Which Fastener?

[cv2065]

Hey all. Wrapping up my research on the forum for my build. Thanks again to everyone that posted a build thread...very helpful!

Leads me to a fastener question. I know a lot of different sized rivet nuts are used for certain things as well as rivets themselves, stainless and otherwise.

Although I'm sure that it is subjective, I thought it might be helpful to new builders like myself if there was one thread that spoke to which type and size of fastener was best used in which location. Would greatly help with planning ahead.

Thanks in advance!

[wallace18]

On the Roadster I personally have not used a lot of rivnuts. I have used 1/4-20 and 10-32 S/S button head screws. The frame can be tapped for these in some locations. The 10-32 work well in the frame to hold various things. My suggestion is look at as many build threads as you can and decide which way you want to go. I highly suggest you look into mounting the dash so it can be removed without the body being taken off. Best of luck on your build.

[phileas_fogg]

I standardized on #10-32, because I wanted as many threads as possible when I tapped directly into the frame (like for brake & fuel line clips). I used this single size everywhere - tapped into the frame, riv nuts, and two-lug anchors (http://www.aircraftspruce.com/catalog/hapages/anchornutsk1000.php?clickkey=598922).

I recommend the two-lug anchors over the riv nuts because there's no chance of them spinning. This is a real possibility, especially if you're installing into just a single thickness of 0.040" aluminum.

Cheers,


John

[initiator]

I recommend the two-lug anchors over the riv nuts because there's no chance of them spinning. This is a real possibility, especially if you're installing into just a single thickness of 0.040" aluminum.

John - we used two-lug anchors at Boeing (although we called 'em rivnuts!) but they installed with solid rivets. Do you use pop rivets on yours? I spun a swaged rivnut mounting my fuse panel and would have much preferred not to go through the pain of hacksawing the bolt and drilling out the rivnut.

Thanks for the tip.

[mikeinatlanta]

The only place my car has rivnuts is on the dash mounts. Everything else is nut plates. All rivets with two side access are solids. Blind fasteners are only used in blind locations. Most frame small hardware attachments are 10-32, but they aren't threaded with a tap. I used self tappers to make all threads and then replaced with 10-32 hardware. Self tappers will make a stronger and tighter tolerance thread than a tap on relatively thin tubing.

[phileas_fogg]

John - we used two-lug anchors at Boeing (although we called 'em rivnuts!) but they installed with solid rivets. Do you use pop rivets on yours? I spun a swaged rivnut mounting my fuse panel and would have much preferred not to go through the pain of hacksawing the bolt and drilling out the rivnut.

Thanks for the tip.

Yes; I used pop rivets. Note that for the #10-32 anchors you need 3/32" rivets (or if there's not going to be much force on the anchor you can drill the holes to accept a 1/8" rivet).

Under my dash I had one riv nut that spun. Fortunately, I was able to grip the nut with some pliers and get the screw out. Then I ran a tap through the riv nut, and was able to avoid drilling it out. The riv nut doesn't hold anything now, but that particular screw was cosmetic anyway.


John

[shark92651]

I standardized on #10-32, because I wanted as many threads as possible when I tapped directly into the frame (like for brake & fuel line clips). I used this single size everywhere - tapped into the frame, riv nuts, and two-lug anchors (http://www.aircraftspruce.com/catalog/hapages/anchornutsk1000.php?clickkey=598922).

I recommend the two-lug anchors over the riv nuts because there's no chance of them spinning. This is a real possibility, especially if you're installing into just a single thickness of 0.040" aluminum.

Cheers,


John

John,

On those nut plates you linked to at aircraftspruce, what size rivets are used to attach, 1/8"? Also if attaching these to the 3/4" frame tube where you cannot access from behind, do you use countersunk rivets? Are the rivet holes in the plate already countersunk?

Thanks,
David

[flynntuna]

Since we're discussing fasteners, here's a link to a thread discussing adhesives.

https://thefactoryfiveforum.com/showthread.php?26311-Adhesive&highlight=Structural+adhesive

[phileas_fogg]

John,

On those nut plates you linked to at aircraftspruce, what size rivets are used to attach, 1/8"? Also if attaching these to the 3/4" frame tube where you cannot access from behind, do you use countersunk rivets? Are the rivet holes in the plate already countersunk?

Thanks,
David

Hi David,

The two-lug anchors take 3/32" rivets. I mostly used standard pop rivets in this size; when I ran out of 3/32" I drilled the holes out to accept 1/8". The holes are not countersunk. The picture below shows how I used the anchors to secure some wiring.


