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Old 19-09-2010, 22:28   #1
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Aluminum Parts Corroded Together . . .

In disassembling our Hood roller furler, we've run into a problem. There's an aluminum casting that's inserted into the end of an aluminum tube. In the years they've been installed, they have managed to corrode together. We've gotten it to move a LITTLE, but only about 1/8", in beating and soaking with PB Blaster.

I've done some research, an it appears that ammonia or NaOH might be better solutions. Anyone have an ideas? In order to disassemble this, I really need to get these apart.

Thanks in advance.
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Old 19-09-2010, 22:44   #2
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Sodium Hydroxide/lye/Draino

A little Draino should work but don't leave it on very long as it rather quickly turns aluminum into hydrogen and a fiew other byproducts.
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Old 20-09-2010, 05:14   #3
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A little Draino should work but don't leave it on very long as it rather quickly turns aluminum into hydrogen and a fiew other byproducts.
Sodium Hydroxide (NaOH, or Lye), AKA Drano Crystals (not liquid Drano), will aggressively attack aluminum.
Do your own due diligence, and be extremely careful.
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Old 20-09-2010, 05:33   #4
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My aliminum whisker pole is mounted on deck forward. Gets a lot of sea spray. PO never used it, so the release mechanism was frozen solid. I soaked it in PB Blaster almost every day for about a month. It works well now
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Old 20-09-2010, 05:57   #5
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try heating up the parts separately ... heating causes expansion of metals and can often weaken a corrosion bond sufficient to break it ... start with boiling water, perhaps graduate to a low heat gas torch ... and much WD40 (or kerosene) ... but not near the flame
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Old 20-09-2010, 07:09   #6
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Heat, penetrating oils and time if you don't want to break it.
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Old 20-09-2010, 07:38   #7
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Hydrochloric acid will attack the oxide preferentially, but will also etch the aluminum, so it must be used with care and rinsed off after a few minutes.
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Old 20-09-2010, 07:54   #8
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Originally Posted by bstreep View Post
In disassembling our Hood roller furler, we've run into a problem. There's an aluminum casting that's inserted into the end of an aluminum tube. In the years they've been installed, they have managed to corrode together. We've gotten it to move a LITTLE, but only about 1/8", in beating and soaking with PB Blaster.

I've done some research, an it appears that ammonia or NaOH might be better solutions. Anyone have an ideas? In order to disassemble this, I really need to get these apart.

Thanks in advance.
If your furler is similar to mine ...

Sail Delmarva: Hood Seafurl 800 Bearing Replacement

you may not need to get that portion apart. I didn't. I was succesful in re-buildng the furler and have been very happy with the results; however, I did have to secure the furler line to the drum with a clove hitch and stopper knot instead of useing the hold in the drum, because it wouldn't open. No problems.

I tried PB blaster and some other persuation (big vise, heat, sledge, press) and stopped before I damaged the parts.
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Old 20-09-2010, 08:41   #9
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Thanks for the hints. It MIGHT be possible to do this without removing the tube, however this is where the adjustment is - and I think I need to loosen the rig a bit before I pull the pin. Otherwise, I may not get the pin back in! All the same, I may go for this approach.

I have drano crystals on the boat. NaOH is great for some things - but it is really VERY nasty stuff.

I also thought about using heat but 1) my torch was at home and 2) I worry about heat hardening or working the unit. I don't want to damage it.
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Old 20-09-2010, 08:48   #10
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Can you boil the thing?

We have boiled some corroded part and they let go.

b.
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Old 20-09-2010, 10:04   #11
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Thanks for the hints. It MIGHT be possible to do this without removing the tube, however this is where the adjustment is - and I think I need to loosen the rig a bit before I pull the pin. Otherwise, I may not get the pin back in! All the same, I may go for this approach.

I have drano crystals on the boat. NaOH is great for some things - but it is really VERY nasty stuff.

I also thought about using heat but 1) my torch was at home and 2) I worry about heat hardening or working the unit. I don't want to damage it.
Ofcourse, I have a different model, so I may not understand....

If by adjustment you mean the forestay turnbuckle, in my case I had to take the whole unit off and take the forestay loose. This is done by first sliding the drum up the forestay, before any taking-apart begins (there is a cap and pin about a foot above the drum that allow the parts to seporate). I recall there is a small set screw that comes out that allows half of the cap to slide up which allows the pin out that allows rest of the cap out and the furler to slide up, or something like that. This gives access to the turnbuckle. Clearly, you want to bring some halyards forward first, and back off on the backstay and mainsheet!

Then, the furler can be slid off of the forestay and taken home for repairs--everything is easier at home The foil stays on the forestay, held up by a pair of vise grips.

But I probably misunderstood. What model furler?
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Old 20-09-2010, 15:33   #12
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Ofcourse, I have a different model, so I may not understand....

If by adjustment you mean the forestay turnbuckle, in my case I had to take the whole unit off and take the forestay loose. This is done by first sliding the drum up the forestay, before any taking-apart begins (there is a cap and pin about a foot above the drum that allow the parts to seporate). I recall there is a small set screw that comes out that allows half of the cap to slide up which allows the pin out that allows rest of the cap out and the furler to slide up, or something like that. This gives access to the turnbuckle. Clearly, you want to bring some halyards forward first, and back off on the backstay and mainsheet!

Then, the furler can be slid off of the forestay and taken home for repairs--everything is easier at home The foil stays on the forestay, held up by a pair of vise grips.

But I probably misunderstood. What model furler?
It's a 3250. I have a hydraulic split backstay - and having had those off recently, it took a LOT of work to get the pins back in. The rig is VERY tight, and the mast has a bit of a bend to it. #15 into #14 is the problem child. I'm going to see if I can attach an exploded diagram:
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Old 20-09-2010, 16:12   #13
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It's a 3250. I have a hydraulic split backstay - and having had those off recently, it took a LOT of work to get the pins back in. The rig is VERY tight, and the mast has a bit of a bend to it. #15 into #14 is the problem child. I'm going to see if I can attach an exploded diagram:
Yeah, I think that is going to have to come apart. Sorry to hear that. The equivalent part on mine was loose.
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Old 22-09-2010, 09:27   #14
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OK, talked with my 89 year and 355 day old father, a corrosion engineer. Why didn't I do THAT earlier. He said to try a mild alkali, such as calcium hydroxide. I have that - it's pickling lime. You can also make it by baking calcium carbonate. Sodium hydroxide, which is drano, may work but it's VERY caustic and dangerous.

Also will try the heat to the tubing, cold to the casting thing.

We'll try a few things, hopefully this weekend.
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Old 22-09-2010, 10:04   #15
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Make sure you examine the exploded view very carefully. Especially where the foil goes into the lower drum.

I tried disconnecting the "second" joint and it would move up and down a bit like you describe. What I didn't know was that the first joint was inside the drum and the pin was in the drum unit. After I got the entire foil off the boat and on the bench (a few benches) in the boatyard I figured it out.

There was a tube in the lowest section to hold the aluminum slug of the first joint in place. Once I pulled that tube out from the bottom after the drum was removed the second joint released.

Hard to explain, I have a different unit than yours but the fact you describe it will move a little bit makes me suspect you haven't figured out the chinese puzzle yet.

Aluminum will corrode but it will have to be very visible and severe corrosion to lock the two pieces together and you do say it moves 1/8" - just like mine.

In regards to reassembling the forestay we had to completely slack the shrouds and back stay.

I am with thinwater - I think you have to get the entire foil off the boat.
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