Date: Fri, 19 Nov 2004 09:57:05 -0500

Author: Roger Boyce

Subject: Re: vacuum bazooka


Thanks everyone. I am looking for better than 99.5% success. I give the
big buildup put on the ear protection, poke the hole and instead of the big
bang and the can getting ripped to shreds, it goes phhhttt. Makes me look

I have tried all of the different seal materials. While testing a heavy
packing material and testing for leaks, the material failed while my hand
was in front of the muzzle. The ball hitting my hand was like hitting it
with a hammer. The ball split apart scratching and bruising my hand in
several places and smashing a finger nail.

If the pump is sufficient to work 80%, it should work 100% so I am ruling
out the pump. Since I often must reload for a second show I have a concern
about bits of tape being carried down the pipe. To make that less of a
problem, I have been placing a small piece of paper towel on the sticky
part of the tape so there is less chance of tape sticking inside the
pipe. When I am through for the day, I swab the inside of the pipe with
alcohol and spray WD 40 in the pipe and swab it out again with a clean
swab. I'll try a single 5 foot length but I want lots of noise and
destruction, two elements of a successful road demo.

At 08:32 AM 11/19/2004 -0500, you wrote:
>Hi Roger,
>My success rate using thin packing tape is 100%. No vacuum grease, no
>machined ends, and no external fittings. Have you tried taping the center
>seam with packing tape of duck tape? Or better yet, just use a four-foot
>vacuum cannon while on the road.
>The projectile velocity of my five-foot cannon is less than 200 mph -- not
>fast enough to break a can. However, I haven't tried it yet with the 40mm,
>harder-shelled balls.
>John Cockman
> > Roger Boyce wrote:
> >
> > > What is the success rate people are having with their bazookas? I have
> > > suspended taking mine on the road because it only works about 80% of
> > > the time. My hearing is not good enough to hear leaks is a big
> > > problem, I'm sure.
> > >
> > > I use the packing tape and I have machined end fittings to allow more
> > > surface area for the tape to stick to. To allow it to be portable, it
> > > is in two, four-foot pieces. One length has a coupler cemented in
> > > place. When I connect the two pieces, I use vacuum grease and wrap
> > > duct tape around the connection that is not cemented. It is an awesome
> > > road show demo but a demo that is inconsistent in that environment is
> > > practically useless.
> > >
From Fri Nov 19 10:09:44 2004