If a team has continuous bumpers all the way around their robot which are 5 inches tall when laying on the floor, constructed from ¾” birch plywood, and wishes to cut two notches along the top of the wood that are 1” deep and 4 to 6 inches wide each, both on the front side only, to allow the arm to go below the top of the bumpers, and not below the top of the frame perimeter, is this allowed? The bumpers would be securely mounted 7 inches above the floor when on the robot. The notches are 6" away from the corners.
That might cause some weird issues with bumper rules stating that only minor protrusions/pockets into the bumper that are <=1/4" are allowed. I would instead recommend cutting out an entire slot in the bumpers so that they don’t go all the way around but rather have a small gap where your intake/arm swings through. Hope that makes sense
No but you could cut out that section of the bumper and mount it lower than the rest of the bumper.
3 Likes
Look carefully at the bumper wood height tolerance as well…there’s a way to make that work.
3 Likes
Or, since you are further than 6" from any corner, omit that section entirely.
1 Like
Are you saying cut a half inch notch (to 4-1/2" tall bumper wood) and also lower bumpers 1/2 inch to get to the 1" needed?
I think he is pointing out this part of the rule.
So technically the bumper could be 4.5 to 5.5 inches tall and still be legal. If most of your bumper was at the max height and the notch was cut to the min height you would be legal to the letter of the rulebook based on my understanding.
I don’t know if I would be comfortable showing up with bumpers utilizing these limits. Your LRI might view this rule differently. I suspect the intent of the rule is to allow teams a good amount of manufacturing tolerance not for clearance features.
3 Likes
It would also be legal to have bumpers that were a consistent 5" in height, but which were not identically placed in the bumper zone. There is no rule precluding bumpers either with a stepped appearance (see below) or with bumpers that are sloped (non-horizontal).
------------ ------------
------------------------------------------------
------------------------------------------------
------------------------------------------------
------------------------------------------------
------------------------
3 Likes
We have used bumpers like this. It invited a ton of scrutiny from inspectors but was ultimately allowed to pass
1 Like
Yeah if it stays within the bumper zone…
There is a surprising amount of freedom in the bumper zone rules. All it is gonna take is one season for a team to exploit a few rules to really cause some havoc.
2 Likes
The rule says the wood can be 4.5" tall.
We match our Noodle diameter x2 for a clean appearance. It’s usually a quarter inch under nominal or so.
OP, you’ve got plenty of options. The notch will definitely invite scrutiny, but is legal if you have at least 4.5" of wood.
I’d do 4.5 all the way around, personally, so that fabric wraps better and it looks cleaner and invites fewer questions.
If you do a deeper notch to less than 4.5, it’s possible you could be forced to remove the notched section at comp.
2 Likes
Building right at 4.5’ runs a risk that an inspector measures it a spot that happens to be 4.48" and says “no good”. I would definitely leave myself some margin for error (in construction and potentially in measuring).
2 Likes
This is a photo of what 2640 is referring too I believe :
I believe this would be scrutinized heavily at competition. Any LRIs care to comment?
1 Like
That’s fundamentally the same at this setup we ran for 2018 and 2019 (literally the same bumpers):
For other reasons those bumpers got a lot of scrutiny, but no issues with that trick.
4 Likes
besides them being only 4" tall here you mean, which could be redone with some mounting changes to the wood. @thehotbotz2640 I think you have a few answers now!
2 Likes
Thank you all so much. We are reworking the bumpers now, two days before competition :-). I wish I had asked you before I told them “hey sure - if you can cut a whole side off I’m sure you can notch them.” 
But we got it now!
1 Like
What was the purpose of doing them that way?
Neat trick. Gonna stick this in the ole brain archive.
Probably clearance to prevent hang up on hap or the scale platform.
1 Like
Yep, and we normally run a 5.5" bumper backing to get a bit more protection and weight anyway.
1 Like