We did all our sheet metal on 3538 this year (and there was a lot of it) with these two tools our of 1/16" 5052.
30" Super Cheap Harbor Freight Brake
This has been in the 3538 shop for years and didn’t get used much. We upped our sheet metal game this year by adding a backstop and some beefier clamps and we were able to get really consistent bends. We could not bend 1/16" 5052 full width on this if our flanges were less than an 7/8". We successfully did 24", but that was an effort. In general we just don’t design for parts that require that.
8" Vice Brake
This was necessary for some bends this year because of proximity to each other. Also makes it a lot easier to get precision bending compared to the harbor freight brake. This is probably your best (cheap) option for bends in the middle of parts or close together ones. Also worth noting this is a bit of a hazard for your toes. I recommend a cheater bar for the vice.
Not sure if your 48" brake is a finger brake or a cheap HF one that is all one piece on the clamping area, but the finger brakes where you can move the fingers enable a lot more functionality. If you want to do 1/8" you’ll likely end up needing some sort of press brake or a hydraulic press and some tooling that fits in it. Bead rollers sound cool, but I’ve never found it necessary in FRC - if you think of a part where a bead is better than bending I’d love to see it.
On 67 we didn’t use the press brake in the shop until 2019, before that all of the sheet metal stuff was done on a 48" finger brake - that should do just about anything you need for FRC.
A few tips for home brew sheet metal (these don’t all apply if you send your stuff out)
- Design with a consistent flange length (I like 7/8", but you do you), this can’t be too short because you need material to grab when you bend. It also makes your robot look good if all the flanges are the same length.
- Use a backstop, this means you don’t have to setup your brake every time you want to bend a part. This takes ~30 seconds to do and significantly improves the accuracy and consistency of bends. Set the backstop distance on a caliper. Use the caliper to space out a 30 thou thick piece of lexan and tape it down. It’s easy to adjust and remove. Double check the tape between parts, duct tape held fine for us.
- If your bend needs to be within 10 thou for the part to work the design probably doesn’t work.
- Don’t put precision holes on either sides of a bend in a part. They won’t end up the right distance apart. Clamp and match drill when you can get away with it (most of the time you can). Exception if you can get away with a slotted hole.
- Two Cs that are designed to nest, will still nest if their flange lengths are all off by the same amount. This is why you should use a backstop and design them with the same flange lengths - the bends will all be the same even if they’re wrong, it won’t matter. This is the most of the reason the 67 sheet metal chassis went together.
- Use geometry over thickness. Lightening holes don’t get you very far in 1/16" aluminum, but most of the time small brackets that were 1/8" can just be down sized and flanges can be added and then it’s way stiffer and lighter.
- If it’s not stiff enough, you can tie the flanges together with a piece of angle or another bent sheet, this will give the part significant torsional rigidity.
- Don’t put holes near bends.
Other cool things I’ve wanted to try but never got around to - 3d printed press brake tooling and 3d printed stamping dies. Also putting darts in parts sounds cool.