---
product_id: 812136517
title: "Knurled Insert Nuts, 50pcs M3 x 4mm L x 5mm OD Brass Heat Set Insert Nuts, Female Threaded Knurled Embedding Nuts for 3D Printing Laptop Automotive Plastic Shells"
brand: "sunkoo"
price: "€ 14.27"
currency: EUR
in_stock: true
reviews_count: 6
category: "Sunkoo"
url: https://www.desertcart.hr/products/812136517-knurled-insert-nuts-50pcs-m3-x-4mm-l-x-5mm
store_origin: HR
region: Croatia
---

# Brass heats evenly for smooth install M3 x 0.5mm precision thread Knurled surface for max grip Knurled Insert Nuts, 50pcs M3 x 4mm L x 5mm OD Brass Heat Set Insert Nuts, Female Threaded Knurled Embedding Nuts for 3D Printing Laptop Automotive Plastic Shells

**Brand:** sunkoo
**Price:** € 14.27
**Availability:** ✅ In Stock

## Summary

> 🔥 Lock in strength and style with every insert!

## Quick Answers

- **What is this?** Knurled Insert Nuts, 50pcs M3 x 4mm L x 5mm OD Brass Heat Set Insert Nuts, Female Threaded Knurled Embedding Nuts for 3D Printing Laptop Automotive Plastic Shells by sunkoo
- **How much does it cost?** € 14.27 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.hr](https://www.desertcart.hr/products/812136517-knurled-insert-nuts-50pcs-m3-x-4mm-l-x-5mm)

## Best For

- sunkoo enthusiasts

## Why This Product

- Trusted sunkoo brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Durable Brass Build:** Superior corrosion resistance and heat conductivity for long-lasting, professional-grade assemblies.
- • **Effortless Installation:** Integrated guide tip ensures perfectly aligned, counterbore-free heat-set embedding.
- • **Versatile Compatibility:** Ideal for PLA, PETG, ABS plastics, automotive shells, and laptop enclosures—upgrade any project.
- • **Precision Fit, Every Time:** M3 x 0.5mm threads engineered for flawless fastening in your 3D prints and prototypes.
- • **Unmatched Grip & Stability:** Aggressive knurled design locks inserts firmly in place, resisting loosening under stress.

## Overview

This 50-piece set of M3 x 4mm brass knurled heat-set insert nuts delivers precision threading and superior grip for professional 3D printing and plastic assembly applications. Crafted from durable brass, these inserts heat evenly for smooth installation and feature an integrated guide for perfect alignment. Their aggressive knurled surface ensures reliable, torsion-resistant fastening in plastics like PLA, PETG, and ABS, making them a must-have upgrade for engineers and makers seeking lasting, high-performance connections.

## Description

Knurled Insert Nuts, 50pcs M3 x 4mm L x 5mm OD Brass Heat Set Insert Nuts, Female Threaded Knurled Embedding Nuts for 3D Printing Laptop Automotive Plastic Shells: desertcart.com: Industrial & Scientific

Review: Speaker repair. - It worked as it should.
Review: Reliable, High-Grip Inserts for Durable 3D Printed Assemblies - If you are tired of screws stripping out of plastic or want to build professional-grade 3D printed enclosures, these brass heat-set inserts from Sunkoo are a great choice. They provide strong, reusable machine threads for any project involving PLA, PETG, or ABS. Design and Installation The standout feature of these inserts is the aggressive knurling and the integrated guide. Easy Alignment: The small pilot or "guide" at the tip makes it much easier to keep the insert straight as you press it in with a soldering iron. This reduces the risk of crooked threads, which is a common headache with cheaper inserts. Uniformity: Out of the 100-piece pack, the quality is remarkably consistent. I didn’t find any with clogged threads or malformed outer diameters. Grip and Durability Compared to other M2.5 inserts I have used, these have a slightly larger "pitch" or more aggressive knurled surface. Pros: This larger texture provides a more substantial bite into the plastic. Once the plastic cools and shrinks around the brass, these inserts feel incredibly secure and resistant to being pulled out or spinning under torque. Cons: Because the outer knurling is a bit more substantial, they do require a slightly larger footprint in your 3D model. You’ll want to ensure your printed parts have enough wall thickness to accommodate them without bulging the exterior. Pros Superior Grip: Aggressive knurling makes them feel more durable than standard smooth-knurl inserts. Excellent Conductivity: Brass material heats up quickly and evenly for smooth installation. Clean Threads: M2.5 bolts thread in smoothly with no grit or resistance. Great Value: 100 pieces for roughly $7 is hard to beat for this level of quality. Cons Larger Footprint: Requires a bit more space in your design compared to "slimmer" M2.5 options. Final Verdict: 4/5 Stars These are high-quality inserts that prioritize strength and ease of installation over miniaturization. If you have the room in your design for the slightly larger outer diameter, the extra durability they provide is well worth it.

## Features

- Package:Thread Size: M3 x 0.5mm(Dia*Pitch); Overall Size: 4mm x 5mm / 0.16" x 0.2"(L*OD); Package Content: 50pcs x Knurled Insert Nuts.
- Material:Made of durable brass, offering superior hardness, corrosion resistance, and heat conductivity. Built for precision fastening needs.
- Feature:These Brass Heat Set Insert Nuts feature a guide for effortless, counterboring-free installation.
- Enhanced Grip & Stability: The knurled surface provides superior friction, ensuring these 3D Printing Brass Nuts resist loosening under torsion and tension for reliable performance.
- Wide Compatibility: Ideal for ultrasonic or heat embedding in plastics and injection molding. These 3D Printing Brass Nuts Female Threaded Inserts provide tight, reliable fixation in 3D prints, prototypes, and molded parts.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B0DPQH2KX7 |
| Best Sellers Rank | #19,993 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #30 in Nut Inserts |
| Brand | Sunkoo |
| Color | Gold |
| Date First Available | December 6, 2024 |
| Exterior Finish | Brass |
| Fastener Type | Insert |
| Finish Type | Unfinished |
| Inside Thread Size | M3 |
| Item Weight | 3.53 ounces |
| Manufacturer | Sunkoo |
| Material | Brass |
| Metal Type | Brass |
| Number of Pieces | 50 |
| Package Dimensions | 1.97 x 1.18 x 0.79 inches |
| Set Name | 50-Piece Set |
| Size | M3*4*5 |
| Thread Class | Class 2A |
| Thread Size | M3 |
| Thread Style | Metric Internal |
| Thread Type | Iso Metric |

