Big Blue Saw Blog
- Parent Category: Big Blue Saw Blog
- Created: Wednesday, 09 December 2015 18:46
- Written by Simon Arthur
Many of our customers' applications demand lightweight thin material such as the popular 1/8 inch (~3mm) thick aluminum 6061.
What do you do if you need to attach something with a screw to a plate of that thickness? You could just use a nut, but what do you do when the nut needs to be on the INSIDE of the thing you're screwing onto?
How about tapping threads? At 1/8 inch thickness, it can be difficult to tap threads: it yields only 3 threads when using a standard #10-24 machine screw. This isn't a lot of meat for screw to hold onto and could lead to the screw stripping the threads.and assortment of thread sizes.Using nutstrip can solve this. Another possibility to use rivet nuts. Rivet nuts are threaded inserts designed to be crimped in place in thin material. Rivet nuts come in an assortment of thread sizesand variety of styles to work with a range of material thicknesses, from 0.02 inches to 0.3 inches.
Two plated steel rivet nuts. The left one has a 1/4-20 thread, and the right one a #10-24 thread.
I happened to get a good deal on a bunch of steel rivet nuts a few years ago. I keep them in a gallon container.
Rivet nuts do require a special tool to seat them properly. I bought one made by Marson that came with accessories for riveting several sizes of nuts in place.
Here's a rivet nut installed into the chassis of my fighting robot Jaws. You can see that on the inside, the thread starts a little way down inside the rivet nut.
Note that when correctly installed with the crimping tool, the ribbed section expands to bite into the sheet material and hold it to prevent it from falling out or rotating in place. When they're subjected to extreme loads or shock, as can happen in robot combat, rivet nuts do tend to come loose. That's why if I'm installing a rivet nut in that kind of situation, I'll put a little retaining compound around the head of the rivet nut before crimping it.
Note that the waterjet was used to make the hole in which the rivet nut sits. This is faster than drilling them by hand and allows you to position the hole more accurately relative to the other holes and to the overall part. I would suggest making the hole 0.01" oversize in diameter to make sure that the rivet nut can fit.
Rivet nuts are available in a variety of thread sizes and materials from the major industrial suppliers: McMaster-Carr, MSC, Grainger, and the like.
Let us know: have you used rivet nuts with waterjet or laser cut parts?