How to Reduce or Eliminate Backlash in a Ball Screw Assembly

Find where the backlash comes from first

Backlash in a ball screw assembly does not always come only from the nut. Bearing preload, support installation, coupling looseness, end machining dimensions, guide clearance, and control compensation can all affect reverse positioning.

Rather than guessing, measure it in sections. Indicate the screw end, the nut housing, and the table in turn with a dial gauge, push each by hand in both directions, and read the difference each time:

Indicating point	A large reading means	Where to work
Table	Guideway or assembly	Check guide clearance, block preload, mounting rigidity
Nut housing	Nut clearance or wear	Fit a low-backlash or preloaded nut, or adjust preload
Screw end	Bearing preload, support unit, coupling	Check the lock nut, bearing arrangement, coupling tightness
All three small but positioning still poor	Control compensation or thermal growth	Recalibrate and check temperature rise

The gauge resolution sets how small a difference you can see: a 0.01 mm gauge resolves differences at that order, which is enough to sort the source. Once this is done, the fix is usually already decided.

Nut backlash is only one part

If the nut is worn or originally has normal clearance, changing to a low-backlash or preloaded nut may help. But if bearings or coupling are loose, replacing the nut alone may not solve the issue.

Nut preload is built two common ways: a double nut adjusted by shims or a threaded collar, or a single nut with an offset lead that is preloaded at manufacture. The first can be adjusted on site, the second cannot — so identify which arrangement you have before ordering. For what preload means and when it helps, see ball screw nut preload explained.

Bearing preload and mounting rigidity are often overlooked

The fixed side usually carries a pair of angular contact bearings, with preload set by the lock nut: too loose and the screw moves axially, too tight and it runs hot. Support unit fixing to the frame and guide-to-screw parallelism also eat the accuracy margin — none of it comes back by changing the screw. For how grade relates to clearance, see C5 vs C7.

Keep old-part information for repair

For repair projects, record the old part model, end dimensions, support model, failure symptom, and measurement method. The supplier can judge whether to copy the old part, upgrade the nut, or adjust end machining. For how to measure a replacement screw, see how to measure a replacement ball screw.

Describe which axis and direction has backlash.
Send photos of the screw, nut, support unit, and coupling.
Record reverse positioning error or manual shaking condition.
Confirm whether low-backlash or preloaded nut is acceptable.

FAQ

If there is backlash, should I directly change to a preloaded nut? Not always. If backlash comes from bearings, support units, coupling, or mounting rigidity, replacing only the nut may have limited effect. Locate the source with the gauge sections above first.

Can control compensation replace mechanical repair? No. Backlash compensation only covers a small amount, and the clearance itself keeps changing as parts wear; without fixing the mechanical source, compensation just hides the error.

Is more preload always better? No. Preload raises stiffness but also friction, heat and wear. Choose the preload level for the positioning requirement, and on a replacement copy the original design first.

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.

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