Background: As is known to us all, China held no 2022 games due to the lockdown policy towards the COVID-19.And thats why our local commitee hold a 2022 game this summer holiday to “fulfill the blank”.
We have just finished our first day of the game, and we found that our shooter had a serious problem. We use two falcon to motivate the flywheel directly, which means we have to use 2 shaft coplers to connect our falcon to the shaft our flywheel. However, our structure aren’t as durable as we’d expected, cause our flywheel to fall off during the game as soon as we reveive collisions.
So I was wondering, for teams using the similar way,How did you prevent this from happening?
Also, what could we do to strengthen the connenction between the shafts in a short time, so that we can finnish the game tommorow.Any help is appreciate, for we are really running out of time and ideas.
Here’s the picture of our structure.
Are the side plates able to flex or twist, causing the shaft to pulled out from the shaft couplers? Are the screws in the couplers well tightened? Is there enough shaft in each end of the coupler for good overlap/engagement?
Where does your shooter drum (upper photo) fit into the robot chassis (lower photo), or am I missing this altogether? If the shooter goes on the two shaft stubs with the spur gear (near the thumbs in the second photo), I would expect that you don’t have enough shaft engagement on the couplers; looks like a millimeter or maybe less. Though none of the shafts I see seem to have enough clearance around them for that drum.
If you’re correct about the shaft location, then I agree; that is too little engagement on the couplers. You could swap to a longer shaft on the portion on the robot chassis to get more engagement with the coupler. If the coupler is already filled by the shaft going through the drum, you could shorten it so it takes up half the coupler. Then, the shooter drum shaft fills the other half.
It looks like the “shaft stubs” might be driven by spur gears on Falcon shafts. The Falcons may be covered up by hands in the lower photo.
If the couplers on the shooter wheel shaft are expected to be driven and retained by the tiny little stubs of hex rod beyond the spur gears, it is no wonder that the shooter wheel assembly is popping out. It seems like longer hex rods might make a big difference. Also, if these guesses as to how the shooter wheel is being driven are correct, why not use one long hex rod all the way from pulley to pulley across the shooter? It looks like everything in the assembly might have hex bore. A single hex rod would be far better than using two couplers.
Architecturally, the falcons direct driving the shooter flywheel with falcon-spline-to-hex adapters is the problem. You are holding the weight and vibration of the fast spinning flywheel on the tiny internal falcon bearings and those small shafts. Many teams year found success putting the falcons elsewhere and belting or gearing them 1:1 with the flywheel shaft, having the flywheel shaft be longer and go into the outer plates. However, I don’t see a way to really make that change without cutting new sideplates.
I think like others have said there are only a few options:
- Increase length of adapter on falcon shafts to make them engage more with the coupler.
- Make sure coupler is fully tightened, use Loctite and let it cure
- Add additional structure to stiffen sideplates and prevent flexing (a crossbar, standoff, some wood). It would need to out of way of ball path and within frame perimeter.
I’m assuming the original design was to be able to shoot into the high goal.
If you can’t get your flywheel working, it’s possible that you can shoot into the low goal by altering your vertical ball elevator a bit. The low goal is about stomach height of someone and the picture indicates your robot is about that tall. I’m not sure if this is more reasonable than fixing the flywheel, though.
Hopefully you can fix your flywheel, but otherwise designing/altering for low goal might be the best option.
If you want a quick and dirty solution, you could try tapping these holes to a compatible screw size and using them like a set-screw to hold the shafts together.
If you’re really desperate, you could even drill through the shafts where these holes on the couplers are and through-bolt them in place (this will weaken the shaft so it’s not good for high-load situations; might be fine for a flywheel though?)
Seconded
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