Thread: advice on using solid Ali rivets

I have an old 90's (I think) Alicraft which works well so far.

It is leaking from approximately 6 rivets. about 2L every hour. Nothing a bailer can't handle.

I would like to drill and replace them. Going off some youtube videos the way to go is whack the shit out of them with a hammer or air hammer with something solid on the other side. Supercheap has an air hammer for 30 bucks and I've found a flat steel fitting off ali express for 15 bucks.

I have assumed that since everything is welded the manufacturers won't have the tooling.

Anyone used solid rivets? I could possibly find some 100 percent Ali pop rivets.

cheers

Couple of options - find some ali stemmed rivets but be aware they can end up corroding anyway as the stem is a different grade and treatment to the body which is often enough to start a fizzing. You can disassemble the rivet and coat it in bedding compound (not Sika 291 but the much thinner variant that is more like a silicone sealant but still an elastomeric compound which is better for flexing).

Next is finding a solid ali rivet and setting it with some elastomeric compound - more stuffing about but likely a longer service life.

Final and most bubba-ish is a 316 stainless gutter screw with a thin nylon isolating kit on each side and a good dob of the elastomeric poo. The nylon comes like a little tube with a piece of basically ice cream container lid plastic as the washer on top and bottom - basically these just prevent any electrical contact between the hull and the bolt and help it seal. If you use a nyloc nut it self-locks in position and the benefit of this is that if it starts leaking again you can either tighten it a little or take it out and reseal it... Nut on the inside obviously! On an older hull, you basically just want to keep it going with minimal flexing and risk of cracking or the ali parts wearing against each other any more...

Are the rivet heads domed? You may need a "set" to help form the new heads. Basically it is a Block of steel with the head shape machined into it, held against the shank when the hammering is done. You have the same machined into the head of the pneumatic hammer.

Have a look at youtube for film of the old riveters shipbuilding - back when men really were men.

And deaf. Really, really deaf.

Can you just re-set the rivets rather than replace them? I've got a mate who's an aircraft engineer for Air NZ, he's made me a couple of bits from aircraft grade aluminium riveted with solid rivets, I could ask him if you like? After all, they still use them on planes!

Do not use silicone it will leak and peel off bostik seal and flex polyurethane is great in grey between lap joins . You can tighten existing rivets 1 person inside upside down hull with ear protection and hold a sledge hammer head on each rivet while out side man hits each rivet twice with a hammer , get a builder mate with his hammer to do it so no miss hits . Done this on few fyrans and parkercraft , works a treat , remember all parkercraft are at least 40 yrs old and alicraft the same .sikaflex makes good urephane aswell but twice the price .

This stuff look great

On a hull that old I honestly wouldn't bother trying to reset old ali rivets. They are old, likely worn and corroded and if there's been movement in the skins there could be a wear point inside on the rivet's shank. Smacking it could just crack it leading to a failure and the rivet popping apart in use. Ask me how I know this one - "Why are you sticking your foot there at that stupid angle?" - "Oh, right - guess we will head back now...".

bjp is right with aircraft - although they have a much less corrosive operating environment and a much better selection of inspecting and testing kit to know when to replace them. Also aircraft don't usually get bounced off things like boats do so don't usually have such a rough life.

Sounds rough, but a stainless gutter bolt with elastomeric sealant of some form and a couple of plastic isolators is one of the better options for this job as you can set the tension no question to keep the skins in place. And tighten it up once you've had the thing out and it's had a bit of a flex and bang about - which is bloody hard with a one-time rivet!