NetFabb Repair Tutorials

Cutting and repairing models with NetFabb

Many times we have a model that we need to cut into one or more pieces prior to printing.  NetFabb does a good job of cutting the model, but sometimes fills in holes that should be left open.

Here is how to fix that:

First we load the model we fixed in the previous tutorial, using the "Z" slider select a place to cut the model (about half way, or 6mm in this particular case).  Click Execute Cut, and new tab appears with information and some options.  By default the Triangulate Cuts box is checked.  Leave it checked. Another available option is Only Selected Parts".  If your model is made up of multiple parts, you can select to cut all, or only a few by SHIFT selecting the parts you want to cut and checking this box.

Click Cut.  Your model is now in 2 separate parts. Unfortunately, both your new parts have errors (The yellow bang on the main window and next to each part in the upper right parts list window.

While in the parts windows, click the Eye icon next the part name to make that part invisible.  You can now see we have errors.  NetFabb attempted to triangulate the cuts, but also closed the center rectangular hole as well as the semi-circle holes under the 2 domes, which should have remained open.

NOTE:  The reason for the error is that the openings were filled with a single "wall" open surface.

Right click on the part and Select Repair. Using the Surface Selector click the top and you'll see that the entire top is a single surface, including the areas that should be open.  You can also see the yellow outlines of the openings.  Those are actually the edges of the openings which the triangulation process didn't properly handle.

So we'll use the Triangle selector and manually select the triangles inside the center square opening (holding the SHIFT key), then hit the Delete key.  We need to do the same thing for the other openings.  Because of the circular nature of the opening, the surface is made up of dozens of small triangles. In fact the higher the resolution of your model, the more triangles there will be.

Holding the SHIFT key, start on one of the edges and simply drag the cursor slowly across the surface.  The faster you go, the more likely it is it will skip a triangle or two, so slow down.  Zoom in as close as you can get to see the edges and click the missed triangles until the whole area is selected.  When you have it all, delete them.

The only thing left to do is stitch the open edges, apply the repair and save the repaired part.

Next up, an alternate way to do this same repair.

+1

I don't have the necessary access to turn this into a sticky, the moderators would have to do that, as far as adding it to the wiki, if someone wants to do that feel free, I'll simply post here.

couple questions on Netfab when doing the fast repair with pull down giving 2 options either default or simple. whats the dif and can others be added to list?

then when applying repair it asks if you want to remove old part or not. when would you not want to?

also I had a Netfab tech fix a model once for me and he said to "explode' parts to repair sub assemblies inside etc then re-assemble with some features in Netfab.

I know one feature disabled in free version is Boolean stuff what ever that is. but like others here I havnt begun using over 90% of the free versions tools and Netfab seems to be able to do about any fix needed if we know how to use it. one thing I have not found yet is how to cut or separate parts of a group of objects. or delete unwanted parts e.g. clean up flash on a scanned model etc.

these are a few things a short tutorial could be made for.
I have most other programs available for repairs/editing stl files too but even more lost on how to use parts of them. and Netfab is much easier/user friendly.

The effects of positive and negative volume objects  -  Part 1

Some asked on another thread how to add text to an already existing object.  The response primarily suggested using a modelling program (like Cubify) to start from scratch.

There are 2 problems with that approach.  One, it assumes the user is capable or willing to invest time and money to learn the program, and two, it assumes the model he has can be imported and modified.

There is however another approach, and luckily it involves simple, easy to use, and most importantly free programs:  ScketchUp, NetFabb and Repetier.

SketchUp will be used to create the lettering, NetFabb will be used to create the negative volume object, and Repetier will be used to blend the two.

In the example below we'll assume the 2 objects, text and other model (in this case a rectangular block) are already done.

First we import the text STL in NetFabb, then we select it, and click the repair button.

Then we use the "Shell Selector" tool to select all the separate letters.  If the text is cursive and one pieces, it may just be a single shell.  Once all the shells are selected, click the "Flip Selected Triangles" to invert the face orientation.  This effectively creates a negative volume shell.  Click "Apply Repair", when prompted click "Delete Old part".

You can tell the part is now in error, as it 's completely highlighted in red.  Export it out to an STL.

Next Up, we'll use Repetier to merge the two objects.

The effects of positive and negative volume objects  -  Part 2

Import the 2 models in Repetier.  In the example below, I simply centered the 2 models.  Since they are both the same height, the negative volume should displace the the letter shape from the block when sliced, leaving a nice cutout.

And here are the results

Here is an alternative way.  You can reposition the negative shell model (the letters so it only partially intersects the other model, giving you an engraved look.

That's it for now.