The rules and constraints for bumper contruction are in the rulebook released on kickoff.

• 3/4" Plywood
• 2.5" (+-0.25") Pool Noodles
• Bumper Fabric
• Bumper Numbers or Paint
• Staple Gun and Staples
• Aluminum Corner Brackets
• Aluminum Mounting Brackets
• Bevel Bolts
• Nuts

The length of each pice will depend on the robot size designed that year. However, the width and process generally remains the same every year. The width is typically 5" and the robot is most likely rectangular (often a square).

How we like to fit the frame together is with a "rotating" design. If you just cut the plywood to the side lengths of the robot, you'll leave the corners empty. How we like to solve this is by extending each board by 1 inch, and then placing them such that each board is flush with the robot on one side and sticking out an inch on the other.

We haven't done any work or tested to see if this design is superior in any way to an H style system, but it has worked so far for us. Additionally, you'll want to oversize them a little bit to allow for them to fit over the robot and to account for the thickness of the fabric.

Now we need to join the boards together. Since we don't have the wood working skills or tools to do any joinery, we just use large metal brackets on every corner. The old drivetrain C-channel is a good source of stock to make these brackets out of. First, cut the stock down to a <5 inch length, and then, you'll cut it in half to make two fairly even L brackets that can span the entire width/height of the bumper boards.

These brackets will go on the outside of boards so that they can sit flush with the robot. To attach them we use bevel bolts that are attached from the inside. This means we can countersink the hole in the wood so the bolt does not protrude at all from the wood on the inside.

Mark the holes on the bracket if there are not holes there already (if using the drivetrain C-channel, one side will have holds already). Four holes on each side is a good amount. Drill them out and then clamp the bracket and the two boards it is joining together. This will hold everything in place so alignment can be maintained. Drill a hole for the bolt. Try to use the smallest sized drill bit that will let the bolt through (If you can barely screw/thread the bolt through that is good). Then, using a countersink bit, countersink the wood side until the bevel bolts sit flush on the inside. Too much countersinking is better than too little. Once all the holes are done, put in all bolts with nuts on the other end to hold them in, and you're done with the frame.

For pool noodles, you can get solid core or hollow core noodles. The ones typically used in pool applications and readily found in stores are hollow, but these offer less protection than solid core noodles as they compress more easily, letting more energy impact the robot versus the bumpers.

Ultimately it will depend on what you have available. If you are able to plan ahead of time you can get solid pool noodles from [oodles of noodles] for a pretty good deal (of course any other source is also viable). However, since we typically have left bumpers until a very last minute thing, we have often been forced to run to dollar tree or home depot for pool noodles. We have even arrived to competitions to ask other teams for help on materials and finishing our bumpers.

Two pool noodles stacked on top of each other need to go all the way around the bumpers. Its pretty straightforward except for the corners. There are multiple methods listed in the rules, but we like the variant with a short noodle placed vertically in the corner. Compared with the other variants like the mitered corner, butted corner, or the wrap around, we've found this one to last longer/provide more protection on corner hits.

Fit the pool noodles and then tape them to the boards. You can use pretty much any tape available, but a stronger tape in terms of physical strength and adhesion is prefered (gaffers, duct, packing, etc) though other tapes will work for an event or two (painters, masking, electrical, etc). Tape around 3 times per side or <10 inches apart and loop the tape all the way around at least once if using a less sticky tape (Its good to do it regardless of tape type, but this uses up a lot of tape).

Bumper fabric is something you'll want to get right as they are what actually gets hit or rubbed against during the match. Tears can occur due defense or crashing into sharp field elements, so abrasion resistance is usually the first priority. Additionally, friction is a consideration for defense. Slick fabric lets you slip past defenders while rough and grippy fabrics will hold onto other robots during pins.

We've typically just bought the [standard andymark bumper fabric]. Its good and tested. Their slippery fabric has durability issues, and its more convient than buying fabric from some other fabric supplier (we can also use the andymark voucher we get every year).

The fabric comes in large rolls so you'll need to fit it and cut it into sections. Fit the fabric by wrapping it around the bumpers. Mark where you'll need to make cuts and where the numbers will go.

You can either use iron-on vinyl numbers or paint the numbers. Both have their tradeoffs.

The iron-on numbers can be cut out of vinyl sheets or purchased from a couple of sources. These run the risk of being torn off during competition, but they are unlikely to come off if done well. IMPORTANT: if you are using iron-on vinyl bumper numbers, you needs to put the numbers on before putting the fabric over the pool noodles. The heat will melt/burn the pool noodles.

[insert andymark video for bumper numbers]

Painted numbers are easily and cheap, but they don't look as good and can create more hassle. First, you'll need to draw an outline for the numbers. Use pencil or a thin pen so the line doesn't show up after painting. Paint using a generous amount of paint and apply muliple coats. Keep adding coats until the numbers are satisfactorily solid.

After cutting the fabric out and ironing on or painting the numbers on, you can staple on the fabric. Make sure to keep a tight fit of the fabric over the pool noodles and hold the stapler tight so the staples get driven in all the way.