[TowerTalk] Info/Advice re: Exothermic Welds

[K8RI]

On 8/20/2012 7:55 PM, ve4xt at mymts.net wrote:
>
> I would also recommend ensuring the wire is secured from movement before letting off the charge.I had one wire get blown out of the mould by the charge. The putty Gene and Jim mentions might hold it in, but a brick over the wire to keep it from moving wouldn't hurt.
> 73, kellyve4xt

When working with wire the size of #2 or larger, I dress the run so the 
wire is under a slight bit of compression pushing straight in.

There is very little pressure from within the shot caused by its 
burning, but if there is any tension when everything melts the wire will 
spring back. It'll spring out if under enough tension.. I cut the wire, 
then make sure it's under compression, pack the dirt around it, fill the 
container, double check, install the cap, pour in the small igniter 
charge, and touch it off.

IIRC One shots come in various sizes to fit the wire. The ones I had 
were a snug fit on #2.

73

Roger (K8RI)


>
>> From: ersmar at verizon.net
>> To: knowkode at verizon.net; towertalk at contesting.com
>> Date: Mon, 20 Aug 2012 19:14:58 -0400
>> Subject: Re: [TowerTalk] Info/Advice re: Exothermic Welds
>>
>> TT:
>>
>>       I second Jim's recommendaton about using electrician's putty to seal
>> the holes in the Cadweld Oneshot molds.  I didn't do that for the first shot
>> I fired and lost most of the liquid charge into the dirt.  The second and
>> all subsequent charges went well for me after I used the putty, especially
>> underneath the mold where the ground rod penetrates.
>>
>>       As an aside, I had expected a lot of fireworks when the shot went off.
>> I was disappointed - it was mainly smoke and very little flame.  Stay
>> upwind!
>>
>>
>> 73 de
>> Gene Smar  AD3F
>>
>>
>> ----- Original Message -----
>> From: "Jim Hoge" <knowkode at verizon.net>
>> To: "towertalk" <towertalk at contesting.com>
>> Sent: Monday, August 20, 2012 5:00 PM
>> Subject: Re: [TowerTalk] Info/Advice re: Exothermic Welds
>>
>>
>>
>>
>> Art,
>>
>> Cadweld is one product, made by Erico. Thermoweld is another. Erico calls
>> their single use products Oneshot and yes, the ceramic mold can remain after
>> the fact. One shots are cheaper up front because you are not buying the
>> molds and the handles. A different mold is required for each different
>> application, ie: one wire #4 to ground rod, 2 wire to rod, a #2 wire to
>> ground, etc. I know Thermoweld makes products for flat strap to rod or
>> plate. One note on the Cadweld Oneshots- the wire openings on the molds are
>> a bit oversized and weld material can run out. If you wrap the mold with
>> electrician's putty, it will remain in place long enough to prevent the
>> runout. The thermite weld mix lights very easily with a flint igniter. I was
>> surprised the first time I used it.
>>
>>
>> 73,
>> Jim W5QM
>>
>>
>>
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