CyclingFool95 

For the last six months or so, I've had a Pinarello Record with stuck Cinelli stem soaking in WD-40 to no avail. FInally on Friday I gave up and sawed the thing off. Turned out the headset was so well gummed onto the fork that I demolished the nut and top race trying to remove them, finally using a pair of vise grips once the hexes had been thoroughly rounded. Not one of my finest efforts. End result of the demolition derby shown:

CyclingFool95 

But, I still have a chunk of aluminum thoroughly stuck in the fork. I dont know why the picture looks so awful but the threads on the fork are fine

CyclingFool95 

Now, the fork is sitting upside down in a tomato sauce jar of drain cleaner, out on my driveway, bubbling away quite happily. Liquid is now completely black, and the jar is noticeably warm.

One molecule at a time, though, I think this is going to take a while.

bubbling (Click on the link for a video - the sound, other than the birds, is the sound of hydrogen being emitted)

ridelikeaturtle

If more than just a cursory lesson in biology, chemistry, physics, and calculus, were imparted on the masses, the world would be a much better place.

CyclingFool95 

It's probably worth pointing out that the main chemical in drain cleaner (ie lye) can cause severe burns, blindness, etc. And, the hydrogen gas emitted by the reaction is extremely flammable (think Hindenburg). So, exercise extreme caution ye masses and don't try this in the house.

Mad Honk 

Yes! Dangerous indeed. But it works so well. you are going to have some pretty clean steel when you are finished. Lye does work but just a bit slow. Smiles, MH

cyccommute 

The hydrogen generated is flammable but the concentration you are generating isn't. Aluminum is a reactive metal but it's a slow reaction.

And the lye doesn't really "burn". It hydrolyzes the fat under the skin...turns it into soap. The blisters are formed from the skin not being connected to the fat anymore.

kaos joe

[QUOTE=cyccommute;21536031.....And the lye doesn't really "burn". It hydrolyzes the fat under the skin...turns it into soap. The blisters are formed from the skin not being connected to the fat anymore.[/QUOTE]

My middle school chemistry teacher took a bizarre relish in describing this phenomenon to us. I remember this satanic gleam in his eye as he said the word "saponification". He was a character for sure.

CyclingFool95 

Falls under the list of things to avoid so I dress appropriately

Phoenix800

Get a bucket. Fill it with muriatic (hydrochloric) acid up to about two inches deep. Carefully place the steerer tube end of the fork in the acid. Then - RUN AWAY!!!

The muriatic acid will dissolve the stem in a couple of minutes. Do not breath the gas that results from this reaction.

squirtdad

Just to note wd40 is not a good penetrating oil. I have have best luck with freeze off

good luck on the chemistry

CyclingFool95 

Thought about acid but it could damage the steel. The strong base will not. I'm not really in a hurry.

DeadGrandpa

I use a product called "PB Blaster" for loosening rusted things. Don't know if it works for aluminum, but it's a miracle for breaking the rust bond.
It penetrates like crazy.

SethAZ 

When I was a teen I'd collect hydrogen in a balloon doing this and re-enact the Hindenburg. But yeah, it's dangerous stuff if misused or safety precautions aren't taken.

If I'm understanding this correctly, the purpose of soaking that steerer tube in the lye is to react away enough of the aluminum that it can be removed from the steerer tube, all without harming the steerer itself?

ramzilla

I've had really good luck using diesel fuel to loosen rusty stuff. It does a great job. If you can rig up a containment system to soak seat post tubes or bottom brackets for several days it works even better.

CyclingFool95 

That's exactly it. Works with a steel steerer and aluminum stem - obviously wouldnt work well if your fork had an aluminum or carbon fiber steerer.

CyclingFool95 

My jar of Lye powder just arrived. Has a warning on the label not to allow it to come into contact with Aluminum. Also that its safe on Chrome. Sounds like a win-win.

I filled a sauce jar about 4-5" up (to fully cover the stem) and added a generous amount of lye powder - about 1/2 cup to a cup I'd guess (not a fan of measuring). Stirred using the steerer tube. Stepped back. Within seconds the jar was too hot to touch and the reaction is tremendous - far more than with the drain cleaner. This may not take so long. If I see the top of the steerer resting on the bottom of the jar, I'll know its done.

