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This seatpost is a fair bit thicker. I think I'm going to make a setup with the pipes I have about so some waste pipe that was suitable diameter for crown race setting and I'll get an end for it. With any luck I'll be able to make a bung/cup/end to go over the seatpost and pour in from the BB side with a funnel.
Clockwise-
Sounds like a plan, have you bought your caustic soda yet, I got mine from Robert Dyas, was only a couple of quid. I reckon mixing the soda crystals with hot water first to make a solution and then pouring it in is the way forward, imagine it'd be better than trying to pour them directly into the seat tube. This way you can also experiment with different concentrations until you find one which gives a controlled reaction. For bungs old wine/champagne corks should do the trick, the hot solution would soften/melt blu tack etc.
GreatSince78
Yeah I saw that vid a while ago, looks like a good set up, I think ideally having a hose pipe on hand would also be useful, that way you can cool the area on the outside of the seat tube where the reaction is going on and stop your paint blistering. I guess maybe powder coat might handle the heat but the hose could also be handy to wash away any solution that splashes on yourself etc.
You'd think for someone who did a chemistry degree I'd favour the caustic soda approach, but I reckon hack sawing is still the way to go, I suppose if it doesn't work the next step would be the chemical option.
I found the final step of this guy's method good, he basically does the hack saw thing, but when it wouldn't budge even after cutting he inserted a steel rod via a hole in his bb shell and smacked it, although I suppose this would only work if you have a bb shell with a cut away like his...
http://patricktheaker.com/?p=223