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Post by franz on May 24, 2011 1:45:41 GMT -5
You ever given any consideration to eroding broken bolts & taps using an arcair carbon with kerosene running through the hole and a TIG machine for power?
I have a good hunch it can be done.
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Post by markkw on May 24, 2011 10:42:36 GMT -5
Doubt it would be of any value as arc is doing all the work anyway and the vaporizing liquid would wipe out the arc control. For deephole field work, one is best armed with cored piercing tube if the hole diameter is sufficient to allow such. For small diameter critical dimension work, best to use EDM if the part cost warrants the salvage work. For most field work I used a CCAG rod with an independent extraction source.
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Post by franz on May 25, 2011 2:52:45 GMT -5
First the kero doesn't vaporize, it goes thru so fast it remains liquid and floats the cooked metal away.
There was the beginning of a discussion on Homeshop Machinist but them chip kids went and diverted it over to wire EDM. Many years back I played with a tap disintigrator for a while, and other than all the juice squirting around it worked pretty good.
I'm thinking either a square wave TIG or sawtooth wave might be of some use.
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Post by markkw on May 25, 2011 23:25:32 GMT -5
Kerosene
Flashpoint: 98-149°F
Boil point: 302°F
Auto-ignition: 428°F
Melting point of common HSS: 2600°F which puts the cut at roughly 2300°F above the auto-ignition temp of the Kerosene. You'd have to have one heck of a flow volume to keep the cut not only flooded but also with sufficient excess to absorb and carry away the heat without allowing the kero to reach 98°F or you'll get a vapor flash.
I really don't see what benefit one could possibly gain from this since some granulated thermosilica would accomplish the slag float far more efficiently and a whole lot safer. This sounds a lot like the hype over the gasoline scrap yard torches they were pushing in the 90's, all fine and dandy until they found out the expansion is easily driven into a feedback loop until the whole rig blows sky high.
Seriously, if you're going to go through all that, why not just do a stick & heat and turn it out? Or, a thermal shock? Bigger diameter taps are easily taken out with a cored piercing rod, was on a jobsite one day when the fire sprinkler contractor busted a 2.5" NPT off in a standpipe fitting that was poured into a 20" thick concrete & brick wall. Granted I was set-up already installing air handler frames so it only took 15 minutes to save the sprinkler crew many thousands if dollars and lots of man-hours for their boo boo.
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