For some reason I can't post pictures, but here's the dropbox links to the pictures; The piston. https://www.dropbox.com/s/nhmkcauz87gssoe/P1150485.JPG Piston seals tear beacuse the waasher concentrates stress on the seal at the boundaries. We have filed down the washer, but it still occurs from tim...

I operate coaxial piston cannons for my college. We get the freshmen to shoot them every year as part of a student project - [youtube]http://youtu.be/Q5UmqJPJ1eY[/youtube] I know, the above video's lame, this is more interesting. [youtube]http://youtu.be/7SO2rKWPHEk[/youtube] Anyway, 2 years on and ...

Hey guys, sorry to bump an old thread. Any idea how to place a marker for me? I'm in Singapore.

Hi guys, Does anyone here have a 1.5" Spudtech rifled barrel? I'm thinking of making my own, and I'd really appreciate if someone could help me measure the groove width and depth. I have checked pictures on the Internet, however they are all too blur to actually get accurate measurements out of them...

Thanks jimmy101. I'll put that in.

DYI they actually asked for a pretty basic analysis using freshman concepts - pressure*area, work-energy theorem, etc.

We're aiming to get the highest mark in the whole batch because nobody else is giving as detailed a report as we are.

Well yeah, the rifling wasn't my idea though, it's theirs. Their purpose for building it as to give freshmen "a taste of the real world" - ie that real world problems aren't as nice and ideal as in say high school physics. Anyway, you're very right, there's no way that you can make a potato consiste...

Anyway, after 3 weeks of rushing deadlines......1 more week till finals are over. I discussed with the 2 MIT professors about what plans they had for spudding, they said they'll probably start experimenting with making rifled barrels. Therefore, I think I'll probably propose this plan to them. - Mak...

@DYI I'm a freshman. This is a freshman project, we're just doing extra by giving them a comparison of our experimental result versus GGDT and Launcher Range Calculator combined. Actually I'm looking for the source of the rough rule of thumb formula on the Spudwiki site for calculating Cv: "A rough ...

Well, my uni told us to go model a spudgun for a project. I used the rough rule of thumb of calculating Cv as detailed in the Spudwiki - http://www.spudfiles.com/spud_wiki/index.php?title=Gas_Gun_Design_Tool Problem is, I can't find a proper source to cite that actually uses that. If I cited spudwik...

No, it's not a T shirt. Yeah, I can toss it out, but the shirt is gray and it's just the white paper towel fragments stuck on it that make it look wrong.

This was an accident - I didn't wear it to the workshop, have no idea how the PVC cement / epoxy got it's way there.

Looks like I'll just have to write off that shirt, and look smart in the garage.

What about PVC cement? Any ideas?

I only discovered after I washed my clothes, so it just sucks.

Yeah, it's 105. Just that it didn't mention squat about contaminated clothing.

Good thing is the shirt is gray. Bad thing is the tissue paper just had to get stuck inside.

Material is cotton. The epoxy in question is West System epoxy.

Come to think about it, I think it might actually be PVC cement which spilled on my clothes and not epoxy. I asked the PVC cement company to email me a copy of the MSDS a few weeks back, but they have kept on dragging their feet.

Had an accident, some cured epoxy got onto a shirt that I wanted.

So now I got an epoxy stain on the shirt. To make things worse, some paper towel got caught on it. So now it's a dirty white spot.

JSR - does boiling water or the iron+paper bag method work on getting the epoxy out?

Thanks.

Limbeh