How to Measure a Replacement Ball Screw: 6 Dimensions

Record the basic dimensions first

Start with diameter, lead, overall length, thread length, and working travel. If the old part is worn, state where it was measured and what error is possible.

Six key dimensions, in an order that leaves nothing out:

Diameter: measure the thread outer diameter with a caliper, away from worn areas.
Lead: the last two digits of the model number; if the marking is worn, mark the shaft, turn the nut ten revolutions and divide the travel by ten.
Overall length: face to face, a tape is enough.
Thread length: the usable length from the start of the thread to its end.
Working travel: the distance the nut has to move. State clearly whether the figure is travel alone or travel plus nut length.
End steps: journal diameter and length at each end, recorded step by step.

Measure in an unworn section where possible and photograph with a ruler or caliper in frame. On a badly worn screw the diameter measured in the worn zone reads undersize, and copying it produces a screw that will not fit.

Nut and shaft ends matter just as much

A model number alone is usually not enough. Nut shape, flange direction, mounting holes, shaft-end journals, lock thread, keyway, and retaining groove all decide whether the part fits back onto the machine. For the detailed shaft-end measurement steps, see how to measure ball screw end machining dimensions.

How to take useful photos

Photograph the full screw, both shaft ends, front and side views of the nut, any marking text, and the key dimension positions. Photos help the supplier decide whether a drawing has to be reviewed.

Include a ruler or caliper when photographing key dimensions. Use enough light, avoid reflections, and keep the camera square to the measured face where possible. Send the photos with the measurement record and mark any blurred or uncertain reading.

Buyer decision table

Measurement item	How to capture it	Why it matters
Diameter and lead	Caliper plus travel per revolution	Identifies the basic ball screw model.
Overall length	Measure full shaft end to end	Prevents replacement length errors.
Thread length and travel	Tape plus a stated basis	Decides whether the nut completes its travel.
End machining	Measure each step diameter and length	Determines whether custom machining is required.
Nut and flange	Photo and hole spacing	Confirms nut style and mounting fit.

Replacement RFQ checklist that can be quoted

Send these details so the supplier can assess a standard replacement, cutting to length, or end machining:

Overall old-part photos and close-ups of both ends, the nut, and markings.
Diameter, lead, overall length, thread length, and working travel.
Shaft-end steps, bearing journals, keyways, lock threads, and retaining grooves.
Support-unit model or mounting dimensions, machine use, quantity, and target delivery time.

RFQ checklist

Check the package above before sending:

Keep dimension records with the corresponding photos, including nut style, flange direction, and mounting holes.
State the machine model, use, quantity, target delivery time, and destination.
Mark uncertain dimensions and worn areas so weimute can review them before quoting.

Send us old-part photos and measurements

Send weimute the photos and measurement table together. Our manufacturing and sales team will tell you which dimensions are enough, which are missing, and whether a drawing is needed before production. For the detailed shaft-end measurement steps, see how to measure ball screw end machining dimensions.

FAQ

Can I request a replacement quote without a drawing? You can send an initial request with old-part photos and key dimensions. Photos alone or a model code alone are usually insufficient. Shaft ends, nut mounting, and support-unit dimensions affect whether the replacement fits the machine.

Can I measure a worn part where it is worn? Better not. A worn section reads undersize and copying it produces a screw that will not enter the support unit; measure an unworn section and note where the wear sits.

What is the most common replacement mistake? Overall length and shaft-end steps. Overall length is often taken without the machined ends, and end steps get collapsed into a single diameter. Both end in a part that will not fit.

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 replacement dimensions View custom ball screw service