Fasteners extending outside the FRAME PERIMETER

[martin417]

I plan to have this question posted on the Q&A, but thought I would ask the CD community as well. What do you think?

<R16> During normal operation no part of the ROBOT shall extend outside the vertical projection of the FRAME PERIMETER, except as permitted by Rule <G30>.
Note: This means no “mushroom-bots.” If a ROBOT is designed as intended, in normal operation you should be able to push the ROBOT (with BUMPERS removed) up against a vertical wall, and the FRAME PERIMETER will be the only point of contact with the wall.

In the past, there have been allowances for fasteners, ie: bolt heads, rivets, etc used as fasteners for holding parts of the robot together, have been allowed to extend outside the FRAME PERIMETER. Will that be the case this year, or are teams required to design their robots so that all fasteners are flush with the frame?

[engunneer]

Originally Posted by martin417

In the past, there have been allowances for fasteners, ie: bolt heads, rivets, etc used as fasteners for holding parts of the robot together, have been allowed to extend outside the FRAME PERIMETER. Will that be the case this year, or are teams required to design their robots so that all fasteners are flush with the frame?

you need to adjust the placement of your end quote tag

Also, I don't recall there being a provision allowing fasteners outside the 28x38 footprint. Can you point to a Q&A or rule from the past? If your fasteners are outside the 28x38 size limit, you won't pass inspection. If your robot expands to play the game outside of that limit, then you are no longer in NORMAL CONFIGURATION per the rules.

We've certainly played the game before where we had to shave 1/8" off the robot to fit in the box. Switching from hex head to flat head bolts/screws can help you a lot in a pinch.

[silv940]

Originally Posted by martin417

I plan to have this question posted on the Q&A, but thought I would ask the CD community as well. What do you think?

No, they slide a bar that checks to see if you robot is in compliance. If a bolt is sticking out and the bar hits it, you don't pass. You would have to shave the bolt or take it out so that the bar can slide freely. They will make you shave off as little as 1/32 if the bar doesn't slide. They haven't allowed allowances since we joined FIRST in 2005. We keep our robot at 27 1/2" by 37 1/2" to allow for bolts.

[MrForbes]

They check the overall size (by sliding the bar across the sizing box), so if ANYTHING exceeds the 28 x 38" limit it will not pass.
But last year they had a QA response that allowed fasteners to fit into small cutouts in the bumper, and be outside the frame perimeter

We make our robot an inch small on each side...it always grows!

[IndySam]

The question is not outside the robot max size but outside the frame perimeter.

because of this being allowed again this year

<R07> D. Each BUMPER segment must be backed by a piece of ¾-inch thick by 5-inch tall piece of plywood. Each piece of BUMPER backing must be a minimum of 6 inches long. Small clearance pockets and/or access holes in the BUMPER backing are permitted, as long as they do not significantly affect the structural integrity of the BUMPER.


I would assume they will allow some protrusion again this year.

[Teched3]

If you have protrusion on the exterior of the frame, I believe that rules (IMO) intention is to allow you to provide clearance so the bumpers will fit solidly against the frame. Your robot must go into the sizing box and pass. Make your frame smaller to ensure it will pass with protrusions.

[engunneer]

Thanks for clarifying that. Your interpretation that the head of a bolt can be outside the frame perimeter appears to be correct, as long as there is a small clearance pocket in the bumper backing.

It may be worth it to Q&A this for heights not contained in the bumper zone.

[martin417]

Originally Posted by engunneer

you need to adjust the placement of your end quote tag

Also, I don't recall there being a provision allowing fasteners outside the 28x38 footprint. Can you point to a Q&A or rule from the past? If your fasteners are outside the 28x38 size limit, you won't pass inspection. If your robot expands to play the game outside of that limit, then you are no longer in NORMAL CONFIGURATION per the rules.

We've certainly played the game before where we had to shave 1/8" off the robot to fit in the box. Switching from hex head to flat head bolts/screws can help you a lot in a pinch.

Not sure about your comment on the end quote tag, the entire question I plan to ask on Q&A is inside the quote, and nothing else is....

But as to the rest, I said FRAME PERIMETER, I said nothing about exceeding the maximum dimensions of 28" x 38"

What I was talking about was the parts used to hold the frame together. If I built a robot that was constructed of 12" long pieces of aluminum channel, mitered at the corners, the frame perimeter would be 12" x 12". If I held those pieces of channel together with screws, and those screw heads protruded above the surface of the channel, they would be outside the FRAME PERIMETER. I cannot cite the reference, whether robot rule or Q&A (I don;'t have time time to go look) but there was a specific note last year about fasteners outside the frame perimeter being allowed. I know this to be true, and our robot had such fasteners, and passed inspection at Peachtree, Palmetto, and championships. I just want to be sure the same allowances are in place this year.

