No drips – Making Parts Watertight With Netfabb

watertight 3d printing netfabb

Making It Watertight

In the early days of 3D printing, the term “watertight” did not mean a whole lot.  There was (and still is) this fabulous slicing program called “Skeinforge” that was very tolerant of less-than-perfect parts.  Meaning, you did not have to dot all your i’s and cross all your t’s when creating your part.  Skeinforge would usually take what you created in STL (or alternative) form and turn that into gcode for printing.

Fast forward to today.  Not everybody has the patience to slice with Skeinforge.  For one, it is very complicated to the inexperienced (as well as experienced in some cases) 3D creator.  Second, Skeinforge tends to take a comparatively long time to “slice” parts.  The most common alternative is a great program called “Slic3r.”  With Slic3r, one can quickly set their printer up and have printable gcode in a matter of seconds.

Only one problem – manifold edges.  In exchange for speed, Slic3r tends to prefer perfect, or near perfect, parts.  Meaning that if you were to fill your part up with water, a proper part would not let any water escape.  In the real world, this can be very difficult to accomplish, especially if you are new to CAD or using older software.  Without a watertight part, Slic3r may simply reject the part, creating abstract gcode that does not print with your printer.

This is where Netfabb ( comes in.  Netfabb is a wonderful (and free) program that can easily repair meshes to create “watertight” parts.  Once the part is watertight, Slic3r will tolerate it and create correct gcode.  Here is how to do it:

Open up Netfabb and add your part:

watertight manifold


Once the part is viewable, you may notice a caution sign.  Other times, you may not.  Either way, select the “+” symbol from the top menu bar (for “repair”).

watertight manifold

Now click “automatic repair”, choose “default repair” and click “execute”:

watertight manifold

Now click “apply repair” and then “Yes” to remove the old part:

watertight manifold

Congratulations, your part is now fixed!  The last step is to export your part by selecting “part” from the top menu bar and exporting as an STL (go ahead and click repair if you get a second window prompting you to do so):

watertight manifold

Your part should now be ready for slicing!