[Elecraft] Elecraft Construction Questions

[Ron D'Eau Claire]

Terry, be aware that the correct amount of torque is determined as much by
the objects being fastened by the screw as it is by the strength of the
screw. 

In some places, a screw threads into soft plastic. Any extra movement beyond
the point at which the head touches the surface will strip the threads out
of the plastic.

In other places screws secure plastic bezels to a panel. These can take a
little more torque than the screw-into-plastic situation but not much before
the plastic cracks or deforms. 

And in some situations the screw threads into fairly thin sheet metal with a
threaded hole which makes it very easy to strip the threads. 

The Elecraft manuals provide guidance in the steps where the above occur,
but they also presume you are using a manual screwdriver and paying close
attention to the feel of the screw as it tightens. 

Even where the only concern is to keep the screw from breaking, there is
little gain from tightening the screw past the point where you feel the
resistance suddenly increase. At that point the screw has stretched
slightly, clamping the parts together. 

Lock washers are called for wherever it is likely a screw will work loose.
You only need to tighten a screw with a lock washer until the lock washer is
compressed, whether it is a split ring or a star type. Squeezing the lock
washer past the point at which it is flat does nothing at all and may
actually be counter-productive. The amount of torque required depends upon
the type of lock washer more than the screw. 


73,

Ron AC7AC



-----Original Message-----

2. are there recommended torque settings for fasteners?

   I typically use torque limiting drivers that are set as follows for
metal fasteners:

   2-56 threads = 2 in-lbs
   4-40 threads = 3 to 5 in-lbs
   6-32 threads = 6 to 10 in-lbs
   8-32 threads = 15 to 20 in-lbs
   10-32 threads = 25 to 30 in-lbs

   ok? not ok?


Regards - Terry

ps: anyone know what power connector is used on the KX3?
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