[VAC] Re: Removing rivets and rusty screws

[Dr. Gerald N. Johnson, electrical engineer]

Aluminum next to steel whether cadmium or zinc plated makes a battery
when damp or wet and the steel suffers rapid corrosion. In amateur radio
antennas having that combination the steel turns to a ball of rust
flakes. The only sensible hardware for an airstream skin should be
aluminum or stainless steel. There are aluminum self tapping screws but
they aren't likely to cut threads in steel frame parts. While the pop
rivet is more of a pain (at least conceptually) to remove, an aluminum
pop rivet won't corrode to a mass of corrosion just being next to more
aluminum.

Stainless steel hardware can be expensive unless bought in bulk from
places like McMaster-Carr (www.mcmaster.com). In the ham radio magazines
there are a few dealers who specialize in stainless steel hardware for
antenna construction.

Aluminum hardware is not too common but aluminum pop rivets are commonly
available.

Phillips screw drivers do wear with use and once rounded are only
suitable for conversion to tent pegs. They must be replaced regularly or
will round out screw heads instead of turning them. Flat blade
screwdrivers can be filed to shape and should be the same width as the
screw head and the same thickness as the screw slot, otherwise they will
not turn the tight and rusty screw effectively. The flat blade
screwdriver should never be used as a pry or a chisel and should have
square edges and corners to hold tight in the screw. One should own a
collection of sizes and a good flat file for squaring up the tips as
they wear. Grinders are too hard to control compared to a file and
nearly all practical screw driver bits can be filed to the proper shape
as fast as they could be ground to the wrong shape.

I dislike rotary files. I have one or two and have used them with an air
die grinder. They did remove metal. They removed it in sharp slivers
that accumulated in my skin when ever I touched the work bench for weeks
afterwards. I prefer small grinding bits and wheels and particularly a
cut off wheel. Its peripheral speed that grinds, and a 1/4" diameter
wheel has to turn at ungodly speeds to be more effective than sandpaper,
but a 3" cut off disk can do great work at 15,000 or 20,000 rpm in the
dremel or die grinder. Dunmyer of this list recommends the air operated
cut off tool that has more guarding than the plain die grinder for use
with the cut off disks. A 1/16" thick cutting disk can take a screw head
off by splitting it down the middle rapidly. And with care without
marking the work the screw head held (much).

Gerald J.



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