Rivet Nuts

I am primarily looking into rivet nuts for their quick installation into tube, however after going through other threads I have found vague, mixed reviews on them. Do teams that use them find that they tend to slip? Are there recommended ways or types(knurled, locking, hex) to install them to make sure that they don’t slip. Are PEM nuts and weld nuts better?

Having a small relationship with these guys back in 2010 & 2011 on my old team, I can try and give some insight.

I clearly remember that we had used hex for mounting our brackets to our frame for our arm supports. During season, they weren’t really a big problem at all when it came down to failing. I never had the chance to see the chassis after the season to inspect the nuts but I can say they held up well within the 1/8" plate that they were secured in.

However, I do believe that because of the justification that the experience on my end and your end is rather low that the single best option would be to either make separate plates and tap where necessary or just tap directly into the tubing. Also, in some cases, thru bolting might not be a bad choice either.

Weld nuts are by far the best because they are welded in place. Pems are great if you have a press to install them. Rivnuts are good depending on where you are going to use them, but I have experienced them pulling loose.

The general problem with all of the above solutions is their inability to be fixed on the fly. A bolt and nut, bolting all the way through a tube is by far the best solution. Just make sure that you provide something to avoid crushing the tube. I prefer wooden blocks inserted into the ends, but there are also bushing that can help to support this.

http://products.kvt-koenig.us/katalog/katlist.jsp?kat=9&txt=FILKO+BLIND+RIVET+NUTS&gclid=CIjF0vH627MCFSPhQgodpSIApg

Rivnuts are great for creating strong threads on thin wall tubing less than .125" thick. We will use a rivnut if the mating part needs to be removable. Otherwise we would use a pop rivet and join the parts together.

The correct pilot hole must be drilled for the hardware. We tend to stick to #10 nuts. When installing the hardware a manual hand gun can be used. We have a pneumatic gun to install the hardware fast and exact every time. Takes a couple of times to get a hang of using the tool. A incorrectly installed rivnut will spin in the hole not allowing the user to unscrew the hardware.

Here is a youtube of the pneumatic gun

Thanks for the tips Roy. Do you guys use the standard, knurled, or hexagonal shank rivet nuts?

Cory, thanks for the idea on the extra plate. We might do that if rivet nuts start stripping. I don’t think we can tap our tube because we plan to primarily use 1/16 wall tube. Also I don’t like nuts because it is another thing that we can lose if we run into a quick change in eliminations.

Greg we will look into weld nuts and pem nuts if Roy’s suggestions don’t end up working. We hace access to both a press and a welder, but it seems like the rivet nuts are the easiest to install.

We’ve used rivnuts in some places and often have some difficulty with them turning in place. I try to avoid using them for anything critical and would favor a captive or welded nut if possible.

If you have work done out of house, you might also investigate form drilling as an option.

Micheal,

Zinc plated steel, knurled, counter sunk head, grip range .020 to .140, open ended

The manual insertion tool is ok but requires practice to get it right. The pneumatic gun is the bomb but costs$$. Amortize the cost over the life of the tool and it’s value to the robot.

The nuts come in different thread sizes but we try to standardized all our hardware on the robot. A #10 screw is a good choice for mounting manipulators. 1/4-20 is a little overkill.

FYI if the material is thick enough >.120" you can tap the material. If the thread strips you can drill out the thread and install a Rivnut. If you have alum pop rivets shearing because of load forces a steel rivnut and a screw can be used.

Try them out and see if it works for your application. Don’t be discouraged when others say they have problems with using this hardware. It’s good to have a understanding of what you can do with these in your Robot toolbox.