Need help separating corroded aluminum parts

[Beach View]

Hello CF,

I hope you can help me separate my anodized aluminum cockpit table legs from their anodized aluminum bases. The bases are bolted & bonded to the deck so I have to work on them in place. I have new legs, but I have to save the bases.

The legs are tapered at each end to fit into the tapered holes in the bases. Over the years they have corroded themselves together. I’ve tried soaking them in penetrating oil, and I McGyver’d an adapter to be able to use a 2 ½ ton bottle jack to pull the legs up while beating on them, but no joy.

Does anyone know of any way to separate them or something (acid?) that would dissolve the corrosion?

My last resort is to cut the legs off as close to the bases as I can, make cuts from the inside of the stumps to the bases (the hard part), then bang the pieces out with a hammer.

Thanks in advance,

Bill

[coopec43]

Have yiu tried these ways?

https://www.wikihow.com/Clean-Corroded-Aluminum

[StuM]

Originally Posted by coopec43

Have yiu tried these ways?

https://www.wikihow.com/Clean-Corroded-Aluminum

I don't see anything there that would help the OP with two aluminium components locked together by corrosion.


If anyone does have a method, I'd love to free up the old aluminium screw covers to my emergency steering. They are locked solid.

[skipmac]

Originally Posted by StuM

If anyone does have a method, I'd love to free up the old aluminium screw covers to my emergency steering. They are locked solid.

Also have a few Al parts that have become one with each other. Also a never ending gang of SS bolts permanently bonded with Al masts, booms, hatch frames and various other boat bits.

I keep thinking that there must be something, some acid or solvent that would react with the aluminum oxide without dissolving the aluminum or SS at the same time but have struck out. Even asked a friend who is a chemist but wasn't his area of expertise.

If I can ever find this magic elixir I'll sell it to all the boaters and become rich beyond my wildest dreams.

[tkeithlu]

"I keep thinking that there must be something, some acid or solvent that would react with the aluminum oxide without dissolving the aluminum or SS at the same time but have struck out. Even asked a friend who is a chemist but wasn't his area of expertise."

My chemist friend (I'm married to her) says there's not one that would not dissolve the aluminum itself. She recommends a chisel. Cut tthe legs off and then split the stumps.

[skipmac]

Originally Posted by tkeithlu

My chemist friend (I'm married to her) says there's not one that would not dissolve the aluminum itself. She recommends a chisel. Cut the legs off and then split the stumps.

Hope she's a very good friend.

This however is not what I wanted to hear. Sure she couldn't go back and do some post graduate work in metallurgy and invent some wonder goop?

[Nord Sal]

Perhaps a big pipe wrench could break them loose in torsion with a good quick snap? Or just chew up the leg.

[skipmac]

Originally Posted by Nord Sal

Perhaps a big pipe wrench could break the
m loose in torsion with a good quick snap? Or just chew up the leg.

From personal experience I doubt anything less than C-4 will be ineffective.

[Bycrick]

I have had good luck over the years by applying dilute muriatic acid, drop by drop, over days. My best/worst example was having to remove the spacer block where the shift levers are mounted on an Edson binnacle to get at a broken cable. 4" screws where the shoulder went through a 3” tall spacer before screwing into the top of the binnacle. It took almost a week with a cup of acid and a tiny paint brush, but they eventually came out.

[merlinuxo]

Originally Posted by skipmac

Also have a few Al parts that have become one with each other. Also a never ending gang of SS bolts permanently bonded with Al masts, booms, hatch frames and various other boat bits.

I keep thinking that there must be something, some acid or solvent that would react with the aluminum oxide without dissolving the aluminum or SS at the same time but have struck out. Even asked a friend who is a chemist but wasn't his area of expertise.

If I can ever find this magic elixir I'll sell it to all the boaters and become rich beyond my wildest dreams.

Try vinegar or coke. Oxalic acid is also very mild but I don't know about soaking aluminum in it. Might test with some scrap.

I do know that strong acids like muriatic will dissolve aluminum.

[tilostahl]

It sounds to me like you need the mechanical solution: flush saw cut, then drill a pilot hole and use a grinder bit to clean up the taper.

[donradcliffe]

I've used the muriatic acid and eyedropper technique before. It preferentially attacks the aluminum oxide, but you have to live with some loss of the aluminum. I used high strength acid, and had a hose handy to dilute it when things opened op--total project time about a hour.

[jakkum]

I take volts out of aluminium housings by putting the while thing on the drive.
That is impossible here, but if You put Aert cloth around thelegs that go in and gaat but carefull, aluminium melts gast, Heat up the stands, they willexpand faster than the legs.
If IT does not work the first time, cool everything down completely and try again.

[Boatguy30]

Those compents are generally made of daily poor quality aluminum. I have never personally tried the acid, just heat and PB blaster or other penetrating oil.

I'm thinking you really need to just get new bases as well. Regularly treat them with something like Woody Was or T9 spray. I think Woody was is just a cleaner was mixed with something like t9.

[SRQsailor]

I have had to free many steel bolts from aluminum engine parts, (cylinders, heads, Etc.) Aluminum vs ferrous metal is usually easy. A little penetrating oil and heat from a heat gun (please, no open flames!). The aluminum expands more then the ferrous, and the bolt usually works free.


For a tube inside a collar with aluminum / aluminum you'll need to provide cooling inside the tube and heat on the collar. Can you get some crushed ice inside the tube, or a wet rag that will keep it a bit cooler? Apply the heat to the collar, but shield the surrounding deck with wet rags, or a sheet of wood/metal) Obviously the temperature differential has to be significant.


Personally, I would revisit removing the collars from the deck. What are they bonded with? If you can remove the bolts and work the collars loose, a little grinding and re-bedding may be the less hassle.


Cheers,
MLT