Fitting Teflon Bushings

[barre46@ibm.net]

Hi Del,

The only instruction I have received about teflon bushings was in a class by Fred
Drashe, (Spelling probably wrong). He liked them too and mentioned converting his
personal piano to teflon. In his class he stressed the importance of both sides being
of equal friction but I don't recall him mentioning fitting the bushing to the hole.
That certainly makes sense. It does seem however that the reamers you had made are
quite expensive. My question is, do you think that the straight reamers available from
Steinway are not good enough for this procedure or were they not available when you
got yours?

Norman Barrett
Memphis, TN

Delwin D Fandrich wrote:

>
>
> 3)    Ream the bushings.  This is the most critical step of the whole procedure.
> And the secrete is in having the proper reamers.  Do NOT use a knurled center pin,
> it will simply make your problem worse.  It does wear away a bit of the Teflon,
> but mostly it just temporarily compresses it.  This will give you the illusion
> that you have obtained a proper fit but the center WILL tighten up on you later.
> You must actually cut the hole to the proper size.  I had my reamers custom made
> -- The name Johnson Carbide comes to mind, but remember I had these made some 25+
> years ago.  As I recall the set cost me about $90.  -- of solid carbide in 0.0005"
> increments from whatever to whatever.  I think the smallest was the diameter of a
> #18 pin or a #19 pin.  There were seven of them.  They had five flutes and they
> were ground in a "reverse" spiral.  This kept the tendency to chatter down and
> made it easier to cut a nice clean hole in the Teflon.  The flutes were only 4 mm
> long.  I could carefully press the cutting end of the reamer all the way through
> the first bushing and cut the second bushing using the first as a guide to keep
> the hole straight.  I would then -- again, very carefully -- pull the reamer out,
> turn the fork over and repeat the process cutting the first bushing.  I would then
> verify the fit and friction of the pin before assembly.  Make sure that you have
> the same amount of friction in each bushing.  With just a bit of practice this
> became a one-shot operation.  Once you have verified this you can assemble the
> center.  Check overall friction of the center and trim the pin.  Don't worry about
> the slight burr.
>
>