[TheForge] Aluminum

[Jerry Frost]

That's a new one on me Mike. I get the principle but I've never even heard
of it before. I wonder how you connect the blade without endangering the
bearings in the wheels?

A cutting torch works on steel because iron oxide has a lower melting
temperature than the steel and the combustion temperature of steel is much
higher than either.

A torch won't cut metals where the oxide has a higher melting temp than the
parent metal. Aluminum oxide has a higher melting temperature than
aluminum's combustion temperature and aluminum has a really HIGH combustion
temp, think thermite. It's why it makes such a useful additive to things
like rocket fuel and explosives, the hotter the burn the more explosive
expansion.

A good tungsten carbide circle saw and some common sense operation makes
short work of aluminum. Heck, if it's not too oxidized a carpenter's hand
saw works fine.

Jer

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Mike Spencer
Sent: Thursday, October 3, 2013 9:04 AM
To: theforge at mailman.qth.net
Subject: [TheForge] Re: Aluminum


Here's a method for cutting difficult pieces that I heard about 3rd- or
4th-hand somewhere.  I've never met anyone who's done it or seen it done.

    Rig a vertical bandsaw to run at wood-cutting speed (or faster?).
    Connect the blade, via an existing or added roller, to one side of
    an arc welder.

    Connect the workpiece to the other side of the welder.  Insulate
    the workpiece (electrically) from the table with a sheet of some
    non-conductor (Masonite?  plastic?).

    When you advance the workpiece into the blade, an arc is struck.
    Allegedly the air-draft around the blade carries the slag away
    while the speed of the blade prevents it from remaining in the arc
    area long enough to heat up. (It's possible that there was an
    added blade-cooling air jet or something that my source didn't
    mention.)

I was told that this was devised at the U-Haul trailer fab shop to cut some
part when it turned out that there was no way on hand to suitably cut a
piece of (hardened? tough alloy?) steel.

Never heard any more about it so it has the status of a yarn.

Anybody ever see this done? I have an old 24" bandsaw that works well on
flat-belt drive but I'm kind hesitant to try this just for a lark. 

If it works at all, it should work for aluminum as well as steel.  I once
set a magnesium transmissin case on fire with an oxy-acet torch so I'd be
even more hesitant to try it with magnesium.


- Mike