pic: Wheeled shirt launcher

[NWChen]

[cdm-description=photo]42959[/cdm-description]

[Sperkowsky]

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.

[swaxman12345]

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

[asid61]

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.

[Jon Stratis]

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.

[bEdhEd]

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.

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?

[NWChen]

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.
Team 1058 approached the idea (https://youtu.be/o14KW2gpzoA?t=1m28s) 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.

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.
I wonder how tight of a roll the shirt needs to get any meaningful compression from the wheels?
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, I've already built this device (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.

[NWChen]

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

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

[slickvic2252]

4451 had a wheeled launcher at palmetto this year.

[asid61]

Team 1058 approached the idea (https://youtu.be/o14KW2gpzoA?t=1m28s) 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, I've already built this device (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.

That's awesome then! Do you have any videos of it shooting?

[BetaHelix]

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)

[Brandon Zalinsky]

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.

[D_Price]

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 (https://www.team254.com/shockwave/). But yes I do admit, the pneumatic plus the compressed air storage is a little pricey.

[JoshWilson]

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!

[NWChen]

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 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.

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

That's awesome then! Do you have any videos of it shooting?
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!
Thank you. I don't expect to have videos up within the next 2 weeks on account of midterms unfortunately.

[Taylor]

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.

[D.Allred]

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.
https://youtu.be/SnaXhoxGsy0?t=8m1s

What information do you need?

David

[Taylor]

What information do you need?

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.

[Chris is me]

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.

[inorbert]

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

Sent from my LG-D851 using Tapatalk

[nuclearnerd]

We built the a test version of a wheeled shooter this summer with Andymark 8" wheels, and VEX clamping gearboxes. See here: https://goo.gl/photos/hjbNw8vYjDLF34nG9. After a bit of iteration (added a second stage, and reduced compression to only about 1") we got it shooting about 75 ft. There's still a bit of work to do before we can mount it on a robot (and I think we can tweak it to shoot further) but we might use the test version as-is as a "T-shirt mortar" into the stands at this fall's STEMley Cup

[roboruler]

For something like this, it would probably be a lot better and cheaper to buy some Brushless outrunners and brushless ESC's rather than try to keep to FRC legal parts only. Your spinning a flywheel in one direction at highspeed so it's basically perfect to be made Brushless.

[Chris is me]

For something like this, it would probably be a lot better and cheaper to buy some Brushless outrunners and brushless ESC's rather than try to keep to FRC legal parts only. Your spinning a flywheel in one direction at highspeed so it's basically perfect to be made Brushless.

It really wouldn't, though. Even assuming they don't reuse old parts, a CIM is $27 and a Spark is like $45, which together is comparable to or cheaper than a 12V 300W brushless motor. You can get non-reversible PWM speed controllers for brushed motors for less than the cost of common FRC reversible controllers.

Edit: I didn't see they were feeding the CIM through a VP, which I honestly think they could skip if they wanted and just cantilever the wheels off CIM shafts with hex adapters. Kind of sketchy but it would be fine for an offseason robot.

[Andrew Schreiber]

For something like this, it would probably be a lot better and cheaper to buy some Brushless outrunners and brushless ESC's rather than try to keep to FRC legal parts only. Your spinning a flywheel in one direction at highspeed so it's basically perfect to be made Brushless.

I'm gonna ignore the cost argument. But I'd have concerns if your shooter wheels had any significant mass. There'd likely be some reconfiguring of the ESC required to get it working without starting a small fire.

DC motors can be abused and, given how students tend to do things, that's a good thing. I'd stick with maybe some 550 motors and appropriate VP gearboxes if required.

[NWChen]

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 (the two of us, no longer our team :) ) have achieved 60-70ft running 6" Colsons directly off MiniCIMs. Compression is a huge factor. Refer to this thread for more information:
https://www.chiefdelphi.com/forums/showthread.php?t=149446

Video should be up soon, since we'll be at Maker Faire NY this weekend.

[Sperkowsky]

since we'll be at Maker Faire NY this weekend.

See you there! Will be very interested to see what you built in action.

[inorbert]

Took a bit but here (http://youtu.be/2rgxjk68LFU) is ours, you cannot see where the t-shirt lands but it is about 115 feet away. The front two wheels are each powered by a CIM and the belts in the back are each powered by a Mini CIM. We couldn't keep testing because we lost the key to one of the mini-CIMs and don't have any extras

[NWChen]

One of several videos from Maker Faire (https://goo.gl/photos/yHcxhfc42XZ5frtp6). We estimate about 70ft in the air. The compression of the shirt is very important (our best shots were made with very tightly rolled shirts).