Seeing as we all play the same game, similarities between designs are all but an inevitability. That is, there are typically a few “common designs” for each game that are used simply because they work well. However, what can really set two seemingly identical robots is execution, or HOW the two teams went about implementing a design.
That being said, I’ve seen bots function equally well despite having minor or major structural differences. My question for you is this, VEX forumites, are there structural norms that your teams tend to stick to? This goes from what size metal you use for the drive (ex: 2-hole C-channels VS 5 hole, C-channels VS Rails, etc) to how you support the drive itself to how you choose to translate motion (gears vs sprockets, HS chains vs normal chain) to how you go about mounting your articulation . How different are your mounting systems between articulation types?
^I apologize if that was too long or extremely redundant.
I believe I understand what your asking. You’re asking what do teams commonly do on all of their robots? I believe GUS seems to always use rails as their inner supports and angles on the outside, we allllways use lock nuts, and we seem to like four wheel tank, with two omnis and two high traction, gearing is normally 3:5. This year though, we’re really working on prototyping some brand new stuff and find out what works best! I’ll throw some pictures up of our prototypes as the get done!
Basically, yeah. My team will be meeting in the next few weeks, so we might post a few things on the forums soon enough. Unfortunately we probably won’t be getting parts until around the last week of August so it’ll be limited to sketches and CADs and things like that.
Well my team tends to go with direct drive on the base and we tend to use rack and pinions a lot on our robots. We also try to be creative and unique in all of our designs.
Not trying to get off topic, but is 687 CAMS hosting an event this season?
My team (though this year will be different) loves to use linear slides. We also usually use a standard tank drive with 2 traction wheels and 2 omni wheels. We also love using the vexplorer claw (or modified versions of it) for grasping game objects. As for chain, we never use the low strength kind. It breaks too easily. I will say though that 254a did just fine with it this year by doubling it up.
A lot of teams seem to prefer the 5 hole C-channel in their chassis design. I’m not sure why.
Personally, I like to use as many of the 2-hole parts as possible. It’s just easier to make a minimal, rigid chassis with those parts than it is to try and make 5-hole C channel work effectively, in my opinion.
Odd as it may sound, our team doesn’t like using triangles. Triangles are awkward shapes in Vex and attaching them to standard pitch metal is bothersome. Our structure is based around just having a lot of square supports, but in places that have the best “leverage” against the forces they hold against.
We managed to make a really strange-looking but efficient drivetrain on 2x25 c-channels with motors mounted vertically by using pillow blocks and vertical bearing blocks when we ran out of those.
We never use lock-nuts, but tighten the keps nuts ridiculously tight. Murdomeek has stripped many screws, broken allen keys and one time it even made sparks when the key slipped.
Personally, I’m in favor of triangular reinforcements, but I do believe that most triangles on VEX robots are hugely over-built. Take a look at this robot, down in the lower right-hand corner. That tiny 1x strap on the tower took a floppy vertical and made it rock solid. You don’t need much metal to improve stiffness.
we tend to never use them because before the days of Aluminum, they were HEAVY
also, if a motor clutch becomes stripped, or a motor comes loose, you must dismantle your whole “compact” system just to change out one thing
with the 2 hole c-channels, repairing and replacing is much easier in our experience
a small triangle like that should work on a short tower with a light arm with a low ratio (1:7)
but when we go up to 18" towers with super heavy arms and geared 1:5, we need a 1x 25 that goes from all the way from the top of the tower to the front area of the drive in order to “stabilize” things when the arm moves up and down quickly
its doable and sometimes we need to stack the 1x25’s to have double thickness, but they still are awkward to put on especially when none of the “hypotenuse’s” fit the pitch of the metal
I think you might be surprised. That little 1x strap is amazingly strong in tension – try bolting a handle onto one, and I bet you could hang from a single piece. Towers that only handle a load in one direction (that robot in the picture only dealt with weight in front of the tower) need tiny amounts of reinforcement. If it took loads in the other direction, I might double it with a similar piece on the other side.
I’ve mentored Exothermic Robotics since the FVC days, and I don’t think any of our robots used big triangles in their final configurations.
Another standard feature of Exo robots is the aluminum sheer plate about halfway up the towers. This acts as a giant “triangulator” between 2 to 4 towers, and provides a fabulous anchor for the controller, batteries, and other stuff. Here’s a picture of a typical sheer plate, although Exo usually uses the giant 5-hole-wide c-channel instead of a flat plate these days. The c-channel adds additional stiffness without much extra weight, although it can make it harder to screw on accessories. You will note that in Clean Sweep several Exo robots had their controllers mounted on the sheer plate, but on this old pic of Zippy the controller was on the base.
We are using the 5 hole c channel this year because it can conceal the top of our wheels, which makes mounting our lift a lot simpler.
We used the 2-hole c channel last year for easier changes and repairs. We also wanted to use a little less metal.
We use lock nuts for everything, our instructor hates kep nuts because he “keeps” picking them up. We only use them for prototyping and those areas where lock nuts don’t fit.
As for chain, we avoid low strength chain as well. Before our last order, we were practically fighting for chain. The low strength chain kept breaking and slipping for us, although it is much easier to get that perfect tension with this chain. We still need more sprockets for the chain, we ate up our last order.