Thread lock vs jointing compound on ss screws into aluminium

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srah1953

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I am in the process of adding a couple of mast steps using stainless steel screws to attach them to the mast. I had intended using Duralac jointing compound to minimise electrolytic corrosion between the different metals. Having regard to the relative thinness of the aluminium mast section I was wondering whether it might be better to use loctite 243 thread lock instead. Any thoughts?
Thanks
 
srah1953 said:
I am in the process of adding a couple of mast steps using stainless steel screws to attach them to the mast. I had intended using Duralac jointing compound to minimise electrolytic corrosion between the different metals. Having regard to the relative thinness of the aluminium mast section I was wondering whether it might be better to use loctite 243 thread lock instead. Any thoughts?
Thanks
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Duralac is normally used for that, but I would suggest that monel rivets are really much better for fastening mast steps than "screws", presumably tapped into the thin wall of a mast.
 
NormanS said:
Duralac is normally used for that, but I would suggest that monel rivets are really much better for fastening mast steps than "screws", presumably tapped into the thin wall of a mast.
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Yeah i agree though screws are used a lot. I think the screws will peel off the duralac - a blind self-tapper cuts itself a thread in the soft aluminium. The idea of the duralac and other stuff is to fill the small gaps in between male and female tapped threads. Probably not a massive deal, really. After all, what's the worst that can happen?...
 
I doubt that thread lock will do anything useful for a self tapper. Corrosion is a far bigger issue, so use Duralac whatever fixing method you select. As has been said, pop rivets are a lot more secure than self tappers.
 
Thank you for the replies. I had intended using rivets and had bought a very expensive rivet gun for this purpose but when I tried to do it because of the way the plastic step is constructed the rivet couldn't get close enough. I could I suppose have drilled out a wider opening in the plastic for the rivet to sit closer.
 
srah1953 said:
Thank you for the replies. I had intended using rivets and had bought a very expensive rivet gun for this purpose but when I tried to do it because of the way the plastic step is constructed the rivet couldn't get close enough. I could I suppose have drilled out a wider opening in the plastic for the rivet to sit closer.
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If the rivet gun head is obstructed put a sleeve/tube around the rivet nail thus extending the rivet gun head.
 
Probably does not need to be a monel rivet, load is lighter than rigging?
Ordinary ali rivets are way cheaper and quite strong.
I use a few nuts (M4?) to extend the nose of the rivet gun, but they will fall off as the rivet tang breaks. You could prevent that by wrapping the nuts and nose of the gun with tape or heat shrink perhaps.
If the mast wall is quite thick, you might even be able to drill and tap it?
 
Why not use Rivnuts instead, they provide the benefits of being able to use properly threaded screws/bolts into what is effectively a captive nut, without any of the drawbacks of poprivets.
 
srah1953 said:
I am in the process of adding a couple of mast steps using stainless steel screws to attach them to the mast. I had intended using Duralac jointing compound to minimise electrolytic corrosion between the different metals. Having regard to the relative thinness of the aluminium mast section I was wondering whether it might be better to use loctite 243 thread lock instead. Any thoughts?
Thanks
Click to expand...

Try Rivnuts (or similar). Baseline recommend attaching their steps using M6 screws straight into the mast. Horrific thought.

Rivnuts seem to give the best of everything but you still need to pay attention to corrosion. You need a high mechanical advantage to close SS versions. One of my staff is like a gorilla but he couldn't pull an M8 one into ali box using a hand device. I think you can hire a powered version.
 
Rivnuts are a good call.
You can get ali ones.
I would have thought M5 strong enough?
Google the spec for the brand you have in mind, I think there are several?
 
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