ZBrush 3D printing best practices

I've recently started playing around with the 3D printers here at work. There's a space called the Microsoft Garage where they allow you to use several different printers free of charge. It's been awesome since I've been able to experiment with several different printers without having to worry about financing it - a tiny print at the maker shop near my house in Seattle can cost up to $60.

For learning's sake, it's pretty much essential to have access to a printer free of charge (or at least just materials charge), since you'll likely have several failed prints if you're trying anything custom you might make in ZBrush.

I figured I'd document my findings for any future ZBrush artists who are looking to print their sculpts. Most of the printing guides online suppose you are using a pre-existing model from Thingiverse, which is great if you're just trying to learn how to use the printer but not so good if you're trying to print your own original work. Most of the popular models online are already proved printable, but without the explanation what made them that way. It's one thing to print something that's proven, and another to prove that something is printable! 

Prep

Here's a quick list of the materials I used:

  1. ZBrush and .ZTL file - for these prints, I used my WIP Legend of Korra bust
  2. 3D printer - I tried several, and my favorite was the MakerBot Replicator 2 which comes with very easy-to-use MakerBot software
  3. Blue painters tape
  4. Spool of appropriate material - I used 1.75mm PLA filament from Maker
  5. Windows 10 PC - it comes with a simple, handy 3D printer app that will save you time cleaning up your model between ZBrush and the MakerBot software
  6. Webcam - not required, but helpful for streaming a video feed of the printer so you can check progress from anywhere instead of being tied to your printing desk all night

Exporting from ZBrush

If you're printing anything complex, it's likely that you have several subtools in ZBrush.

Having all these different pieces will make your print more likely to fail, since the printer will get confused when trying to lay down layers between seams. Here is a set of steps that will take you from your multi-subtool highres sculpt to a single, manifold mesh that is more 3D printer friendly:

  1. From the Tool palette, choose Subtool->Merge->MergeVisible, which will create a new unified ZTool from all the subtools
  2. In the new ZTool, create a duplicate copy so you don't overwrite your original work
  3. Switch to the duplicated subtool and, starting with 128 resolution, convert it to a sealed, manifold mesh using Subtool->Geometry->Dynamesh
    his may seem like a strange thing to do, but the other remeshing options like Decimation Master and ZRemesher will keep your subtools as separate mesh groups
  4. If you lost too much detail, undo and increase the Dynamesh Resolution slider from 128 to your desired level of detail - Dynamesh resolution is dependent on the scale of your mesh, so under the Deformation palette, you can choose Unify to get more consistent Dynamesh results
    Now you are ready to create a low resolution version for use in the printer
  5. Create a duplicate copy of the subtool, and under ZPlugin, choose Decimation Master
  6. Make sure all the options are unchecked, and choose Precompute Current - depending on your Dynamesh resolution and density, this can lock up your computer and take some time
  7. When the precomputation is done, choose a decimation quality level - I chose between 20K and 80K using the "k Polys" slider
  8. You should now have a low resolution, manifold version of your original sculpt that maintains most of the silhouette of the original - quality and detail loss should be expected, since the printer will not be able to match the detail of your original
  9. With this new, decimated subtool selected, under the ZPlugin tab, choose 3D Printer Exporter
  10. Make sure only the "Selected" subtool is set for export, and choose .STL (most common printing format)

<Gallery of the steps>

The ZBrush work is done! On to the unfamiliar stuff...

Cleanup in the Microsoft 3D builder app

Now that you've got your .STL file, you should be able to double-click it on Windows 10 to open it in the 3D Builder app that comes with the operating system. If you don't have this app installed, click here to get it from the Windows app Store:

Download from Windows Store

In the 3D builder app, follow these steps:

  1. Choose a measurement - since we're printing art instead of mechanical parts, any will do (I chose in.)
  2. Repair the model - this step always seems to be required with ZBrush .STL exports
  3. Rotate it
  4. Move it, to place flat on the platform
  5. Save as a new version of the .STL file

<Insert another gallery of these steps>

Now you're ready to move on to the printing stages.

MakerBot software and print setup

I recommend signing up for a Makerbot account, since it will let you upload your models to a personal library for free, and sync them across devices to access from any computer with Makerbot installed.

  1. Open up the Makerbot software, which can be downloaded from here
  2. Open up the .STL file saved from the 3D Builder app
  3. Scale up or down as desired
  4. In Settings, the key items to turn on are
    1. Supports - choose Breakaway supports, as any solid or criss-crossing support will be too difficult to remove once the model finishes
    2. Raft
    3. Bridging 
  5. Make sure to lay down a layer of blue tape on the bed

<Upload settings file used for Korra>

Livestreaming

While this is an optional step, if you don't own your printer and don't plan to spend the entire night sitting next to it, it's very helpful to livestream the progress to yourself. My first attempt at this involved using Twitch but <hyperlink> according to their Terms of Use, no 3D printing is allowed. Needless to say, I was banned...

The best solution I found is Livestream's deprecated webcam streaming service - it's free, doesn't require any auxiliary streaming software, and they don't seem to mind 3D printing. Only downside is that the site is flash based, so no luck for mobile support.

  1. Sign up at original.livestream.com
  2. Choose to signup for a free account
  3. Once you've signed up, click "Broadcast Now"
  4. Make sure you've got a USB webcam handy, and in the popup window, pic your camera
  5. You should be able to watch your print from any computer by going to http://original.livestream.com/<yourusername>

 

failure should be expected

Expect to print 20 copies, have the printer jam, or need to reload the filament several times. 3D printing, even on a MakerBot, isn't always user friendly. It took me a week's worth of nights in the printer lab to figure out how to get this far. Here's a pictorial representation of my failure to make you feel like you're not alone:

<Photo of all the failed prints in a row>

Ironically, the first version was as close as I got to a full print until it finally worked!

To troubleshoot failed prints,

  1. Try printing at a smaller size, then scaling up - trying your print at a smaller size will take much less time and you'll be able to see where problem areas are
  2. Try turning off Active Cooling in settings
  3. Try a hotter nozzle and bed (if applicable) heat - this may help your raft stick better or prevent nozzle clogs
  4. Try a slower extrusion speed

To trouble shoot a clogged nozzle,

  1. From Info and Settings->Preheat Settings->Right Tool->Preheat up to 280 - setting this value as high as possible will hopefully heat up the clog and let you push it through
  2. Choose Utilities->Change Filament->Unload Right 
  3. Pull strongly up on the filament - it'll come loose eventually
  4. Choose Utilities->Change Filament->Load Right 
  5. Push the filament through - the clog should pop out

To load new filament, use the device menu. Trying to eject filament from the PC is much harder.

  1. On the device, choose Utilities->Change Filament->Load Right
  2. Follow the on-screen instructions
John MacComment