Squeaking and creaking HP 28C

[Pjwum]

I wanted to share yesterday's experience with you all. Recently I bought an HP 28C in good condition from TAS.



In good condition at least visually and fully working. But acoustics ..! The hinges of the folding mechanism felt annoyingly sticky with a terrible squeaking and creaking sound.

It is not necessary to open the calculator case. A small drop of my preferred bike chain wax lube did a perfect job.



Applied 8 drops of lubricant onto the 4 hinges front and backside. Then worked it into the gaps with a piece of paper. The lube will penetrate, build a thin film and is well suited for plastics.

Opening and folding the 28C is now very smooth and silent. Since I don't want to promote any product I didn't include a brand name. Any wax or Krytox based bike chain lubricant will do; just stay away from oil or WD40.

Just in case

Patrick