Monday, September 27, 2010

FIX: Mounting the Battery Holders in the KX-1


Looking closer at the battery holders, I noticed that there seems to be some meat around the recesses where the screw heads rest, and decided to try embedding nuts in them.

First, I took an X-Acto knife and reamed the threads in the screw holes in the case (since they seem to already be stripped now), so that they just clear the screw threads.

A much longer 2-56 screw (as a tool) holds the nut against the recess, and I can pull _gently_ on the screw head with little pliers or a hemostat, while heating the nut with the iron (or a solder gun - briefly!) and pulling it down into the melted plastic _just_ until it is even with the surface. Set it aside and let it cool before moving. Then remove the long screw(s).

Now I can put the 2-56x3/16" screws in, with the head outside, and the end of the screw just even with the face of the nut. Put a drop of threadlocker on the inside on the nut. The thin blue liquid runs into the threads, and over some hours, sets up into a 'chewing-gum' consistency as a vibration-resistant lock, but still removable for repairs.

Find it at auto-parts stores, along with other, more aggressive, versions, coded with different colors. I'd used the blue before, to hold fans on top of EGSE racks for the Cassini mission to Saturn. You _really_ don't want a loose nut falling down into the electronics during a test of flight hardware. [Photo hpim1505]

Sunday, September 26, 2010

Mounting the Battery Holders in the KX-1






Building up my second KX-1 (this one for KG6SPV) I came (again) across the little screws holding the battery holders to the aluminum case back, instantly stripping out, no matter how carefully I tried to put them in. First, I tried longer screws (2-56x3/16")and small-pattern nuts, with some blue threadlocker on the nuts outside the case, but it wasn't really elegant, as befits an Elecraft build. [Photo hpim1441, hpim1442]