23-02-2010 06:43

martin417

Re: pic: Team 2503 Teaser #2

I never like posts that point out possible rules violations from teaser pics without enough information, but..

It looks like you ground the threads off the end of that cylinder. If so, it will not pass inspection. You may not modify a pneumatic cylinder in any way, including grinding.

If I am mistaken, my humblest apologies.

23-02-2010 08:31

Greg Needel

Re: pic: Team 2503 Teaser #2

I think that things like this are going to be hard to enforce this year, due to the fact that there are hundreds of legal cylinder configurations that they could buy. I would be shocked if you could not buy a cylinder without threads on it from somewhere.

That being said the team should make sure to bring documentation on where they got it from to make the inspection process easy.

23-02-2010 08:35

IndySam

Re: pic: Team 2503 Teaser #2

official Q&A

23-02-2010 09:31

wilsonmw04

Re: pic: Team 2503 Teaser #2

I understand the wording of the rule, but can someone tell me the rationale of it? If it's a safety issue, I just don't see how grinding the threads off the piston affects the safety of the piston in this application.

23-02-2010 09:50

Joe Johnson

Re: pic: Team 2503 Teaser #2

This is all well plowed ground. FIRST is adamant about these types of rules. They view them as major safety concerns. You can argue till you're blue in the face, but it will not get your robot past inspection.

My advice. Save yourself the trouble. Plan on making the changes to your robot necessary to allow you to use mod free cylinders.


Joe J.

23-02-2010 09:57

wilsonmw04

Re: pic: Team 2503 Teaser #2

Joe,

Again, I understand the rule and we have never used a modified piston on our team's robots. I was just looking for some information regarding the purpose of the rule. Thank you for your feedback.

23-02-2010 11:15

GaryVoshol

Re: pic: Team 2503 Teaser #2

Saying "Thou Shalt Not" creates a steadfast rule. Saying, "unless it's deemed to be safe" puts the onus on the inspector to evaluate the safety of every modified piece.

23-02-2010 11:50

Chris Fultz

Re: pic: Team 2503 Teaser #2

My perception of the why for this rule -

#1. There are many things you could do to a pneumatic cylinder that would be completely safe. These modifications would not affect the integrity of the "pressure vessel" portion of the cylnder and the pneumatic could be as safe as a new one off the shelf.

#2. There are also many things you could do to a pneumatic cylinder that might look completely safe, but would affect the integrity of the "pressure vessel". These changes could seem simple and safe, but after repeated cycling of pressure / no pressure, could cause a failure.

And from a safety perspective, it can be extremely difficult to tell the difference between modifications that fit #1 and the ones that fit #2.

And so, to be safe, FIRST does not allow ANY modifications to pneumatic components, so that a modification does not get missed at inspection, and so that an inspector does not have to turn into a specialist to determine if a modification is safe or not. Very few people have this experience or expertise, and in reality, only the component OEM could really tell you if a modification was safe, because only they know what their design is capable of and the margins they have built in.

A pneumatic component failing at 120 PSI or 60 PSI could be a major event. Ruptured metal, pieces flying, a sudden move of a component that is in place, etc.

23-02-2010 17:29

hyperdude

Re: pic: Team 2503 Teaser #2

Thanks for raising that to our attention. We'll get to work finding a replacement for this cylinder.