[BC] lightning & grounding

[Lamar Owen]

On Friday 20 May 2005 15:58, Phil Alexander wrote:
> On 20 May 2005 at 11:16, Lamar Owen wrote:
> > I've brazed 10 gauge bare copper to 0.125 before.  The worst was brazing
> > some 0.062 to some half inch angle iron at an ATU.  I've also done 0.062
> > to steel sea container frames.  Careful heatsinking of the copper is
> > extremely important, and good control of the oxyacetylene rig is
> > critical.

> I've brazed more #10 to .030 x 4" copper than I want to think about and
> have always used bronze rod and a flux can. I've never needed a heat
> spreader for that, just a careful touch with the torch and good heat
> control - plus a calm day helps. <g>

#10 to 0.030 is a fairly good match; to 0.125 the #10 nearly melts if it's not 
heatsinked.  And doing it with bronze sure does get the filler's solidus 
uncomfortably close to copper's melting point.

I used bronze to do one of the steel to copper connections; but the others I 
did with 45% copper-silver (no phosphorus) and borax flux.

> bad as trying to gas weld aluminum. <g> I started thinking TIG might be
> better but I don't have a rig for that. (And I do mean TIG, not MIG. <g>)

Good TIG work looks very pretty, too.  You can weld copper to copper very 
easily with TIG (aka 'Heliarc' which is a trademark of Lincoln, if I remember 
correctly).  TIG is as controllable as a torch with very few of the torch's 
problems.  Cast aluminum (or aluminium for Clive) can be welded with TIG; so 
can cast iron, copper, and many other things that you couldn't do any good 
with a torch or other means.  But TIG is expensive and requires AC power 
(three phase for the good rigs).

For those not familiar with TIG, you weld with it in a similar fashion as you 
would with a torch; the tungsten electrode in the 'torch', swathed in helium 
or other inert gas, acts as an incredibly high temperature 'flame' source 
when you strike an arc with it.  You then add filler like with a torch, 
rather than with MIG or regular arc welding where the filler is the 
electrode.  Good TIG weldors (using Haynes' terminology to reduce confusion 
between the equipment (a 'welder') and the operator (a 'weldor') command 
better wages than most broadcast engineers and are nearly artists.  Good TIG 
welds are works of art.  I have a friend who is employed as a mold weldor; he 
gets paid very handsomely for welding molds, where the weld fillet is part of 
the actual mold surface and will be reflected in the molded product.  He gets 
over $100 per hour to contract out welding.

> Phil Alexander, CSRE, AMD

I know what the CSRE is, but what is the AMD for?
-- 
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
(828)862-5554
www.pari.edu