[martin417]

Originally Posted by IndySam

The question is not outside the robot max size but outside the frame perimeter.

because of this being allowed again this year

<R07> D. Each BUMPER segment must be backed by a piece of ¾-inch thick by 5-inch tall piece of plywood. Each piece of BUMPER backing must be a minimum of 6 inches long. Small clearance pockets and/or access holes in the BUMPER backing are permitted, as long as they do not significantly affect the structural integrity of the BUMPER.


I would assume they will allow some protrusion again this year.

Since the frame of the bots this year will likely be quite tall (the bumper zone starts at 10" off the floor), the bumper zone is relatively small in proportion to the height of the bot. My concern is with fasteners in the current design that are below the bumper zone. No pockets in the bumper backing will be required to clear the bolt heads, but they are ~3/8" above the surface of the frame, therefore, by strict interpretation of <R16> would be in violation. I will need to see a ruling from the GDC.

[MrForbes]

My experience with the sizing box in 2008 makes me want to build the parts that are below and above the bumper zone to a size at least half an inch smaller than the bumper part of the frame.

Something about the sizing box not having a level base. We checked it. Not something you want to have to deal with.

[mikelowry]

I just asked the question on the Q&A.

[sanddrag]

It seems to me that if you have a fastener head sticking out of a frame member, then that fastener head now defines the frame perimeter. If you wrap a string around your robot and over the fastener heads, and it is more than the allowed dimensions, you are in violation. Why even take the chance? Build it smaller.

[martin417]

Originally Posted by sanddrag

It seems to me that if you have a fastener head sticking out of a frame member, then that fastener head now defines the frame perimeter. If you wrap a string around your robot and over the fastener heads, and it is more than the allowed dimensions, you are in violation. Why even take the chance? Build it smaller.

I don't understand the difficulty people are having with this question. I clearly stated that the question did not involve extending outside the allowed NORMAL CONFIGURATION (28" x 38"). And the definition of FRAME PERIMETER IS CLEAR:

"To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT at the level of the BUMPER ZONE

(emphasis mine) I also stated that the protruding bolt heads are below the bumper zone (again, well within the 28" x 38" requirement) so no, the bolt heads do not define the FRAME PERIMETER. I have been through inspection, and understand clearly how size requirements are tested.

I do know that in the past this allowance has been made and wondered if it would be again.

[Al Skierkiewicz]

Martin,
The language is the same as in previous years. The frame perimeter includes the bolts and whatever else may be sticking out of the robot frame. It is this size that is determined to be within the robot sizing parameters when in the box. The rules for pockets in the bumpers is the same as well. It allows teams to make small holes in the back of the bumpers to accommodate secure mounting of the bumpers to the robot frame without the added clearance provided by fasteners.

The full definition is this..
FRAME PERIMETER – the polygon defined by the outer-most set of exterior vertices on the ROBOT (without the BUMPERS attached) that are within the BUMPER ZONE. To determine the FRAME PERIMETER, wrap a piece of string around the ROBOT at the level of the BUMPER ZONE - the string describes this polygon.
As further explained here...
<R16> During normal operation no part of the ROBOT shall extend outside the vertical projection of the FRAME PERIMETER, except as permitted by Rule <G30>.
Note: This means no “mushroom-bots.” If a ROBOT is designed as intended, in normal operation you should be able to push the ROBOT (with BUMPERS removed) up against a vertical wall, and the FRAME PERIMETER will be the only point of contact with the wall.

Therefore as I interpret the sum of rules, the bolt heads that are in the bumper zone define the frame perimeter and any other projections outside the bumper zone cannot extend beyond those set by the frame perimeter except as applied in <G30>.
Hope this helps.

[Vikesrock]

I was hoping the GDC would be rather speedy in responding to this question as it affects our frame design as well.

As it stands our upper frame is 26.5" wide. The lower frame is the same width, but the bolt heads for the wheel axles will protrude from the lower frame. In prior years this would not have been an issue as the bumpers were at the height of the lower frame and could have a clearance hole drilled in the back for each bolt head.

With the rules as they stand now, it seems like there may be a quick fix if the GDC comes back saying that fastener heads outside the Frame Perimeter at a non-bumper zone height are illegal. You could put identical fastener heads protruding from the frame members supporting the bumpers and drill clearance holes in the bumper for them. These fasteners would redefine the frame perimeter to a size large enough to cover the fastener heads on the lower frame.