I'm getting to the point were I need to figure out how I'm going to fasten things together. I know most BH builders use nut plates galore but I hate installing nut plates, like really really hate it. My intention is to use only rivet nuts and tinnermans. What problems do you all see with this? Having a bolt corrode in a rivet nut can cause some problems because the rivet nut can break loose and spin with the screw but not using rivet nuts in areas susceptible to corrosion will help.

I think there's some widespread hatred for rivnuts because they can spin and be very difficult to change out, but it also depends on where they're used.

I'm using nutplates for much of my boot cowl fastening.

whee wrote:I'm getting to the point were I need to figure out how I'm going to fasten things together. I know most BH builders use nut plates galore but I hate installing nut plates, like really really hate it. My intention is to use only rivet nuts and tinnermans. What problems do you all see with this? Having a bolt corrode in a rivet nut can cause some problems because the rivet nut can break loose and spin with the screw but not using rivet nuts in areas susceptible to corrosion will help.

You will regret using rivnuts... They will spin even without corrosion. I disliked nutplates as well until I spun a few freshly set rivnuts while test fitting a part. Nutplates were not so bad after that. Do you know about the nutplate jig tool? It makes it a lot easier.

I hate rivnuts. I hate rivnuts. I hate rivnuts. I hate rivnuts. I hate rivnuts. I hate rivnuts.

During my my 15 years as a seaplane mechanic I spent no less than 3 months dealing with corroded or poorly set rivnuts. They won't take any torque from the fastner. They require a big hole to be drilled in the material for installation.

I love nut plates. I've installed thousands of them. Get a nutplate jig or 2 and go to town.

http://www.browntool.com/Default.aspx?t ... 47&Level=a

If you must use a single hole or blind threaded insert then go with the A-T knurled inserts, vastly superior.



You can get them from Spruce.

There are plenty of rivnuts on a Maule and like the rest of the airplane they're a bit of an acquired taste. I've grown to like them*. Simple, quick, effective and inexpensive. If they're set and maintained properly (i.e. screws not left in for years to corrode as mine were by the previous owner), they're no problem. The "keyed" type can be used where necessary/appropriate.

* but I also like Citroen automobiles...

PJ

There are a few places where I have to use a blind threaded insert, most of the remaining fasters can be tinnermans. I'm sure most everyone thinks of this as a lousy way to put together an airplane but I really do hate but plates and in most places I don't see the need. Sure, I'm going to use them to attach the engine cowl to the firewall and probably to attach the tunnel to the boot cowl but the floorboards and other interior panels can be tinnermans. I'm already using rivnuts on the instrument panel.

Loctite has some products that would greatly help secure a rivnut. Combine that with some anti-seize and they might be ok.

Ever heard of clickbond fasteners? Very widespread use among military aircraft. These things ain't cheap but very fast and slick. Several types to choose from. I used several of the nut plate type and some of the zip tie hold downs on my RV.

Helpful in places without access to buck or squeeze a rivet. I did my wing tips entirely out of click bonds (in lieu of 100+ nut plates) to save time. Much lighter too

http://www.clickbond.com

I didn't "like" nut plates, but we didn't know any better either. After the first couple of hundred, they weren't so bad. I use the plates themselves and a cleco as a template (one use only, then install). I found they were easy for a helper to install with only a few minutes of training, provided I drilled all the main pilot holes for the screw locations first.

I would advise against using Rivet nuts or Tinnerman nuts anywhere that's truly blind (like the floorboards, rear bulkhead, inside the wings). If they fall off and disappear into the tail section (Tinnerman), or if they start to spin (Rivet nut), you will wish you spent an extra two minutes installing a nut plate in those places.

Yes installing several hundred nut plates on each wing is a total drag, about two days work. But I wouldn't want a Tinnerman there. The screw thread would be rubbing against the alloy and could lead to excessive wear, or even cracking, maybe. Same goes for much of the cowling where the vibration is high, I doubt a Tinnerman or Rivet nut would last as long as a nut plate.

That/s my opinion. Glad I did use nut plates now, in hindsight, when I come to do maintenance. I wasn't happy installing them all.

I don't envy you with all those wing nutplates in front of you... Before I started, I once calculated how many holes I had to drill, wish I never did that.

Hoeschen wrote:Ever heard of clickbond fasteners? Very widespread use among military aircraft. These things ain't cheap but very fast and slick. Several types to choose from. I used several of the nut plate type and some of the zip tie hold downs on my RV.

Helpful in places without access to buck or squeeze a rivet. I did my wing tips entirely out of click bonds (in lieu of 100+ nut plates) to save time. Much lighter too

http://www.clickbond.com

Those look awesome. Might have to give them a try.

Battson wrote:I didn't "like" nut plates, but we didn't know any better either. After the first couple of hundred, they weren't so bad. I use the plates themselves and a cleco as a template (one use only, then install). I found they were easy for a helper to install with only a few minutes of training, provided I drilled all the main pilot holes for the screw locations first.

I would advise against using Rivet nuts or Tinnerman nuts anywhere that's truly blind (like the floorboards, rear bulkhead, inside the wings). If they fall off and disappear into the tail section (Tinnerman), or if they start to spin (Rivet nut), you will wish you spent an extra two minutes installing a nut plate in those places.

