Fixing STL Files With Errors .

Ensure your 3D CAD Models are ready for 3D Printing with these tips and a step by step tutorial .

To set the scene with an analogy . There’s a book that a number of people have recommended to you , it has all the answers to solve this particular problem you have . The only issue is that the only copy of that book you can find is in another language , though luckily you found a loose translation . You open it and flick to the chapter you need , it starts off – ‘Cooking when the party is of new intellect and has no room to move.’

… What the hell does that mean ? Unfortunately the rest of the book is worded the same and almost useless to you .

The raw data used for 3D printing parts are CAD files. As 3D printing ( as it’s commonly known ) becomes more widespread and accessible, more people who are your everyday hobbyists, inventors, gadget gurus and even school kids will begin to think of things to make, and they all start creating parts .

This means we have a lot of different file types being sent around, but in terms of 3D printing there is one that has become standard, the humble STL ( STereoLithographic ). This is what ‘3D Printers’ use, then with some material and a bit of heat ultimately ends up as a physical part in your hands. Being such an important piece of the puzzle you want to get it right, and often there is nothing wrong with your modelling skills. However, a problem can creep in when the software you use exports its native file type into an STL.

This problem is that the mesh ( the surface geometry of the part ) may not have been generated correctly and you end up with a ‘loose translation’. This means that subsequent software programs don’t understand what the mesh is trying to be and do the best they can to make sense of it , usually with a lot of errors .

So BEFORE you send us a file, here are some steps to take to ensure that the model you send us to print is going to work.

Fix As Many Errors As You Can In The Software You Modeled It In .

That’s step one , it makes the following steps (if they’re even necessary) much easier.

Check For And Fix Errors .

  – Netfabb Basic is a program that’s great for checking your model and repairing common problems.

Free download here

 – Meshmixer is easy to use, has powerful editing tools and is also good for repairs.

Free download here

  – GOM Inspect is software which is especially good at fixing if you also have a 3D Scanner and have created your model that way.

Check it out

 – Netfabb Cloud is similar to Netfabb Basic but requires no software download and is so easy to use you almost don’t have to do anything ! Simply create a free account , upload your STL file (100mb max size) and download the fixed version when it’s finished.

Netfabb Cloud Home

There are many more programs out there to discover and utilise, so don’t be afraid to experiment.

Quick Guide On How To Fix Some Basic Errors In Netfabb .

Download the Basic version from the link above . Set it up and when done open it and go to ‘File’ – ‘Open’ . You will be greeted by the following (it may or may not have errors depending on your part).

If it does have errors – shown by the Error Triangle in the bottom right – look for a Red Cross on the top Icon bar at about mid screen, click it. This will take you into Part Repair mode .

On the bottom right you’ll see a section with numerous options and some basic information on your part. Below that are two buttons : ‘Automatic Repair’ and ‘Apply Repair’. Click ‘Automatic Repair’. Of the options ‘Default Repair’ is the more powerful .

Time to evaluate the result . You can tell from the statistics in the repair section and from the part view if it’s bug free. Click ‘Update’ on the option box on the right to ensure your information is up to date. Visually there should be no more than one colour on the part, so no red surfaces. Also is your model still what it’s meant to be ? Sometimes during the fix a part may have surfaces changed, resulting in an incorrect model .

Another important thing to check is number of shells ( found under the statistics part of the repair section ). Shells are separate entities within the part file. So if you’re file has multiple parts nested in it then the number of shells should equal the number of parts. With the example above and similar parts, there is only one part, so there should be only one shell. If you have one part but multiple shells that means that the parts mesh is not stitched correctly. If it’s not you will need to dig a bit deeper with the repairs.

If your model is now ‘watertight’, then click ‘Apply Repair’ on the bottom right of the screen, and remove the old version. Save your model as an STL file and upload it to get a quote for printing.