Which dimensions need attention before casting tooling?

Begin with how the part sits in the assembly

A motor end cap may locate on a flange while supporting a bearing in its central bore. The bore size matters, but so does its relationship to the locating feature. A housing can pass separate size checks and still create assembly problems if those relationships are poorly defined.

Identify the mounting, locating and sealing surfaces on the drawing. These provide a practical basis for discussing machining setups and measurement alignment. Do not assume that the largest cast face is the best reference.

Keep cast surfaces and machined features distinct

Mark the surfaces that must be machined and those that can remain as cast. Applying the same tight requirement to every external surface can add operations without improving function. Conversely, an important assembly face left under a general note may receive too little attention.

If a feature is measured from a cast surface, discuss how the part will be located and how variation on that surface affects the result. A stable inspection setup should represent the drawing and the function, not just produce a convenient reading.

Resolve competing files before the sample is made

A 3D model may carry nominal geometry while the drawing contains a later hole change or a different datum scheme. Establish which document controls each requirement and issue the agreed revision with the order.

If you are unsure which dimension needs a tighter limit, describe the assembly problem. A drawing review can focus on the bearing, seal or fastener interface rather than tightening every dimension.

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