, but (to save on printing cost) it might be better to design a part that contains the entire 9-engine cluster.

I'm currently planning to scratchbuild the rest of the rocket, but maybe there are more parts that can be printed. We'll see.

The tools I've settled on: AC3D and Netfabb Studio. I'm going to use Shapeways' printing service.

NARSES2 · August 09, 2011, 07:23:30 AM

Interesting stuff Harro. Best of luck - it's way above my head

Hobbes · August 13, 2011, 11:10:44 AM

I chose this model as my first foray into 3D CAD since these parts are simple to draw.

I started by finding a good drawing of the shape I want to create:

I imported this into the CAD program and traced it.
The next step is to add the wall thickness, basically creating a cross-section of the part:

Then I can use the 'revolve' command to drag my shape around a circle, converting my cross-section into the final part.

This trick only works for parts that have rotational symmetry.

rickshaw · August 14, 2011, 03:25:21 AM

Which CAD system are you using?

Hobbes · August 14, 2011, 04:14:23 AM

I'm using AC3D, by Inivis. The last screenshot is from Netfabb (an application that helps to correct flaws in the CAD file in preparation for 3D printing).

Hobbes · August 23, 2011, 10:54:39 AM

Progress on the engines has been slow, it's taken me a while to fix issues with the 3D model. But I've made progress and am learning a lot.

This is the basic shape of the engine:

I need to add some details, then put 9 of them in a grid:

frank2056 · August 23, 2011, 02:56:46 PM

Harro,
If you can see facets on the engines, then your polygon count may be too low. Other than that it looks good. How big is this? Around 12mm - 15mm?

Frank

Hobbes · August 23, 2011, 11:45:04 PM

The engine diameter will be 7.25 mm. The wall thickness is going to be critical with this part: it's now at 0.5 mm, so I'll need to use Frosted Detail.

You're right, the polygon count is too low, this was the last of a series of tests that I did to find the errors (with low polygon counts to speed things up): Netfabb kept complaining about holes. Now that I've found them all, I'll refine the model.

NARSES2 · August 24, 2011, 03:09:11 AM

I have to say this is way over my head but absolutely fascinating none the less