Swing Test

[John Musselwhite]

At 10:59 AM 24/04/96 -0600, Ron T. wrote:

>>with an appropriate hole.  Its weight is 5.6 grams.  I had one of those
>>thingies with the S&S logo embossed on the top but I am unable to find it
>>now.

I still have mine after 15 years, sitting in a metal box with all the other
Teflon equipment. I might add I keep a small bag of silica gel in the box to
help protect the stuff against excess moisture just as I do in all my tool
boxes.

>Problem I find with these solid teflon parts is that I can't seem to get
>the darned flange to move in a fluid motion.  It's *jerky*!  How the heck
>are you supposed to measure friction when breaking inertia is half of the

Give them a few quasi-violent swings first to warm up the pins in the teflon
before you measure them. If that doesn't work and they're still jerky, ream
and repin if necessary.

I've found improper reaming can create a jerky feel. If they are correct,
they should run smooth and the swing test may not show the small drags that
checking with a gauge will. Don't forget to keep lots of spare bushings
around as sometimes popping out the old bushings and inserting and reaming
new ones is the most efficient way to fix them.

Some people have mentioned they don't use Steinway pins on teflon parts. It
is very important that when repinning teflon bushings you ONLY use pins
finished on both ends such as the pins Steinway sells for this purpose.
Cutting one end of a common pin to size could quite possibly make them drag
and might ruin the bushing as well as making future work more difficult.

If nothing else, using ordinary pins isn't the correct way of doing the job
and will slow down the process. One of the advantages of teflon should be
ease of service. Despite the slightly increased frequency of service, at
least it's faster than servicing felt bushings.

                John
John Musselwhite, RPT
Calgary, Alberta Canada
musselj@cadvision.com