Ball Screw Shaft-End Drawing Checklist: Bearings, Couplings and Mounting Datums

A ball screw model number does not completely describe the ends that connect it to a machine. Bearing seats, locking features and the motor coupling must work together with the chosen support arrangement. A clear drawing helps prevent a quotation from being based on different interface assumptions.

Start with the installed support arrangement

State which end is driven and how each end is supported. Include the bearing-block references and a sketch of their positions relative to the nut’s working travel. Mounting arrangement and span affect permissible compressive loading and rotational speed, so an end drawing should not be reviewed separately from the installed axis.^[1]

Distinguish usable travel, threaded length and overall shaft length. Leave room for nut overrun limits, end supports, the coupling and installation access. A short shaft shown in a website model is not evidence of the length required by your machine.

Describe the interfaces that must fit

Use datums and inspection requirements deliberately

Identify the surfaces or axes used to locate and inspect the part. State required fits, runout or other geometric controls only where the design requires them, with units and the applicable drawing convention. If those requirements have not been established, ask for a proposed interface drawing rather than approving an incomplete one.

Keep screw lead accuracy, assembled positioning accuracy and shaft-end geometric requirements distinct. Positioning also depends on clearance, stiffness, temperature and guide behavior. An accurately drawn bearing seat alone does not establish the accuracy of the finished machine.^[2]

For a replacement, separate measurements from requirements

Provide the original drawing or part identification if available, plus clear photographs of both ends and the nut mounting. Label measurements taken from a used part as measured observations; wear, damage or incomplete access may make them unsuitable as manufacturing requirements. Do not infer a bearing fit or thread specification from a photograph.

Note which existing components must be retained and which may change. A supplier can then flag an interface conflict before the replacement is treated as a direct fit.

Send one controlled quotation package

• Screw family, candidate model, lead and nut orientation, where already known.
• Drawing number, revision, units and a clearly identified approved or review status.
• Both shaft ends, complete length relationships and the mating component references.
• Operating stroke, load direction, speed, duty cycle and environment.
• A short list of unresolved dimensions or interfaces requiring confirmation.

The PFU product page and miniature ball screw family can help identify a starting configuration. They do not replace an approved end-machining drawing or confirm that every requested interface can be supplied.