BF Ball Screw Support Unit – Supported Side Square Type

The BF Ball Screw Support Unit is a square-type support unit installed on the supported side, also commonly called the floating side, of a ball screw assembly. It supports the opposite end of the screw shaft while the fixed-side unit establishes the axial position of the ball screw.

DLY supplies BF10, BF12, BF15, BF17, BF20, BF25, BF30, BF35 and BF40 models. The supported-end shaft diameter d1 ranges from 8 mm to 40 mm. BF support units are commonly paired with corresponding BK fixed-side support units in standard ball screw installations.

When ordering a complete ball screw assembly, DLY can help check the ball screw, shaft-end machining and support-unit combination according to your drawing or installation dimensions.

BF Ball Screw Support Unit Models and Dimensions

The BF series includes nine commonly used sizes. Unlike the BK fixed-side series, however, the number in a BF model does not always equal the supported-end shaft diameter. For example, BF10 has a d1 dimension of 8 mm, while BF12 has a d1 dimension of 10 mm.

For this reason, the correct BF model should be confirmed from the actual shaft-end and mounting dimensions rather than selected only from the model number.

All dimensions are in millimeters. Dimensions b and h have a specified tolerance of ±0.02 mm. Please confirm the complete dimensional drawing before machining the mounting surface or placing an order.

What Does the BF Support Unit Do?

A ball screw support system normally has a fixed side and a supported side. The BF unit is used on the supported side of the ball screw shaft. Its purpose is to support the opposite end of the rotating screw while working together with the fixed-side support.

The BF side should therefore be considered as part of the complete ball screw support arrangement rather than as an independent replacement for the fixed-side bearing unit.

In a standard BK/BF configuration, the BK unit is installed at the fixed end and the BF unit is installed at the supported end.

BF10 and BF12: Check d1 Before Selecting

One detail that is easy to overlook when selecting BF support units is that the model number does not always represent the supported-end shaft diameter.

This is why DLY recommends checking the actual shaft-end dimensions or drawing instead of assuming that BF10 automatically requires a 10 mm bearing seat.

How BK and BF Work as a Pair

BK and BF support units are commonly used together, but they have different positions in the ball screw assembly.

If you require both sides, DLY can supply the corresponding BK and BF units together. You can also view the complete Ball Screw Support product range.

How to Select a BF Ball Screw Support Unit

The most reliable way to select a BF support unit is to begin with the supported-end machining dimensions of the ball screw.

Check the shaft-end diameter d1 first, followed by the support-unit center height, housing dimensions and mounting-hole positions. For existing equipment, the original BF model or a dimensional drawing can normally be used for confirmation.

For a newly designed ball screw assembly, the support arrangement should be confirmed before shaft-end machining. This helps ensure that the bearing seat and other machined sections correspond to the selected support unit.

Mounting Dimensions to Check

In addition to the supported-end diameter, several housing dimensions affect whether a BF support unit can be installed directly on an existing machine.

The supplied BF dimensional data includes housing width B, overall height H, center height h, mounting-hole pitch P, through-hole diameter X, counter-bore diameter Y and counter-bore depth Z.

The mounting arrangement uses four through holes with corresponding counter bores. Because these dimensions change with the BF model, the mounting plate should be checked against the selected size before drilling or machining.

Ball Screw End Machining and BF Matching

The supported end of the ball screw must be machined to match the selected BF support unit. For replacement applications, send DLY the existing support model or shaft-end dimensions. For new ball screw assemblies, the support model can be confirmed together with the shaft-end machining requirement before production.

This is especially important for BF10 and BF12 because their d1 dimensions do not directly correspond to the number in the model designation.

Customers ordering the ball screw and support units together can send one complete drawing so that the related dimensions can be checked as one assembly.

Typical Applications

BF ball screw support units are used on the supported end of ball screw drive systems in CNC machinery, automation equipment, positioning systems, linear modules, packaging equipment, woodworking machinery and other industrial motion systems.

The application itself does not determine the BF model. The final selection should be based primarily on the ball screw shaft-end dimensions and machine mounting structure.

Ordering BF Support Units from DLY

DLY supplies BF10–BF40 supported-side support units for replacement, machine assembly and batch purchasing. MOQ starts from 1 piece, with model matching and customization available according to the ball screw and installation requirements.

For faster quotation and model confirmation, please provide:

• Required BF model, if known
• Ball screw model and diameter
• Supported-end shaft dimensions or drawing
• Required quantity
• Whether a matching BK fixed-side support is also required