Frame Perimeter Tolerance

[cadandcookies]

Originally Posted by DevenStonow

In regards to this, previously, I've had the "issue"(ie. it wasn't really an issue) where the LRI further clarified that that rule is simply there in respect to your own FP-ie. if you're 27.5x27.5, those protrusions are okay, but if you're 28x28, they would NOT be okay, because (as said in other posts) 112 inches is 112 inches, so no matter what you still need to fit under the 112 inches-including protrusions.

Keep in mind, this was just one LRI's interpretation, but I assume it'd be fairly consistent across the board.

That's an *ahem* interesting interpretation of the rules.

Regardless... seriously, good luck to the OP. Also:

[Cal578]

I was at an event a few years ago in which the team across from us failed inspection due to their frame being half an inch too wide. They only had 5 students on their whole team, so I sent a few of our students (and some of our tools) over to help them remake a whole lot of their robot. Very frustrating for that team (but I admired how they accepted and handled the situation).

If you have any possible way to take a quarter inch out now, I'd highly recommend it. Much better than going to your first regional with a 50% chance of failing. Maybe you can round off the corners a bit? But be careful about bumper rules...

[Al Skierkiewicz]

The recommendation from experienced (OK Old) mentors is to build to 1/4" under in every dimension. Tolerances in bending are finite and they could be too big. Whatever way the Inspection team decides to measure the Frame Perimeter, it better be less than 112". The guideline is using a 112" string wrapped around the robot frame. Boltheads, welds minor protrusions are different than a misplaced bend, angle stock in the corner or a transmission that stick outs from the frame. We call this practice "playing with fire".

[Hallry]

Instead of asking Chief Delphi, which is as official as asking a pet goldfish, ask the question on the OFFICIAL Q&A, where you'll get an answer who know is correct: https://frc-qa.usfirst.org/Questions.php

[cadandcookies]

Originally Posted by Hallry

Instead of asking Chief Delphi, which is as official as asking a pet goldfish, ask the question on the OFFICIAL Q&A, where you'll get an answer who know is correct: https://frc-qa.usfirst.org/Questions.php

Albeit a very well informed and intelligent pet goldfish.

Stil, it's true: FIRST Q&A is the only place you'll be getting an official answer.

[Gregor]

I'd recommend you take the advice from this thread now, not on the Thursday of your competition when you'll need to do it anyway.

http://www.chiefdelphi.com/forums/sh...ighlight=frame

[cgmv123]

I hope it never comes to this, but remember that the pits (especially the ones at Championship) can be rather toasty. Aluminum expands 12.3E-6 inches for every extra degree Fahrenheit. If your build space is rather cold like ours is (~60° F), and the pits are ~76° F, a 28x28 inch robot could gain 0.0220416 inches in its perimeter. That could cause you to fail inspection. Build smaller on purpose!

(The calculations in this post are intended as a thought exercise and are not intended to be scientific.)

[Jon Stratis]

If you're going to build your robot so close to the max dimensions that you're worried about tolerance, I highly recommend bringing a big bag of candy to bribe your inspector with before he/she starts the measurement! I recommend Godiva chocolates.

[MetalJacket]

Like I said, at this point we're a little committed to our frame - I don't mean this to sound like I am ignoring people's advice. Once we have the drive assembled I will double and triple (probably even quadruple) check the frame perimeter to make sure we are legal and if needed, we can modify it.

[kevin.li.rit]

[quote=DevenStonow;1331383]

Originally Posted by amesmich

28" inches is 28" regardless of whats on it, however they do say things that protrude out like nut ans bolts < than 1/4" are ok so I would bet it would be ok, but thats just my bet. I would think that if you asked they would say what I said in my first sentence.
/QUOTE]

In regards to this, previously, I've had the "issue"(ie. it wasn't really an issue) where the LRI further clarified that that rule is simply there in respect to your own FP-ie. if you're 27.5x27.5, those protrusions are okay, but if you're 28x28, they would NOT be okay, because (as said in other posts) 112 inches is 112 inches, so no matter what you still need to fit under the 112 inches-including protrusions.

Keep in mind, this was just one LRI's interpretation, but I assume it'd be fairly consistent across the board.

Was this issue when they still had the sizing box and the size limit of 28"x38"? Because back then that was the correct interpretation.

[Steven Donow]

[quote=kevin.li.rit;1331449]

Originally Posted by DevenStonow

Was this issue when they still had the sizing box and the size limit of 28"x38"? Because back then that was the correct interpretation.

Yes, this was 2012. So yeah, maybe since then that is a different interpretation (I didn't read into the exact wordings in the past manuals)

[artdutra04]

Originally Posted by Alan Anderson

There is no tolerance on the frame perimeter measurement. It is either 112.0 inches or less, or it is out of compliance with the rules.

There technically is a tolerance but it's asymmetrical; it's 112.0 +0.0 / -112.0

[gabrielau23]

Originally Posted by jee7s

Must be a Texas thing then. Lubbock, San Antonio, and Houston used the tailor's measuring tape to check the frame perimeter.

I stand corrected.

I think Chesapeake and DC used it as well?

[nathannfm]

Last year at one of the MAR qualifiers the inspector used a metal measuring tape with the bow in it to keep it extended. When he wrapped it around our bot naturally it was way over because of the bow, so I asked him to pull it a bit tighter and jokingly said it was 112 in the CAD. after pulling It tight it was pretty hard to tell the exact size, but the tape still wasn't conforming to the frame properly so he just gave it to us.
My advice (if there is really no way to change it) would be to bring a cloth tape and pull it out if they give you any trouble after trying a metal one, no guaranty they will accept it but but be nice about it and maybe they will pass you.

[dtengineering]

Originally Posted by MetalJacket

Like I said, at this point we're a little committed to our frame -

And FRC is a little committed to the rule book.

Jason