Press fit nut / threaded inserts analysis
This page links analysis done on nuts with 3D printed parts. Currently, we are using embedded nuts to form connections between parts. Exploring other options for joining parts was brought up in CAD weekly, including Threaded inserts and Helicoils.
Fortunately, previous analysis was done by CNC kitchen, links are embedded at the end of page. Analysis was done to compare, directly adding a screw in a hole with tight tolerance, threaded inserts, Helicoil, nuts inserted from bottom and from the side. In pib we are using Bottom packet in most connections and a few side pocket joints. CNC kitchen experiments were done on PETG and PLA, luckily those materials are the ones usually pib is printed in. Additionally, tests are done on M3 screws which are the same used in pib.
Tests included are torque test, pull out test and shear test. The higher the failure load, the better the connection is.
In the pullout test, bottom packet is the best while side pocket is the worst with still good enough failure load.
For the shear out, we get a very similar ranking with bottom pocket being the best and side pocket the worst
From the shown tests and additional ones in the videos, I conclude that stability wise, bottom packet is the best option with recommendation that we try to limit side pocket as much as possible. If we add the usability factor, we find that the method was threaded inserts are inserted with a soldering iron poses more trouble and hazard than the difficulty of adding a nut with some bit of force if there is a tolerance difference due to different printers. Nevertheless, the number of nuts in pib are not very user friendly and should be reduced as much as possible.
Links
(31) HELICOIL®, Threaded Insert or Embedded Nut in 3D Prints? - YouTube
Helicoils, Threaded Insets and Embedded Nuts in 3D Prints - Strength & Strength Assessment — CNC Kitchen
Threaded Inserts for 3D Prints - Cheap VS Expensive 💰