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mepsnbarry 04-21-2009 03:08 PM

Cleaning up stainless fasteners in aluminum masthead
 
3 Attachment(s)
I have to remove remove most of the stainless fittings and fasteners currently in my aluminum mastheads.

How do I do this with the least damage to the masthead?

Is it important to remove old bolts that are already sheared off? Should I just cut them off flush on the other end?

What can I do to make it easier on the next poor sucker (probably myself!) who has to work on it years later?

Should I try to re-paint them after I finish other stuff?

I have two composite masts, but the masthead is a thick aluminum plate. (I believe it has a pipe welded to it and then glassed inside the mast) The masts are approaching 30 years old, and there are a BUNCH of stainless fasteners in it. Some are tapped. Some are through-bolted. Some were sheared off by a prior owner. Some were sheared off, but left dangling on the bottom. There are a few extra holes. It was once painted, but much of that has come off as well. Here are a few pictures.

Attachment 3794
A view of both masts from the top; Mizzen on left, Main on right

Attachment 3795
The bottom view of the Main mast top

Attachment 3796
The bottom view of the Mizzen mast top

tommays 04-21-2009 03:22 PM

Well you sure cant use HEAT and things like PB BLASTER are marginal once the SS and Alu have tried to become one piece



This leaves drilling for the stuff that breaks BUT i cant see why the locknuts would not come off ?

mepsnbarry 04-21-2009 05:28 PM

Quote:

Originally Posted by tommays (Post 478228)
This leaves drilling for the stuff that breaks BUT i cant see why the locknuts would not come off ?

There are some "leftovers" which had the bolt head sheared off, and just a bit of threaded stainless in the plate and sticking down on one side or the other.

I expect the nuts will come off without any grief, but I'm not sure the bolts will come out next--I've created more of those "leftover" parts myself on other mastheads.

This time, I have the luxury of time to do my research to figure out the right way--Other jobs are keeping us busy until we get started on this.

sailingdog 04-21-2009 05:33 PM

This is a good reason why you should be using TefGel or Lanocote when fitting fasteners. It helps prevent this from happening. :)

Heat isn't the greatest idea, since the aluminum may be tempered and will lose much of its strength if heated by a torch. PBlaster is a good option, but generally takes a lot of time and is not always successful one badly corroded aluminum.

imagine2frolic 04-21-2009 05:37 PM

Put a piece of pipe over the ends of the wrenches, and bust those suckers off. Then you might be able to punch them out, or at least get some PB directly on the problem......i2f

tommays 04-21-2009 05:48 PM

Looking at the top pictures i see 1/4-20 flat head screws and looking at the bottom i see 1/4-20 lock nuts or 5/16 what size is the wrench (7/16 or 1/2)that fits the nuts

The fact that ARE nuts leads me to believe that your stuff is through bolted and the screws should be pretty easy to get out


It is a carbon mast SO i would go REAL easy on the hammer :)

mepsnbarry 04-22-2009 09:27 PM

And now the hard part....
 
2 Attachment(s)
OK, I did the easy bit--I sprayed everything with PB Blaster (a couple times) and I got all the nuts off except for two that had resin all around them.

I believe I succeeded in removing bolts that only had two or three years to corrode in there. The "hard cases" are left--mostly factory installed bolts from 1981. They include a few sheared off bolts (#10 and #8), a bunch of #10 flathead bolts, a couple of 1/4-20 bolts, and the bolts for the ground lugs.

I can think of a few options to get them out:
  1. Heat doesn't sound like a good idea, but I could get some freeze spray and see if that loosens them.
  2. Start with a screwdriver, and mangle the head. (A miracle could occur and it might just unscrew) Then when a screwdriver will no longer try to turn it, switch to vice-grips on the head. Prior experience hints that the vice-grips can generate enough torque to shear the head off, unless it comes out first.
  3. For ones with hex heads, the a wrench will probably provide enough torque to shear it off without the vicegrips :)
  4. I have a fairly powerful drill/driver, I could use it like an impact wrench, stepping up through the torque settings until the screw head is mangled or sheared off (or removed)
  5. Hammer on the long end on the bottom to try and break it loose or drive it out. I would probably put a nut back on it first so that I don't "peen" the small end over. I don't want to do this too hard, with a composite mast.
  6. After the head is sheared off, Grab it on the bottom with vice grips and try to twist it out. Some are already that way, and even bent too....a prior boat owner had the same problem, I guess.
  7. Give up entirely, cut them off, grind them flush, and drill them out if I need a hole in that place again. If all of the above fail, this is where I'll end up.
The paint is obviously in terrible condition, I roughly scraped the worst of it off. I expect to work re-painting this in with some epoxy and painting work on the mast itself.

Which ones on my list would you try?

Here are views of the current state, top and bottom. Ignore the odd strings--I also removed cables and left stuff for pulling new ones in.
Attachment 3804
Attachment 3805

sailingdog 04-22-2009 10:04 PM

If you're going to use a screwdriver, at least use a screwdriver in an impact wrench or impact driver... it is far more likely to work and far less likely to strip the head.

Sarguy 04-22-2009 10:51 PM

  1. Heat doesn't sound like a good idea, but I could get some freeze spray and see if that loosens them.
  2. Start with a screwdriver, and mangle the head. (A miracle could occur and it might just unscrew) Then when a screwdriver will no longer try to turn it, switch to vice-grips on the head. Prior experience hints that the vice-grips can generate enough torque to shear the head off, unless it comes out first.
  3. For ones with hex heads, the a wrench will probably provide enough torque to shear it off without the vicegrips :)
  4. I have a fairly powerful drill/driver, I could use it like an impact wrench, stepping up through the torque settings until the screw head is mangled or sheared off (or removed)
  5. Hammer on the long end on the bottom to try and break it loose or drive it out. I would probably put a nut back on it first so that I don't "peen" the small end over. I don't want to do this too hard, with a composite mast.
  6. After the head is sheared off, Grab it on the bottom with vice grips and try to twist it out. Some are already that way, and even bent too....a prior boat owner had the same problem, I guess.
  7. Give up entirely, cut them off, grind them flush, and drill them out if I need a hole in that place again. If all of the above fail, this is where I'll end up.
The paint is obviously in terrible condition, I roughly scraped the worst of it off. I expect to work re-painting this in with some epoxy and painting work on the mast itself.

Which ones on my list would you try?

On #1: You are right about heat. Freezing the aluminum will shrink it, and might free it up. I don't see any downside.

On #2: Since you are not going to reuse the screws, knock yourself out.

On #3: You are right, go ahead.

On #4: I don't hold much hope, but again, nothing to lose.

On #5: NO NO NO. You can fracture the carbon mast. You can't take back that last tap with the hammer.

On #6: As you note, probably a waste of time, but nothing to lose.

On #7: I would start here. If you need a hole in this location, get GOOD drill bits, the size of the hole, use a center punch backed up by an anvil or something equally as dense so that it doesn't transmit shock to the mast, and drill away. It will be the least like to do damage, both to the mast and to yourself.

HOWEVER, note that I am only looking at pictures, it's not my boat, and the guy on scene can get a better idea of how hard the bolts and screws are siezed in the holes. You don't seem to be cursed with impatience, and that's a good thing. Good luck.

Sarguy 04-23-2009 01:43 AM

PM to follow


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