Tooling and Machining Editing and Proofreading Services

A drawing arrives with a position tolerance on four holes and no datum reference frame. The machinist can hold the holes to each other beautifully, and the part will still be rejected, because the inspector will measure from a different face than the one the machinist worked from. Nobody was wrong. The drawing never said which face the part is supposed to be located by.

We edit what machine shops and toolmakers produce — drawing and dimensioning requirements documentation, datum scheme and geometric tolerancing guidance for customers, inspection and measurement plans, first article and dimensional reports, process and setup documentation, tooling and fixture design documentation, capability and feasibility responses at quotation, non-conformance and concession requests, cutting data and process parameter records, and technical guidance for designers on manufacturability. Our editors work on the drawing information a machinist and an inspector must read identically.

The datum scheme and its tolerancing are what determine whether a part can be made and measured consistently, and their failure is a drawing that dimensions features without establishing how the part sits. A tolerance without a datum is a tolerance measured from wherever the inspector chooses. We work through these and the queries that go back to customers so the datum reference frame is identified and, crucially, matches how the part is actually located in its assembly, since a part datumed on a face that touches nothing in service will be rejected for a deviation that does not matter and accepted with one that does; so each geometric tolerance names its datums in order of precedence, because a position tolerance to A|B|C and one to A|C|B accept different parts; so the measurement method is agreed for anything that cannot be checked with hand tools, given that a profile tolerance on a curved surface requires a decision about probe density that changes the result; so any feature whose tolerance the process cannot hold is queried at quotation rather than at first article, along with what it can hold; so the general tolerance and the drawing's standard are stated, as a drawing citing no standard leaves the interpretation of every symbol open; so the datums are physically accessible for both machining and inspection; and so the queries are raised as a list with proposals rather than as a series of emails. Drawings clarified this way produce parts that pass first time.

Everything you send is treated in confidence, including drawings, inspection data and customer information. We are editors rather than manufacturing or metrology engineers, and we offer no view on tolerancing, measurement or conformance. What we can do is make the drawing say the same thing to the machinist and the inspector.