Strong Metal Threads for 3D Printed Parts
Screwing straight into plastic works once or twice, then the thread wears out. Heat set inserts fix that: press a knurled brass insert into a printed hole with a soldering iron, the plastic flows around the knurling, and you are left with a metal thread you can assemble and take apart many times.
This kit gives you a working stock of every common size, so you can design with inserts from your very next project.
Why Use Heat Set Inserts
Reusable Threads
Brass threads survive repeated assembly, so lids, access panels and electronics enclosures can be opened and closed without stripping the plastic.
Works With Most Filaments
The knurled brass locks firmly into PLA, PLA+, PETG, ABS and Nylon prints, and into most resins.
Simple to Install
Set your soldering iron to the filament's printing temperature plus 10°C, rest the insert on a hole sized to the chart below and press it in straight and slowly. Let the part cool before tightening a screw into it.
Kit Details
Full Kit Contents
Every item is picked from our regular stock, so you can top up any size from its own product page.
Hole Sizes
| Insert | Length | Insert diameter | Hole diameter |
|---|---|---|---|
| M2 Long | 3 mm | 3.5 mm | 3.1 mm |
| M3 Short | 3 mm | 4.5 mm | 4 mm |
| M3 Long | 5.7 mm | 4.6 mm | 4 mm |
| M3 Thick | 4 mm | 5 mm | 4.4 mm |
| M4 Short | 4 mm | 6 mm | 5.5 mm |
| M4 Long | 8.1 mm | 6.3 mm | 5.5 mm |
| M5 Short | 6 mm | 7 mm | 6.2 mm |
| M5 Long | 9.5 mm | 7 mm | 6.2 mm |
Set your soldering iron to the filament's printing temperature plus 10°C and press the insert in straight and slowly.
Frequently Asked Questions
Which screws fit these inserts?
Standard metric machine screws of the same thread size, so M3 inserts take M3 screws. Our M3 Fastener Starter Kit pairs well with the M3 inserts in this kit.
Short, long or thick?
Short inserts suit thin walls and shallow bosses. Long inserts give more thread engagement where there is room for a deeper hole. The M3 Thick insert is wider and 4 mm long, a common size in printer builds.
Can I buy more of one size?
Yes. Every size is available individually from our heat set insert listing, with bulk pricing on larger quantities.