Launcher/ Punchers

Hey all,

So when in line for the practice field at Detroit, I was talking to this awesome #300somethig team about their Barker Redback like cube launcher. They told me they used parts from a WCP gearbox to shift a shaft connected with springs into a neutral state to launch a puncher to hit the cubes up to the scale. I’m really interested in doing some off-season experimentation with a mechanism like this and maybe make a shirt cannon or arial assist bot. Does anyone have any CAD of similar punchers/ launchers that I could reference to better understand the inner workings? Also, what are the best parts to use for something like this?

In order to shoot to scale, we had a relatively simple pneumatic puncher which consisted of 4 8" stroke 3/4" bore cylinders from Automation Direct. We removed the front fittings from all of the cylinders (for increased air flow), and used high flow rate valves (0.78Cv). In order to retract the cylinders, we picked up some low-gauge surgical tubing from McMaster and affixed it to both the shooter plate and the back of the cylinder, which worked effectively all season long.

Here’s a video of it in action: https://www.youtube.com/watch?v=9S6OuKORLMA

And here’s a CAD from earlier in the season (before we added the air tanks, and made a unified shooter plate instead of 4 separate circle plates): https://grabcad.com/library/6502-robot-2018-1

We used a similar mechanism for Aerial Assist. We customized an AndyMark sonic shifter and used it to pull our plunger back using a strap. The plunger was locked in place with a latch mechanism and we used surgical tubing for the spring to launch the ball. The latch was opened and closed using a small pneumatic cylinder.

A question to teams that used a puncher this year: did you see different results depending on if you punched the open face of the crate (mostly just contact with the fabric) or the closed face of the cube (mostly contact with the plastic)? I haven’t seen many of these designs in person and we didn’t prototype one ourselves, but my initial thought would be that cube orientation could introduce unwanted variation in the shot.

Yeah, there was a lot of variation when shooting different faces. We had separate fire buttons for vertical and flat cubes, because the normal “flat cube” angle would shoot a vertical cube straight up and back down onto the robot.

In 2014, 67 used a linear launcher to score the big ball. The launcher was powered by constant force springs, loaded with a chain drive, and latch/fired with a vehicle trunk latch actuated by a servo.

Everett

we used a linear puncher in 2016 using a window motor. we managed tu turn that linear motion and transform it into a mini catapult to save space. 400# of spring force made it quite scary

We did as described in the OP. Custom ballshifting gearbox with a ratchet on it, the moving stage pulled the puncher back and the fire stage allowed the full force of 4 springs to take over (this doesnt feel good going into your hand can confirm). The whole system worked great and it would’ve been great if we did it for say stronghold and not power up.

Good chance that was 314, The Megatron Oracles (Fondly referred to by Michiganders as Big MO). Here’s their site, perhaps you can get ahold of them and see if they are willing to share the design? https://www.bigmo314.com

In 2014 we had a custom gearbox (no shifter) for retraction into a pneumatically controlled archery clip, with 4 50-lb springs for launching.

It definitely did make a difference. However I think we noticed more variation if we punched closer to the edge of the cube vs. in the center of the face.

I personally am a fan of the “choo-choo” mechanism for linear punchers (a-la 1741 in 2016):

We have a similar mechanism on one of our offseason bots (a tennis ball catapult that could likely be modified into a mechanism for Aerial Assist), I’ll see if I can dig up some photos. Well, I can’t find any photos right now so here is what we did:

A Rocketbox PTO (from AndyMark) that had one output connected to an afterburner winch with a sprung arm screwed to the winch instead of a coil of rope. The motor in the PTO would pull back the arm until it hit a limit switch and then would switch to the other output which did nothing. This let the arm spring forward and launch the tennis ball. This could probably do what you want with a few modifications (i.e. make it linear instead of rotational by using a coil of rope pulling back a spring-loaded puncher.

My favorite launcher bot was 5205 which is probably the closet bot I’ve seen in FIRST that looks like something out of the Star Wars universe. It would lift the cube up and hold it back behind the robot and fling it at the scale.

These robots were my favorite launchers.

2451 https://www.thebluealliance.com/team/2451

180 https://www.thebluealliance.com/team/180

323 https://www.thebluealliance.com/team/323

Hi there! Yes it was team 314! I was their drive coach this past year and would be more than happy to comment on our design, feel free to shoot me a DM anytime!

I was shocked how accurate 180 was tossing cubes up on the scale!

They were on Curie with us and it really blew me away the first time I saw them make that shot. It was one of those “they built WHAT” moments.

Cutest robot I’ve seen since 86’s 2010 Tumbler.

Oh my…this takes the yeet to a whole new level :stuck_out_tongue:

That was really cool!

Also, does anyone have experience with using the vulcan springs from the Kit of Parts? Im looking further into developing one of the 314 / 67 punchers, and I’m not 100% sure how they work or how easy they are to work with.