pic: Wheeled shirt launcher



A break from all the Stronghold furor.
Shirt launcher powered by electricity rather than compressed gas.

Servo-actuated ratchet-and-pawl indexing mechanism.
A small servo pushes the current shirt, within the chamber, forward ~2" in order to contact the BAG motor’s wheels.
BAG motor -> 1:3 VersaPlanetary ejects the shirt from the chamber.
CIM motor -> 1:1 ratio accelerates the shirt at ~30ft/s tested.

Please offer criticism/advice.

Ooooh very nice.

My team was discussing making a WCD pneumatic t-shirt cannon as an offseason project but we were discouraged away from it slightly due to the cost of making a safe t-shirt shooter.

This looks like a pretty cheap (around $300 - $400) and easy build using the a build style more applicable to an FRC robot. Maybe we could work together to make it a reality.

Do you think you could upload the CAD model? I’d like to take a closer look if possible.

I’m not sure how well wheels would interact with the shirts. One would have to make sure that the shirt doesn’t get torn up or unroll while shooting.
What if you used a can of some sort to hold the t-shirt in while going through the wheels, but gets hardstopped before it can leave the cannon? That way the t-shirt gets acceleration but the shirts are not damaged.
Love the use of 2 stages btw, that seems like it would be useful to get longer distances.

Have you done any tests with using a wheeled shooter to propel shirts? I’m wondering how much grip you would get, if the wheels would mark up the shirt from slipping, etc.

My thoughts exactly. At first glance I actually thought that the casing for the shirt was propelled by the first set of wheels, then stopped before contacting the second set, wherein the shirt gets ejected from the casing by momentum and taken by the second wheel set to be shot. Now I realize that the shirt gets propelled all on its own. I wonder how tight of a roll the shirt needs to get any meaningful compression from the wheels?

Team 1058 approached the idea several years ago fairly successfully.

In testing, a very tight roll is not even necessary to eject a properly ranger-rolled shirt. When the forces on the shirt are perpendicular to the direction of the roll, it seems to be difficult to unravel even by hand.

The shirt compresses to about 2/3 of its normal diameter for an effective shot (independently tested with the first shooter stage and second shooter stage, but not together). The wheels do not mark up, although a few cloth fibers sometimes gather after several shots.

To clarify, (http://imgur.com/yQhUkQo). There’s a bit more wiring to do before it’s ready to test in its entirety. Indexing with the ratchet and pawl is functional. The total price of the unit is approximately $350.

STEP file: https://drive.google.com/file/d/0BygPZFs_a9vrcVZaXzFTZ1VUakk/view?usp=sharing

4451 had a wheeled launcher at palmetto this year.

Have you tried using mini-cims rather than full CIMs? It would be slightly smaller and the wheels would spin faster.

Also do you know if this would work belt fed or with saboted shirts? (Just hypothetically. :D)

I was surprised to see one of 1058’s old projects in here! That t-shirt launcher was a cool little mechanism- the indexing system you designed reminds me of ours, except you used motors and servos instead of pneumatics, which increases simplicity and eliminates the need for two separate power systems. To the note about the shootability of the shirts- in that video, we had wrapped the shirts in masking tape so that they would maintain their shape better.

We are currently using a pneumatic 3 t-shirt shooter but for the offseason are looking to upgrade to something similiar to the Poofs uniquely styled 10 t-shirt shooter. But yes I do admit, the pneumatic plus the compressed air storage is a little pricey.

Nice job, I especially like how you’re able to do it with the wheels, and have that work well. Hope you’ll post a video and let us see it in action!

I plan to get some Mini CIMs in a few weeks and try those out.
I had considered a magazine-like approach to loading shirts, but a revolver-like cylindrical action seemed less prone to jamming and more aesthetically pleasing.

If you have any images/video/documentation of 1058’s device beyond that video, I’d love to see it.

Thank you. I don’t expect to have videos up within the next 2 weeks on account of midterms unfortunately.

Slight resurrection, but I’m curious - has your team moved forward with this project?
We are also looking at wheeled t-shirt launcher designs as an offseason project (and practice for the upcoming American Football game), and there simply aren’t many to be found.

We built one last year similar to the OP’s design with a few key differences. We used a cylinder to push the shirts into the wheels. We also had a pvc pipe on the shooter to keep the shirts straight. There are slots in the side of the pipe for the shooter wheels.

Here’s a brief tour of the shooter.

What information do you need?

David

At this point, we are most interested in your launcher wheel RPM and the optimal compression on the shirts. I think we can puzzle through the rest.

2791 briefly built a prototype of a wheeled T-shirt shooter in late 2014, and I think they found that marshmallow wheels (“Sure-Grip Drive Rollers” on McMaster, Buna-N) were the best wheels for shooting T-shirts. The compliance helps deal with small variances in shirt packing density or size, and it imparts more energy into the shirts. I would give those a try.

I need to get pictures from my teammates but 5811 built a t-shirt shooter prototype and were able to get roughly 38 yards out of it. We used 2 6" andymark wheels with 2 timing belts to feed into it

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