# Cadweld



## drsparky (Nov 13, 2008)

They makes molds for welding to just about everything. Exothermic is without external heat. They get hot enough to melt steel and copper.


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## mattsilkwood (Sep 21, 2008)

They make them now with premeasured shots and an electric igniter.


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## JohnR (Apr 12, 2010)

Generally, a conductor comes through the bottom of the mold, the mold is clamped against the side of an I-beam or somehow held there, (you can do this by hand but takes nerves of steel), Just as the two conductors have a powder pack at the top, this does as well. Light the powder and BAM there you have your weld. 
Wait a little for the metal to cool, then release the clamps, and then open the mold. Make sure that you do not damage the molds as they are very expensive. They do make one shot molds that are more reasonable.

If you use the incorrect shot size or do not make sure the two metals are dry, then you will get a lousy looking weld and will have to knock it off and do it again. If you can knock it off, the weld was lousy even if it looked good.


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## RIVETER (Sep 26, 2009)

Maybe you mispoke. A cadweld IS an exothermic reaction that does give off heat in the process. It is great for connections that are strong and should never corrode. However, it should not be confused with FUSION welding because in FUSION ,you don't add extra metal.


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## JohnR (Apr 12, 2010)

Sounds like exothermic Con-fusion:jester::laughing:


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## RIVETER (Sep 26, 2009)

JohnR said:


> Sounds like exothermic Con-fusion:jester::laughing:


Speedy, Speedy...we may have another one.:thumbsup:


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## HackWork (Oct 2, 2009)

I've used a lot of the Burndy Weld lately, I liked it better. They came out perfect every time. No leaking, the molds seem to last a lot longer.


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## Murphy (Dec 10, 2009)

i did some cadwelding today.. had trouble getting it to stick to some fence poles.. does it work better with a smooth clean surface.. or is it better with a filed down clean surface with ridges?


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## RIVETER (Sep 26, 2009)

Murphy said:


> i did some cadwelding today.. had trouble getting it to stick to some fence poles.. does it work better with a smooth clean surface.. or is it better with a filed down clean surface with ridges?


The cleaner the surface, the better. But it would depend on if the mixture was contaminated.


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## frenchelectrican (Mar 15, 2007)

Murphy said:


> i did some cadwelding today.. had trouble getting it to stick to some fence poles.. does it work better with a smooth clean surface.. or is it better with a filed down clean surface with ridges?


 
I will advise ya keep the surface where you want to stick the best way is to keep the area clean and any debries can really affect the cadweld.

And keep that spot dry if damp take a blow torch to dry it out before you use the cadweld.

Merci.
Marc


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## McClary’s Electrical (Feb 21, 2009)

Murphy said:


> i did some cadwelding today.. had trouble getting it to stick to some fence poles.. does it work better with a smooth clean surface.. or is it better with a filed down clean surface with ridges?


 

You have to grind through the galvanized and get to the metal


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## RIVETER (Sep 26, 2009)

Murphy said:


> i did some cadwelding today.. had trouble getting it to stick to some fence poles.. does it work better with a smooth clean surface.. or is it better with a filed down clean surface with ridges?


What circumstances were you in that you had to cadweld a fence post?


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## frenchelectrican (Mar 15, 2007)

Riv.,

I have a feeling it have to do something with bonding espcally near switchboard especally with MV and HV class that you denfinely need it.

Merci.
Marc


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## RIVETER (Sep 26, 2009)

frenchelectrican said:


> Riv.,
> 
> I have a feeling it have to do something with bonding espcally near switchboard especally with MV and HV class that you denfinely need it.
> 
> ...


I can see where it would be appropriate to bond/ground a fence post if the fence is surrounding a transformer pad, or such. But I don't see the need of a cadweld to accomplish that...with the post being in the ground.


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## HARRY304E (Sep 15, 2010)

RIVETER said:


> I can see where it would be appropriate to bond/ground a fence post if the fence is surrounding a transformer pad, or such. But I don't see the need of a cadweld to accomplish that...with the post being in the ground.


 a ground lug will be fine


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## mikeh32 (Feb 16, 2009)

I have done so many of these. Many fence posts like some one said. Cell towers are a pain in the ass. 


Also, When it is below 0, make sure that you always heat the pole, or what ever you are welding too


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## MDShunk (Jan 7, 2007)

You want something dramatic, cad weld a damp piece of steel. That'll pop and carry on like the world is coming to an end.


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## MDShunk (Jan 7, 2007)

horsegoer said:


> Ok, I believe Cadweld is just the name used by Erico but is the same thing as an exothermic weld. I know this is used to join two conductor together without heat by using a chemical reaction. Can you Cadweld a conductor to building steel and if so how. The Cadwelds I saw involved putting the conductors into an enclosure and pouring the shot in. So I was wondering how that would work when welding to building steel. Thanks.


