Bumper Rule Question

[MormonLad]

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.

[Jon Stratis]

Start with the Team Update from 1-17:

[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.

And end with the Q&A forum answer:

Q. Pertaining to R33, namely the (i.e) line about the ends of bumpers needing to be attached to the frame perimeter, does it mean that the vertices of the bumpers need to be attached, or does the rule mean to specify a different type of “end”? If so, how far away from the corner can they be attached?
A. The specific part of Rule [R33] referenced means that Bumpers may not extend beyond any segment of Robot frame beyond that which is expressly permitted in [R28] and the rest of [R33] regarding unsupported sections.

[SteveGPage]

Originally Posted by MormonLad

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.

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?

[MormonLad]

Originally Posted by SteveGPage

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?

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?

[SteveGPage]

Originally Posted by MormonLad

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?

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

[adrianfarmer]

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?

[EricH]

Originally Posted by adrianfarmer

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?

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.

[DonRotolo]

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

[nitneylion452]

Originally Posted by DonRotolo

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

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.

[Al Skierkiewicz]

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.

[Hallry]

[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.

(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.

[Al Skierkiewicz]

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.

[Hallry]

Originally Posted by Al Skierkiewicz

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.

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

[gearheadcapital]

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?

[EricH]

Originally Posted by gearheadcapital

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?

[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.