Yes installing several hundred nut plates on each wing is a total drag, about two days work. But I wouldn't want a Tinnerman there. The screw thread would be rubbing against the alloy and could lead to excessive wear, or even cracking, maybe. Same goes for much of the cowling where the vibration is high, I doubt a Tinnerman or Rivet nut would last as long as a nut plate.

That/s my opinion. Glad I did use nut plates now, in hindsight, when I come to do maintenance. I wasn't happy installing them all.

I don't envy you with all those wing nutplates in front of you... Before I started, I once calculated how many holes I had to drill, wish I never did that.

I can't remember for sure but I think the only place on the wings that doesn't have nut plates already installed is the wing tips. I got lucky on that one. 6MK had tinnermans holding the floorboards down, which I took up a couple times; they seemed to work fine.

It has been a couple years since I installed nut plates so maybe I'm more skilled now and they won't annoy me so much I'll be installing them on firewall flange so I guess I'll find out.

I hate timmermans!! They never seem to line up right or shift when putting panel in place.
DENNY

whee wrote:Loctite has some products that would greatly help secure a rivnut. Combine that with some anti-seize and they might be ok.

Yes, that has worked for me. Loctite, stainless screws, a whiff of Kroil on the thread, annual disassembly, and keyed rivnuts where spinning would really be a PITA.

PJ

Rivet Nuts Suck!!

Nut plates are the best.

Tinnermans are OK just be sure to use "B" screws!

Please don't use any rivnuts unleash you have to!

My T210 has lots of tinnermans, very few rivnuts, and a massive number of nut plates. I changed a couple nut plates on this annual because they were damaged by ham handed Maintenance techs of days gone by. Very non-invasive replacement. This airplane is now 42 years old, and some of these screws are removed even more often than every annual. It's a pleasure to work on still, and the machine screws in the nut plates just exude quality. You can get tinnermans that are installed with two rivets like a nut plate if you prefer sheet metal screws and don't require them to be structural.

My 185 has had several rivnuts installed in exterior skin for float strut fairings that will never be used again. What an eyesore on an otherwise beautiful airframe. The holes would be huge if I removed them and require a patch. Think about that. If you ever have one spin, it's going to take a patch to repair it. If they had used nut plates, a few flush rivets and the holes could be made to nearly disappear.

You're a young guy. You'll own this airplane you're building for decades. Build it to be serviced, and to last.

Rivnuts can spin, but the knurled ones are better, and the hex styles are even better. Glass filled epoxy adhesive applied to the shank prior to install pretty much addresses most of the spin problems. I don't know why this isn't done more often. It addresses some corrosion risks as well.

Nothing beats a nut plate but they can be a real adventure to replace in hard to reach places and the good jigs are a bit pricey and the install can turn into a two person job to buck them in.

Be choosy about where to use clickbonds. They are pricey, require good surface prep, and have not held up as well in hot or petroleum rich areas that see a lot of vibration. Fine for wires, but for me, not for loaded attachments. Adhesives are fickle.

N-Jacko wrote:

whee wrote:Loctite has some products that would greatly help secure a rivnut. Combine that with some anti-seize and they might be ok.

Yes, that has worked for me. Loctite, stainless screws, a whiff of Kroil on the thread, annual disassembly, and keyed rivnuts where spinning would really be a PITA.

PJ

Be aware, stainless screws in direct contact aluminium will cause galvanic corrosion. That starts under the paint and bubbles the paint in months, not years. Al and S/S are far enough apart on the galvanic scale that all you need is a little electrolyte (water will do, salty water is better) to get the process started. Cad or zinc plated hardware is better, if you can get it.

Clearly they are good in some applications, but I've learned a few lessons lately about building things to last.

Rivnuts are garbage! Ask any decent mechanic and he will tell you that nutplates are king! Buy the jigs and some #40 clecos and go to town. You wont regret it. I am also not a fan of stainless screws, the heads strip easy, they gaule easily and theyre more expensive. Nothing beats a good old plated steel fastener in a riveted nutplate.

But a nut plate jig, it's not a big deal. Rivnuts suck

Pinecone wrote: You're a young guy. You'll own this airplane you're building for decades. Build it to be serviced, and to last.

I appreciate everyone's thoughts. I think what Pincone said had the greatest effect. Some places I have to use a blind fastener, other places will get tinnermans while the vast majority will get nut plates. I want this plane to last.

I hate installing nut plates.

While using the nut plate as a guide for one hole then a cleco to hold it is one way - I have done enough to say, "BUY a nut plate tool!" Much faster and more accurate.

I had to use rivnuts to install Knots 2U flap gap kits. The kit came with smooth sided rivnuts, but there are rivnuts with a "spine" to help prevent spinning. Sort of like an old slotted - tapered - axle with a key.

I filed a minor notch and used some leftover VG glue from a larger 'industrial' size kit just before sliding them up into the hole. No spinners as yet.

Tinnermans can be rather easy to "strip."

Hope yer kit does not require a collection of "Hole Finders."
Trim

I despise rivnuts. And rarely ever install them unless I have NO choice. Back in the day you could easily find the notcher and rivnuts with the small key and then maybe they wouldn't spin..... I would recommend spending the money on a good set of nut plate jigs and a good squeeze and install nut plates. Or even tinnerman nut plates.

Ben