[TowerTalk] Cadweld help

[Tower (K8RI)]

The starting material is in the bottom of the cartridge.
http://www.rogerhalstead.com/ham_files/ground.htm might help although there
is no image of the starter compound.

If you look at an empty cartridge you will see what look like 4
reinforcements about a quarter inch deep, across the bottom. The starting
compound is normally in these and *should* stay put when you dump the
regular material out. However if you have shaken the plastic cartridge or
dropped it, the likely hood is the two powders have mixed.   The compounds
are slightly different in color and very different in texture.  The starter
looks like "powdered Aluminum" while the working mix is granular although
relatively fine.  The starter feels almost like Talc while the working mix
is gritty.

I'd take one apart, shoot some photos and add to the page, but at $10 to $12
each I don't have a lot of incentive to waste one.  I do have two more
ground rods to tie in so I'll try to remember to shoot some photos of that
stage. Of course that doesn't help you now.

I pour the material into the ceramic cartridge, place the ceramic cover in
place, and then set the plastic cartridge on top of it with the open end
down.  "Thumping the container a couple of times with your finger should
dislodge the starting powder into the depression in the ceramic top and
enough should flow down through the hole to make contact with the working
mix.

I wear sunglasses and leather gloves. Then light it with a match.  I haven't
lost any eyebrows or skin yet.  Don't try matches without leather gloves or
you may lose some hide and certainly you will have to wait for the hair to
grow back.



> Is the starting powder for the Cadweld combined with the welding metal or
is
> it separate? I ran the gamut of a spark igniter to a  propane torch. The
> powder glowed red but no exothermic reaction. What am I doing wrong?

You are missing the igniter for one reason or another.  A propane torch is
not hot enough to start the reaction.

I have used an acetylene torch with a very small tip when I accidentally
lost the starter. (slightly oxidizing flame and not a lot of flow)  All you
need is a tiny hot spot.  Anything more and you are likely to blow the
material right out of the cartridge.  Too little and you are likely to ruin
the torch tip.

Be Careful! This stuff is hot and it is bright as any welding. (note photo
in link)  Do not look at it once it fires and keep a bit of distance.  They
*normally* burn much like a railroad flare, but they can spit and sputter
molten metal around and are much brighter.  This stuff can burn a hole right
through concrete, let alone steel and other fragile materials. <:-))  Keep
it well away from water. Water will not put it out, but it may splatter
badly, or even cause a small explosion.

Treat them with caution and respect and use well away from other combustible
materials.


Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair (S# CD-2)
www.rogerhalstead.com
> Howard...K2HK
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