This Cadweld type stuff was originally invented for cadwelding to railroad tracks, so doing steel is something that has been done for a very long time.


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## erics37 (May 7, 2009)

RIVETER said:


> I can see where it would be appropriate to bond/ground a fence post if the fence is surrounding a transformer pad, or such. But I don't see the need of a cadweld to accomplish that...with the post being in the ground.


Maybe a substation or something. I always see big ol' bonding jumpers on the fence at those places.


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## mikeh32 (Feb 16, 2009)

erics37 said:


> Maybe a substation or something. I always see big ol' bonding jumpers on the fence at those places.


you have to do them with ground rings for cell towers. that and roller coasters


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## drsparky (Nov 13, 2008)

I had to Cadweld some fence posts but the shots were burning through the thin posts. I used a oxygen acetylene torch and brazed them. Specs call for a nonreverable connection, and clamps cause problems with loose connections down the road. I also had to bond the fence fabric.


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## McClary’s Electrical (Feb 21, 2009)

horsegoer said:


> Ok, I believe Cadweld is just the name used by Erico but is the same thing as an exothermic weld. I know this is used to join two conductor together without heat by using a chemical reaction. Can you Cadweld a conductor to building steel and if so how. The Cadwelds I saw involved putting the conductors into an enclosure and pouring the shot in. So I was wondering how that would work when welding to building steel. Thanks.


 

Walk behind me and pick up a mold after a few shots with bare hands


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## McClary’s Electrical (Feb 21, 2009)

drsparky said:


> I had to Cadweld some fence posts but the shots were burning through the thin posts. I used a oxygen acetylene torch and brazed them. Specs call for a nonreverable connection, and clamps cause problems with loose connections down the road. I also had to bond the fence fabric.


 


no offense, but what did you do, chew that up and stick it on there? That's some bubble gum looking chit.


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## JohnR (Apr 12, 2010)

Someone used to make a ground clamp I forget what type, that was irreversible by having the head of the bold wring off leaving a round wedge shaped head. When the proper torque was reached, the head would wring off and the shoulder of the wedge would keep it tight.


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## drsparky (Nov 13, 2008)

mcclary's electrical said:


> no offense, but what did you do, chew that up and stick it on there? That's some bubble gum looking chit.


I hadn't picked up a brazing rod in 30 years! It may be ugly but it is strong. Actually it is better looking than most exothermic welds.


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## McClary’s Electrical (Feb 21, 2009)

drsparky said:


> I hadn't picked up a brazing rod in 30 years! It may be ugly but it is strong. Actually it is better looking than most exothermic welds.


 


You did a fine job, and better than most people:thumbsup:

I only picked because I can braze like an professional welder:whistling2:


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## Jlarson (Jun 28, 2009)

mcclary's electrical said:


> I only picked because I can braze like an professional welder:whistling2:


Pictures or it didn't happen...


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## Voltech (Nov 30, 2009)

I have to Cadweld some Steel sch 40 3" and 2" post at a cell tower in the coming weeks. I have done some Cad Welding before but never to fence post. Can anyone point me in the right direction to get a mold or one shot for this?

I know "cad welding" is a trade name, what the process called..

Thanks


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## ElectricJoeNJ (Feb 24, 2011)

Voltech said:


> I have to Cadweld some Steel sch 40 3" and 2" post at a cell tower in the coming weeks. I have done some Cad Welding before but never to fence post. Can anyone point me in the right direction to get a mold or one shot for this?
> 
> I know "cad welding" is a trade name, what the process called..
> 
> Thanks


Exothermic welding


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## wildleg (Apr 12, 2009)

isn't fence post usually galvanized ? Can you do that ? I've only ever cad welded to grade 60 steel.


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## MWayne (Nov 8, 2010)

Voltech said:


> I have to Cadweld some Steel sch 40 3" and 2" post at a cell tower in the coming weeks. I have done some Cad Welding before but never to fence post. Can anyone point me in the right direction to get a mold or one shot for this? I know "cad welding" is a trade name, what the process called.. Thanks


Used to do quite a bit of cad welding for catholic protection purposes, we only had a flat mold and if a bond was needed on an odd or poorly situated surface we would cad weld onto a small flat piece of metal and then arc weld that to whatever.


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## Rollie73 (Sep 19, 2010)

wildleg said:


> isn't fence post usually galvanized ? Can you do that ? I've only ever cad welded to grade 60 steel.


I know this is a 3+ year old thread but what the hell..........

Yeah.....you can exothermic weld to galvanized pipe or steel but you have to grind it down first then do the weld. Have to cut that galvanizing away......be sure to spray it down with cold galvanizing spray after welding though because that pipe will rot away overnight (seemingly).

They do make a mold that fits to the curve of a pipe in various sizes. I usually get something close.....clamp it on and pack the joint where the mold meets the pipe with lots of duct seal. I usually don't use the entire shot either....I dump about 3/4 of the shot in there, maybe a bit more because it will burn through a thin wall pipe pretty quickly.


