Brass Heat-Set Inserts - #4-40 x 0.135" (50pcs)

Heat set brass inserts allow a user to add mounting holes and hardware to any 3D printed or soft plastic enclosure. Use the heat set tips with your soldering iron to heat the brass inserts and then gently push them into place.

Heat set inserts are brass nuts that are specially designed to be heated up and pressed into an undersized hole. The outside of the insert has spikes and fins that help the plastic flow around and form a tight bond with the surrounding material. While standard hex nuts can be used these brass inserts have much greater rigidity.

These inserts work with common 4-40 screws and come as a bag of 50pcs. We recommend using a No.24 drill to create a 0.152" hole to press the insert into.

We do not plan to regularly produce SparkX products so get them while they’re hot!

Experimental Product: SparkX products are rapidly produced to bring you the most cutting edge technology as it becomes available. These products are tested but come with no guarantees. Live technical support is not available for SparkX products. Head on over to our forum for support or to ask a question.


  • Drawing
  • Outside Diameter: 4.37mm
  • Length: 4.37mm
  • 4-40 Thread
  • Suggested hole size is 0.152" (No. 24 drill)


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