SC Linear Bearing Block for CNC Rod Rails 8-25mm

The SC linear bearing block is a compact aluminium housing with a pressed-in linear ball bearing, made to ride on a round shaft and carry a moving carriage or gantry. It suits builders and technicians assembling motion axes on CNC routers, 3D printers, laser gantries and other machines that use round-shaft linear guides rather than profile rail.

The SC series spans bore sizes from 8mm up to 25mm, so the same basic block design covers small hobby printers through to larger router gantries without needing custom brackets. The shaft slides through the bearing bore while the block’s flat base bolts to a plate or frame, transferring load and keeping travel aligned along the rod.

Details / Specifications

Dimensions, data, and technical drawings are provided with reasonable diligence. Minor deviations may occur due to production batch, without affecting quality.

Features of the SC linear bearing block

Each block combines a die-cast or CNC-machined aluminium body with a sealed linear ball bearing pressed into the bore. The bearing carries recirculating balls that ride along the shaft surface, giving low-friction sliding motion and consistent repeatability from one pass to the next.

The mounting base has two or four bolt holes on a standard pitch, so the block bolts directly to a carriage plate without machining. Because the SC linear bearing block uses an open design rather than a fully enclosed carriage, it stays lighter and cheaper than comparable profile-rail blocks.

• Pressed-in linear ball bearing for low-friction travel
• Aluminium body with a bolt-on flat base
• Available across bore sizes in the 8-25mm range
• Open-block design for easy access to the shaft
• Standard bolt pattern matches common carriage plates
• Works with round shaft of matching bore diameter

Where it’s used

These blocks appear on the X and Y axes of hobby and semi-professional CNC routers, on the Z axis of small mills, and on the linear guides of FDM 3D printers and laser engravers that use round shaft instead of square profile rail. Two or four blocks per axis, mounted on a common plate, form a simple sliding carriage.

They also appear in workshop fixtures such as sliding jigs and DIY linear stages, wherever a shaft-and-bushing motion is simpler to build than a full profile-rail system. Browse compatible shafts and motion parts in the CNC parts shop to match bore size and shaft length for a complete axis.

What to check before buying

Bore size matters most for the SC linear bearing block: a block sized for an 8mm shaft will not run on a 12mm shaft, and a loose fit on an oversized shaft leaves play that shows up as a rattle at every direction change. Confirm the exact shaft diameter before ordering and match it to the correct SC code.

A common mistake is buying the block without checking the shaft’s straightness and surface hardness; a bent or soft shaft wears the bearing balls quickly and brings back backlash within weeks. Also check the bolt hole spacing on the base against the carriage plate you plan to use, since not every plate follows the same pitch.

Installation and maintenance

Fit the SC linear bearing block onto a clean, lightly oiled shaft, and support the shaft at both ends so it cannot flex under load. Tighten the mounting bolts evenly to avoid twisting the body, which would bind the bearing and increase friction. For background on how recirculating-ball linear bearings work, see the linear-motion bearing overview on Wikipedia.

During regular use, wipe the shaft clean of swarf and dust and add a drop of light machine oil so the balls roll rather than slide. Replace the block if play develops that realigning the shaft supports cannot remove, since the sealed bearing is not designed to be re-packed.

FAQ

What bore sizes does the SC linear bearing block come in? The series covers round-shaft diameters from 8mm through 25mm, each identified by its own SC code.

Can I use an SC block with square profile rail? No, these blocks are made for round shaft only; profile rail needs its own dedicated carriage block.

Does the block include the shaft? No, the shaft is sold separately and must match the block’s bore diameter exactly.