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PostPosted: Fri Jun 07, 2013 12:00 pm 
Dirt Disciple
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Joined: Sun May 19, 2013 5:51 pm
Posts: 46
Location: Seaford, East Sussex
Bought this Orange P7 on ebay a few weeks ago, and was apparently all fine until I realised I had to drop the seat as was too high for me.

Unbeknown to me, or apparently the seller, the alloy seat post is properly corroded into the P7's steel tubing.

I have tried all known methods: basic turning of the post impossible; more forcefull approach with a vice also failed, even my bike shop was unable to make it move even half a mm; leave soaking in decent penetrating oil; pour in Coke plugging all holes with plasticine, use combo of heat and cold, general swearing and shouting, more brute force attempts etc.

Only thing didn't try was ammonia or Caustic Soda, although I did buy a bottle mostly because there is simply no cavity/space for any liquids to penetrate , so decided to leave these till the last stage which is cutting.

And that's where I am now, started off OK, but what you see in the photos literally took 8 hours of sawing and filing just to be able to peel back a few strips from the top. The real mare is that the post is about 5" down into the frame, so regular saw blades proving hard to get and reach the posts end.

I think in time, with more gentle sawing, open up a few more cavities, I can try the Coke and Caustic liquids again. If that fails then it's back to just more time consuming sawing and poking.

A few photographs to show the pain:

Image
Image
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PostPosted: Fri Jun 07, 2013 1:35 pm 
Windmilling for a Scotch Egg
Windmilling for a Scotch Egg
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Joined: Tue Feb 15, 2011 10:27 am
Posts: 4840
Location: Huddersfield, West Yorkshire
Looks like you are being careful with it anyway - keep patient and it'll be sorted out - the sense of joy when it's free and you clean it up and slip a new post in will be worth the pain!


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PostPosted: Fri Jun 07, 2013 1:43 pm 
retrobike rider / Gold Trader
retrobike rider / Gold Trader
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Joined: Sat May 09, 2009 11:46 pm
Posts: 3924
Location: East Riding of Yorkshire
I have to say I would have resorted to caustic soda before spending 8 hours sawing.

Now you've got that far with the sawing it seems a waste to switch to another method, but at the same time, if it's still going to be a few hours work I'd be tempted to react it with caustic soiad to get rid of it more easily.


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PostPosted: Sat Jun 08, 2013 10:11 am 
Old School Grand Master
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Joined: Mon Jun 14, 2010 9:06 pm
Posts: 4431
Location: Herts UK
i reckon you are wasting your time sawing and risk damaging the seat tube. put a bung in the frame and let the soda do the work for you.


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PostPosted: Sat Jun 08, 2013 12:37 pm 
retrobike rider
retrobike rider
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Joined: Tue Apr 18, 2006 8:00 pm
Posts: 344
Location: Rustington
Ah that will buff out, keep going your on the right track I had exactly the same issue in a Ti Merlin frame and a 400mm Thomson post that was in 3/4 of the way. Keep sawing and peeling back as you are doing. I'm sure you are but a long handle hacksaw with a long blade should reach down that far.



Good luck


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PostPosted: Sat Jun 08, 2013 8:26 pm 
Old School Hero
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Joined: Tue Jan 08, 2013 8:47 pm
Posts: 199
Location: Barrrkshire
I know the feeling :facepalm:

I had to do the same with my P7
A well known and respected frame finishing company said heat was the only way to free my seat post which would have ruined the Nickel Finish then cost me another £100 for a respray
I was desperate to keep the nickel so I resorted to caustic soda
Took me a weekend of mixing the soda as concentrated as I could ( forget the recommendations on the bottle) wear glasses and gloves and do it outside. I must have filled and rinsed 20 times but it was quite cool to watch the soda do it's stuff and such a great feeling when there was no alloy left
No physical effort let the chemicals do their work, your time spent so far will not be wasted as you have reduced the amount of alloy left to dissolve

Good luck in whatever you choose to do

It will be worth it in the end P7's ride so good!


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PostPosted: Sun Jun 09, 2013 3:28 am 
Retro Guru
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Joined: Fri Jan 13, 2012 2:28 am
Posts: 1057
Location: Near Gatwick
Aluminium Ohhh wrote:
Took me a weekend of mixing the soda as concentrated as I could


I find if it's to concentrated it boils and doesn't do a lot. I mix it so it heats the water to about 50ºC, a couple of goes usually removes a seat post.
I did post some photos from the last time I removed a post.


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PostPosted: Sun Jun 09, 2013 8:14 am 
Old School Hero
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Joined: Tue Jan 08, 2013 8:47 pm
Posts: 199
Location: Barrrkshire
You may well be right, my mix did boil, maybe wrong but I thought it was doing more dissolving this way, whatever is was quite dramatic at times :shock:

I would leave around 45mins between flushing and starting again assuming there was no power left in the soda, I may not have done it the most efficient way but it worked :D

How long did you leave your mix in the frame?


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PostPosted: Sun Jun 09, 2013 7:11 pm 
Retro Guru
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Joined: Fri Jan 13, 2012 2:28 am
Posts: 1057
Location: Near Gatwick
Mix it so it doesn't boil and froth/steam out of the frame.
It will get hot while it's dissolving ali, so you chuck it in and you can feel it heating
the frame, you don't want to much heat if there are paint or stickers nearby.
I guess the reaction has slowed down a lot by the time it's stopped heating the
frame. I put the caustic in in the afternoon and the frame has usually cooled down in
a few hours or so, but I leave it till the next afternoon to clean it out and put more in.
I put enough caustic in the water to raise the temp so it feels warm not hot, I measured the temp at ~50ºC and it worked as usual, I thought 50ºC, even though it felt right, sounded to cool so I added more caustic for the second go[70ºC], it boiled and squirted out of the bottle bolt hole, I quickly poured a bit of water in to dilute it. I must be getting it about right as it's quite quick and a little bottles of caustic would last ages if I didn't use it for other things.


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