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Good work Tom, been reading about your caustic soda exploits with interest, getting rid of the alu residue is one things that puts me off this method. I've got three frames with seized posts, but think I'll try the hacksaw method first and if the cutting is too tedious I'll break out the chemicals.
It seems the tricky part of cutting with a hacksaw is being able to cut evenly all the way down to the bottom of the post. My plan is to get a length of wooden dowling and fix a hacksaw blade into it, that way I'll be able to get all the way down the posts and apply even pressure. Will post pics when I get round to giving this a go...
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Guess what this is...
It's out. There's still a little 5mm ring of old seatpost a bit further down the inside of the tube but I think it's far enough down not to interfere. There are also quite a few little nicks from my screwdriver and a lump of blu tac from a previous bung which has now gone native. I've tried flossing it out with some brake cable outer but to no avail. Maybe it will just have to be my bike's mascot.
I think I've flushed enough GT-85 laced soapy water through the tubes that I can build it up tomorrow.
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I have a seatpost to remove, took it over to @privatepatterson to stick it in a vice and didn't move so now looking at chemicals. I have chopped it about an inch from the end of the frame and measured sticking a tape measure down to hook the end of it that 13cm of post are inside the frame.
Looking now at the caustic soda methods, has anyone tried slower repeat applications or is it always going to be a violent thing with chemicals splashing about?
Also how long does it take, if I had say 4 hours to let it sit and bubble and reapply would that be enough?
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It takes about a week.
Basically:
1.) Plug the frame with Blu-Tac
2.) Wear goggles, Marigolds and protective clothing
3.) Mix the caustic soda in a really strong solution (eg. 250g of crystals to 500ml water) in a small batch (only enough to fill the tube) and pour it in
4.) Leave it to fizz for ages and then drain and re-fill with another batch
5.) Repeat ad nauseum (it took me about a week)Alternatively, take it to Armourtex and they'll get it out for £35. Either method will mess up your paint.
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Found this, I think I'm going to setup something with pipe like this.
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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...
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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.
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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.
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I'm looking at plastic pipe over the seattube end and I need to make some sort of seal around that and the top of the seattube, fingers crossed only the paint on the very top clamped bit is damaged which could then be covered with the seat clamp.
The diy crownrace plastic waste pipe tool I'll be cutting short is like this.
I just need to work out a suitable material to go between that and the end of the seattube that I can jubile clamp around, unsure about using innertubes tho lots of people seem to be using them to protect from chemicals.
Solution will be 2:1 water:crystals, has been suggested by a few people as a good mix.
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Blu-Tac is fine and isn't melted by the heat.
Mixing and stirring it before you pour it in is definitely the way to go, otherwise the crystals can solidify and block up the tube and you'll have to chisel it out.
There really is no need to heat the water first, if you mix a strong enough solution (I recommend doing it in a plastic bottle you can shake/swish around) it will heat up instantly anyway.
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For the time and effort I find stuck seatposts are often easier to take to your LBS. I had a carbon stuck in a steel frame and took it to Tom in Cycle PS who did a sterling job. Hacksaw method mainly
Previous I had a Mercian that needed a respray so sent it back to Mercian, took it out and I think looking at about £30-£40 costs
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I meant to post this link a while back:
http://www.theseatpostman.com/
The guy apparently has a method and tooling to remove any seized seatpost without causing damage to the frame or seatpost. We are sending a customer's frame away soon for this service.
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Yeah I was intrigued and spoke to him last year about it, he said coming from an engineering background he'd designed and built his own tooling to remove posts but didnt give any more than that away. If only he was based in or around London as I found the cost of shipping a bike/frame up to him and then back again a bit off putting, although for something fancy or with sentimental value it's totally worth it.
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Not steep at all if you've got a Hetchins or something of value and there's no damage to the frame and paint.
If it's just a beater then yeah that's a bit of dough.
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Removing stuck or seized seatpost?
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I attacked it with a screwdriver and managed to get between post and tube for about the length of the screwdriver blade all the way around. I tipped another batch of XX strength in so hopefully more will have gone now. Armourtex said £25-£35 for the reaming and that it could be done today or tomorrow latest so it might be worth that just to get it over with if this hasn't worked either. I've done the hard part!