CyclingFool95 

3 hours later, I've had to refill the cauldron twice with water and lye powder. At one point it was bubbling so fiercely gas was pouring out of the steerer opening like it was a chimney. At last refill, a half hour ago, all that was left was a layer of aluminum around .030" thick, where this morning it was at least 1/8". It might be done by now.

I'm really entertained by this entire exercise, whether the actual application of high school chemistry, or the painless solution to a six month headache,

CyclingFool95 

One last follow-up. The science experiment is complete. Aluminum stem is gone. Steel and chrome are unharmed. I washed the fork down thoroughly with water and then sprayed every inch of it with WD-40 both inside and out. "Sanded" the chrome with a wad of tin-foil and the foil/WD-40 combo took off whatever rust there was on the chrome. Beautiful, clean, ready to re-install once I find a new headset.

This sliver of stem is all that was left in the fork when I took it out of the bath. Had I left it a little longer, even this would have been gone.

bikemeister

Alot of guys at a tool forum I frequent are ecstatic about a 50/50 mixture of acetone and automatic transmission fluid. I mixed up a batch - gotta say it rarely lets me down. Stuff is amazing on un-sticking frozen mechanisms. Maybe it'll work for ya? Cheap to try in any case.

dmark 

20 hrs in an enameled pot with close to 1lb of lye freed up the fork to my curb find 88 Ironman Master. Started yesterday afternoon.

JanMM

Aptly named thread, indeed!

WizardOfBoz

Guys, I'm all for the use of chemistry to make things better (BS and PhD in Chemical Engineering), but I've gotta say I'm really concerned about the rather casual disregard for safety. As cycommute says, lye will turn your skin from a water resistant barrier to a water soluble bar of soap, pretty much killing all the cells in its path. Seriously, this stuff can do grisly damage.

Some recommendations:
1) To remove a piece of aluminum (seat post, handlebar stem) from a tube that you have access too, like the OP's stem, the machinist's classic approach is a) penetrant, like Kroil, PB Blaster, or 50/50 ATF and acetone, and if that doesn't work b) heat, using a torch. You apply the flame to the steel tube (AFTER you remove all traces of the penetrant!) and the heat expands the tube and breaks the grip of the corrosion. If this doesn't work, depending upon the value of the fork, it might also be worth electrical discharge machining (EDM) to slice up the stem enough to remove.
2) A mechanical approach (coupled with penetrant and heat) helps. Put a steel bar into the bottom of the fork, rest the fork shoulders on your vice with some leather to protect finish, then wail on the bar with a hammer to pound the stem out.
3) If you use strong bases like lye or potash,
a) Wear a face shield and googles and use thick chem resistant rubber gloves
b) NEVER add water to base. NEVER EVER!. Dissolving base produces so much heat a splash of water into the base can create something like an explosion of caustic material. If you feel compelled to use lye or potash, add the base a small amount at a time to a large amount of water that is in a heat-proof (not plastic!) vessel. Stir with a glass rod or a stainless utensil (you're still wearing gloves and goggles and a face-shield, right?). You can repeat this process to get the amount of base dissolved you want, but monitor the vessel temperature. Dumping a large amount of base into a small amount of water can lead to the released heat boiling the liquid and producing a small explosion of boiling caustic.l The gradual process allows time for heat to transfer out of the liquid.
c) Be careful how you dispose of the left-over liquid. It may be illegal to dump this down the drain, or on the ground, in your locality. Check before doing. If you are allowed to put the stuff down the drain, it should be done with the cold water faucet in a utility base turned full on, and the waste liquid added very gradually. Then run the faucet for 10 minutes or so after you've emptied all the caustic solution. The water initially dilutes the stuff so you don't have pockets of strong base in the sewer system. Leaving the tap on ensures that all of the base gets washed out of your pipes into the sewer.

If you use a septic tank and field, I would not use caustic. I would not dispose of caustic into that field.

Finally, I probably would never use chemical means to remove a stem. I would have clamped the fork vertically and would then have used heat and progressively larger drills to drill the stem till it was loose enough to knock out.