Tapped fixings vs rivet-nuts

oldbilbo

oldbilbo

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I've always had problems getting a good clean 'vertical' start when trying to drill 'n tap into thin-wall aluminium - such as a boom or mast wall. It's certain I am there's a devious real engineer's trick to it.

So I'm wondering if I shouldn't just go for rivet-nuts, for more certainty of a secure fixing.....

Yes, I do have some big lazy-tongs manual 'pop rivet' setting tools, but on a boat it's usually most difficult to use 'em to best advantage - and even harder to inspect the result, if a little suspect. I've resorted in the past to big blobs of epoxy as internal back up to 'pop rivets'.

Views, opinions and prejudices welcome..... :rolleyes:
 
I have a prejudice for rivnuts and use them a lot from brass through ali to mild and stainless, simple, replacable easily and almost always available in the material they are inserted in and particularly useful on thinish material (mast) where even a well made tap would only give a very low number threads for often heavy stuff like radar. They can also be inserted without the proper tool if you only have a few to do.
 
You can get a drill press that simply stands on the item to be drilled, that should get your hole straight, and the first cut tap tends to pull itself in straight. I like the concept of Rivnuts, but tend to hurt my knuckles when the big, f**k-off rivetter slams shut! I can't control lazy-tongs any better when the mandrel snaps, so there are quite a few scratches on the mast where I used large rivets to fasten a bracket. if I could, I'd set a nut in a blob of epoxy rather than rivet, but Rivnuts seem to be the best compromise. Possibly Big-heads could be an alternative?

Rob.
 
Rivnuts are a superior fixing to the screw thread in mast route. They are also replaceable if you manage to cock up the thread too.

I use CamLoc.
 
I've also been very happy with riv-nuts, but haven't used them for any marine applications. I guess one problem If you use stainless ones (and stainless fasteners to avoid the electrolytic problems) is that it's a real bu99er for galling-up the threads if done up tightly - especially if it's something that needs to be undone and re-done often.
 
Avocet said:
I've also been very happy with riv-nuts, but haven't used them for any marine applications. I guess one problem If you use stainless ones (and stainless fasteners to avoid the electrolytic problems) is that it's a real bu99er for galling-up the threads if done up tightly - especially if it's something that needs to be undone and re-done often.
Click to expand...

Monel and Duralac may be your friend....
 
David2452 said:
I have a prejudice for rivnuts and use them a lot from brass through ali to mild and stainless, simple, replacable easily and almost always available in the material they are inserted in and particularly useful on thinish material (mast) where even a well made tap would only give a very low number threads for often heavy stuff like radar. They can also be inserted without the proper tool if you only have a few to do.
Click to expand...

+1 for the rivnuts; like David I use quite a lot of them and find them easy to use, although it is important to use the correct size drill.
 
The only problem with rivnuts is if you don't set them tightly enough. I used a few to attach the gooseneck track to the mast and, on one, the thread got damaged. (Probably incompetence - it was the first time I'd used them.

I then needed to move the track and when I tried to undo the bolt, the rivnut just turned, so I was stuck with a bolt that wouldn't unscrew and no access to the back of the track. I had to bend the slot the track fits in so I could sneak in with my trusty Lidl "Dremel" and cut the bolt flush with the nut. If that hadn't been possible, I don't know how I'd have got it off.
 
I'd like to try Rivnuts when I make a few alterations this winter. Having only watched the company videos, a couple of questions for those who have actually used them.
Projection inside the mast is going to be much greater than with rivets, and much snaggier too by the look of it. Problem with halliards, cables etc in the mast?
Do you countersink the underside of the attachment to accomodate the flange of the rivnut?
Not particular to rivnuts, but if you replace, say, a cleat with a larger one drilling out one hole for the larger fixing plus one new hole - would you trouble to fill, somehow, the leftover hole? Would it make any difference other than to the appearance? (I'm not talking about just one hole here. There could be quite a few in mast and boom by the time I've finished)
 
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