## Product Details

- **Color:** Gold
- **Exterior Finish:** Brass
- **Fastener Type:** Insert
- **Material:** Brass
- **Thread Size:** M3

## Images

![Knurled Insert Nuts, 50pcs M3 x 4mm L x 5mm OD Brass Heat Set Insert Nuts, Female Threaded Knurled Embedding Nuts for 3D Printing Laptop Automotive Plastic Shells - Image 1](https://m.media-amazon.com/images/I/71TygJuOXrL.jpg)
![Knurled Insert Nuts, 50pcs M3 x 4mm L x 5mm OD Brass Heat Set Insert Nuts, Female Threaded Knurled Embedding Nuts for 3D Printing Laptop Automotive Plastic Shells - Image 2](https://m.media-amazon.com/images/I/61y2UPVn55L.jpg)
![Knurled Insert Nuts, 50pcs M3 x 4mm L x 5mm OD Brass Heat Set Insert Nuts, Female Threaded Knurled Embedding Nuts for 3D Printing Laptop Automotive Plastic Shells - Image 3](https://m.media-amazon.com/images/I/71NWFCUozzL.jpg)
![Knurled Insert Nuts, 50pcs M3 x 4mm L x 5mm OD Brass Heat Set Insert Nuts, Female Threaded Knurled Embedding Nuts for 3D Printing Laptop Automotive Plastic Shells - Image 4](https://m.media-amazon.com/images/I/71P42+8TLoL.jpg)
![Knurled Insert Nuts, 50pcs M3 x 4mm L x 5mm OD Brass Heat Set Insert Nuts, Female Threaded Knurled Embedding Nuts for 3D Printing Laptop Automotive Plastic Shells - Image 5](https://m.media-amazon.com/images/I/71itPHxppoL.jpg)

## Available Options

This product comes in different **Size, Number Of Items** options.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Speaker repair.
*by F***R on February 17, 2026*

It worked as it should.

### ⭐⭐⭐⭐ Reliable, High-Grip Inserts for Durable 3D Printed Assemblies
*by B***Y on February 22, 2026*

If you are tired of screws stripping out of plastic or want to build professional-grade 3D printed enclosures, these brass heat-set inserts from Sunkoo are a great choice. They provide strong, reusable machine threads for any project involving PLA, PETG, or ABS. Design and Installation The standout feature of these inserts is the aggressive knurling and the integrated guide. Easy Alignment: The small pilot or "guide" at the tip makes it much easier to keep the insert straight as you press it in with a soldering iron. This reduces the risk of crooked threads, which is a common headache with cheaper inserts. Uniformity: Out of the 100-piece pack, the quality is remarkably consistent. I didn’t find any with clogged threads or malformed outer diameters. Grip and Durability Compared to other M2.5 inserts I have used, these have a slightly larger "pitch" or more aggressive knurled surface. Pros: This larger texture provides a more substantial bite into the plastic. Once the plastic cools and shrinks around the brass, these inserts feel incredibly secure and resistant to being pulled out or spinning under torque. Cons: Because the outer knurling is a bit more substantial, they do require a slightly larger footprint in your 3D model. You’ll want to ensure your printed parts have enough wall thickness to accommodate them without bulging the exterior. Pros Superior Grip: Aggressive knurling makes them feel more durable than standard smooth-knurl inserts. Excellent Conductivity: Brass material heats up quickly and evenly for smooth installation. Clean Threads: M2.5 bolts thread in smoothly with no grit or resistance. Great Value: 100 pieces for roughly $7 is hard to beat for this level of quality. Cons Larger Footprint: Requires a bit more space in your design compared to "slimmer" M2.5 options. Final Verdict: 4/5 Stars These are high-quality inserts that prioritize strength and ease of installation over miniaturization. If you have the room in your design for the slightly larger outer diameter, the extra durability they provide is well worth it.

### ⭐⭐⭐⭐⭐ Add professional M2 threads to your 3D printed part
*by A***W on March 6, 2026*

These are the most robust way to add threads to a 3D printed part. Design the part with a hole longer than the insert and wide enough to fit the tip (for the M2 size, a 3.7mm hole worked best for me), place the insert in the hole, and use the tip of a soldering iron to push the insert in. For a perfect flush finish on a flat surface, stop just before the insert reaches the surface, and use a flat metal tool to push it in the rest of the way so it stops perfectly flush (the insert will remain hot enough for this if you are quick about it). Doesn't get much easier than that! Once installed, you have durable metal threads that will survive repeated assembly/disassembly and won't strip out like threaded plastic, even under load. For the (very reasonable) price, you get a 100 pack which should be enough for many projects.

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**Shop now:** [https://www.desertcart.hr/products/812136517-knurled-insert-nuts-50pcs-m3-x-4mm-l-x-5mm](https://www.desertcart.hr/products/812136517-knurled-insert-nuts-50pcs-m3-x-4mm-l-x-5mm)

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*Product available on Desertcart Croatia*
*Store origin: HR*
*Last updated: 2026-07-11*