Removing SS Bolts in Mast

[mikefossl]

Next year I'm planning on changing the standing rigging and doing a complete overhaul of the mast. I'm concerned about all the frozen SS fasteners in the spars and aluminum fittings. In my experience, any fastener bolted into aluminum and exposed to the elements has either broken off if small enough or not budged. I guess the rig was put together before tef-gel became a standard.

I came across a "trick" where jumper cables and a hi-amp 12V source are used to free stubborn fasteners. The current flows easily in the aluminum but the extra resistance in the stainless causes the fastener alone to heat up. Has anyone tried this?

[Ian McColgin]

Cool sounding method. I never tried more than penetrating oil, a little spot heat on the head to draw the oil in, and a tap with a hand impact tool. If it's really electro-corrosion-welded in place, I drill since to get good metal you'll be making a bigger hole anyway.

[allene]

I did a little math on this method and although I have never tried it, it might be useful. Stainless steel has a resistivity of about ten time that of copper. The head of a screw is probably about 1/2 a square. The copper wire you would use to hook up to the screw might be 1000 squares (1/4 inch wire 6 feet long) or 200 times the resistance of the stainless. Likely, it will be the copper wire that heats up in your experiment, not the stainless. On the other hand, the aluminum oxide might be high resistance and it might actually be that you are trying to heat. But heating the stainless is unlikely with this setup. In my opinion, you are more likely to weld something together with a high current source than you are likely to free it up. My advice is don't try this without talking to someone who has done it and found it to work, which is what you are doing anyway.