Date: Thu, 3 Oct 2002 15:09:13 -0400

Author: "Jason St. John"

Subject: Re: Vacuum Cannon question

Post:

Stephen,

I had exactly the same problem with mine. I was unhappy with the
performance of thicker clear packing tapes (which won't puncture
catastrophically enough) and the same tape that you're using (which is
surprisingly difficult to make a good seal with). John Cockman is exactly
right: find that same thin, clear tape in the three-inch width, and you
can be as debonair as Zig was at the Boise public demo show. Just about
impossible to get a bad seal or a premature.... firing.

-Ringing ears in Boston.
--
Jason St. John
Boston University
Curator, Physics Demonstrations Collection
617.353.2634
stjohn@bu.edu

On 2002-10-03.14:30 owner-tap-l@listproc.appstate.edu sent:

Hi,

3" tape should be plenty large if you're using 1-1/2" pipe (good for
ping-pong balls). Ziggy told me about this same problem when he first
started doing this demo -- it turned out that his vacuum was too powerful.
Do you have a weaker pump? Also, look for the thin brown boxing tape. When
I first made mine, I tried 3M clear tape. It worked, but it was a little
too thick.

John



----- Original Message -----
From: "Stephen Irons"
To:
Sent: Thursday, October 03, 2002 2:13 PM
Subject: Vacuum Cannon question


> Hi All,
>
> I've just put together a vacuum cannon and I need advice on what the
> best way to seal the ends is. I've used ordinary clear 3M packing tape
> with some success, but the ordinary stuff isn't quite wide enough so I
> have to put two pieces across each end to cover it(kind of a drag and it
> is prone to leaks). Furthermore, if the cannon isn't fired
> expeditiously, the tape eventually fails catastrophically and
> unpredictably. I then tried ordinary heavy duty Reynolds (as suggested
> by the NCSU website), but that failed almost as soon as I started to
> pull the vacuum. Is there a heavier duty foil I should use? (I checked
> MMC, but they appear to have only 0.001" thick which is the same as
> Reynolds Heavy Duty).
>
> Thanks for your help.
>
> -Stephen.
>
> **********************************
> Stephen Irons Yale
> University
> Director, Instructional Laboratories Department of Physics
> tel: 203-432-3664 P.O. Box
> 208120
> fax: 203-432-6175 New Haven,
> CT 06520-8120
> email: stephen.irons@yale.edu
>
>

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