Bumper Rule Question
 

According to the bumper rule (R27) we need at least 8 inches of bumper space on each side of each exterior vertex. My question is, even if we don't have 8 inches of frame on each side of the vertex, do we just cover all the available space, or do we have to extend the frame? Please help.

Re: Bumper Rule Question
 

Start with the Team Update from 1-17:
And end with the Q&A forum answer:

Re: Bumper Rule Question
 

Can you attach a sketch of what you are asking? Are you saying that one side of your robot is less than 8 inches, or are you saying that you have less than 8 inches on a segment of your frame adjacent to an exterior vertex?

Re: Bumper Rule Question
 

We have a 32 1/2 inch frame with a 19 inch gap in the middle for ball intake, with 6 inches on each side. So can we just have 2 inches of bumper over hang, or do we have to make the frame wider?

Re: Bumper Rule Question
 

That configuration would be illegal. You need to have 8 inches on each side. You cannot have the 2 inches of bumper over hang. See Team Update 2 (January 13) for more information.
http://frc-manual.usfirst.org/TeamUpdates/0#term 86

Re: Bumper Rule Question
 

To clarify our question: In the front and back of our robot, there is an opening for the balls to go through. On each side of the opening, the frame of our robot is only 6.25 inches. Our question is if we don't have 8 inches of robot to cover, do we just build our bumpers to fit what we have?

Re: Bumper Rule Question
 

Your frame perimeter is defined by the external vertices of your frame, not the frame itself.

You build the bumpers 8" long and rebuild the frame to support them as required by [R33]. Bumpers measuring less than 8" from the vertices of the frame perimeter are grounds for not passing inspection.

Re: Bumper Rule Question
 

To make it even clearer: You MUST have 8" of frame, 6.25 inches is 1.75 inches too short.

Re: Bumper Rule Question
 

They could get away with a support on the other end. That is their 6.25" of bumper, a 1.75" gap and a piece of c-channel behind it supported by something attached to the inner part of their frame. I'll post a drawing in a bit to make what I'm saying easier to visualize.

Re: Bumper Rule Question
 

Perhaps it is easier to answer that all bumper rules must be satisfied. That is, 8" on either side of an exterior vetrtices, and supported at the ends, and no gaps in the frame larger than 8", and small gaps of less than 1/4" are allowed when those gaps are generated by hardware, welds, or frame joiners, etc.

Re: Bumper Rule Question
 

(emphasis mine)

Wouldn't that be impossible though, at least for two of the bumpers? Doesn't the wood have to overlap the wood of the perpendicular bumper? How would the end be rigidly attached to the Frame Perimeter then? Or is 'end' a relative term, and just means 'as close to the end as possible'? I have an example picture below:



Thanks in advance. ::rtm::

Re: Bumper Rule Question
 

Ryan,
The picture shown is a new, allowable corner defined by the GDC this year. The thought being that one bumper gives support to the other and teams who wish to design one piece bumpers can take advantage of this new ruling to strengthen the corners.

Re: Bumper Rule Question
 

Ah, thanks. My apologies, I missed the previous image showing that the perpendicular overlap is not needed (as shown below).

Re: Bumper Rule Question
 

I have one question regarding what Mr. Skierkiewicz wrote. Specifically, he said there cannot be a gap in the frame of more than 8". I didn't read that proviso in the rules. Does this mean we cannot have more than an 8" segment cut out of the frame or does he mean that the bumper cannot cover more than an 8" cut out in the frame? Put another way, can you remove more than an 8" segment of frame perimeter, provided that there is at least eight inches on either side of that opening or are you limited to an 8" maximum opening?

Re: Bumper Rule Question
 

[R33]
Bumpers must be supported by the structure/frame of the Robot (i.e. each end of the Bumper must be rigidly attached to the Frame Perimeter, the gap between the backing material and the frame must not be greater than ¼ in. and no section of Bumper greater than 8 in. may be unsupported). See Figure 4?7.

Al forgot to specify that that gap was behind the bumper. You can remove more than 8" of frame perimeter, provided that you do not try to mount bumper across the gap, and provided that you leave the required bumper areas at the corners fully supported.

Re: Bumper Rule Question
 

I'm not picking on Eric, but his comment points out the possible difficulty people are having discussing or understanding this whole thing. The frame (or chassis) is distinct from the frame perimeter. A gap in the frame may be thought to be that area of your chassis which does not reach the frame perimeter. Bumpers are placed outside the frame perimeter based on various gap rules between them and the frame. Bumpers are also governed by the vertex coverage dimension for the frame perimeter. Because bumpers have support rules as they occupy a volume outside the frame perimeter, impositions on the frame construction are in effect.