Chief Delphi - Aluminum angle on bumpers

Chief Delphi (http://www.chiefdelphi.com/forums/index.php)

- Technical Discussion (http://www.chiefdelphi.com/forums/forumdisplay.php?f=22)

- - Aluminum angle on bumpers (http://www.chiefdelphi.com/forums/showthread.php?t=74247)

Magnechu

12-02-2009 13:43

Aluminum angle on bumpers

Is there any limit to how much you can have? Or can you just put it on the corners? Our bumpers only weigh 12.5 pounds, so we want to add another 5 pounds onto them in order to maximize our weight at the bottom of the robot to have an even better low center of gravity.

Any and all help is appreciated!

Russ Beavis

12-02-2009 14:18

Re: Aluminum angle on bumpers

You could use steel angle instead to add weight. You can add whatever material you'd like in that 1" deep "hard parts only" zone.

Russ

MrForbes

12-02-2009 14:32

Re: Aluminum angle on bumpers

I was thinking about this...we might need to reduce the length of our plywood bumper backing if we add angle, to keep the hard parts from extending past the bumper perimeter on the adjacent side, that is, into the corner.

ZakuAce

12-02-2009 15:58

Re: Aluminum angle on bumpers

I've been smacking my head on the wall about this. What is the point of the aluminium? Last year we just stapled the cloth in place. I know it isn't really my place to contridict the allmighty GDC, but I'm flipping out about this because it is making my job of building the bumpers somewhat more complicated. Also, it says to attach the aluminium with wood screws, but won't the screw heads stick out a bit from the bumpers? Or do the screws go in from the top of the bumper, in which case the plywood has a better chance of cracking from the screws?

Argh, I wish this hadn't been thrown on me so late in the game. Oh well.

EricH

12-02-2009 16:00

Re: Aluminum angle on bumpers

FYI, http://forums.usfirst.org/showthread.php?t=11394 says those angles are optional.

ZakuAce

12-02-2009 16:05

Re: Aluminum angle on bumpers

:O Now I feel dumb. Thanks a lot, that helps. Disregard my sillyness, we're hectic here over other things.

dlavery

12-02-2009 19:01

Re: Aluminum angle on bumpers

Quote:

Originally Posted by Russ Beavis (Post 819361)

You could use steel angle instead to add weight. You can add whatever material you'd like in that 1" deep "hard parts only" zone.

Russ

That is definitely NOT the case. You CANNOT add "whatever material you'd like" in the "hard parts only" zone. Please do not do this!

If there is any question about what can or cannot be incorporated into the bumpers, please be sure to ask that question on the official Q&A forums. Remember, any answers found here (including this one) are unofficial and will not carry any weight with the inspectors.

-dave

.

Russ Beavis

12-02-2009 20:22

Re: Aluminum angle on bumpers

Dave,
My understanding of the rule is that, as long as there are the 2 stacked noodles + durable cover that's securely fastened to a 3/4" thick x 5" tall plywood backing, there is no reason why teams can't add a 1/8" thick steel plate all around the plywood. That was the rationale behind my "add whatever material you'd like" comment (emphasis on "add").

Russ

Mike8519

12-02-2009 23:10

Re: Aluminum angle on bumpers

Perhaps the point Dave is trying to make is that you cannot add whatever you want inbetween the robot and bumper if it is non-functional from an attachment point of view?

But.... if your multi-part bumper attachment system (R08-H) uses thick steel brackets for strength there is no reason why that is illegal.

GaryVoshol

13-02-2009 08:06

Re: Aluminum angle on bumpers

Quote:

Originally Posted by Mike8519 (Post 819697)

But.... if your multi-part bumper attachment system (R08-H) uses thick steel brackets for strength there is no reason why that is illegal.

Unless we are to interpret Figure 8 - 1 as a definition, whereas Figure 8 - 2 is only an example.

MrForbes

13-02-2009 08:48

Re: Aluminum angle on bumpers

Gary--that might be the case, because

Quote:

<R08> ...... BUMPERS must be constructed as described below and illustrated in Figure 8 – 1.

The angle shown in Fig 8 - 1 is labeled "aluminum", not "steel", and it does not appear that the angle is optional...???

