Ball Screw End Machining for BK/BF Supports

BK/BF is a support unit pair

BK is usually the fixed side, while BF is usually the support side. End machining must match bearings, lock nuts, shoulders, and coupling dimensions, not only screw diameter.

The fixed side is more sensitive

The fixed side often includes bearing journals, shoulders, threads, and locking structure. A small dimension error can prevent bearing preload or move the coupling position.

What to provide in the RFQ

Provide support model, brand, end drawing, overall length, thread length, and coupling end requirements. If no drawing is available, send old part photos and measured dimensions first.

Fixed-side and support-side models.
Bearing journal diameter and length.
Lock thread, shoulders, and grooves.
Coupling end diameter, length, and keyway requirement.

Typical buyer situations

This topic usually appears in distributor stocking, repair replacement, machine retrofit, automation projects, and drawing-based purchasing. If a buyer sends only one model number, the supplier cannot judge the real use, packing risk, or whether machining upgrades are needed.

Details to confirm before quotation

To reduce repeated questions, the RFQ should cover product specification, use case, and delivery expectations together. The following points can be copied into the RFQ form or email.

Purchase purpose: distributor stock, repair replacement, machine project, or sample testing.
Specification: diameter, lead, overall length, thread length, nut type, and quantity.
Machining: cut-to-length, end machining, and whether BK/BF, FK/FF, EK/EF, or other supports must be matched.
Delivery: target quantity, expected lead time, packing, labels, shipping method, and whether shipment photos are required.

Common mistakes

A common mistake is asking only for unit price without application, quantity, or packing details. Another is sending photos without dimensions. This turns quotation into guesswork and can create errors in end machining, nut matching, or long-part shipping.

Next step

If the specification is clear, submit an RFQ directly. If the model or accuracy grade is still uncertain, describe the machine use and old part details so the supplier can recommend a standard part, bar stock, cut-to-length, or end machining route.