PEM nuts, or something like that for sheet metal

Just put a nut on a screw, and a couple of washers, run the screw into the rivnut, and with a wrench turn the nut so it pulls in the rivnut. The screw is stationary and does not turn, hence neither does the rivnut. You can do this into a blind hole, as well. No expensive tool needed. I’ve done a bunch of these.
 
Winegrower said:
Just put a nut on a screw, and a couple of washers, run the screw into the rivnut, and with a wrench turn the nut so it pulls in the rivnut. The screw is stationary and does not turn, hence neither does the rivnut. You can do this into a blind hole, as well. No expensive tool needed. I’ve done a bunch of these.
Click to expand...
Good to know and the price is right. Only need to do four holes, so not eager to spend $76. If I were doing a lot of these then I'd consider the tool.
 
WobblyHand said:
That's a better link. Double the price since 2016.
Click to expand...

Yea and it does seem pretty straightforward to do it with a nut and bolt. Even with the tool you have to spin it in/out of each rivnut.
 
brino said:
I have this one:
https://www.princessauto.com/en/45-pc-threaded-insert-rivet-kit/product/PA0002925204

basically the same as this:
https://www.harborfreight.com/45-piece-threaded-insert-riveter-kit-1210.html

I have used it for years and it's always done what I need.

Brian
Click to expand...
Thanks for posting that Brian. I didn’t know HF had a rivnut tool. Shoulda known they did. Another tobuy next time. That’s two adds today on H-M today!

I made a rivnut set years ago that was just drilled rod for 1/4, 5/16 and 3/8 sizes. That rod was long enough that I could grip it with vice grips to keep from twisting. The end of the drilled rod that contacted the rivnut I took a chisel and made a serrated pattern to grip the rivnut. Put some grease on the bolt and used a impact driver to squeeze it home. Had to be careful not to over do it. But it worked. The pliers are definitely and over due upgrade.
 
If this is about mounting a circuit board, there's a lot of plastic hardware for the purpose, with snaps, or
screw threads, or both; <https://www.aliexpress.us/item/3256803159767202.html> is kinda typical.
In the old days, there were ceramics as well. The snap action means one end doesn't become
lose hardware without you WANTING it loose...

On the other hand, if you really want to set a rivnut, it doesn't look too hard to modify (for instance)
a Whitney punch to do that kind of thing... depending on clearance, of course.
 
Last edited:
WobblyHand said:
This is only 1.25mm thick aluminum. Nothing to thread really.

Was wondering how the rivet set tool held the rivet from rotating. It seems that all one might need is a hex with a through hole tapped to the right size and a counterbore to let some of the rivet to drop in place. Then hold the hex with a wrench and screw in the screw until the rivet is set. Hmm, doesn't sound that hard. I'll practice on a few before trying on my box though!
Click to expand...
!.25mm is exactly the kind of thin metal that would need some kind of rivet nut. Of course, given the huge range of sizes, one should choose something appropriate. 1.25mm might be able to hold up to M3 or maybe M4.

The term "rivet nut" is, I think, interchangeable with "hank bush", but we note there are a variety of types, and they can be had to rivet secure onto various thickness ranges. You need to get the right one.

I have come across a type which looked engineered to something like airframe standards, with passivation plating, and the rivet shank part was serrated lead-in. The hole is drilled so that the end only just fits, and when it is pulled into the sheet metal, the serrations cut into the metal to make an anti-rotation spline, before the back end expands into being a rivet.

For me, the norm is to put the nut on the metal underside, so all it can be is a nut that stays in place, but there are situations where the need is to have a nut fixing, but with no access to the rear for initial fitting. I think one can use a tool akin to a pop-rivet to fit these types into a blind hole. I confess that, in a pinch, I have even put a stainless pop-rivet into sheet metal, then tapped it out to make my own ghetto version of a threaded bushing.
 
whitmore said:
If this is about mounting a circuit board, there's a lot of plastic hardware for the purpose, with snaps, or
screw threads, or both; <https://www.aliexpress.us/item/3256803159767202.html> is kinda typical.
In the old days, there were ceramics as well. The snap action means one end doesn't become
lose hardware without you WANTING it loose...

On the other hand, if you really want to set a rivnut, it doesn't look too hard to modify (for instance)
a Whitney punch to do that kind of thing... depending on clearance, of course.
Click to expand...
I'm mounting a stepper motor driver, which is in a metal case. It doesn't weigh much but it would be good if it had some thermal contact to the outer box. Thinking a rivnut to the outer box is one of the better choices. I could drill and tap the driver case flange, but it's aluminum as well and not all that thick.

Clearance is always the problem. Shoehorning stuff in a chassis box is always fun. Always have to think ahead about having enough room for everything and having the ability to work on the pieces when everything is installed. Now staring at connectors and thinking about clearance for installation and removal while the other cables are present. It's all to easy to pack the connectors too tightly.
 
WobblyHand said:
it would be good if it had some thermal contact to the outer box. Thinking a rivnut to the outer box is one of the better choices.
Click to expand...

Rivnuts have a flange so will prohibit contact with the surface.
 
You must log in or register to reply here.
Back
Top