FRC Blog - Some Tidbits Before Kickoff

[aldaeron]

Originally Posted by FrankJ

But it means that if you design a gear box, publish enough information that a reasonable person could make it, you can use the same plans. You also cannot use critical information you withhold. Something that was a little unclear in previous years rules blue box descriptions.

Like a good many rules in First, it is relying on the GP on teams to fully follow the rule.

This explains what I was going for pretty well.

<digress>
I worked as a Mechanical Design Engineer for 8 years in Aerospace. The released drawing package must be standalone and unambiguous at all times. The customer can pull their design and have someone else make it at any time (and they sometimes do!). Perhaps this makes me a little more "detailed" than many others with regard to documentation.
</digress>

Most drawing packages I have seen in industry include a STEP modeled to nominal dimensions without tolerance.

From the many STEPs I have seen on CD, things often missing are:
- Fastener details (.190 nominal shank is a #10, but is it 24 or 32 TPI?) (Please don't model the threads and make me count them. It makes so many more faces for the STEP importer!)
- Bolts, screws, snap rings, etc missing (I can see a feature for retaining the shaft but no idea what goes there)
- Vendor specific parts missing (where can I buy it?)
- Lubricant/epoxy/thread-locker/etc callout missing
- Tight tolerance parts (+/- .005 assumed, but a few parts are probably +/- .001)

I don't think you need a full ANSI-Y14.5 compliant drawing to accompany your STEP file. But a quick spreadsheet of the parts and where to buy them and a 1 page write-up on how to assemble the parts (including any weird things about the assembly) would cover it IMO.

As my first boss always said: "Use your best engineering judgement"

-matto-