Time for me to read up on more Q&As....

edit: apparently the angle is optional

http://forums.usfirst.org/showthread.php?t=11394

GaryVoshol

13-02-2009 09:48

Re: Aluminum angle on bumpers

As opposed to

Quote:

I. BUMPERS must protect all exterior corners of the BUMPER PERIMETER (see Figure 8 - 2).
J. Corners and joints between BUMPER segments may be filled with short pieces of vertically oriented pool noodle, by wrapping the pool noodles around the corners, or by beveling the ends between adjacent segments so they form a tight and complete protective surface (see Figure 8 – 2).

And, as you've found in Q&A, the clamping brackets are optional. (Although an earlier post http://forums.usfirst.org/showthread.php?t=11219 said they are required; that's OK, the GDC can change.) If 8 - 1 is to be definitive a note indicating the brackets are optional should be added.

MrForbes

13-02-2009 09:55

Re: Aluminum angle on bumpers

Exactly! :)

Magnechu

13-02-2009 13:24

Re: Aluminum angle on bumpers

So are steel brackets okay or not? :P
I'll try and ask on the Q&A but what do you all think?

AlexD744

13-02-2009 13:32

Re: Aluminum angle on bumpers

I know we could add weight by sticking steel robs in the noodles. It's brilliant. jk. :p

dlavery

14-02-2009 08:10

Re: Aluminum angle on bumpers

See this Q&A forum answer. No steel angles. No steel plates. No lead weights. No small rodents. No Chinese food from lunch. You have to make the bumpers out of the items that they have always said they must be made from - plywood, pool noodles, fabric covering, aluminum angles, and fastening system. Nothing else.

-dave

.

jgannon

14-02-2009 08:29

Re: Aluminum angle on bumpers

I really don't mean to derail this thread, but I'd like to point out for future GDC consideration that this is an excellent demonstration of how defective the wording of bumper rules was this year. Calling the rules unclear is inaccurate; they are very clear... the only problem is that everyone seems to find them clear in a different way. If there are any two people on this planet who should accurately understand these rules, they are Dave Lavery, a guy who helped write the rules, and Russ Beavis, the guy in charge of telling inspectors how to enforce them. For there to be this substantial of a disagreement this late in the season is really troublesome.

I don't think there's any question that literally hundreds of teams are going to show up to competition with illegal bumper configurations this year. For many of them, it won't be because they didn't read the manual, but rather because they read it, applied a reasonable degree of logic, and still ended up with a different interpretation than the one intended. I'm afraid it's going to be a huge mess, I feel like it could have been avoided, and I'm very hopeful for vast improvements next year.

Taylor

14-02-2009 09:24

Re: Aluminum angle on bumpers

Quote:

Originally Posted by dlavery (Post 820478)

Since this opinion was on Chief Delphi, it is not necessarily correct or even accurate. Only those views expressed from the GDC (or FRCOPS) on the official Q&A are to be regarded as gospel. Quite frankly, I don't trust this "dlavery" fellow.

Boommaster713

14-02-2009 09:48

Re: Aluminum angle on bumpers

would it be considered illegal if steel brackets are used as part of the robust attachment system seeing as how there are no definitions on what a robust attachment system is?

MrForbes

14-02-2009 10:38

Re: Aluminum angle on bumpers

ummmmm.....how about you ask on the Q&A? :)

My wild guess it that you could use steel brackets and large steel bolts as part of your robust fastening system. Last year we used 5/16" coupling nuts (they're over an inch long) as part of our nut-and-bolt fastening system, they're much easier to hold onto that normal nuts.

Mike8519

14-02-2009 10:41

Re: Aluminum angle on bumpers

Well apparently the only robust attachment system allowed is a bolt with a tee put into the plywood as per figure 8-1. Even though parts G and H of R08 seems to imply there is a possibility of other robust fasteners. The note in the primary paragraph of R08 ("To achieve this, BUMPERS must be constructed as described below and illustrated in Figure 8 – 1") defeats the later subsections of the rule.

MrForbes

14-02-2009 10:44

Re: Aluminum angle on bumpers

Which is why I suggested asking on the Q&A. According to fig 8-1, the aluminum angle is a required part of the bumpers, but the GDC said it's optional on the Q&A. If you want to find out, ASK ON THE Q&A.

