The MGN series miniature linear guides are the standard for 3D printers, small CNCs and precision handling systems. At DHM-online you will find them in two main sizes - MGN9 and MGN12 - and in two product lines: DHM (entry level) and DHM pro (professional). In this guide we help you choose.
MGN9 vs MGN12: the differences
|
Feature |
MGN9 |
MGN12 |
|
Rail width |
9 mm |
12 mm |
|
Rail height |
6 mm |
8 mm |
|
Rail weight (per 100 mm) |
~18 g |
~32 g |
|
Carriage load capacity H (radial) |
~3.1 kN |
~5.2 kN |
|
Fixing screws |
M3 |
M3 |
|
Rail hole spacing |
15 mm |
20 mm |
|
Typical application |
Lightweight 3D printers, fast axes |
Lightweight, CNC 3D printers |
Short carriage (C) vs long carriage (H)
Each rail is available with two carriage types: the short carriage (MGN9C or MGN12C) is more compact and lighter, suitable for small spaces and light loads. The long carriage (MGN9H or MGN12H) has multiple rows of recirculating balls, offering greater load capacity and rigidity. For 3D and CNC printers, the H carriage is almost always the best choice.
DHM entry level vs DHM pro
The DHM line is characterised by a very attractive price/performance ratio. These are entry-level linear slides suitable for simple linear systems, prototypes, entry-level 3D printers and medium-precision positioning. The carriages are not interchangeable with guides from other batches.
The DHM pro line offers performance comparable to reference brands such as HIWIN, Bosch Rexroth and THK. They are characterised by load ratings equivalent to professional products, improved radial play, ground reference surfaces on the rail and carriage, and installation compatibility with guides of other brands thanks to standard dimensions. Preloading ensures rigidity and vibration absorption.
Which one to choose for your project
For a hobbyist 3D printer with Cartesian kinematics, the entry-level MGN12 DHM are an excellent choice on a budget. For a Voron or other high-performance CoreXY printer, the MGN9 or MGN12 DHM pro provide the precision needed for quality prints at high speed. For a small CNC, the MGN12 DHM pro are the recommended minimum, with the rigidity and load capacity to handle the cutting forces.
Mounting tips
Correct mounting is critical to performance. Use a mounting surface with proper flatness. Tighten the rail screws in sequence from the centre towards the ends. Lubricate with lithium grease before commissioning. Do not interchange bogies and rails between different kits. See the assembly guide on the DHM-online blog for detailed instructions.
Linear guides at DHM-online
At DHM-online you will find MGN9 and MGN12 linear slides in the DHM and DHM pro lines, in lengths from 100 to 1000 mm with cut-to-length service. MGN9C, MGN9H, MGN12C and MGN12H also available separately in 100Cr6 steel and 440C stainless steel.
Frequently asked questions about MGN miniature linear slides
1. What is the difference between an MGN9 and an MGN12?
The main difference lies in the size and load capacity. The MGN12 has a 12 mm wide rail and offers superior stability, making it the standard for the X and Y axis of most 3D printers and lightweight CNCs. The MGN9, at only 9 mm wide, is lighter and more compact, making it ideal for high-speed printheads or axes where weight savings are critical to reduce inertia during rapid movements.
2. Is it better the short carriage (C) or the long carriage (H)?
The long carriage (type H), like the MGN12H, contains more recirculating balls than the short carriage (type C). This results in a higher load capacity and greater structural rigidity. For mechanical applications such as 3D printers CoreXY or small CNC milling machines, the H carriage is the recommended choice because it provides better force distribution and reduces vibration during machining or printing.
3. When is it worth investing in the DHM pro line compared to the entry-level line?
The DHM pro line is necessary when looking for professional performance comparable to brands such as HIWIN. These guides have ground reference surfaces, reduced radial play and a preload that ensures constant fluidity of movement. They are the obvious choice for high-performance machines (such as Voron) or for those who need interchangeability, as DHM pro slides maintain standard tolerances that allow components to be replaced without having to change the entire slide.
4. Is it possible to mount the carriages of one brand on the rails of another?
Generally, in entry level slides ( DHM line), carriages and rails are factory matched and are not interchangeable with other batches or brands. In contrast, the DHM pro line follows international standards that guarantee dimensional compatibility. However, for maximum precision and smoothness, the technical advice is always to use bogies and rails from the same manufacturer and quality line.
5. What maintenance do MGN profile rail guides require?
MGN linear guides require periodic lubrication to prevent premature wear of the balls and raceways. Before commissioning, it is essential to clean the rail from the protective factory oil and apply a thin layer of high-quality lithium grease. In dusty environments, such as in CNCs, it is a good idea to clean the rails regularly to prevent swarf or debris from entering the ball recirculation, compromising the accuracy of the carriage. At DHM-online you can find both complete kits and specific lubricants for the optimal maintenance of your system.
