center pin reamers, homemade

[Horace Greeley]

Don,

You wrote:

>Since Schaff is set up to make them, I think it's easier to just buy a
>set. I'd feel so even more strongly if they paid me something for them
>. . .

So, uh, like, uh, where should we, like, send the bread?

But seriously, folks, I have, and use, two sets of these reamers.  Wouldn't
be without them.
Use one for rough work, and then the second for more fine stuff as needed.
(see infra.)

>My main complaint with using center pins as reamers is that they don't
>stay sharp, and each time you make a new one it cuts a little
>differently. Hammer centers especially need to be consistent in
>friction, and hard steel reamers make this much easier to accomplish,
>especially if you are burnishing the bushing to smooth it during the
>reaming process.

While the center pin method has been around probably since there have been
center pins, it received quite a boost in the late '60s and early '70s when
Freddie Drasche was trying to teach folks how to work on the older Teflon
action centers.  (Yes, _those_.)  Since these latter were perfect in every
possible way, it was some time before anyone thought that field service
might be advisable, let alone necessary.  Thus, the fluted parallel reamer
kits were not yet available, and technicians had a whole bunch of pianos
that drove like old, chain-drive Diamond Ts.  Anyway, on those old
bushings, the center pin/reamers were really only good for about one cut
before they started cutting unevenly.  Quite the thing for consistent work.

Point is, pianists will feel inequality in the action through variation of
the hammer flange pinning _almost_ before they feel it anywhere else (that
isn't really obvious).  So, you can have an action that is otherwise in
excellent condition, and yet be musically unacceptable on the basis of
hammer flange pinning alone.  (Yes, there are a couple of good stories
hanging on the end of this one; but you have to ask nicely.)

I know, you knew all this already.  For those who might not have, think of
this a moss covered, ancient history.

>You can dig up my old article from the October '88 Journal to get the
>full description of how to use this type of broach.

Recommended reading.

>Motorized burnishing works pretty well if it's not spinning too fast
>as mentioned by Horace, but if this is used to enlarge the hole much
>it tends to generate too much heat, and the bushing will sometimes
>tighten back up again.

One of the things I tried at one point was to use a heated broach similar
to the one describe for use on damper guide rails.  The project was only
modestly successful.  The problem seemed to be keeping the wire in the
broach evenly heated, and therefore consistent in diameter.  I used wire
treated as Don described, soldered to brass all-thread.  Oh, yes, as these
were to be used as polishing broaches rather than as reamers, I did not
rough them up.    Maybe someone else would have more luck.

The lack of success with the above lead to using the process described
earlier.  I should note that the slow speed on my Milwaukee is about 180
rpm with a fresh battery.  In earlier days, I used the speed control
mention by the person whose name I have forgotten, and to whom I therefore
apologize.

Dave Stanwood's system advances some of these concept, but I think that he
would agree that good, basic technical work provides the best foundation.

Best to all.

Horace




Horace Greeley			hgreeley@leland.stanford.edu

	"The defining statistic of death is that it has a one to one ratio."

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