I’ve been on a team in the past the made this style of bumper and we loved how easy it was. We were fortunate enough to have at the time, a members grandfather who was really good with sewing. I don’t suppose you have any tips or suggestions for going about making these? I think this style would be fantastic for the team I’m with now, but am a little stumped with where to start…
That might be something fun to have around the shop
I developed kind of a different style of folding the corners for fabric and have been leading the assembly of 254’s bumpers since we started using sailcloth in 2014. You can see the difference in the way the fabric is folded if you look at robot photos on our website from 2011-2013 vs 2017-2019. The following attached photos were taken during assembly of our 2018 Summer Project Offseason swerve bot we took to MTTD which we made with Cordura cause it was leftover.
Like others suggest we use solid core round pool noodles, do all the sides including getting the numbers straight and centered, and then do the corners last. You allow any excess material on the sides to “bubble out” towards the corners where you can use knives to cut slits/reliefs to absorb that extra material.
To do the corners you pull the fabric straight along the diagonal axis over the corner of the wood and staple into the top of the wood to hold this flat flange there. Then you use an exacto knife or scissors to cut the flange along the 45deg angle up to the corner, separating the flange into 2 flaps. These flaps can then folded down and stapled, before excess material is cut away.
Once all the fabric everywhere is fully cinched down, we use a knife to trim away excess fabric and use a hammer to ensure all the staples are fully flattened.
We then cover the inside of our bumpers with strips of 2" wide colored gaffers tape which hold the fabric edges down and be replaced in the pits if worn down (unlike spray paint that has to dry, etc). Blue bumper exterior + interior makes a big difference, if any aluminum for mounting brackets are visible we get them anodized black.
Exactly the type of guide I was looking for! Thanks!
Where do you source your solid core noodles?
They used to be pretty hard to find so bought a big stockpile a few years ago we’re still getting through, don’t remember from where. Looks like you might be able to get from Walmart now though. Probably helps if buy them now while it’s still Summer rather than in January.
Basically, it’s making two full bumper covers with sewn corner gussets. You then mate them with the back side of the fabric toward each other and sew them together with a middle seam, then sew one of the two sets of sides together along the edges. This gives you two single-layer ends that you attach to the board and a double-layer that can be reversed over either end. It helps to sew the corner seams on the layers that will be doubled a little bigger than the ones that will be attached to the board so they fit over easily. I’ll try to make a video of our current bumpers today and post it with some explanation of the process.
A video would be great if you get the time, for now though that description helped me visualize it a ton! I’ve finally got it worked out in my head how they work (I think…).
THE LEGENDARY BUMPER SECRETS
I’ll try to get it up tomorrow. I didn’t have time to swing by the shop today.
By the way, a word about the backer boards for bumpers. We always use poplar (a relatively light-weight hardwood) dimensional lumber for our boards, not plywood. Poplar can be joined at the corners with only glue and screws rather than needing other hardware to support the corners, while being as strong as you’ll ever need it to be (unlike a softwood like pine.) Plywood is no lighter and must have hardware to join the corners, which I’ve always seen as a drawback. You can easily buy it at any home center or lumberyard and it’s not very expensive, so it’s an all-around good choice.
Here’s that video I promised. Hope it helps.
That’s fantastic! Can’t thank you enough for this. Really hit home the idea and how to execute it for me. With any luck I’ll be able to make a set this fall as a prototype.
Our team does bumpers exactly the way you said. They are pieces of plywood with aluminum sheet metal frames that has the tabs for latches. The latches are from McMaster-Carr, and they fasten our bumpers on to a nut on the drivetrain rails. We have three latches that latch on to three different nuts and they just click into place if the bumpers are aligned correctly on the driverail, so swapping our bumpers are effortless.
https://www.thefoamfactory.com/closedcellfoam/polyethylene.html looking for a more affordable option but these work.
Edit: not technically pool noddles, use at your own risk.
Didn’t see if it was mentioned in the video, but where do you guys get your noodles from?
Has the poplar ever cracked along the grain? I use it a lot for my personal projects but have always used good quality plywood for robot bumpers, the more layers the better.