Modifying and 3D Printing a Downloaded Part for R&D with SOLIDWORKS

By Jacob Ifft on

In this blog article I will use geometry from a downloaded part to make a part that was not available for download. Sometimes, rather than looking up specific dimensions for things like threading or pipe sizes, it is easier to download a part that is close to what you are looking for and modify it slightly to meet your needs.

For this example, I will be designing a hand adjustable plug based off of a downloaded 3D model of a ½” NPT plug. When finished I will save the part as an STL file for 3D printing, so having detailed threads is important. Instead of trying to model the more complex tapered threads for printing, it will save a lot of time to start with a model that already has them. McMaster-Carr is a great resource for engineers that has highly detailed SOLIDWORKS files for download of most of the parts that they sell. Editing files in this manner can apply to various R&D situations where you want to test fit some components, or in this case, you just need a low pressure plug that you can screw in by hand.

If you were using this file in a large assembly, showing all the thread detail would be a lot of extra information to compute and could slow things down. If showing the threads isn’t required, suppress them in the feature tree (if available) to make the parts open faster.

Initial Model

Initial model

Modifying the Downloaded 3D Model

Since the part was already native to SOLIDWORKS it has a usable feature tree, and we can see how the drafter modeled it. This makes modifying pre-existing features easier than working with imported geometry. I will simply add a cylindrical extruded boss, then cut a singular groove, and circular pattern the cut in order to give the outer cylinder of the knob texture to increase the comfort and grip of turning it by hand. I finished it off with some chamfers and fillets to smooth some edges. The features that I added simply show up at the bottom of the feature tree from the downloaded 3D model.

Saving an STL File

In order to print this model and make use of the downloaded thread geometry, I will select “save as” and save the file as an STL. If something is odd when you open your STL file, make sure the Options are set up in a way that makes sense for what you are trying to save. According to my 3D printing slicer software the plug will be ready to screw into my manifold block for a low-pressure airflow test in 38 minutes of printing time and a material cost of approximately 27 cents per piece. For this type of application, printing is not only a cost saver but a huge time saver because you don’t have to source, purchase, or wait for the product to be delivered. 


There are many parts that can be printed with a similar technique, imagine the possibilities. I have personally printed low pressure hose barbs for cooling systems, brackets, and various other components that were needed in a rush during R&D projects using this technique. Other manufacturing methods could be used to make the part after you have the model also, but none of the other options would have such a quick turnaround time.

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