This article addresses belt sanders but we also need
to keep in mind that aluminum and brass shouldn't be
ground on bench grinders. At least not on wheels
designed for ferrous metals. These metals will build
up on the wheel surface, clog the wheel pores and
cause overheating. Heat expands things and the wheels
aren't flexible -- they come apart at the absolute
worst times, like when you are standing in front of
them.
Some powdered metals are flammable for sure. I set a
small accumulation of powder on fire once when I was
grinding on a chainsaw handle with a Dremel sanding
drum. It burned hot and fast plus it wasn't real easy
to extinguish.
Barry
--- Holly and Chris Mills <scmills@tntech.edu> wrote:
> Saw this on the FIAT list. Thought it was good
> reading that applied to all
> of us - no matter what you drive and work on. The
> original person that
> posted this claimed they got it from a Kennedy Space
> center safety report.
>
> Can any of you verify this is a real danger or
> another INTERNET hoax?
>
> Subject: Aluminum dust explosive danger
>
> Im sending you the following details of an incident
> that has happened to me
> while using a 1 belt grinder. I feel it might be
> applicable for publication
> in the newsletter as a warning for others. Although
> I was using a commercial
> model (Delta model 31- 050) I feel it is just as
> applicable to any type
> grinder, commercial or home made.
>
> On 25 January, I was using the grinder to smooth the
> edge of a hacksaw cut on
> a 2 length of 1.5 angle iron. I had been grinding
> for about 1.5 to 2
> minutes when there was a loud THUMP accompanied by
> an approximately 2-foot
> diameter brilliant yellow- orange fireball. The
> fireball lasted no more than
> = second and then completely extinguished itself. It
> completely enveloped the
> machine and my hands to half way up my fore arms and
> to the top of my
> stomach.
>
> As soon as it went out it was obvious that I had
> suffered some serious burns
> to my hands. Besides large white areas on the heel
> of each thumb and the palm
> of my left hand, the skin was hanging from the heel
> of both hands, from my
> little finger to my wrist, and from the finger joint
> of my left hand. Also
> the right cuff of my shirt was smoldering, my face
> felt burning, and I could
> hear the front of my hair sizzling. Nothing on the
> bench was burning. The
> only evidence was a few streaks of white powder on
> the bench top and on a few
> items lying on the bench. The workshop was filled
> with dense white smoke with
> very little odor. My fingers and the ends of my
> thumbs escaped relatively
> unscathed as they were resting on the machines
> table and were protected from
> the heat flash by it.
>
> Besides the burns to my hands, my neck, chin,
> cheeks, lips and the end of my
> nose suffered first-degree burns and have recovered
> after peeling as if a bad
> sunburn. I was wearing glasses and these protected
> my eyes, which appear to
> not have been damaged. I also lost half my
> moustache, B> of my eyebrows, and
> about 1 off the front of my hair. My eyelashes were
> curled by the heat but
> not singed .The burns to my face were caused solely
> by radiant heat, as the
> fireball did not come that high.
>
> Initially I could not understand how I could have
> suffered such severe burns
> from such a brief exposure to the heat. Later that
> evening after some
> thinking and questioning of my son (who also uses my
> workshop), it became
> clear what had happened. A few days earlier he had
> ground the heads off about
> twelve 1/8 aluminum pop rivets. Finely divided
> aluminum mixed with finely
> divided ferrous oxide (the black powder residue from
> grinding steel) produce
> a compound called THERMITE. Thermite is used to fill
> incendiary bombs and
> commercially to weld large steel items (e.g. railway
> rails) into continuous
> lengths. It burns at approximately 3500 deg. C (6300
> deg. F), hence the
> extensive burns from such a short exposure time. The
> end result was,
> excluding my fingers; I suffered deep second-degree
> burns to about 60% of my
> left hand and 50% of my right hand.
>
> Interestingly there is no warning of this possible
> occurrence in the safety
> section of the manufacturers owners manual. As a
> result I have sent a copy
> of the contents of this letter complete with
> pictures of my hands to Delta
> Machinery. Their reply should be interesting! In
> light of my experience I
> feel there should be a very STRONG warning passed on
> to the readership as to
> the dangers posed by grinding steel after having
> ground aluminum, unless the
> machine is thoroughly cleaned of all aluminum dust.
> The potential is
> certainly there for even more serious injury. Due to
> the potential
> seriousness of this incident I have also sent a copy
> of this letters
> contents to the editors of ME, MEW and ElM in order
> to maximize the
> dissemination of this information
>
> Chris in Mid-TN
>
> ICQ# 5944649
>
> 1978 Volkswagen Westfalia (almost
> done, Rolls-Hardly Engine)
> 1965 VW Beetle with a Type IV power (perpetual
> project)
> 1949 Chevy 3100 p/u (daily driver)
> 1999 Honda CR-V (wife's ride)
> 1981 Honda CB900 Custom moto-sickle (other daily
> driver)
> 1972 Hodaka Wombat (FOR SALE) (needs new home)
>
> 1997 Wife named Holly
> 2000 model son named Zane
>
> several used felines (2 shiny black, one in primer)
>
> Use the contents of this message at your own risk.
> Reproduction is allowed
> with reference to me, the author -- if and only if
> you can verify the
> information contained within is correct.
>
> If you find that the information is flawed, in poor
> taste, incorrect,
> evidence of mental treatment required, or if the
> statement/question was
> just plain dumb - you don't know me...
> oletrucks is devoted to Chevy and GM trucks built
> between 1941 and 1959
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