Tristan Lall

14-02-2009 23:04

Re: Aluminum angle on bumpers

Quote:

Originally Posted by squirrel (Post 820540)

Which is why I suggested asking on the Q&A. According to fig 8-1, the aluminum angle is a required part of the bumpers, but the GDC said it's optional on the Q&A.

That's a perfect example of two problems with the rules this year.

One: if the angle is optional, why don't the rules say so? (And why haven't the rules been updated, given that this question was first raised weeks ago?)

Two: if the Q&A advises something that isn't directly supported by the rules, what do teams do? (And what do you expect the inspectors to do? Assume that a Q&A is as good as a rule change, and make the teams comply with the Q&A?)

EricH

14-02-2009 23:17

Re: Aluminum angle on bumpers

Somebody remind me to nominate Tristan to the GDC, if that's possible. If nothing else, he can check for clarity in the wording of the rules.

MrForbes

15-02-2009 00:31

Re: Aluminum angle on bumpers

Quote:

Originally Posted by Tristan Lall (Post 820937)

Two: if the Q&A advises something that isn't directly supported by the rules, what do teams do?

Print the question and answer, and have it with you at inspection time, just in case there's an issue.

MikeDubreuil

15-02-2009 01:01

Re: Aluminum angle on bumpers

Quote:

Originally Posted by Tristan Lall (Post 820937)

Quote:

Originally Posted by Tristan Lall (Post 820937)

Two: if the Q&A advises something that isn't directly supported by the rules, what do teams do? (And what do you expect the inspectors to do? Assume that a Q&A is as good as a rule change, and make the teams comply with the Q&A?)

The GDC would say they provide clarification, meaning the Q/A responses are direclty supported by the rules. (that sentence may get me in trouble)

For me personally this has been a very tiresome year. The GDC wants a very specific bumper design. Unfortunately, the rules seem to be very non-specific and the graphics are confusing. Some folks around here find it simple and straight forward. They think that anyone who doesn't is either: A.) Trying to advance an illegal robot design, B.) lawyering the rules, C.) a moron; which have led to some viscous personal attacks. Quite frankly I don't pour my seemingly dwindling free time into something that I think is a waste of time. I think the rules discussions are important because it provides a platform for the GDC to understand where our thought process is- how people, who don't know the GDC's intent, interpret the rules.

MrForbes

15-02-2009 10:05

Re: Aluminum angle on bumpers

Quote:

Originally Posted by MikeDubreuil (Post 821045)

I am assuming in Figure 8-1, you are supposed to infer that the use of aluminum angle is optional because no bumper rule expressly tells you to use aluminum angle.

Of course the tricky part is knowing just what you are supposed to infer

That's why we have the Q&A, I guess!

Al Skierkiewicz

18-02-2009 08:51

Re: Aluminum angle on bumpers

Do your best and the Inspection Team will help, if needed, get you the rest of the way. We have and will be discussing the bumpers on our phone conferences and your inspection team will be up to date on the GDC decisions at each event. With the 18 lb limit, construction should not be a problem. Bowing to the Great Karnack, I will predict that we will see teams with issues using weak fabric, something other than 3/4" plywood backing, hard parts in the corners, and less than rigid fastening systems. And I also predict we will see teams with sections less that 6" long, and no robot structure to back up the bumper.

Russ Beavis

18-02-2009 08:59

Re: Aluminum angle on bumpers

To the more experienced teams out there - please consider bringing plenty of extra fabric, aluminum brackets, pool noodles, plywood and "robust fastener systems". Since these can all be unmodified COTS items, you can bring as much as you'd like.

Your robot inspectors and rookie teams (ie your potential alliance partners) will be VERY grateful. There will probably be a LOT of bumper re-building on Thursdays.

Russ

Mark McLeod

19-02-2009 10:10

Re: Aluminum angle on bumpers

Quote:

Originally Posted by Russ Beavis (Post 823908)

Since these can all be unmodified COTS items, you can bring as much as you'd like.

Unless you've pre-cut your COTS 4' x 8' sheet of plywood into bumper width strips...
Luckily, I don't believe we'll be anywhere close to our 40 lbs of fabricated parts and can donate some of our weight allowance to these spare bumper parts.

