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Re: Arcs off the fingers and getting killed in the process...

Hi Adam,

At 10:00 AM 02/02/2000 -0500, you wrote:

>
snip...
>
>Although there is still something to be learned here... many people are
>using plexiglas and lexan in tesla projects these days.  This stuff is not
>like wood!  There are definitely safety risks in cutting and drilling this
>stuff, and use of wood tools is rarely safe.  I had a few near-accidents
>when trying to drill the holes in my plexi primary form, using multi-purpose
>bits and a drill press.  When the drill bit exits the workpiece, it grabs
>and chips a big "exit wound", and if you've not restrained the workpiece
>properly it can become a propellor, which gets sucked rapidly upwards
>towards the drill chuck.  Very bad.  I was wearing googles, and heavy duty
>leather work gloves, and had all body parts accounted for at the end of the
>day, but I fear for the person that does not take all possible precautions--
>even the ones that don't seem necessary, are!
>
>I would not repeat these drillings, and I have had all plexi panels
>professinally cut since, at the plastics shop.  They have the right tools,
>and the cuts are *perfect*, a far cry from the rough, burnt edges I would
>have gotten with a table saw.  I do all plexi drilling with a hand drill
>now, and I usually stand on the workpiece to keep in in place.  I also got
>suitable drill bits at the plastics store where I get the plexi.

I cut plastics aluminum and other non-wood materials all the time for Tesla
coils and such.  People are always encouraging me just to cut theses
materials in my table saw.  However, after seeing that direct drive monster
effortlessly throw big chunks of wood clean "through" a wall (ended up in
the neighbor's driveway), I can't imagine how bad such a mishaps would be
with a big sheet of Plexiglas or aluminum.  Like high voltage, I always
just figured the people that did this knew something I didn't...  I never
really wanted to go through the trial and error learning curve ;-))  The
variable speed saber saw is slow and jagged, but not much can go wrong...

I bought some special Plexiglass drill bits myself yesterday!  I drill it
with a nice slow variable speed drill were I can instantly stop.  The drill
press can quickly turn a chunk of Plexiglass into a spinning shrapnel bomb!
 I am now starting to use lexan which is far easier to cut and drill (still
with a slow hand drill and saber saw ;-)).

Glad to know someone else out there finds cutting plastic and metal in
table saws as only a "spectator" sport...

BTW - Cobalt drill bits are now becoming commonly available (Sears).
However, when these things break the metal literally explodes into Hundreds
of razor sharp projectiles!  I have spent hours with tweezers pulling them
out of my face and hands...  

I wear plastic lens glasses all the time (like typing at the computer now)
even though I have 20/20 vision.  I have bounced a number of vicious
projectiles off them over the years and I know that they have saved me many
trips to the hospital and in one case probably save an eye.  

We can get hurt all kinds of ways by things we don't understand.  High
voltage is a bit worse than most things because you never know exactly were
it is and it is silent.  Worse yet, it will reach out and get you even if
you don't touch it first.  If one compares two dangerous stunts like
sitting on a running Tesla coil or juggling with a bowling ball and a
running chain saw, Everyone knows and can imagine the dangers of the chain
saw stunt.  But the dangers of the high voltage stunt are far less obvious
and intuitive.  The Tesla coil stunt "looks" like a lot of fun and others
want to try it too.  The temptation to sit on a coil and try it is fairly
great.  Not too many people run out into garage with a bowling ball and a
chain saw to see if they can repeat the chain saw stunt themselves...

When they wheel one into the hospital saying your were trying to juggle
with a chain saw, the doctors and all will give you a certain look,
silently saying "Wow! your really dumb!".  If one gets wheeled into the
hospital for sitting on 250,000 volts barefoot trying to shoot four foot
arcs off your fingers, they will give you the same look...  Telling them
about the nerves not responding to RF currents will go about as far as
other the guy explaining he was wearing a really thick leather jacket...
The explanation is the same...  "I just never realized that....."

Experts can juggle chain saws, ride motorcycles over canyons, and sit on
Tesla coils.  The difference is that Tesla coils do not seem to inspire the
same self preservation instincts as the others.  The dangers or not as
obvious or as easy to explain.  Nor are they all known and understood
nearly as well.

Cheers,

	Terry

>
>
>-Adam
>adamsmith-at-mediaone-dot-net
>
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