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Creating Threaded 3D Printed Parts

By <a href="" target="_self">Rich Annino</a>

By Rich Annino

Posted on January 10, 2023

Design to manufacture is a series of projects showcasing the talents of our experts. They execute 3D printed part design and production. First, they brainstorm part geometry, 3D model the part in SOLIDWORKS, then utilize our in-house Stratasys machines and GrabCAD Print software to create the final threaded 3D printed parts.

In this article we’ll be highlighting Stratasys P3 technology on the Stratasys Origin One. We created a texture bar part equipped with printed threads, secondary reamed threads, and a brass threaded insert in Henkel LOCTITE’s 3D 3843 clear liquid resin material. I’ve been using the Origin One printer for almost a year and put a lot of thought into creating a component that really tells the story of what this technology is all about!

Programable Photopolymerization (P3)

The technology behind the Origin One, Programable Photopolymerization or P3 for short, enables users to create incredibly high detailed models that rival injection molded parts quality, in a variety of industrial strength thermoset resins from a range of manufacturers. For the majority of materials, we’re capable of printing the entire build capacity of the printer inside of an 8-15 hour period.  The 4k light engine allows easy printing at 100 microns (or less; this is toggleable) on the Z axis with a 50-micron pixel size on the x/y axis. 

The materials range in mechanical focus from low cost and easy to print, to strength, durability, and even to high temperature, chemical resistance, and beyond.  Finally, when compared to other similar additive machines in the DLP printing space, P3 resins are all single part resins; where other machines use two part resins that have a very short workable window (typically 12-24 hours before they harden in the printer), P3 resins typically have a safely usable window once loaded into the machine of several weeks, and can be unloaded from the printer, stored, and used again down the road if you want to change to another material.

Ultimate Origin One Sample Part on the Build Tray Completed

Completed Build

The Resin

For this demonstration part, I’ve chosen to focus on using Henkel LOCTITE 3D 3843 resin.  This resin is available in Clear, Black, and White. For this part we’re using the clear variant, because it: looks cool, prints the fastest, prints VERY well at 50 Microns (we’ll talk more about that in a bit), and allows us to easily see the internal features of the component that we’re making.  Why 3843, and not one of our other materials? 

3843 has mechanical properties that enable it to be easy to print and clean, offers incredible high resolution fine detail, is strong and durable, and is machinable. We’re going to take advantage of ALL those properties in our part!

Ultimate Origin One Sample Part Ready for Post Processing

Removing Parts from the Build Tray

Ultimate Origin One Sample Parts Being Cleaned

Cleaning the Parts

Ultimate Origin One Sample Part Being UV Cured

UV Curing the Parts

The Threaded 3D Printed Part

Screws and Threads. The design intent of this sample part is to use a real metal screw in a variety of thread types. When I first started working on my design, I wanted to build the part to have three different thread features in both the planes parallel to the print head, and perpendicular to the print head to demonstrate orientation build quality. Each of those are: printed threads, tapped threads, and press fit inserts. The 3D printed threads are a no-brainer; this resin can print with a 30 degree unsupported angle easily, at either 50 or 100 microns.

Those threads are going to be super smooth, so we can print the threads straight into the part! Tapped threads are the most interesting option to me. The other two options are pretty easy to do, but for a resin to also be easily machinable stands out to me as incredible, so demonstrating tapped threads is a must!  And lastly, we’re going with press fit inserts because thermosets don’t melt like their thermoplastic brethren, so we are looking to design a cavity with tight clearances to ensure that the insert’s barbs tightly grab hold of the sidewalls.

For all of our threads, we’re going to use a half inch long ¼-20 bolt; a universally easy to find and low-cost option. If these bolts slip through your fingers and disappear, you could easily replace them with a quick trip down to the hardware store.

We’re also going to heavily take advantage of the extremely smooth and high detail printing resolution of the Origin One.  As I mentioned before, we’re printing with x/y axis pixels of 50 microns, and while the default Z axis height is set to 100 microns, we can make a true 50-micron pixel with a quick change in the GrabCAD Print software. 

Depending on the material, size of the part, and other factors, you may need to tweak the cure settings to ensure optimal print quality at 50-micron layer height, but in the case of this demo part, I changed nothing other than the layer height and it prints fantastic!  What are we doing with that super high resolution 50-micron x/y/z?

  • Of course, our very smooth printed threads, both parallel to the print head and perpendicular to it.
  • Next, we’re inserting some text and logos on the part: The word TriMech on one wall, identifier text on another, the TriMech logo on one end, and finally we’re inserting a slot to put a QR code sticker on the far end of the part with an embedded “QR” to mark the sticker placement. Some of you may have found this article by scanning it!
  • Third, one of my favorite features of this project, I’ve hidden some very fine, sharp, high detail knurling on the underside of the part!
  • Finally, and taking most advantage of the 50-micron printing height is the SOLIDWORKS 3D Texture feature I’ve added to create an extruded Carbon Fiber texture on one of the surfaces that prints with incredible accuracy!

The Numbers

Let’s review the build data for this part. We can fit 11 of these straight to the print head of the machine with zero support structures used at all.  Each build at 50-micron layer height takes 2 hours and 22 minutes to print.  In a standard 8-hour workday we’re printing at least 44 copies of this part, potentially more if we add an additional shift to the production schedule.  Given the benefits in print quality and part strength and durability of the 3843, it is actually one of the most cost-effective 3D printing resins I’ve come across. 

Our part is 3.5” long by 0.75” tall by 0.6” wide, and in raw material usage this part costs only $1.50, which is actually lower in cost than the two press fit inserts we’re adding to it, which cost a dollar each!

If we run numbers with a theoretical maximum of a 3-shift schedule, we could potentially produce 15,730 copies of this part annually. Factoring in the cost of ownership of the printer, operating costs, and labor for cleaning of the parts, our cost per part in total (including material usage) is only $4.62! 

GrabCAD Print Build Tray for Origin One Parts

GrabCAD Print Build Tray for Origin One Sample Parts

The Conclusion

After using the Origin One P3 3D printer for over a year now, I am confident that this compact part does the best job possible of showing off nearly every aspect of the printer’s capabilities!  It’s capable of producing low cost, high quality, durable, machinable, end use parts. 

Considering the Origin One’s incredibly quick print speed, this system is a fantastic fit for low to medium scale production; depending on part geometry. It is easy to envision a world where the Stratasys Origin One is the preferred alternative to the traditional injection molding process, which has long lead times. The Origin One is one of the most versatile new production-ready additive manufacturing platforms on the market. It demolishes the barriers of the commonly held beliefs of what 3D printers are capable of!

Article by <a href="" target="_self">Rich Annino</a>

Article by Rich Annino

Rich Annino is an Additive Manufacturing Solutions Consultant from TriMech