T-Shirt cannon pnuematic set ups

[Mr. Freeman]

Originally Posted by Tom Line

I wonder what type of professional engineering or material engineering degree this person has.

No offense, but I could ask you the very same question. I don't think you've explained what degree you hold.

[EricH]

Originally Posted by Mr. Freeman

No offense, but I could ask you the very same question. I don't think you've explained what degree you hold.

Neither have you, programmer. What materials courses have YOU had?

As for the original question, I'm pretty sure high school students don't have degrees in engineering. They may have experience or expertise in doing stupid things, but I'm not sure I'd trust that.

On the other hand, a mentor whose rookie year was 1999, even if he was a freshman in high school at the time, would most likely have an engineering degree by now and a year or so "in the field", minimum. If said mentor is in any form of mechanical, materials, civil, or possibly even industrial or electrical engineering, I would be willing to bet that he's had at least one materials course, and possibly more. There's a chance even if he's more of a computer type of engineer. If said mentor was older than a freshman in his rookie year, it's still more likely that he's had both the education and the experience.

If I had to choose between a high school student with no training other than experience in doing things that aren't necessarily safe and a mentor who's most likely had the training and the experience of doing things the safe way, but not guaranteed, I'd take the mentor every time.

[Mr. Freeman]

My point wasn't to start an argument about who has taken what classes here. It was more to emphasize that asking people rhetorical questions in an insulting manner isn't the best way to solve this PVC vs. no-PVC argument.

Anyway, in another thread about air cannons someone mentioned that what actually causes PVC to fail when using it with compressed gasses is the shock loading. I haven't seen that mentioned here, it's probably important.

[Tom Line]

My original post had a good dose of sarcasm - I get that way when I see someone putting others in harms way with no good proof.

Here are a few more resources:
http://www.articlesbase.com/technolo...ld-495648.html

http://www.lni.wa.gov/Safety/Basics/HazAlerts/902.asp

http://erd.dli.mt.gov/safetyhealth/b...dgassafety.pdf

Here are some wonderfully instructive videos on what happens:
http://www.crazybuilders.com/forum/showthread.php?p=29

http://www.astm.org/Standards/D1785.htm

http://www.ppfahome.org/pvc/index.html

If, by now, this discussion is not at an end, I the person here said it best:
http://www.garageofevil.com/faq/showdoc.php?id=35

If that does not answer the question as to why you should not use it for this purpose, you should add yourself as a corpse prop to your haunt now.

[Matt Howard]

Now that this thread has been completely hijacked by an Ego contest....


When I built my air cannon in high school, I had the help of my father who has worked in Water Treatment for about 30 years, so thankfully I was blessed with knowledge from above about pressure ratings.

I used 4 inch Galvanized Steel, and typically ran it at 135 PSI.

I was able to launch aluminum baseball bats about 250 yards with about a gallon of water in the barrel.

Enjoy some very dated pictures:

[billbo911]

Originally Posted by Matt Howard

Now that this thread has been completely hijacked by an Ego contest....


When I built my air cannon in high school, I had the help of my father who has worked in Water Treatment for about 30 years, so thankfully I was blessed with knowledge from above about pressure ratings.

I used 4 inch Galvanized Steel, and typically ran it at 135 PSI.

I was able to launch aluminum baseball bats about 250 yards with about a gallon of water in the barrel.

Enjoy some very dated pictures:

The wisdom to take from this post is that the pressure tank was built out of steel, not PVC. Secondly, from the looks of what was built, I would say it really didn't cost that much to build either, and could be easily reproduced.

Now my next question.
From the looks of the pictures, that shattered bat happened before it hit the ground. Take a close look a the bottom of the picture showing the canon firing. Look at the shadow, it looks like the bat has broken already. Is this correct?


BTW, I love the use of water to seal around the bat and act as a sort of Sabot! Besides, it looks AWESOME!

[Matt Howard]

It was actually somewhat expensive to build. The 4 inch galvanized steel pipe with all the fittings was about $160 at a pipe house. Also, large pipe wrenches were required to assemble it.

The result however, is something I wont have to worry about overcharging, as well as insanely durable.

I'm going to have to say, yes the bat was broken.

We Launched it across a field into the back of a concrete wall just to see what would happen. (This is what happens when freshmen and sophomores are left unsupervised with an air cannon) Turned out the bat launched far more effectively after the end had broken off, as the inside of the bat was hollow, and allowed for a sort of "rocket" effect.

Oranges are great projectiles, as they explode on impact like a paintball. Never actually tried a potato, but considering that this is more of a pneumatic "anything that will fit into the 11 foot barrel cannon".....

[gorrilla]

Originally Posted by Matt Howard

It was actually somewhat expensive to build. The 4 inch galvanized steel pipe with all the fittings was about $160 at a pipe house. Also, large pipe wrenches were required to assemble it.

The result however, is something I wont have to worry about overcharging, as well as insanely durable.

I'm going to have to say, yes the bat was broken.

We Launched it across a field into the back of a concrete wall just to see what would happen. Turned out the bat launched far more effectively after the end had broken off, as the inside of the bat was hollow, and allowed for a sort of "rocket" effect.

what's the wall thicknesss?

[Matt Howard]

About a foot of reinforced concrete.

[billbo911]

Originally Posted by gorrilla

what's the wall thicknesss?

Originally Posted by Matt Howard

About a foot of reinforced concrete.

I think he may have been asking about the pipe.

[gorrilla]

Originally Posted by billbo911

I think he may have been asking about the pipe.

In fact I was

and I never thought that bats could "pop" like that

[jspatz1]

Our Lunacy robot this year used a catapult to launch moon rocks up to 35ft, so it is ready to go as a t-shirt launcher with no changes! Just need to bundle up the shirts into an approximate ball.

[Matt Howard]

Originally Posted by gorrilla

In fact I was

and I never thought that bats could "pop" like that

Lol, that somehow flew completely over my head.

I don't know the wall thickness. It's class 150 Galvanized Steel.