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[TowerTalk] CadWeld OneShots (Long)

To: "Rob Atkinson, K5UJ" <>
Subject: [TowerTalk] CadWeld OneShots (Long)
Date: Sat, 24 Jan 2004 01:11:42 +0000
List-post: <>
How about one of you telling the rest of us what we need to purchase, what 
the stuff is called so we know what to ask for, what we're going to need and 
how to use it? 

OK, I'll take a stab at it.  There's a small learning curve but you can do it 
and once you've got it you'll be amazed at how easy it is.  First as an 
industrial capital project manager, I've seen electrical contractors do this at 
the plant for years, only they use the permanent molds.  The OneShot are 
exactly that, one mold, one use only but more affordable.  

As some have explained, you go to the website and navigate through 
their selection pages for Cadweld molds.  You select the type of mold (wire to 
rod), the size of rod, then size & type (stranded, solid, etc.) of wire, and 
finally it gives you the OneShot part number.  Then you will most probably need 
to place a special order (I have to go in boxes of 12 min) with your local 
"industrial" electrical supply house.  Not HD and not a commericial supplier 
but industrial supply.  Here in Chicago we have Steiner and Crescent, to name a 
few.  Some of you may not have any suitable locally.  But then there's the 
Harger & RF Connections (?) connection.  Anyway order your molds and wait.

Do a presentation.  You know I've actually been planning to do just that for my 
local club 'cause they all have the same questions.  But I'll give a go at 
explaining it here; email me privately if you need more info.

The OneShot is a cylindrical white ceramic mold with a ground rod sized hole in 
one end (ground rod side) and open at the other (powder side).  Surrounding the 
rod side hole is a rubber washer.  The mold slips down onto the top of the rod. 
 I use a big metal file to ensure that any mushrooming from pounding them in is 
removed.  Also it's best if the top of the rod is flat and not jagged.  It'll 
be a tight fit and you may need to file and try to install the mold onto the 
top of the rod a number of times.  The mold will fit about 1 & 1-2" onto to the 
top of the rod.  Buff shiny the sides and top of the rod so that the mold makes 
a good bond.  In the sides of the mold, just at the location where the top of 
the rod comes to, are other holes for the wire.  You need to specify the number 
of wires when you specify the mold part number, ie one wire only, one in and 
one out (on a run), two in one out, two in two ou, etc.  I only use the one in 
one out or two in two out types, since I 
 have to buy a minimum case quantity.  A trick is one can fill any extra holes 
with short stubby pieces of wire just to fill up all holes. 

You then insert your wire ends which have been buffed shiny also into these 
holes in the sides of the mold.  What I do is to pound in my ground rods and 
dig a six inch deep hole around them to get access to the ground rod tops. Then 
I make my ground wire trenches between the rods and then install my ground wire 
(I use #4 bare solid) into the trenches and lay it across on top of the rods. I 
then use wire snips to cut the wire right at the top of the rod.  You install 
the mold onto the rod, per above, and then insert the wire ends into the sides 
of the mold.  There are small metal ferrules which slip onto the ends of the 
wire and these in turn are inserted into the side of the mold.  These just 
protect the mold sides from damage; it's ceramic so you can break it if you 
Now picture this if you look down from the top (powder side) of the mold you'll 
see the mold sitting on top of the rod with the end of the rod showing inside 
the bottom of the mold and the ends of your wires are protruding into the sides 
of the mold and are laying right on top of the rod top.  Pull the wire ferrules 
out a bit if you need so that you can have the bare wire tips are all on top of 
the rod inside of the mold.  You need to make sure that all wire ends are 
laying on top of the rod or else the molten material will not bond all 
together. Bend and massage your wires to make it all work.  Be careful not to 
break the mold.  If the mold won't remain in a vertical position, fashion wire 
helpers to hold the mold in one place rom the outside of the mold.

Now comes the fun part.  Along with the mold, comes a ceramic disk with an 
aluminum center section, a ceramic disk with a small hole in the center, and a 
vial of powder.  Don't spill any of the powder!  You drop the disk with 
aluminum center into the mold.  It will fall down onto the top of the wire/rod 
area.  This will keep the powder from falling out prior to ignition.  If the 
disk becomes wedged sideways gently nudge it with a screwdriver.  If stuck, 
remove wires from the mold and all from the rod and tap it out and start over; 
it must fall all the way to the bottom.  Now open the vial of powder and pour 
it into the mold; use it all.  It will fill the mold almost all the way to the 
top.  Then cap the mold with the disk with a hole in the center.  Warning, 
don't do this when it's raining and definately don't do this in any kind of 
wind.  Trust me.  Now comes the mystery part, at least for me initially.  The 
instructions, which come in every box, say to now pour in the start
 ing powder.  But where is it?  This drove me batty until I had a revelation.  
The starting powder is compacted into the botom end of the plastic vial for the 
powder.  Look into the bottom of the vial and you'll see these plastic baffles. 
 The powder is between these.   Squeeze the bottom of the vial,  distorting it, 
to loosen the powder.  There's not much there so be careful.  Pour the powder 
from the vial into the small hole in the ceramic disk. It will almost come out 
of the small hole.  The actual mold powder is something like a powdered copper, 
aluminum, magnesium mixture and the powder is like gun powder.  You can view an 
MSDS from the Erico website.  Now you merely light the powder and it flashes in 
a bright hot flash, ignites and instantly melts the powder which melts through 
the aluminum center of the disk at the bottom of the mold and the molten blob 
drops down onto the wire/rod end assembly.  Remember that rubber washer that is 
in the rod end of the, it keeps some 
 of the molten blob from falling down alongside the rod and usually will flame 
and smolder.  Leave it alone.  When you ignite the mess, don't be too close.  
Keep the kids and dog noses far away as well as yourself.  The ignition flash 
is really bright, like the sun (you'll be seeing spots) and is really hot.  You 
can buy the flint sparker from Erico or you can use a regular sparker that a 
welder would use to light his torch or to light the campfire propane stove.  
Personally I've tried the torch sparker and find that  I can sometimes have a 
heck of a time getting a spark to drop down just right; maybe the Erico sparker 
is better.  What I've come to use is just my propane soldering torch which is 
used to sweat solder copper water pipe.  One issue with this is that you must 
be careful with the flame or else you'll (and I've done it) blow away the 
starting powder and the mold powder will not ignite by itself, it must have the 
starting powder.  I've also tried busting open firecr
 ackers but to no avail; so, be careful with that starting powder.  All first 
timers, I highly recommend purchasing at least one extra mold just in case you 
mess one up.  You need to wait quite a while for the mess to cool off.  The 
rubber may be smoldering (if it's caught fire, let it go) and the mold may have 
become cracked.  Leave all alone and wait for it to cool; Erico specifies at 
least 30 seconds to allow the molten material to harden.  Once cool, take a 
hammer and gently wack and break the mold away from the wires and rod.  Throw 
all away or just bury in the bottom of the rod hole.  You'll see a copper 
colored blob of metal that has fused itself around the wires and rod.  
Weatherproof and maintenance free.  Voila, finito!  

That's it.  Email me if you need more.  Be careful but it's really easy and 
once done, no more worries about that connection.  Phil  KB9CRY

See:  for "Self Supporting Towers", "Wireless Weather 
Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions 
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