Making Bumper Weight?

[Ian Curtis]

Last year, our robot was completely surrounded by standard bumpers. We built them to specification, with holes drilled in the 3/4" plywood to make weight. As of this Q&A that is no longer legal. Our bumpers are just as specified <R08> and cover the perimeter of the the robot base completely, with the addition of some embroidery fabric. They weigh a little bit more than 16 pounds. Has anyone else run into this problem?

[Manoel]

You guys gotta be using some dense plywood, we usually build our robots to the maximum dimensions and our bumpers never exceed 10-11 pounds!

[thefro526]

+1 on the dense plywood ours only weight like 10 or 11 lbs

[Fab.Master]

could also be the number or type of fasteners used

[EricH]

330's bumpers last year made weight, and they would be fully legal this year (other than having been on a previous robot and being fabricated items).

[jgannon]

Another vote here for 10 or 11 pounds... that's how I remember them weighing in last year, and we had a full set of bumpers for 28x38. Are you sure that's plywood you're using, and not 3/4" aluminum?

[lukevanoort]

Originally Posted by jgannon

Another vote here for 10 or 11 pounds... that's how I remember them weighing in last year, and we had a full set of bumpers for 28x38. Are you sure that's plywood you're using, and not 3/4" aluminum?

Or, say, rock maple or walnut plywood (I have never seen either of those in plywood form though... its kind of unfortunate, those would be some darn strong materials). Actually, it wouldn't surprise me if the plywood used was made of birch... while not as heavy as maple, it is a bit heavier than pine, for example (and I think it is used in boats, so it shouldn't be that hard to come by).

[GaryVoshol]

What kind of hardware are you using? I ran into weight problems one year when I used 1 x 1/8 angle to protect the edges. Now we are using 3/4 x 1/16 angle on the 5" ends, 1/2" on top and bottom edges.

If that doesn't help, the only thing I can suggest is to make one or more of the bumpers smaller. You'd have to eliminate about 8-10 linear inches, still covers far more than 2/3, and if done judicially would most likely give you the protection you desire. Good luck.

[MrForbes]

I guess we'll find out today...we are planning on using heavy hardware so it's easy to get the bumpers on and off quickly (bolt and nut, but they are big!), although only two bolts per bumper.

Also we are not planning on using the aluminum angle, because it's so much work to make all those parts and screw them on. Lots of staples will have to do....again...

Thanks for the reminder to check weight before we actually put them together!

[lancerbotics]

If we have read the rules correctly, as long as you are using the standard bumpers as they are diagrammed in the rules, they do not count against your weight or dimensions. Is this correct or are we totally off base?

[EricH]

Originally Posted by lancerbotics

If we have read the rules correctly, as long as you are using the standard bumpers as they are diagrammed in the rules, they do not count against your weight or dimensions. Is this correct or are we totally off base?

Correct...HOWEVER, they have their own weight restriction (15 lbs) and size (in the Bumper Zone, they can't extend more than a few inches from the robot).

[aapl.jlo]

I'd side with these guys, those are some heavy bumpers. Still, I would think that the more weight you could get at the bottom the better since we're going to be using robots that reach up high for the overdrive balls. Still I haven't read enough to know how heavy you can make them.

[Ian Curtis]

Originally Posted by GaryVoshol

What kind of hardware are you using? I ran into weight problems one year when I used 1 x 1/8 angle to protect the edges. Now we are using 3/4 x 1/16 angle on the 5" ends, 1/2" on top and bottom edges.

If that doesn't help, the only thing I can suggest is to make one or more of the bumpers smaller. You'd have to eliminate about 8-10 linear inches, still covers far more than 2/3, and if done judicially would most likely give you the protection you desire. Good luck.

We're already using exclusively 1/16" angle. I'm not sure how they're attached, but in the past it's been with some decently sized bolts. We'll probably look into different plywood.

[Mr.G]

We are also overweight on our bumpers without even using the angle aluminum. I can't believe how much time we have wasted on these things, they came out nice, but are useless right now until we can get some weight out of them. I hope FIRST doesn't keep this mandatory bump rule for next year.

[Mike Schreiber]

I agree,I know they want to cut back on defense, but mandatory bumpers stunt creativity, and force a rectangular robot. They also make any design involving changing orientations really difficult. Personally I dislike bumpers, but rules are rules, and we'll just have to cope.