TIL: Swage nuts


Or: How I Stopped Worrying I’d Break My KX3 and Enjoy Radio (again).

I found, what I thought was a design problem with my (new to me) KX3 casing thumbscrews. It’s second hand and I thought maybe the thumbscrew was damaged (1 looks a little brown…rust?).

In some, hard to replicate, circumstances one of the screw seems to bind, stick, against the body. The only way to fix it is to open the extendable foot. This worried me as I thought it’d damage the thread.

So I look for an answer on the Groups.io KX3 owners list, where I learn the thumbscrew fits into what’s called a swage nut.

A swage nut or self-clinching nut is a type of nut or threaded insert that is used on sheet metal.

It permanently anchors itself to the sheet metal by swaging the surrounding material.

Albert Spokes filed for a U.S. patent on the swage nut in early 1958. The swage nut is descended from an older idea, the clinch nut.

– wikipedia article on swage nuts

Solution

After many messages from men who clearly know more about metal fabrication than I do, I find the answer.

Each thumb screw in the KX3 works against only one threaded fastener. The front thumb screws go into PEM nuts in the bottom cover. The rear thumb screws first go through the bottom cover (clearance holes), then into the PEM nuts in the feet.

[…]

Loosen thumb screws, first; then adjust the feet set to the desired position; then tighten the thumbscrews (but not too tight).

Groups.io Elecraft KX3 owners group message