A look inside the "bleacher reacher" t-shirt launcher

[jackssmirkingrevenge]

I had a bunch of these to service and though I'd share a look inside:

Standard exhaust valve setup but with an interesting configuration that has the piston seal at the front endcap but avoids using a spool or "toolie" type valve. There's no rubber seal on the piston face, it's aluminum on delrin, and it has a floating o-ring to allow air to be filled from the main tank but not to flow back when the pilot is actuated.

Operating in the 300-500 psi range, these things are pretty darn loud!

Also did I mention my workshop has an epoxy floor

[wyz2285]

T-shirt cannon right? I think I have seem something similar somewhere.
Interesting piston setup, any chance of a video (launching something more interesting rather than T-shirts )?

[jackssmirkingrevenge]

T-shirt cannon right?

I guess the post title of "t-shirt launcher" wasn't clear enough

nteresting piston setup, any chance of a video (launching something more interesting rather than T-shirts )?

perhaps

[wyz2285]

Ah the "T-shirt" parts got omitted when I saw it on the recent post section, my bad,
Still trying to remember where i have seem them, pretty pricey stuff too if I'm not mistaken.

[jackssmirkingrevenge]

Manufaturer's page, pretty pricey indeed!

Here's a quick video accelerating an empty soda can at 300 psi:

[youtube][/youtube]

[wyz2285]

Reminds me of this [youtube][/youtube]

[jackssmirkingrevenge]

Another round of servicing, another chance to have a little fun with compressed air

[youtube][/youtube]

[Moonbogg]

What does the chamber look like on these things? I suppose you might get in trouble for uploading a paint drawing of how this thing works?

[jackssmirkingrevenge]

What does the chamber look like on these things?

You should be able to tell from the photos but here is a simplified diagram of the internals:



Green arrow shows where the air is filled from, this is then closed off and another valve is opened at the red arrow to empty the pilot volume and fire the launcher.

The piston has a floating o-ring that allows air to flow from the pilot chamber to the main chamber, but not the other way round.

[Moonbogg]

Thanks for showing that. That's a really great design. I love the short piston travel and front-mounted configuration of the piston housing because that preserves chamber volume. I tried to design my last cannon that way years ago when I first started thinking about a piston hybrid design, but I couldn't find a way to vent a low volume, front-mounted housing like that in a way that i was happy with, but it makes perfect sense for a pneumatic.
No bumpers and up to 500psi? Looks like Delrin is a legit piston material. How does the piston hold up? What needed to be serviced in the cannons?

[jackssmirkingrevenge]

No bumpers and up to 500psi? Looks like Delrin is a legit piston material. How does the piston hold up?

The piston is actually aluminum, as is the housing, and with no bumpers to speak of there is no visible wear.

What needed to be serviced in the cannons?

Mostly leaky threaded connections, and a good cleaning inside because they are used for firing confetti as well and aren't always pressurized before the confetti is loaded up, so some of it gets in the chamber. If it gets between the piston and seat, this causes leaks.

[Moonbogg]

Aluminum piston? Maybe there is a dashpot/air cushion effect preventing a hard slam. That's interesting. And a metal to metal seal. That's also interesting. Those are two things I would never consider to try, yet they work.

[jackssmirkingrevenge]

There's no real design for cushioning the impact, it seems to me that it simply travels a short distance that isn't sufficient to cause any damage.

a metal to metal seal

The piston seats against delrin, the while component in this image. At these pressures I don't think metal on metal would work.

[Brian the brain]

Basically a coax with the reservoir pointed in the opposite direction...I like it!

[5150cannon]

Does anyone have the internal design of the trigger mechanisms for the t-shirt launcher?