Replacement Case: Old-Part Photos and Dimensions Reduce Wrong Assumptions

Case background

A repair buyer needed to replace an old ball screw installed on a machine. There was no complete drawing, only model marks and site photos. Photos help identify the nut, ends, and mounting style, but they cannot replace key dimensions.

Replacement risk

The most common replacement mistakes happen around journals, shoulders, lock threads, keyways, retaining grooves, and nut flange direction. Quoting only by diameter and lead can produce a screw with the right thread but the wrong installation fit.

Confirmation checklist

Full-length photo, both end photos, and front and side photos of the nut.
Overall length, thread length, end lengths, bearing-seat dimensions, and shoulder dimensions.
Nut style, flange direction, mounting hole quantity, and hole spacing.
Machine model, axis position, support unit model, coupling, or installation space.
Whether to copy the old ends or machine new ends from a new drawing or support unit.

Handling approach

Use old-part photos to understand the structure first, then use measured dimensions to confirm the machining boundary. If the old ends are still a reliable sample, state that the supplier should copy the old ends. If the support unit, coupling, or installation space has changed, confirm a drawing again before quotation.

What to prepare before RFQ

Before sending an RFQ, put old-part photos, key dimensions, machine use, and installation limits in the same file or message. Unknown dimensions can be marked as pending, but do not send only one model number or unclear photos.

Old-part photos

Old-part photos should cover the full screw, both ends, nut, flange, mounting holes, marking text, coupling side, and bearing support side. Photos should be used together with a dimension table to reduce end-machining and installation-fit risk.

Next step

Turn this guide into an RFQ

When the specification direction is clear, send the details below together with quantity, lead time, and packing requirements.

Include these details

Old-part overall length, thread length, diameter, lead, and nut style.
Full old-part photos, both end details, nut flange, and mounting-hole photos.
Machine use, whether it is a like-for-like replacement, quantity, and lead time.

Send old-part dimensions View custom ball screw service