6 replies to this topic

[GnarlyItWas]

I have one mast step which is an alu casting with anSS rod threaded into it and probably corroded. How do I get them apart without damaging the alu ?

The old one is attached to the boat and can be cut off. How do I cut it off without damaging the ss thread?

[Bow Monkey]

You could try packing the whole area in ice for a few hours. Aluminum contracts more than stainless. Learned that from the hardcore Lightning folks. It may be enough to break things loose.

[Scottyk]

If you can get to the top of the SS threaded rod then start by grinding it flat and flush with the aluminium casting if you can. Then centre punch exactly in the middle of the threaded rod (or as close as you can get) and the drill the centre of the rod out. Keep using bigger drill bits until it comes loose. You will need good sharp drill bits and plenty of trefolex or similar lube. If you don't need to save the thread in the base the make the last drill bit a bit bigger than the threaded hole.
SS and aluminium don't mix. The seize that they get after a period in a marine environment is amazing, Heat will also get the apart i.e.. an oxy torch. But if the item is still sitting on a boat then this option is out!
Good luck
Scotty

[GnarlyItWas]

Not attached to the boat. I could actually put it in the freezer !

[Bow Monkey]

Not attached to the boat. I could actually put it in the freezer !

Well, chuck it in the freezer over night. No harm in trying the easy solution before drilling it. You may have to let it warm back up after freezing it though, because it should actually be wrapped tighter around that rod. I'm just thinking the contraction/expansion should break the corrosion bond.

[BalticBandit]

Not attached to the boat. I could actually put it in the freezer !

Well, chuck it in the freezer over night. No harm in trying the easy solution before drilling it. You may have to let it warm back up after freezing it though, because it should actually be wrapped tighter around that rod. I'm just thinking the contraction/expansion should break the corrosion bond.

take it down to the local Univ. Physics dept and ask if you can get some liquid Nitrogen

[HobieAnarchy]

Cold is not what you want.

Nor is drilling. Unless you're into drilling out a 9/16" stainless steel rod. That's just brain damage.

Heat is what will work. Heat the aluminum with a torch and bang on it with a wooden mallet to break the corrosion loose. With a regular home use torch, you can't get the aluminum hot enough to damage the casting.

Clamp the dolphin striker post in a vise (hard) and use a well-padded monkey wrench to get the casting off.

If it breaks, HTFU and buy a new one. They're made a lot better these days - beefed up rotation stops and the "chip keeper" in the bottom of the cup.