Why Use Meshmixer?

You can do a slew of things with this program, but these are the two you’re likely to do most often:

• Merge surface files, called .stl files, into a single part that can be 3D-printed.

• Create highly intricate and organic shapes.

Getting Started

When you first launch Meshmixer, the home screen appears, presenting a series of options and essential tools in the middle of the window (Figure 3-2).

Some tools also appear in a menu down the left edge of the window, where they can be accessed when a project file is open.

The following sections take a look at what these tools do.

Import Plane

In this case, we are referring to a flat rectangle, not the “main plane” workspace of 123D Design and other CAD programs.

Figure 3-2. The Meshmixer home screen

Keyboard Shortcuts

Opens a PDF file containing a three-page visual reference (Figures 3-3, 3-4, and 3-5) for Meshmixer’s load of hidden keyboard and mouse commands. You don’t need to know any of them to use the program, but they can save you keystrokes and speed up your work.

Figure 3-3. Keyboard shortcuts for 123D Meshmixer

Figure 3-4. More 123D Meshmixer keyboard shortcuts

Figure 3-5. And more 123D Meshmixer keyboard shortcuts

Tutorial: Seal Up the Bunny

In this tutorial, we open up a sample model, and then fix a gap in the design so that it is watertight. A model must be watertight in order to be printed in 3D.

When a model is watertight:

• Every triangle edge has exactly two neighbors, which means there are no holes or “nonmanifold” edges—that is, a mesh edge with more than two entities attached to it.

• Every node in the triangle is connected to only one “fan” of triangles around it. If the model is watertight, every triangle that shares a node is accessible from any other triangle in the same node by moving across the triangle edges.

• No triangles overlap or intersect with each other geometrically.

• No geometric errors occur that result in unrealistically thin areas in the model.

At the time of this writing, Autodesk provides some pointers on ferreting out watertight problems with models on this web page.

Step 1: Import the Bunny

When you first open the program, you will see the options to import, open, or use the 123D library. Under that, you will see the shapes of a bunny, a sphere, a plane, and a keyboard. Click on the bunny. (Just a heads up: we will be using the same bunny throughout this chapter.)

Select “import bunny” (Figure 3-6).

Figure 3-6. Import the bunny prior to rotation

Step 2: Find the Gap

Notice that there is a blue line around the bottom of the bunny. That blue line indicates that there is a gap somewhere in the object, which prevents it from being watertight.

Rotate the object to see the opening by holding down the right mouse button and moving the mouse, until you can see up inside it (Figure 3-7).

Figure 3-7. The underside of the bunny

Step 3: Close the Gap

Click the Analysis tool, which you’ll find midway down on the toolbar.

Select the Inspector option on the top of the menu.

Once you’ve made that selection, you’ll see a blue barb sticking out from the hole in the bunny’s mesh. Click the blue barb. Then select “done.”

Voilà! The gap in the model is closed, and the blue line has disappeared, as shown in Figure 3-8.

Figure 3-8. The blue line vanishes when the gap is closed

Congratulations! You have just used a very simple feature chain in Meshmixer.

Print

Meshmixer’s print function is the most exciting 3D printing experience you will ever have. If the program consisted of this tool alone, it would be the best 3D program on the market, in our biased opinion.

Click the Print button on the lower side of the lefthand menu, and a separate area of Meshmixer appears: the Print Studio. Here you can work with your design to ensure that you’ll be happy with the final result. Does the design’s scale work with your printer? Do you want to select another printer? Is it watertight? Does it have validated supports? Print Studio is where you can check all these factors.

Print Studio supports a variety of printing services, as well as 3D printers. You can select the service or printer you want to use by clicking on the pre-selected printer, right below the the Import, Open, and Modify buttons. If you do not see the printer on the list of options, select Choose Printers (Figure 3-9) and a new window will pop open. Select the printer you wish to use from those on the available list.

If your printer isn’t listed, click the Add New Printer button towards the bottom right of the window.

Figure 3-9. Choosing the printer

The Printer Properties window pops open. Here you can enter a name for your new printer, as well as the Printer Parameters: the units of measurement, maximum printing dimensions, and so on. If you are uncertain what these settings need to be for your new printer, check in the printer instruction manual, or with the machine manufacturer’s website. Most 3D printer makers post this information online.

From here, you can select to repair the model and then select to validate the supports (if you don’t have supports, it will generate them for you).

Then select Export to get your watertight, supported STL and open it up in your printer driver.

Now go back into Meshmixer by clicking on the arrow in the upper-right corner of the workspace.

Toolbar

Now let’s investigate the other tools in the vertical toolbar running down the left side of the window.