ChrisH

19-02-2009 14:57

Re: Aluminum angle on bumpers

Quote:

Originally Posted by Mark McLeod (Post 824668)

There is a simple solution to that. Leave the pre-cut strips in your vehicle and give them to the other team in the parking lot. Then they become part of the other team's allowance, not yours.

Bob Steele

19-02-2009 17:53

Re: Aluminum angle on bumpers

Great idea Chris...
Perhaps a bumper kit.... strips of plywood 5" wide... t- nuts... 1/4 - 20 bolts... fabric of a neutral shade...staple gun and plenty of staples...

Left outside in the van/trailer/car

We will be doing that... enough for at least 3 robots...

perhaps even more plywood strips.... the fabric could be reused..

R

Russ Beavis

20-02-2009 08:33

Re: Aluminum angle on bumpers

I recommend that you let your know Lead Robot Inspector know if you've got extra bumper parts available. He/she would appreciate being able to point teams in your direction.

Russ

/edit
And, by the way, THANK YOU VERY MUCH (in advance) for bringing such goodies to your regional!!!
edit/

GaryVoshol

20-02-2009 19:03

Re: Aluminum angle on bumpers

Quote:

Originally Posted by Russ Beavis (Post 825316)

Those wouldn't be fabricated bumper parts now, would they? :rolleyes:

AdamHeard

20-02-2009 19:14

Re: Aluminum angle on bumpers

It's too late this season, but next season maybe we should just QnA the entire manual the day QnA opens.

Either that or boycott the QnA, nothing is illegal until it's asked apparently.

Team 973 is bringing a lot of bumper supplies to regionals, and a lot of premade 6" sections. This is not going in our withholding allowance, we are bringing it. Period. End of story.

Quote:

Originally Posted by ChrisH (Post 824889)

There is a simple solution to that. Leave the pre-cut strips in your vehicle and give them to the other team in the parking lot. Then they become part of the other team's allowance, not yours.

Off Topics, but wouldn't this make it legal to split your robot into 3 40 lb sections, and have it entirely brought in at the regional?

EDIT: Would anyone consider bright freaking orange a nuetral shade?

Jay H 237

20-02-2009 19:49

Re: Aluminum angle on bumpers

Quote:

Originally Posted by MikeDubreuil (Post 821045)

The problem is with graphic communication. The GDC supplies graphics in the Robot Manual to help describe what they are specifically referring to in certain rules. However, the graphics may contradict other rules. Unfortunately, the graphics can lead readers to conclusions the GDC never intended. Then us mere mortals rely on the Q/A to clear the confusion.

I am assuming in Figure 8-1, you are supposed to infer that the use of aluminum angle is optional because no bumper rule expressly tells you to use aluminum angle.

In Figure 8-2 (I know, beaten to death), you are not supposed to infer anything and simply look at the "OK" corner configurations.

The GDC would say they provide clarification, meaning the Q/A responses are direclty supported by the rules. (that sentence may get me in trouble)

For me personally this has been a very tiresome year. The GDC wants a very specific bumper design. Unfortunately, the rules seem to be very non-specific and the graphics are confusing. Some folks around here find it simple and straight forward. They think that anyone who doesn't is either: A.) Trying to advance an illegal robot design, B.) lawyering the rules, C.) a moron; which have led to some viscous personal attacks. Quite frankly I don't pour my seemingly dwindling free time into something that I think is a waste of time. I think the rules discussions are important because it provides a platform for the GDC to understand where our thought process is- how people, who don't know the GDC's intent, interpret the rules.

Bingo! Hopefully next year they can clarify the bumper construction, it's hard to be in full compliance when the rules aren't fully clear.

We have our bumpers built with the plywood backing, pool noodles, fabric stapled in place and 3/4" aluminum angle screwed over the fabric where the plywood is. We also have the tee nuts in the plywood for the bolts to fasten the bumpers.

We DO have steel angle pieces that fasten those bumper bolts to the robot frame. Basically the steel angle has bolts on both sides, one to hold the bumpers to them and the other to hold the angle to the robot frame.

All times are GMT -5. The time now is 21:23.