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> If it doesn't really matter, then why is it the specification? Bob: You've called for a 5mm hole here, but you don't have a precision specified? Alice: I re
by michaelt 5y ago
> If it doesn't really matter, then why is it the specification?
Bob: You've called for a 5mm hole here, but you don't have a precision specified?
Alice: I really only need the sort of hole a 5mm drill bit would produce.
Bob: Do you know what level of precision that is? Have you done any calculations to confirm that's the appropriate level of precision?
Alice: Not really, in my judgement this doesn't rise to the level of needing such calculations.
Bob: Well, our drawing quality standards require a precision to be specified. Would ±0.5mm be OK? If not, how precise does it need to be?
Alice: How precise is the laser cutter we're cutting this out on?
Bob: The spec sheet claims ±0.05mm
Alice: The required precision is ±0.05mm
- bee_rider 5y agoThis reads to me like Alice just isn't doing her job properly. If this results in specs that are really hard to fulfill, hopefully the process is accountable enough to trace it back to her.
- ClumsyPilot 5y agoI don't want that Alice near an airplace, i can tell you that
- buildsjets 5y agoIn aerospace, if Alice needed a hole drilled and didn’t care about tolerance, she’d have specified a class III hole per her company’s hole drilling process and gone to get a latte. The process document has the appropriate tolerance called out for each diameter and class. Not every hole needs a tight tolerance, depending on the loading and assembly methods. And manufacturing prefers a standard tolerance range to be specified to enable consistency in manufacturing operations, rather than some weird lopsided super precise tolerance callout. So you determine the largest tolerances that will meet your design requirements, then select a fit class from the manufacturing standard that meets your tolerance requirement.