Meshmix

Offers a variety of simple models that can be added to your model, such as a torus, cylinder, or cube. There are several menus to choose from; if you click the Primitives option, you will find fun things like arms, ears, heads, numbers, and our favorite, miscellaneous.

To add one of these parts to your model, click and drag it from this menu to the desired area on your model.

Let’s try one.

Step 1: Import the Bunny

If you did not already import the bunny in “Tutorial: Seal Up the Bunny”, then go to File → Import, and import the bunny (Figure 3-10).

Figure 3-10. Import the bunny

Step 2: Heads Library

Select Meshmix from the menu options, and find the Heads library (Figure 3-11).

Figure 3-11. Meshmixer offers access to a library of pre-formed head designs.

Step 3: Select and Merge the Bear Head

Grab the bear head from the available options, and pull it over to the bunny’s butt.

Toggle your model by clicking and holding down your right mouse button until you can get a good view of the bear head. Zoom in by rolling your middle mouse wheel.

Use the toggle wheel under the bear head to move it around and resize it (Figure 3-12).

Figure 3-12. Use the toggle wheel to move the bear head around

Once you’ve placed the bear head where you want it on the bunny, toggle the SmoothR command up and down, and watch as it smooths out the rough edge between the two objects.

Click Accept, and you’ll see that the brown tone of the bear’s head changes to the gray tone of the bunny. Keep this bunny open for now, as we’ll use it in the following sections for experimenting with other tools.

My Parts Library

You can also create your own library of parts in Meshmixer. This can be very useful if you are building several objects that utilize the same components, such as stackable plastic bricks or other interlocking parts.

To add a part to your part library:

1. Have the part you wish to add to your library open in your workspace.

2. Press Command-A on your keyboard to select all. You will automatically be placed in the select menu.

3. Go to “Convert to…” and select either Open Part or Solid Part. This will depend on if there is a hole in your part (e.g., as in a vase) or if your part is closed (e.g., as in the bear-butt bunny we’re creating here).

4. Go to Meshmix and check in the My Parts folder (Figure 3-13).

Figure 3-13. You can add the bear-butt bunny to your My Parts library for future reuse

Select

The Select tool allows for various ways of selecting and altering different parts of your model (Figure 3-14).

Figure 3-14. The Select menu

1. With the top button switched toward Brush, you can paint on your selection. Try painting a nose on the bunny.

2. From the Edit menu that pops up, select Extrude. Play around with the bars and toggles to see what happens. Then click the Cancel button (Figure 3-15).

   

   Figure 3-15. Select offers different options for detailing your model

3. Play around with the other choices under the Edit menu to see how they work, especially Discard, Extract, and Offset (Figure 3-16).

Figure 3-16. Additional options under the Edit menu

Sculpt

The sculpt tools include a number of different brushes, each with its own settings, that allow you to draw and carve details into your object. Explore these toolkits, which offer options to create remarkably fine detailing. This tool is simple when you begin but can take a lifetime to master. Just a tip: you should constantly change your strength versus size ratio to get more controlled results.

Edit

The Edit tools are the best way to make big shape edits to your file. You can use them to mirror, transform, and separate out your object. You can also separate your larger models into smaller sections if you want to go big by using the Make Slices tool.

Let’s use the Edit tool to turn the outside shell of the bunny into a cool lattice structure, as depicted in Figure 3-17. This project was created by Instructables member Marshall Peck.

Figure 3-17. Using Edit to make a lattice structure

Analysis

This is the most important menu inside of Meshmixer. It should be used on every model that you ever want to fabricate with a 3D printer.

We have already used this tool menu a few times in this chapter. In Analysis, you can Inspect all of your models to ensure they have no holes in them that would stop them from printing. You can bring in models from any program. You can also generate support for any areas that have a large overhang that your printer may not be able to create, as shown in Figure 3-21 and Figure 3-22.

To do this, go to Analysis → Overhangs. Then click Generate Support.

If you see areas that need more support, you can always click and drag from your model to the grid. That will generate an arm of support for you.

Figure 3-21. If your model has overhangs that need support during the printing process…

Figure 3-22. ...you can generate support for them with just one click

Inspiring Meshmixer Projects

The 3D community has used Meshmixer to create some amazingly organic-looking sculptures. As you can see from the diversity of objects shown in Figure 3-23 through Figure 3-28, the only real limitation is in your mind.

Figure 3-23. A whale by Jesse Harrington Au

Figure 3-24. An example of the Make Slices tool by Christian Pramuk

Figure 3-25. By Craig Barr

Figure 3-26. By Gian Villamil

Figure 3-27. By Instructables member 3D Printing Ninja

Figure 3-28. By Instructables member Le Fab Shop

You can learn more by checking out Autodesk 123D’s YouTube channel and looking for the Meshmixer 101 playlist.