Re: Knob repair tips

Chuck Harris
 

Because the plastic has shrunk, you need to increase
the space for the center hub. The easiest way I have
found is to assemble the parts as well as you can, and
then wrap some rubber bands around the knob to provide
tension.

Then take a soldering iron, and heat the center hub.

The instant the plastic relaxes, remove the heat, and
cool the hub by blowing on it.

After all is done, a drop of acrylic solvent glue will,
seal the deal, so to speak.

-Chuck Harris

Dave Voorhis wrote:

I just acquired a Telequipment (British subsidiary of Tek in the 60’s/70’s) CT71 curve tracer in excellent working condition and good cosmetic shape, but for a cracked knob. Like the usual Tek knobs, it’s a plastic shell around a linear-knurled metal core. The plastic appears to have shrunk slightly, causing it to crack and no longer grip the core.

If I recall correctly, someone posted tips on this forum on how to permanently repair such shrink-cracked knobs, but my search-fu must be broken today because I can’t find the relevant posts.

Can anyone can give me a quick recap and/or point me to the posts on groups.io <http://groups.io/>?



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