The Most Used Insert Size, Ready to Go
M3 is the default thread for 3D printed assemblies: fan mounts, electronics enclosures, printer upgrades and most functional designs you will download or model yourself. This pack keeps plenty of both lengths on the bench so you never have to redesign a part around what is left in the drawer.
M3 Short
At 3 mm long, the short insert fits thin walls, lids and shallow bosses where a long insert would break through.
M3 Long
At 5.7 mm long, the long insert gives more thread engagement and grip in thicker sections and parts that see more load.
Simple to Install
Set your soldering iron to the filament's printing temperature plus 10°C, rest the insert on a 4 mm hole and press it in straight and slowly. Let the part cool before tightening a screw into it.
Kit Details
Full Kit Contents
| Item | Qty |
|---|---|
| Brass heat set insert, M3 Short | 50 |
| Brass heat set insert, M3 Long | 50 |
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 |
|---|---|---|---|
| M3 Short | 3 mm | 4.5 mm | 4 mm |
| M3 Long | 5.7 mm | 4.6 mm | 4 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?
Any M3 machine screw. Our M3 Fastener Starter Kit has countersunk and button head screws in five lengths to suit.
Building a Voron or another printer that calls for M3 x 5 x 4 inserts?
Those designs use a 5 mm wide, 4 mm long insert, which matches our M3 Thick insert, sold individually on the heat set insert listing.
Need other sizes?
The Heat Set Insert Starter Kit covers M2 to M5 in one box.