Question on proper rivnut seating

[mmklaxer]

I started installing rivnuts on some scrap hardware before doing so on the real deal (lesson learned!)

The picture below is 1/8" aluminum. The ribs on the rivnut compressed into the material instead of behind it. Is that ok? I thought it should bubble out behind the material and "squeeze" the metal. About to try on some scrap sheet metal to see if I get a different result...

173785

[egchewy79]

that's impressive. I'm surprised the threads inside the rivnut didn't strip out before the rivnut itself imprinted itself into the material. that should be a pretty solid union. take a screw/bolt to the rivnut and see how much torque you can get before it starts spinning. I'm guessing it'll be more than enough for your purposes.

[460.465USMC]

The rivnuts I've installed had the "bubble out" appearance you described. I'll defer to the more experienced builders, but just wanted to mention the drill bit size is very specific (e.g. 19/64" for the 10-32 rivnuts I ordered from McMaster). Also, be sure the thickness of the material is not greater than the range specified for the particular rivnut.

[John Thuman]

I started installing rivnuts on some scrap hardware before doing so on the real deal (lesson learned!)

The picture below is 1/8" aluminum. The ribs on the rivnut compressed into the material instead of behind it. Is that ok? I thought it should bubble out behind the material and "squeeze" the metal. About to try on some scrap sheet metal to see if I get a different result...

173785

Check your hole size.

[Namrups]

It looks like those rivnuts are for thinner material. You may need longer rivnuts for 1/8" material. McMaster-Carr is good for listing grip ranges and drill sizes. They should "bubble-out" behind the material, not "in" the material.

[JohnK]

That's not ideal. You need different rivnuts with a proper grip range for thicker material.

Edit: To expand (pardon the pun) in your photo the knurls may bite enough to keep the rivnut from spinning, but the flared material is what prevents the rivnut from being pulled out. Yours looks like it will pull out pretty easily.

[ydousurf]

As stated (above) from the feedback, which is all very good! I found that I underdrilled all my rivnuts and then used a round file to do a final opening, for which, my rivnuts were somewhat hard to push in. In other words, a nice close "tight-fit" is your friend. This will give your rivnuts or nutserts the best chance of not moving at all. Also, do a couple tests as advised on sample pieces and find your "rythm or groove" as they say, and only tighten the riv/nut-sert so much. Squeezing too much to where you can't anymore is not good. Just like adding the flair on fuel or brake lines, you don't want to "push-it or squeeze" too much, you'll do more harm to the hardware. Find that nice rhythm with your hand strength and it will all work out nicely. Good luck and happy building...

Doug

[mmklaxer]

The rivnuts I've installed had the "bubble out" appearance you described. I'll defer to the more experienced builders, but just wanted to mention the drill bit size is very specific (e.g. 19/64" for the 10-32 rivnuts I ordered from McMaster). Also, be sure the thickness of the material is not greater than the range specified for the particular rivnut.

I imagine that's what happened. The rivnut wasn't designed for 1/8" thick material. I used the same drill bit/rivnut on an aluminum panel and got a normal "bubble" on the back.

Might need to check out some thicker material rivnuts to go into the 2x2 frame pieces. I don't feel comfortable tapping into that - it's pretty thin tubing.

[edwardb]

I've done my share of rivnuts, and can offer this feedback and advice. Some of which duplicates what's already been given. Practice like you're doing is a very good idea if you haven't done them before.

- It's critical to drill the hole exactly the size of the body of the rivnut. Most come with marking on the package that say what hole size to use. Easy to confirm (and I always do) with a micrometer. The rivnut should just press into hole.

- Also important to use rivnuts with the proper grip range for the material. Also typically clearly spelled out on the package or wherever you order them from.

- It's hard for me to believe yours pulled into the aluminum by displacing it. I've never had one do that no matter how much force. The hole looks too clean. Like it was drilled oversize in the first place. Reference point #1. Regardless, all things being proper they won't look like that.

- Once you start pulling them in with your tool of choice it's important that they're tight so they don't spin. But too tight and you can strip the threads. Or what I've found, especially with the larger sizes which are strong enough not to strip, the threaded part will start drifting off center. Really not nice when you're trying to do precision work.

- Many (including me) will add some additional insurance to make sure they don't spin. Choices: Instant glue, Loctite (I use red), or epoxy (I use good old J-B Weld). Loctite or epoxy a little on the body of the rivnut, push it in, pull it tight, and once set very good chance it won't spin. Instant glue can be applied after it's pulled. I've seen some test results and the added adhesive increase the torque against spinning by several times.

- One last hint. I've seen some rivnuts that have a slight chamfer or radius on the underside. Between the top flange and the body. The very tight diameter of the hole will prevent the top flange from seating completely. When that's the case, it helps to be a slight countersink in the hold. Just a little. Enough to let the rivnut sit all the way down. Off topic, but occasionally see the same thing on some pop rivets.

Good luck. Rivnuts are handy and work great when properly installed. Installed poorly they can be a real pain.

[lance corsi]

Also isn’t a bad idea to keep a tap handy either for the ones that don’t want to play well. As I’m pulling my rivnuts, I make sure that the mandrel is fully screwed into the rivnut. Sometimes this calls for a mid-pull adjustment. Having only a minimal number of threads engaged can strip them from the body of the nut.