contemplating the usefulness of getting a bender for the shop, so I was wondering what were some cool/useful bended parts on different teams’ robots.
I’m assuming by “bender” you mean a bending brake.
We don’t use it a ton, but we have one.
We have used it to bend some polycarbonate. Our 2017 gear ramp was made this way. As was our 2019 electronics cover.
We ended up using bent steel conduit as the frame for our intake in 2019. We originally had an intake made out of aluminum extrusion (versaframe) with rivetted gusset plates at the outer corners. That intake was destroyed at our first event due to a hard impact from a defender that pushed the intake into the cargo ship. The bent conduit frame was a) stronger and b) a continuous frame to that there were no joints to fail. I believe we used a standard conduit bender to shape the frame (you did not specify what type of bender you were talking about) and then bolted on the plates that formed the hinge, held the intake shaft and formed the clevis fittings for the pneumatics.
We used conduit as supports on all sorts of things this year. For my purposes, you don’t really need a dedicated bender as long as you have a bench vice and maybe a protractor, BUT the full conduit intake seems much more complicated than my supports, so it makes sense.
Thinking on pipe bending, both the 2016 and 2014 pneumatapults uses bent PVC. We used a heating blanket (greenlee) then bent it around a form. In 2016 that was a few wheels screwed to a piece of plywood. Filling the pipe with sand make be needed if bending collapses it too much.
Our intakes have been steel conduit, but mostly just the rollers. The structure is welded 1/2" square steel tubing.
We made a bent polycarbonate hopper/intake in 2020. Basically a box bent from 1-2 pieces. Not recommended with how much it broke.
We have not found having a brake very useful. Most brakes are designed for sheet metal to create a tight bend. Aluminium generally requires a larger radius or it will fatigue and crack. I was never able to get our brake to bend AL reliably.
Breaks are not necessary or ideal for polycarbonate either. Simply clamp the polycarbonate to a table edge with a 2x4, soften the area to bend with a heat gun, and when it gets soft bend it with another 2x4. You can actually make a fairly decent DIY plastic bender out of wood, some hinges and nicrome wire. Lots of examples on YouTube.
So unless you intend to start using sheet metal on your robot (we don’t) I would say spend your money elsewhere.
It sounds like you are referring to a box and pan brake here (also known as a finger brake). Those are absolutely, like you said, meant for much lighter gauges than what is typically found on an FRC robot (a really robust box and pan brake you’d find in a small shop or highschool setting might do 16 or 14ga steel at best). But there are definitely other types of brakes out there which most certainly can and will bend heavier gauges. The relatively small brakes we have at work (small from an industry perspective) will bend 1/8" or 1/4" aluminum all day long.
For a team genuinely looking to bend 1/8" aluminum (I’d argue the most any FRC team would need to bend), a press brake would likely be the best route to go. I’ve been considering one of these for my home shop to play around with (heard good things about them elsewhere on the interwebs).
For anyone looking to bend aluminum, make sure to stick to either 3003 or 5052 (common and usually easily attainable in North America). These bend with relative ease and not too large a bend radius. Something like 6061 on the other hand requires a rather large bend radius and careful attention to the grain of the material to ensure it doesn’t crack/snap while bending.
Of course another great option would be to cultivate a good relationship with a local shop and have them form up aluminum using their brakes/equipment.
When bending is important to use a aloy that bends, we use 3003 for our bent parts. Trying to bend things like 6061 can be difficult at best. We use our break a lot.
If you want to see examples of bent steel tubing look at 1024’s past robots. They have this technique down…
A vise box and pan brake has been useful to us. Buy 6in. Vise Mounted Box And Pan Brake at Busy Bee Tools
All of the internal trays and external sheets were bent on a brake. Only a few 80/20 pieces at the bottom and some angle aluminum up the sides.
We are a big fans of bending sheet metal and poly. A sponsor used to bend our stuff but in desperation, we recently got one of these. Worked better than we thought keeping in mind that all these cheapie tools have there limits.
This key shaped piece of polycarbonate became the majority of 4513’s 2020 bot. It had some issues (balls would get trapped) but due to covid the team never got a chance to improve upon it.
In our old shop, we had access to a table top polycarb bending tool (home built) that included this heating element embedded in a plywood table. Once the tool was warmed up, you could just set the polycarb on the table so that the intended bend line was resting directly above the heat element and then just wait a couple of minutes and it would just bend nicely along the line where it was heated. It was much cleaner than using a heat gun (we used the heat gun process for many years with a good percentage of success and only occasionally cracking, bubbling or discoloring the polycarb). We had “calibrated” the tool so that we knew how long to leave the polycarb resting on the table before it was ready to bend (the thicker the sheet, the longer it would take to get to the bending temperature). I highly recommend this method over trying to bend polycarb cold (in a brake). If you have some money to spend on tools and you like to use bent polyarb (and don’t we all), this would be a good investment.
Polycarbonate bends great without heating. Just like sheet metal, but more spring back. Heating just causes bubbles, discoloration, and warping and makes it brittle. I never heat polycarbonate to bend it.
5660 has used this Vise Brake insert a few times to bend polycarbonate and aluminum brackets over the last few years. 4" Vise Brake at Grizzly.com
We’ve got a nice, old finger brake (probably 50+ years old, we’re at least the third owners) and it works great. Yes, we need to adjust the bend radius (there are adjustment bolts for that!) when switching between aluminum and polycarb, but it can easily handle both with beautiful results. With aluminum, it’s important to use the right alloy - the wrong one will definitely crack, no matter the type of brake you have. With polycarb, you need to overbend it due to the springiness, but that’s a learning curve with different material properties, not an issue with the brake. We almost never use heat with polycarb, unless there’s some reason we can’t use the brake for it.
I would 100% get a sheet metal bender. 90% of our robot is bent aluminum, same with many other world class teams (67, 118, 148, etc)
You can make strong and light parts
Just gotta get good at designing for it
Not the best picture but my senior year we added a “funnel” to our manipulator to better support the cargo. From a sponsor, we have a surplus of polycarbonate, primarily 1/8"-3/8". We decided to make the funnel out of 1/4", and we cold bent the polycarbonate to make the funnel. We started with a rectangular piece and machined it down towards the ends after bending it. Although this isn’t that insane of a piece, polycarbonate can be a bit tricky due to the spring back, especially with the thickness of this, and attempting to mirror both sides of the funnel with a single piece. I did this myself using my work’s brake specifically meant for polycarbonate, but was mostly commonly used for 90 degree bends.
I used to have access to a shop with these…
Bends can add a lot of strength for the weight, but it certainly helps to have access to the fancy equipment before going too far with this…
We did our second shooter revision out of sheet metal and saved quite a bit of weight compared to the 1/8" version. This was all bent in either a vice brake or a harbor freight table top brake (https://www.harborfreight.com/30-inch-bending-brake-67240.html). The key to making this work is that every flange on the entire shooter is the same length (0.75") and we set up a backstop so making a bend with that flange length is very repeatable. You don’t need to buy anything fancy - you can get a cheap bender for < $100 and make some great parts.