Hello! My team attempted to make an adjustable hood this year and we were somewhat successful, we ended up using a bearing bore pulley that was rigidly attached to our then cantilevered hood. The system worked… ish. But there was tons of mechanical backlash, and because it was only powered on one side there was almost no rigidity. We see lots of teams 3D printing gear teeth to the back of their hood which sounds like a breeze in controllability and rigidity. How could we do this without the use of 3D printing?
Laser cut acrylic teeth perhaps? It’s probably easier to get access to a 3D printer than a laser cutter though.
IMPORTANT DISCLAIMER: I’m a software guy, so feel free to ignore me if my answer makes no sense
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One way to fix backlash is to apply some form of constant load that removes the backlash but is weaker than the actuator’s safe stall power (like with a spring or surgical tube)
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Rather than gear drive, you could do a lead screw or linear actuator. Not necessarily easier or better though. A capable enough 3D printer is a couple hundred dollars and will open a whole new world of possibilities to you. I’d recommend looking into it further.
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This is a pretty good way to control a hood.
Little slow, but it certainly works.
That said, I think getting a 3D printer is still a good idea, and worth considering.
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A trick I’ve wanted to try for this sort of thing for a while is to use a continuous rotation servo (or I guess a sail winch servo which tend to be 10 turns) with 2305 Series Brass, MOD 0.8, Servo Gear (25 Tooth Spline, 12 Tooth) - ServoCity on it mating to https://www.amazon.com/Focusfoto-Flexible-DP500II-DP500IIS-DP500III/dp/B092PX48Y2/ref=sr_1_9?crid=RL98UFB9051L&keywords=camera+lens+flexible+gear&qid=1648971231&sprefix=camera+lens+flexible+gear%2Caps%2C148&sr=8-9
But if I wasn’t trying to do it mostly with off the shelf parts I’d probably just 3d print it.
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If you have access to a laser cuter/cnc router you can manufacture a gear profile onto your hood, it’s a pretty usefull capability in general, it helps with linear actuators, turrets and much more.
Take a look at what 1690 did this year with their hood design, I don’t want to speak for them (please correct me if i’m wrong) but from what I saw it’s two aluminium parts cut with a tooth profile using a laser cuter, connected by a 3d print that supports the ball (can easily be replaced with an aluminium sheet if that’s easier for you).
Talking from experience it works pretty well, my team (3075) used a similar solution in our 2019 robot for the linear actuators of our climb mechanism. In that case it was a straight rack, but it’s pretty much the same thing.
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We (2230) also used the same solution, we laser cut teeth into a perspex plate, later we switched to onyx because some teeth broke but it was mostly due to using a softer meterial (perspex is softer than polycarb) im sure that if it was cut from aluminum or was thicker (ours was 5 mm) it would have held up just fine. as yuval said, this is a great method that you can achieve also with a cnc router( if you use a larger tooth profile or have a small enough end mill).
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We found that it’s also possible to do it out of wood as well.
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One thing to be aware of with using linear servo actuators that other people have noted is that you don’t explicitly know where the servo is, which makes it difficult to control. So there could be times where you think the hood is at the right angle but it’s actually still getting there.
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But that is solvable, just like a regular motorized hood you can use a potentiometer that is concentric to the shooter wheel to find the angle, we used it and it worked great and was pretty easy to implement.
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How do you control your hood with a linear actuator. Like how do you get what angle it is at if it’s a linear motion?
could you explain this a little bit more? Do you have any pictures?
This is the best image I managed to find. You can see the black hood is connected with 2 standoffs to an aluminum plate that sits on the shaft of our shooter wheel. This plate is connected to a potentiometer(in the other side of this image 
).
This works beacuse we think of the hood as a large spur gear concentric to our shooter wheel shaft.
We set the minimum and maximum angles of our hood as constants in our code and measured the resistance value in our min and max position which gives us the range of values we expect to recieve and from that we find our hood angle. Im supposed to be in the shop on friday so feel free to PM with additional questions or if you need more pictures 
At that point you might as well just drive the hood off of the gear teeth rather than using a linear actuator
Of course, our hood was driven of a neo 550, However, the method of using a potentiometer concentric to the shooter wheel to measure the travel of the hood does fit a linear actuator, or any other kind of adjustable hood( given the hood moves around this axis of course).
I hope it makes more sense now
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My team used laser cut delrin which worked very well.
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We were able to to use a NEO 550 directly coupled to a 1/4-20 threaded rod (poor man’s linear actuator). We first tried the AM linear actuator but couldn’t handle the load (worked for 2020). It is connected to the center of the hood and can handle a pretty good load. This gets tougher depending on if you have a turret of if you need to have it off to the side. It is pretty accurate (within a 1/10 of an inch) and can do full range in about 3 seconds utilizing the encoder on the 550.
A team here at FiT District Championship is using rubber wheel to rotate their turret through friction on a smooth rim. Feedback control from their Limelight controls the motor.
It may also be possible to attach a section of timing belt to the hood and use a small pulley to drive it.
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