Date: Fri, 19 Nov 2004 12:20:46 -0500

Author: Roger Boyce

Subject: RE: vacuum bazooka


Do you know the thickness of the Mylar? Mylar used for overhead
transparencies, perhaps?

Thanks for the suggestion, Yalan.

At 09:03 AM 11/19/2004 -0800, you wrote:
>I experienced the same problems as you do before. Yesterday I tried Mylar
>material sheet to seal the both ends of the tube (with PVC coupler and ring
>clamps) it works so good. Try it.
>-----Original Message-----
>[] On Behalf Of Roger Boyce
>Sent: Friday, November 19, 2004 6:57 AM
>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 12:51:08 2004