How to use threaded inserts ?

🔧 Overview

Threaded inserts allow you to add durable, reusable metal threads to your 3D printed parts. This is essential for parts that need to be assembled/disassembled multiple times, or where strong screw connections are needed. This tutorial covers the process for heat-set threaded inserts, such as those from RothEx, and includes both design and installation instructions.

🧱 Step 1: Design the Hole in Your CAD Model • While modeling your part, design a hole at the insert location. • Use the exact hole dimensions provided by the insert manufacturer (e.g., RothEx). o These typically include:  Hole diameter  Hole depth  Optional: chamfer for easier entry • Example for M3 RothEx insert: o Hole diameter: 4.0 mm o Hole depth: Insert length + 0.5 mm o Chamfer: 0.3 mm x 45° (optional) 📝 Tip: Add a chamfer or slight taper to help guide the insert in smoothly.

🔍 Step 2: Check the Hole Fit After Printing • Once printed, try placing the small-diameter end of the insert into the hole by hand. • If it doesn't fit: o Don’t force it! o Ask your mechanical workshop coach for help using a precision drill bit (or reamer) to correct the hole diameter. 🛠️ Reminder: PLA and PET-G can shrink slightly after printing, so minor post-processing is normal.

✋ Step 3: Place the Insert by Hand • Place the insert manually into the hole, starting with the smaller-diameter end down. • It should sit snugly but not be forced in. • It only needs to start in the hole, not go all the way in — the heat will do the rest.

♨️ Step 4: Prepare the Insert Tool • Choose the correct tip size for your insert (most kits come with several). • Mount the tip on your insert placement tool (commonly a modified soldering iron or insert tool). • Set the temperature to the printing temp of your filament: o 230 °C for PET-G o (Use ~200 °C for PLA, ~250 °C for ABS, etc.) 🛑 Warning: This tool gets very hot. Always place it back on its stand when not in use.

⬇️ Step 5: Heat-Set the Insert • Hold the heated tool vertically and gently press the insert. • Apply light, even pressure. • As the plastic heats up, the insert will begin to sink into the part. • Don’t force it — let heat do the work. • Keep the axis straight to avoid misalignment. 🧭 Tip: Watch the sides of the part — if it starts to bulge, stop. You may be overheating or pressing too hard.

🧊 Step 6: Make It Flush • Once the insert is fully seated, you can use a flat metal tool (e.g. steel ruler or putty knife) to gently press it down, ensuring it's flush with the surface of the part. • This step helps with cosmetic finish and mechanical alignment.

✅ You're Done! • Turn off your tool and let it cool down safely. • Don’t touch the metal tip — it remains hot for several minutes. 👏 Your insert is now permanently embedded and ready for screws!

📝 Additional Tips for Students • Practice on a test print before working on your final part. • Design tolerances matter — always check datasheets. • Don’t overtighten screws — inserts are strong, but the surrounding plastic can still deform.