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nice! what ratio caustic / water did you use?
i take it you bunged up the inside of the tube somehow?
the fabricator i spoke to about removing my post said they'd heat the tube to get it out, thus wrecking the paint, so going to see if any other local companies can do it on a lathe...
bigshape-
In terms of ratio - I'm not sure....I put some cold water in old plastic bottle. Then shook some granules in, aiming for around 5 parts water to 1 parts soda. Give it a shake, it gets hot in the bottle. After about 30 seconds shaking and the bottle starting to shrink, pour it into the top of the post slowly, standing back as the bubbles spit out. You have a bit of time between pouring and bubbling. Wore some big sunglasses and thick rubber gardening gloves.
At the moment, its 100% more fun than the hacksaw. I have no idea how long it's going to take though. I did a few fills an hour apart last night, then left it soaking till morning, did another fill, let it die down a bit before leaving to soak all day in the shed. If it's close by the end of weekend I'll be happy.
Plugged the bottom of the seat tube with blue tack via the BB shell. Seems to be holding remarkably well.
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Also, I heard heating is a no go with alu on steel. Alu expands more than steel, so it gets tighter. You want to freeze it, as alu will contract more. Some folks mentioned using a CO2 canister, or dry ice, to shock freeze the post so it breaks the galvanic weld.
Scrabble
Bubbling has started....