Design Feedback on Surveying Instrument Base Plate: Changes Proposed Before Cutting
A design-for-manufacture review of an aluminium base plate carrying tribrach threads and levelling feet: the features that were expensive to produce, the changes we proposed, and how the function was preserved while simplifying the process.
The drawing review
Before quoting, every feature was checked for tool access, achievable corner radii, realistic tolerances and whether enough clamping area existed.
The part itself is defined by thread accuracy to 5/8-11 with mounting faces flat within 0.02 mm, and that requirement was never in question; what we examined was how much process it took to get there.
What was expensive
The expensive items were a tolerance tighter than the function needed, internal sharp corners that required tiny cutters, and an unnecessary secondary setup for one cosmetic face.
Each of those cost machine time and inspection time without adding anything measurable to the assembled product.
What we proposed
We proposed opening one non-critical tolerance, adding a corner radius matched to a standard cutter, and moving the cosmetic face into the main setup.
Each proposal was written with the reason, the saving and a statement that the function was unchanged, which made review simple for the customer's engineer.
After the change
The customer accepted all three proposals in a single revision and the quote reduced accordingly, with most of the saving coming from cycle time.
The specified quality, thread accuracy to 5/8-11 with mounting faces flat within 0.02 mm, was produced on the first article with no change to the inspection plan.
The wider lesson
Reviews like this cost an hour and regularly save double-digit percentages of unit cost, provided they happen before the first part is cut.
We now ask for the drawing early and return comments the same week, because changes after tooling exists cost ten times more.
Summary
Good results on this part came from preparation, and preparation is the part we now quote time for.