John

https://farm5.staticflickr.com/4307/36289759495_c3514b2dd2_k.jpg (https://flic.kr/p/XhNvbx)IMG_2576 (https://flic.kr/p/XhNvbx) by jhsitton (https://www.flickr.com/photos/91016165@N07/), on Flickr

[Mark Eaton]

Lots of good info in this thread. I really like the two lug anchors and I like Mikeinatlanta's method of using self taping screws to "tap" the chassis and then put in 10-32 screws. I have used some 1/8" pop rivets on my brake line clamps figuring that they are so easy to drill out and replace if needed, why not?

[Avalanche325]

I used rivnuts on things that may have to occasionally be taken off, like the elephant ears and nose aluminum. Both of those being removable has come in handy. I only tapped things that would have a reasonable amount of threads.

Things that will likely never, or once in 10 years, have to come off, were riveted. Most AL panels, etc.

For wire looms, I used what is called a "cable tie saddle support". You screw or rivet it onto the car. Then a zip tie holds the wire loom to the saddle. Permanent mounting, but serviceable.

[mikeinatlanta]

Hi David,

The two-lug anchors take 3/32" rivets. I mostly used standard pop rivets in this size; when I ran out of 3/32" I drilled the holes out to accept 1/8". The holes are not countersunk. The picture below shows how I used the anchors to secure some wiring.


John

https://farm5.staticflickr.com/4307/36289759495_c3514b2dd2_k.jpg (https://flic.kr/p/XhNvbx)IMG_2576 (https://flic.kr/p/XhNvbx) by jhsitton (https://www.flickr.com/photos/91016165@N07/), on Flickr

Of course everyone is entitled to do as they wish, but the photo above is not really using the item as intended. While anchor nut is a appropriate term, more commonly it is called a nut plate. It is intended to be mounted on the back side of the structure, sandwiching the joined parts between the nut and screw head. The 3/32 fasteners only serve to hold the nut plate in place and carry the shear load created by the self locking feature's running torque. In the application above, all load is converted to a tension load onto two 3/32 pop rivets. Not trying to bust anyone's balls, just making sure all viewing are informed. If using blind 3/32 rivets for fastening (solid are more appropriate), they need to be steel solid core blinds. The aluminum pop rivets lack shear strength to reliably overcome the running torque of the nut plate's self locking feature and will frequently shear. If using aluminum blinds, it's best to run a tap through the nut plate to relieve some of the running torque.

Below is a photo of nut plates installed as intended. Also a photo of a small head flush blind rivet appropriate for installing them. The head is a 100 degree countersink shear head, also called a 1097 head. It removes much less material than a standard tension head countersink.
86610
86611

[mikeinatlanta]

John,

On those nut plates you linked to at aircraftspruce, what size rivets are used to attach, 1/8"? Also if attaching these to the 3/4" frame tube where you cannot access from behind, do you use countersunk rivets? Are the rivet holes in the plate already countersunk?

Thanks,
David

My post above shows the correct blind rivets to use. Even if you could slip a nut plate into a 3/4" tube, you would not be able to deburr the holes for a clean fit. Best to use rivnuts on the 3/4" thin wall tube if carrying any load. I use quite a few 10/32 self tappers for holding clamps. If anything ever fails I'll throw in a rivnut.

[phileas_fogg]

Of course everyone is entitled to do as they wish, but the photo above is not really using the item as intended. While anchor nut is a appropriate term, more commonly it is called a nut plate. It is intended to be mounted on the back side of the structure, sandwiching the joined parts between the nut and screw head. The 3/32 fasteners only serve to hold the nut plate in place and carry the shear load created by the self locking feature's running torque. In the application above, all load is converted to a tension load onto two 3/32 pop rivets. Not trying to bust anyone's balls, just making sure all viewing are informed. If using blind 3/32 rivets for fastening (solid are more appropriate), they need to be steel solid core blinds. The aluminum pop rivets lack shear strength to reliably overcome the running torque of the nut plate's self locking feature and will frequently shear. If using aluminum blinds, it's best to run a tap through the nut plate to relieve some of the running torque.

Below is a photo of nut plates installed as intended. Also a photo of a small head flush blind rivet appropriate for installing them. The head is a 100 degree countersink shear head, also called a 1097 head. It removes much less material than a standard tension head countersink.
86610
86611

Thanks Mike. I should have clarified that I'm using these anchors differently than traditionally intended, for applications requiring only hand-tight fasteners.


John

[flynntuna]

Here's a link about thread-loc and anti-seize that compliments this subject.

https://thefactoryfiveforum.com/showthread.php?562-When-to-Loc-Tite-amp-when-to-anti-seize&highlight=Loc-tite