wrk101

Lye is not acid, its just the opposite, its a base. So the neutralizing step after OA is backwards. I have touted many chemical uses on this list, but I would not recommend using lye. YMMV.

+1 Find a machine shop.

Iowegian

Hacksaw 4 slots through the post 90 degrees apart from each other then use a pipe wrench. If the post is truly cut all the way or nearly all the way through, it should break into 4 pieces that can removed 1 by 1. It's easier to get a lot of torque with a pipe wrench than with vice grips and you can position the jaws so that they push the post towards the center to help break the pieces apart and away from the frame. At this point, I wouldn't expect the post to ever turn so you'll probably have to take it out in pieces..

Or take it to a machine shop. Estimates are usually free.

sjpitts 

If you have an inch of seatpost sticking out you could try and drill a hole through the sides of the post-- something that you could put a steel bar through to help you twist the seat post. Then put securely grab the seat post and bar in a bench mounted vise and rotate the frame-- after cooling the seat post down with dry ice.

If you can't secure the seat post in the vise and keep it from rotating I don't know how you could ever break it free.

tashi

I twisted, sawed, hammered with punches, used crap like liquid wrench and still couldn't get a seatpost out. When I plugged the top of the seatpost with caulk and filled the seat tube with lye, the post came right out.

Lotsa popping, hissing and gassing though. That stuff is scary. Be careful.

seedsbelize 

Machine shop. Those guys are artists. They'll guarantee their work. They'll do a fine job. After I've finally made that decision, it always becomes clear it was the only way. Take it in and forget about it.

snarkypup

I also advocate against lye. It's so dangerous, and you have to consider what you will do with the remainder. Just a simple mistake can have horrible consequences. My mother was nearly blinded as a child after spilling lye from a shelf into her eyes. Serious, scary stuff. A machine shop might cost $20 more, but you won't accidentally blind anyone by going there .

ftwelder

I guess I will have to clean house if you ever make plans to come to my shop.




I remove stuck posts all the time. I have a lathe that has been modified and made into a dedicated seat tube reaming machine. I am working on a device that uses mechanical action to remove them (grab and pull)

I watched 30 seconds of Kurts video and came up with a potential solution.

Amani576

If you weren't so far away I'd probably let you do it. But I don't have the money to ship a tandem frame from NC to Vermont.
I'll probably call a local machine shop in a few days. Find out if there's a waiting period or anything for whichever I choose to do it.
-Gene-

rhm

Thanks, I know I knew that once. I've edited my original post.

ftwelder

OK, I made a portable seat post puller. I just can't stand seeing you guys suffer.. It weighs 20 lbs but it's smaller than a tandem. I used it on one of mine and it works fine. I guess how it attaches to the post depends on what's ;eft of the post. I made a claw also not shown

IMG_3888 by barnstormerbikes, on Flickr

IMG_3887 by barnstormerbikes, on Flickr

gaucho777 

Nice work. Now head to patent office! How much load do you suppose the hook/claw could take?

SteveSGP

I realize you're past this point but I had a seat post severely stuck in an old Fuji frame and got it out with one of these,



Mine is similar to that but about 24" long, a pipe wrench with a standard 90 degree head would be better, basically once it's properly adjusted it just gets tighter the harder you push on it and it'll twist almost anything.

I'd imagine you could damage the seat tube as well if it was really rusty and the frame wasn't really strong though.

SteveSGP

That is brilliant!

ftwelder

That hook is part of a cheezy tie-down strap. May be 500 lbs or so. It has something like a 12:1 ratio. I used it standing upright but it would be better with a bracket mounting it to a corner post. Like on of those aluminum can crushers.

I have invented plenty of things and filed patents. In Fact, a one of a kind prototype bike with a unique suspension system I designed was recently stolen. I am much happier letting the stuff go.

southpawboston

that cantilever seatpost extractor doodad is pretty sweet!!!

tugrul

Damn, next time you need to use that thing, take a video so we can all share in the celebration.

nlerner

Frank, is there a possibility that the hold of the seatpost in the seat tube would be stronger than the braze on the seat cluster or BB lug, in which case those lugs would give way before the seatpost does?! I'm mostly thinking of my experience with a stuck stem on my Raleigh Super Course MkII; I had a wheel in the forks and the stem in a vise, trying to apply some serious torque, when one of the fork dropouts came out (and it had very little brazing material on it!).

Neal

Iowegian

^ I like using a 2x4 just below the fork crown (with a spare hub mounted in the fork). I suppose this could crack the fork crown or crush the fork tubes but it's worked for me so far.

ftwelder

It seems to not stress the frame very much. This bike, my Schwinn 1976 Voyageur, I had been riding for two months with the binder loose and regular soakings of oil and it wasn't moving. This thing popped it right out. It really takes very little effort. I would venture that riding the bike is far worse for it.

Roll-Monroe-Co

Now that is manly.

Amani576

BACK FROM THE DEAD!
Okay... I took a break from this project. But it's my only one, now... And that %%$#%@#$%# post is still in there.
I thought seriously about a machine shop, but had another suggestion from a senior mechanic.
A cylinder hone. Cause that's probably what a machine shop would do anyways.
I'm just wondering if, while a cylinder hone (brake cylinder hone) is designed for honing steel, I might be putting the poor thing through absolute hell. The inside of it is just scary. Maybe if I run a 1" drill bit down into it first? I have access to all of these tools now, and that would help clean up/thin out the inside before taking the hone to it.
Think I should do that? I could do it next week.
I'm just sick of this project hanging around. I have the money now to devote to it. And it's (almost) summer for crying out loud.
-Gene-

Veloh

Take a look at this:
https://www.the-climb.net/2011/06/mur...acid-pt-3.html
Be careful if you're going to try but it might be worthwhile. Just let it soak and the aluminum should slowly die.

noglider 

What about reaming it out? It would cost some money in tools, but it would be safe, as the only chemical you would need is cutting oil.

Amani576

That's the problem. I just can't justify the money on a tool I'm only gonna use this one time. And beside that, a reamer costs substantially more than a hone, so even though I'll likely only be using this hone one time, if I don't break it, I'll have it since it's a tool that pertains to my job. It might take longer, but with a drill and some music, I could make it work.
I'd do the muriatic acid, but if I'm gonna go dangerous chemicals, I'd just mess with lye and get it over with.
-Gene-

Alan Edwards

I agree with Tom, beg, barrow or buy some drill bits and drill out the post a little at a time. If you touch or cut the tube stop drilling and start chipping out the post with a small screwdriver. Get it together soon, you have a girlfriend willing to go with you, before it gets cold.