FRC Blog - Some Tidbits Before Kickoff

[FrankJ]

As others have said, it is really not a new rule. Maybe it would be better off as part of the manual that gets released before kick off. 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.

[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-

[Oblarg]

Originally Posted by aldaeron

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-

A lot of the information you list (especially threadcount on screws) is often stuff where you have a fair bit of leeway in implementation, though. I don't think leaving bolts/rivets out of your CAD really constitutes "withholding critical information."

[FrankJ]

Originally Posted by aldaeron

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>
...
-matto-

I think we are pretty much in agreement here. Do realize that publishing a complete package like that is not a trivial task. Even for professionals with years of experience. Which is why design packages often come with project engineers to implement them. I would consider a good faith effort acceptable. Also GP would dictate that the originator be receptive for reasonable requests for more information.

[AllenGregoryIV]

I know people are playing devil's advocate here but for those of you seriously questioning how much to publish. The way I see it is that you should publish what you use to build it. If you use a CAD file then publish the stp. I can't imagine an LRI going through a teams posted documents and determining if something is complete or not.

HQ is encouraging teams to share their designs, so share your designs.

Also in the past the determination between using an old design and redesigning something based on an unpublished design was so vague it barely mattered.

[headlight]

Originally Posted by aldaeron

...
- Vendor specific parts missing (where can I buy it?)
...

I think this a huge thing teams overlook. Half the challenge for me in FRC is figuring out where to source components from so I don't have to make inferior equivalents.

I don't really care about the team's catapult arm calculations, but if they can tell me where they got their COTS release mechanism, that is huge.

[Michael Hill]

For PCBs, wouldn't releasing a zip file of gerbers be fine? All other components that are soldered onto it are COTS parts (well...generally).

[magnets]

Originally Posted by AllenGregoryIV

Also in the past the determination between using an old design and redesigning something based on an unpublished design was so vague it barely mattered.

This is something I've never understood. I've seen tons of teams use the same drive base year after year after year. Sure, they may have changed the overall dimensions, or adjusted the gear ratio, or changed the diameter of the wheels, but it's obvious that the design was based off of last year's design.

I do think it's fine to learn from previous years. We had success with a roller claw in 2007, so we didn't bother prototyping another type of grabber in 2011. My question is, where do we draw the line? If I make a WCD in the offseason, can I make the robot 1" wider, use different wheels, and change the gears in my gearbox and use this during build season without posting the design?

[pwnageNick]

I think we're missing the biggest point. Showing there's an R13 means there will in fact be rules this year. I was a bit worried after the game hint.

[jee7s]

Note that this R13 removed the restriction on parts created before kickoff that existed in 2014's rulebook. Ostensibly, one could create robot elements prior to kickoff and then use them in the 2015 season so long as the design is published before Saturday. In years prior, the team would have to rebuild the part after kickoff using the design published before kickoff. Unless there is another rule prohibiting the use of parts created before kickoff, this change seems to allow teams to build parts now and use them in the 2015 game. Of course, that's only three days away.

[Jay O'Donnell]

Originally Posted by pwnageNick

I think we're missing the biggest point. Showing there's an R13 means there will in fact be rules this year. I was a bit worried after the game hint.

Even better, we know there are at least twelve other rules to look forward to.

[notmattlythgoe]

Originally Posted by jee7s

Note that this R13 removed the restriction on parts created before kickoff that existed in 2014's rulebook. Ostensibly, one could create robot elements prior to kickoff and then use them in the 2015 season so long as the design is published before Saturday. In years prior, the team would have to rebuild the part after kickoff using the design published before kickoff. Unless there is another rule prohibiting the use of parts created before kickoff, this change seems to allow teams to build parts now and use them in the 2015 game. Of course, that's only three days away.

I have a feeling they either split the rule, or this was only part of the rule.

[Electronica1]

Originally Posted by jee7s

Note that this R13 removed the restriction on parts created before kickoff that existed in 2014's rulebook. Ostensibly, one could create robot elements prior to kickoff and then use them in the 2015 season so long as the design is published before Saturday. In years prior, the team would have to rebuild the part after kickoff using the design published before kickoff. Unless there is another rule prohibiting the use of parts created before kickoff, this change seems to allow teams to build parts now and use them in the 2015 game. Of course, that's only three days away.

Hmm, this is a pretty big assumption without seeing all the other rules. I think I will just wait until kickoff in a few days before building a drive system without seeing the field, just to be on the safe side

[TDav540]

Originally Posted by Electronica1

So is a step file good enough? Or do we need to post assembly instructions and part drawings (so a team without cad could read it)?

Hypothetical question, if we haven't actually finished the design, should we just post what we have?

(I know that this isn't official, but I couldn't think of anywhere official I could ask before kickoff)

I think we need an answer to this questions as well, because if something is incomplete, then even the team designing it cannot actually build it. Should any semi-complete designs be posted as well?

[wilsonmw04]

What we have posted today should meet the spirit of the rule. If there are question, that's what the discussion section on CD is for without any guidance on this rule, we are doing the best we can.