air arc welding

I got a nasty little job. The joker that had the backhoe before me tried to repair the loose pin by just reaching down inside and welding on the pin. He
did a real shitty job and just made it damn near impossible to repair right. (BTW, I unbolted the top pin on the same side today, it fell in two pieces, the pin had stress fractured all the way through. I don't know why the hoe hadn't already fell off the tractor)
Anyway, I need to cut a 1.5 inch pin in two reaching down inside the hoe assembly along a crack about 3/4" inch wide. There's not room for the torch. So, I was talking to "the kid" about how to do this and he reminded me I had bought an air arc rod holder and air arc rod at an auction years ago.
Anyway, I found a rod holder that also plugs into an airline and blows an air jet down along side the rod. I also found a few rods labeled "Accate Jetrod" . its brass color tube about 1/2" diameter O.D. by 3/8" diameter I.D. with a black filler material. And half a box of solid brass color rod labeled "Arcair Copperclad". Both rods are very light - I suspect made of carbon.
There. that's all I know about air arc cutting. can anybody fill me in on how to use this to cut my pin? I have an Idealarc 300/300 AC/DC/TIG welder.
karl
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<snip>

I thought you said she could operate it well?
(sorry, I HAD to say it before somebody else did.)
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Tawm sez: "I don't know why the hoe hadn't already fell off the tractor.
I thought you said she could operate it well?"
Tawm,
You bagged me with that one !
Bob (busted a gut) Swinney
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I used to use an AirArc quite a bit but I don't remember ever reaching inside a crack to cut something. The whole rod is conductive and it seems it would be difficult to keep it from arcing on the sides of the gap you are working through. They are great for gouging welds though. Steve
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Up North wrote:

The cutting rods they use underwater are insulated with tape the whole length, and I believe they work fine above water with the only caveat being that you can't put them out so the whole rod will burn. They feed O2 down the center, not air.
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Good point, i'll have to lay a sheet of something non conductive on one side. From google it looks like I go DC straight, hi amps as I can, and undercut gouge to blow molten material away. Any other tips?
Karl
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Karl Townsend wrote:

Have a good fire extinguisher handy and watch out for your hydraulic lines.
John
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Karl Townsend wrote:

Wrap the rod in electrical tape to insulate it from arcing to the sides.
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On Wed, 2 Jun 2010 20:14:05 -0500, "Karl Townsend"

http://www.weldguru.com/CAC.html
http://www.tpub.com/content/construction/14250/css/14250_163.htm
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...

Gunner,
thanks for the great tutorial.
karl
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On Thu, 3 Jun 2010 05:57:09 -0500, "Karl Townsend"

Ive got an Arcair K3000 torch and some 'trodes. Ive only used it twice..but nothing else would do the job.
Sorta fun and sorta scary the first couple times <G>
Gunner
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It sure did the job for me. Melts and blows metal out WAY faster than the torch. I'm pretty messy with it, not a clean cut like the torch. Experience may solve that. But I've owned the unit over ten years and forgot about it. May never need it again.
On another note, I hit my honey with a sledgehammer today. She was holding a 1-1/2 inch pin so I could hit it with the BIG sledgehammer. it got cocky and a blow slid off hitting the vice grip she was holding. Amazing - the lady is still talking to me. But it may be a while till I get help with a metal project again.
Karl
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wrote:

Bloody Hell - why do you guys insist on making things so complicated?
Karl - - try and cut through the crappy welding you refer to - thin blade, whatever size angle grinder it needs, or oxy the thing out from the OUTSIDE - you'll be left with a big crappy hole, but the other method leaves you with a smaller crappy hole - just takes longer, thats all. You will be making up cover plates over the original (elongated) holes, so why be so fussy? And whats the bore on the bucket pin holders like? - see how eccentric/ worn/just plain stuffed they are. (Hope the rest of the machine isn't a wreck as well - sounds like the previous owner(s) weren't into maintenance....
Mate, is this thing a tool , designed to earn its keep, or a project?
Andrew VK3BFA.
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wrote:

All machine tools, from bandsaws to backhoes come into the category of "toys"
:-)
Mark Rand RTFM
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I readily concede your point re toys Mark (we wouldnt do this otherwise) - but its important to distinguish that which puts bread on the table and something thats interesting to tinker with. Andrew VK3BFA.
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