What size linear rail do I need for a 3D printer?

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.

What is the difference between C and H carriages?

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.

How do I determine the correct rail length?

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.

Do I need to lubricate linear rails?

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.

3DPrintCalcs

Linear Rail Calculator — Rail Length & Load Capacity

Calculate linear rail length and carriage load capacity for your printer.

Travel Distance

Desired axis travel

Print Head Weight

Rail Size

Carriage Type

Max Acceleration

How We Calculate This

Linear Rail Calculations

Rail length = Travel distance + Carriage length + 10mm margin
Dynamic force = Mass x Acceleration
Total force = sqrt(Dynamic force² + Gravity force²)
Safety factor = Max load rating / Total force

The safety factor should be above 5 for reliable long-term operation. The calculation combines the dynamic force from acceleration with the static gravity load to find the total force on the carriage.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify settings with test prints before committing to final prints.