3D printing threads is hard! Custom Threads in Fusion 360 makes it easy!
Fusion 360 by Autodesk is simply amazing software. I haven’t written about it before on my site, but I use it daily. For those who do not know, it is free for personnel to use CAD software that combines the power of Solidworks with the flexibility of Sketchup and much much more. There is a bit of a learning curve as it is different than but worth the time investment to get up to speed on.
One of the tools within Fusion 360 (F360) is a powerful threading tool. It is found under the Solid/Create Tab:
Pressing the thread button will present a form for customizing your thread:
From this form you are able to choose from a plethora of standard threads. My favorite to use is ISO Metric. You should also note that you can select an option that models the threads or simply shows a texture. The latter is great for large assemblies to ease up on computer power. The modeled threads print well, and you will find a considerable number of available thread sizes and pitches.
Unfortunately, customization of the threads stops at this selection of threads. This is a problem because if you try and use these standard threads to 3D print with, they will end up being too tight and, for me at least, impossible to really use in a 3D printed model. I needed a way to add a bit of tolerance to the threads. At first, I did this by threading a part and then scaling it in the X/Y direction to “shrink or grow” the diameter of the threads. This worked okay but was a tactical pain to implement on anything more than simple nuts and bolts. I needed a better, more reliable way.
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ISO Metric Threads w/ Adjustable Tolerances in Fusion360
I did a little research and found out the F360 defines the threads using user accessible xml files. Available thread definitions can be found at:
C:\Users\%UserName%\AppData\Local\Autodesk\webdeploy\production\%Hash of Version%\Fusion\Server\Fusion\Configuration\ThreadData
You will need to replace the %text% in the above path with your user/install specifics. The “Hash of Version” will be a weird string of letters and numbers with little rhyme or reason. Additionally, this hash changes with each subversion, which will lead to some difficulty in maintaining current versioning.
If you open any of the files, you will see a human readable xml file. To make my life easier, I imported that into Excel. From there I created a custom macro to add tolerance and create custom profiles.
The large amount of data located in the large table are the values pulled from F360’s ISO Metric thread file. You don’t need to touch these. In the top left you can customize your threads. I recommend you don’t mess with anything except the +/- Tolerance value. This value will adjust the diameters in the table and output the result to a file. The adjustment will result in threads similar to this example:
In the example above you can see the original ISO threads, the Max/Min allowable thread sizes that are still in standard and our adjusted thread with custom tolerance. Using this tool I then produced thread profiles with 0.1mm, 0.2mm … … 0.9mm and 1.0mm tolerances added. These profiles can also be found on my thingiverse page:
If you place any of these files in your F360 thread folder they will become available in F360. Using the above files I then generated 9 test nuts and bolts. These ranged from 0.0mm to 0.8mm tolerance in 0.1mm steps. I printed the set on an Ender3 in PETG and then tried each out. I found I could turn all of the nuts from 0.4mm to 0.8mm with the best “feeling” threads occurring at the 0.5mm tolerance level. Tolerances lower than this on my machine resulted in unturnable threads. An STL file of the 9 nuts and bolts can also be found on thingiverse.
With these new profiles and the test above I now can add 3D printable threads directly in F360 without fearing their compatibility or performing any unsavory hacks to make it work.
I offer the profiles free of charge and free to share. If however you have enjoyed this post or get use out of the profiles please consider buying me a coffee to keep this site active and growing. The easiest way is through paypal at:
Thanks again for the visit and happy making!