Corona Rod failure 20.5.2021

The trapezoidal nut thread in the corona rod adjustement device broke down due to the +40 years of heavy usage and poor choice of lubricant.

The old thread in the screw was tr14/3 p1.5, which means that the 14mm thread protrusion is 3mm in a single turn done with two individual threads.

This thread is somewhat rare and new nuts were impossible to be obtained with a short notice.

A closer look at the screw also revealed wearing marks that could wear a new nut down relatively fast.

For these reasons it was thought to be best to replace the wear down screw with a new tr14/4 single threaded screw and fix the bras holder with a suitable nut that was joined to the rod holder.

New parts fitted perfectly and operation was smooth with a thick old fashion lubricant creace.

The turning motor is now doing 25% more work hence the protrusion per turn is now 4mm when it used to be 3mm. Motor was found to be hot after 10 minutes of test runs, but this is probably not going to be a broplem hence the typical running time will les than 30 seconds. On a plus side the rod now moves 25% faster with the same accuracy than earlier.