KB3D MGN12H Linear Rail / Guide - With Carriage - Multiple Lengths


This stainless steel MGN12H linear rail / guide with carriage set from KB3D is positioned with what we consider the perfect balance of cost and precision. It carries a Z1 preload for proper constraint and is offered in multiple lengths. 

Rail Length

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Frequently Purchased Together

Linear Rail Carriage Lubrication Kit - Mobilux EP2 - 20mL

Linear Rail Carriage Lubrication Kit - Mobilux EP2 - 20mL

KB3D Linear Rail Carriage - Spare - Multiple Types

KB3D Linear Rail Carriage - Spare - Multiple Types

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KB3D MGN12H Linear Rail / Guide - With Carriage - Multiple Lengths

Sold as 1 pair (Rail + Carriage) Each

We searched far and wide for a manufacturer that can deliver a quality Z1 preloaded linear rail and carriage at competitive pricing for use in 3D printer applications. This rail is the result.


Stainless Steel construction for better handling of thermal expansion and easier maintenance.

Z1 Preload to handle any load while still delivering the constraint needed for precise extrusion.

Built-in lubrication ports for trouble-free maintenance

Lengths Offered:








Rails can be cut to any length using an abrasive cutting method. Consider graduated shallow cuts to keep heat down and avoid warp potential. Some folks prefer to mount the rail to spare extrusion which can also help with warp mitigation. 

What is a Z1 preload?

Z1 commands a higher preload between the rail and carriage than a more typical Z0 preload. Preload occurs after all space between two components (in this case the rail and carriage) is closed. Any further interference becomes preload, as these materials are too hard to physically compress. 

Having a higher preload is a benefit for our use case, but does change the way that rails feel when move by hand.

What to expect:

These rails are shipped with a thin coating of shipping oil, a common practice of some manufactures to mitigate corrosion during storage and transport. It is recommended to wipe this oil away and inject Mobilux EP2 (or similar) grease into the greasing ports.

Z1 preloaded rails will not slide as freely by hand when compared to a Z0 rail. Any imperfections in the machining process become twice as apparent when higher preloads are involved with an absence of real load. Want to feel your Z1 rail's true characteristics? Lay the rail on a clean, flat, and hard surface - then push down on the face of the carriage with light force while moving the carriage around. This better simulates real-world behavior.

Aside from linear rails in the highest price tiers, all linear guide rail carriages will benefit from a proper cleaning before being put into service. See here for a great walk through on this process.

Our rails have a built-in lubrication port, so simply displacing the shipping oil with your grease of choice often does just as well!

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