3D Printing Basics In Zbrush

How do you prepare your model to be 3D printed? Well, that's a question I've been wondering myself, so I decided for this assignment that I would do a bit of research on how to get started with it. This blog post isn't about what type of 3D printer you should get, what materials you should get, etc. However, it's a good starting point on printing once you've gotten all of that sorted out.

First off, you need a model thats in polymesh 3D. I used a starting base of a cat that is provided with the Zbrush software.

Here it is. Of course, in reality we might want to refine the model and give it more details, but for this example we are going to leave it like this. The first thing you have to do is prepare the model by printing. You should know what material you're planning to use since each material has it's own requirements for designing to make sure it's printed properly.

Some materials you can print with are:

• ABS
• Aluminum
• Brass
• Copper
• Resin
• Polypropylene
• Steel

Once you've done that, your next step will be to make you model watertight. Meaning you need to plug in all the holes. As well after identifying the material, you will need to make sure your model is the correct thickness for your material. Some materials can handle thinner walls than others. In 3D printing, wall thickness means to the distance between one surface of the model and the direct opposite surface from it.

 

The one on the left has no thickness. The one on the right does. You also have to make sure the models normals are correct so it won't complicate printing. And if can hollow out your model, it might help you save on printer material as well. Depending on your printer, your model may have too many 'polygons' or 'active points' as they're called in zbrush. If that's the case, you will need to decimate the model. Let's take a look at how to do that. Keep an eye on your current polygon count so you can see just how much of a difference it makes!

First step is to go to the Zplugin drop down in the toolbar menu and click on Decimation Master.

 

 

 

From there, you will pre-process all. You can see in the photo below that the default is 20%. You may or not may not have to change the number, but it's a good starting point! Give Zbrush a moment to work it's magic and then go back into that same drop down and click on Decimate All. When it's done, check your polygons.

As you can see above, my model with from almost 840k polygons to 168k. That's really good. Now we are going to export.The 3D Printing tool is in the same Zbrush dropdown as the Decimate Master.

You want to update the size ratio as highlighted in the above image. But first we want to check the size of our model. In Zbrush, bring up your transpose tool by going to either the move, scale, or rotate tool. In the toolbar menu at the top, go to Transform and turn off the icon that looks like a sphere seen below.

Now we are going to measure our model. With the Gizmo 3D off, you can see the tool has changed. It snaps to individual polygons on the model. Click and drag the tool starting at the furthest point of the model and hold shift to drag in a straight line to the furthest point of the model on the opposite end. While hovered over the transpose tool, you can see in the upper left hand corner under the toolbar what the measurement is. Below is a picture of the cat being measured and it's measurement.

From here, go back to Update Size Ratio and click on it. Now you can see that it's asking if you are working in inches or millimeters. For the cat, I'm going with inches.

In the same 3D Print Hub dropdown, you want to move the sliders to your chosen export units. Moving one slider updates all of them. Now onto the exporting format.

STL: Standard file format for 3D printing. Only vertices are exported by default and using the advanced options allows you to export polypaint.

VRML: Best for models with UV mapping and texture applied. Also ideal for color printing.

OBJ: The most common format in the 3D industry. However, it only supports textures and not polypaint.

Clicking any of the buttons will allow you to name the file and specify where textures will be saved. There is also an option called 'Send to Preform' which allows you to export the info pretty much seamlessly into the Formlabs software 'Preform' provided you have it. 

Of course, this is the basics of preparing your model for printing, but there will generally be fixes that need to be made, particularly on small, detailed pieces or thing pieces like ropes, or objects like a chain with interconnecting pieces. But I found this research very valuable to getting started with 3D printing!