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## wildleg (Apr 12, 2009)

MWayne said:


> Used to do quite a bit of cad welding for catholic protection purposes, we only had a flat mold and if a bond was needed on an odd or poorly situated surface we would cad weld onto a small flat piece of metal and then arc weld that to whatever.


did all the catholics you protected thank you , or maybe even the pope ?


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## MWayne (Nov 8, 2010)

wildleg said:


> did all the catholics you protected thank you , or maybe even the pope ?


Auto correct strikes again.


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## searlest (Dec 15, 2007)

*Thanks Rollie 73*

Thanks Rollie73 revived the thread just days before my search for information :thumbup:

I am requesting information on Cad weld / Burndy weld...

* I need to get some type of kit together for a few upcoming paint booth installations the application is cad weld to bean conductor usally on th esmall side #6 - #2 AWG however I want a kit that has several molds for different applications.

I am not the familiar with the tools or process.....Can someone please line me out and suggest Brands of Molds, and related material that I will need to aquire to have the basic "A Kit" to cover common applications 

Thanks :thumbsup:


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## sparky970 (Mar 19, 2008)

horsegoer said:


> Ok, I believe Cadweld is just the name used by Erico but is the same thing as an exothermic weld. I know this is used to join two conductor together without heat by using a chemical reaction. Can you Cadweld a conductor to building steel and if so how. The Cadwelds I saw involved putting the conductors into an enclosure and pouring the shot in. So I was wondering how that would work when welding to building steel. Thanks.


Cadweld is exothermic welding and heat is the main component


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## sparky970 (Mar 19, 2008)

RIVETER said:


> What circumstances were you in that you had to cadweld a fence post?


We do lots of substations where it is spec


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## sparky970 (Mar 19, 2008)

drsparky said:


> I hadn't picked up a brazing rod in 30 years! It may be ugly but it is strong. Actually it is better looking than most exothermic welds.


No, it is not


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## sparky970 (Mar 19, 2008)

If your buying new, go with Cad +


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## Big John (May 23, 2010)

sparky970 said:


> We do lots of substations where it is spec


 Yeah, that's NESC.


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## ShawnM (Feb 8, 2019)

I had an issue with my shots burning through posts today. The 6.5” posts welded fine but the 2” burned through. Is the solution a smaller shot? And will that still provide enough material for a proper weld? My mold is for a range of post sizes so my understanding is that the shot is sized for the size of wire. My mold shows only one size shot for it. Any constructive feedback is appreciated.


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## craigmoney (Feb 14, 2019)

I wouldn't try to change the shot size. My first thought might be to weld a piece of channel iron onto the post and then cadweld to that.


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## telsa (May 22, 2015)

Crudely put, Cadweld is going to melt through EMT as it's configured for RMC.

Anyone attempting to Cadweld to THIN steel is a fool. 

For those curious, the 'exothermic process' goes way, way back. It consists of using aluminum as a powder to pull oxygen away from steel oxide, or copper oxide. Its first use was in shipyards where truly massive propellers were 'Cadwelded' together out of cast segments of bronze. The scale of these welds would blow you mind. Hundreds of pounds of aluminum would be fired off. Later magnesium was added to the brew. It is easier to ignite, that's why.

2Al + 3CuO2 ==> 3Cu + 2Al2O3 + HEAT in staggering amounts

(The Al2O3 is light, and is thus floats away from the weld.)

Super scale propellers was the limiting factor as ships went large late in the 19th Century. At the time, Aluminum was a 'new thing.' (Its price had finally fallen to the point it could be used industrially.)

As for being forced to Cadweld to steel tubing that's too thin: you must beef it up. I'd recommend unistrut. You'll want to get rid of ANY Zn (galvanized coatings) as it will gassify during the melt. This will ph uck up your work rather completely. Gaseous Zn is also VERY toxic. Yes, it'll kill you has fast as make you sick Zn always has trace amounts of Cadnium (Cd) in it too. -- VERY lethal. 

(Cadnium = Devil of Zinc -- so deadly as a vapor it was recognized as such almost from the first.)

The unistrut will have all sides cleaned so that it can be welded to the tubing. Then you can Cadweld to it. Finally, at the end, you'll have to re-Galvanize everything you've touched -- there are liquids and pastes for this situation.

Repeating, you can't work around Zn coated steel and get decent welds -- as the metal will gassify during the weld... causing no end of troubles.

I haven't tried Naval Jelly, but its phosphoric acid might just be the trick. This stuff is painted on. It's been around for years. It removes rust, too. Keep the stuff off your skin and out of your eyes. Use PPE!

The patch metal will have to be welded // brazed to the tubing, of course. 

You can kill hours doing this in bad weather. Fun for the whole crew.


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