What to Confirm Before Replacing a Ball Screw in CNC Repair

Confirm the machine axis first

For CNC repair replacement, start by identifying the axis. The X axis, Y axis, and Z axis may use different travel, load, installation space, and end machining, even when the machine brand and screw diameter look similar.

Check travel together with overall length

Record overall length, thread length, working travel, both end lengths, and nut position. Quoting only by overall length can miss bearing journals, the coupling end, and nut stroke, causing the new part to lose the original working range.

Old part photos should show installation details

Old part photos should include the full screw, both ends, front and side views of the nut, flange, mounting holes, marking text, worn areas, and measurement locations. Photos help structure review but still need dimensions and machine information.

End machining and support unit decide fit

End machining should confirm fixed side, support side, bearing journals, lock threads, keyways, retaining grooves, and coupling end size. The support unit model, such as BK/BF, FK/FF, or EK/EF, should be included in the RFQ.

Nut style and accuracy should be stated

Nut style covers single nut, double nut, flange direction, oil hole position, and mounting holes. Accuracy, backlash, or preload should be described by machine use; repair replacement does not always need the highest grade, but it must keep original positioning and running stability.

CNC repair replacement RFQ checklist

Machine type, brand or model, and the axis to be replaced.
Diameter, lead, overall length, thread length, working travel, and both end lengths.
Old part photos: full part, both ends, nut, flange, mounting holes, marking text, and measurement positions.
End machining dimensions, support unit model, coupling end, nut style, and accuracy or backlash 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.