Stuck aluminium seat post in steel frame

[jayonabike]

Ive tried brute force, boiling water and bashing with hammer and chisel. Is it removable?

 

[Keith Oates]

Get a hacksaw blade and run it up and down the inside of the seat post. It will take some time to cut it through but it can be done.!!!!!!!!!!!!!!!!!!

 

[KneesUp]

You can dissolve the aluminium if you want to go all bubbling-potions level drama.

 

[Illaveago]

Ive tried brute force, boiling water and bashing with hammer and chisel. Is it removable?

View attachment 395788

View attachment 395790

It is a shame that you haven't left any post protruding as you could have used it to fasten anything to it . As the previous person has said you do not have many options left , apart from using a hacksaw blade or a drill down the sides to make segments.
How long is the post ?
You could still try using some caustic soda solution to see if it could break through the seal between the steel frame and the ally seat post. You would have to plug the hole in the seat tube with something like plumbers mate or putty. Make a dam around the top of the frame by the post, and wearing protective gloves and goggles pour some solution around the post and leave it to work.
I was thinking of how you could grip the post once the solution has worked. You may be able to drill down vertically into the post and fit some self tapping screws which may allow you to rotate the post by using a bar between them. If you are lucky enough to see some movement, spray penetrating oil in and keep working it back and forth with slight upward pressure.

 

[KneesUp]

You need a tool that perhaps only exists in my head, and is called an umbrella puller if you want to yank it out. The 'tool' drops inside the postand then once past the post and into the frame you can expand it so it's legs touch the bottom edge of the post. Then pull it out. Sounds like the sort of thing you should be able to get to attach to a slide hammer but that's beyond my pay grade!

Or you could just dissolve it all.

 

[swee'pea99]

caustic soda solution to see if it could break through the seal between the steel frame and the ally seat post

From my recollection of that deranged YouTube vid, the caustic soda doesn't 'break the seal'; it simply dissolves the aluminium. This is definitely the solution of last resort, but it does seem to work.

 

[Deleted member 35268]

I can empathise with your frustration.

 

[jayonabike]

It is a shame that you haven't left any post protruding as you could have used it to fasten anything to it .

That’s because I had the bike upside down with the seat post clamped in a vice. All it did was tear the post so I had to cut it off so there was no jagged edges.

 

[jayonabike]

I can empathise with your frustration.

Yes it is a bugger. It’s a nice frame. It’s only 520cromoly but seems a shame to have it just sitting there. I thought about building it up and using to get to work.

 

[jayonabike]

If I go down the caustic soda route I take it the paint around the top of the seat post will be damaged so we’re talking respray?
Don’t want to spend loads on it so don’t really want to start splashing out.

 

[Deleted member 35268]

My only Heath Robinson solution would be to try and "hook" a long metal section that has an inner edge under the bottom of the seatpost, within the frame... . But I appreciate having a long thin metal something with a nut on the end is going to be hard to source.

 

[iluvmybike]

Now that it has been cut down to that very low level yuor best resort is this guy - http://theseatpostman.com/

 

[Gravity Aided]

My only Heath Robinson solution would be to try and "hook" a long metal section that has an inner edge under the bottom of the seatpost, within the frame... . But I appreciate having a long thin metal something with a nut on the end is going to be hard to source. View attachment 395816

Rather looks like a stem bolt there, you could fit the wedge down there and it might peel it off the inside a bit. Otherwise, it's lye, and that must be done outside, as the chemical by-product of a lye/aluminum reaction is hydrogen gas.

 

[loopybike]

My only Heath Robinson solution would be to try and "hook" a long metal section that has an inner edge under the bottom of the seatpost, within the frame... . But I appreciate having a long thin metal something with a nut on the end is going to be hard to source. View attachment 395816

A length of "all thread" with a nut on will do that. Then use a slide hammer to get it out. If you're anywhere near Telford you could drop it into my workshop and I'll do it for you foc

 

[Gravity Aided]

Another thought would be to get a step drill/reamer and have a machinist turn it down to the proper size and drill it out. But a machinist may have the proper drills to do that in the first place. I also used a dremel once to cut slots in such a problem, until I could very faintly see I was close to the edge of the aluminum. I don't suggest it.