Linear Rail Calculator — Rail Length & Load Capacity

MGN12H is the most common for 3D printers and works well for print heads up to 600g with moderate acceleration. MGN9 is used for smaller, lighter printers. MGN15 is used for heavy toolheads or high-acceleration machines.

H (long) carriages are longer, with higher load capacity and stiffness. C (short) carriages are more compact but handle less load. For 3D printers, H carriages are preferred for their stability, especially on the X-axis.

Rail length = desired travel distance + carriage length + safety margin. The carriage needs to stay fully on the rail at both ends of travel. Add 5-10mm extra for end stops and clearance.

Yes. Lubricate linear rails every 200-500 print hours with a light machine oil or PTFE-based lubricant. Wipe the rail clean first, apply a thin film, and run the carriage back and forth to distribute. Avoid thick grease which can attract dust.