Bumper Wood

[xxvg]

Is it legal to cut off a piece of the bumper wood since it is hitting our robot's intake when the intake comes down? or is it illegal? I need some clarification on this. Thank you.

[Brandon_L]

Originally Posted by xxvg

Is it legal to cut off a piece of the bumper wood since it is hitting our robot's intake when the intake comes down? or is it illegal? I need some clarification on this. Thank you.

Specifics? Drawings? Anything?

It depends where you're cutting from.

[Nirvash]

You need at least 8 inches of bumper from the corners of your robot, if the part hits the bumper after that point, you are okay to not have bumper for that area.

[xxvg]

It is just a v shape cut on the top on the wood, measure about like an inch width, so like a triangle. There's two of them so when our intake comes down to take in the ball it doesn't hit the bumper. The bumper wood interferes with our intake and how it is supposed to take in the ball.

[SteveGPage]

Based on your description, it is very likely that modification is illegal. Additional details, measurements, pictures, etc would be helpful to give better advice.

[Al Skierkiewicz]

XX,
A legal bumper is one in which...
R21
BUMPERS must be constructed as follows (see Figure 4-8):
A. be backed by ¾ in. (nominal) thick by 5 in. (± ½ in) tall plywood or solid, robust wood.

[Daniel_LaFleur]

Originally Posted by Al Skierkiewicz

XX,
A legal bumper is one in which...
R21
BUMPERS must be constructed as follows (see Figure 4-8):
A. be backed by ¾ in. (nominal) thick by 5 in. (± ½ in) tall plywood or solid, robust wood.

Al the full rule reads:

Originally Posted by FRC Rules

R21BUMPERS must be constructed as follows (see Figure 4-8):

A. be backed by ¾ in. (nominal) thick by 5 in. (± ½ in) tall plywood or solid, robust wood. Small clearance pockets and/or access holes in the plywood backing are permitted, as long as they do not significantly affect the structural integrity of the BUMPER.

So the question is: If it is a small access hole (for the intake) and does not affect structural integrity, is it legal?

[Steve W]

Originally Posted by Daniel_LaFleur

Al the full rule reads:


So the question is: If it is a small access hole (for the intake) and does not affect structural integrity, is it legal?

No. The access holes are for bolt heads so that the bumper will fit against the frame.

[Al Skierkiewicz]

Steve's interpretation is the one used in inspection. A notch does not meet that criteria.

[Daniel_LaFleur]

Originally Posted by Al Skierkiewicz

Steve's interpretation is the one used in inspection. A notch does not meet that criteria.

Is that anywhere in the rules, or just interpretation?

[jvriezen]

Originally Posted by Daniel_LaFleur

So the question is: If it is a small access hole (for the intake) and does not affect structural integrity, is it legal?

Realize that you are saying that a 5" wide piece of wood reduced to 4" at one (or two) locations doesn't affect structural integrity. How does that work?

The access holes for fasteners do effect structural integrity of the wood, but overall enhance the robutsness of the bumper system by getting more backing contact with the frame.

[Richard Wallace]

Originally Posted by Daniel_LaFleur

Is that anywhere in the rules, or just interpretation?

See the 2014 FRC Game Manual, Section 5 The Tournament, part 5.5.2: At each event, the Lead Robot Inspector (LRI) has final authority on the legality of any ....

LRIs do not invent rules interpretations on the fly, they base them on training. That training comes from FIRST HQ, through the Chief Robot Inspector -- that would be Al.

[Al Skierkiewicz]

Daniel,
That is the standard interpretation based on past practice. It has always been used to allow a tight fit to the robot frame. (although in some years it was not allowed)

[Danny Diaz]

There was a team at Arkansas who asked the very same question. They wanted to make a notch in the bumper to accommodate their intake mechanism because their intake was designed without the bumpers. Andy, our LRI, said "Absolutely not." Their intake was unfortunately too wide to just "not have bumpers" where the intake and robot body met; they didn't have the 8" on each corner clearance.

You aren't REQUIRED to have bumpers that cover EVERY inch of the perimeter of your robot - depending on the design of your intake along with the rest of your frame perimeter, would it be possible to just NOT have bumpers at your intake point? Is there enough space for bumpers 8" on each side of the corners of your robot?

-Danny

[Jon Stratis]

Originally Posted by Daniel_LaFleur

Is that anywhere in the rules, or just interpretation?

R21.

Based on LRI training, the provisions in part A (allowing small clearance pockets and/or access holes) are there to facilitate meeting part F (rigid fastening system to form a tight, robust connection to the main structure/frame).

We're looking for something that matches the provided bumper cross section (figure 4-8) as closely as possible for its entire length, with exceptions made to allow for tight, robust mounting. The bumper rules don't take into account robot mechanisms - your mechanisms need to be designed to take into account bumpers.

A lot of teams (most teams, probably) leave bumpers until the very end. They spend 6 weeks working on a beautiful robot, then give a freshman a single night to come up with suitable bumpers. Some years, it doesn't matter as it's relatively easy to manipulate a game piece over, under, or around the bumpers. Other years, like this year, the bumpers really play a big role in game piece manipulation for a lot of teams. Having the bumpers in place changes the geometry and motion required for the ball to enter the robot. Personally, I'm a big fan of making some bumpers as soon as you have a frame and strapping them in place. It'll help you remember to include all of the constraints when designing your manipulators.