Mark -
I started writing this this morning, but had to leave. Since then,
Fred has provided a fairly thorough description of the appropriate
techniques. I've just added some additional thoughts.
Mark / Wim -(Fred)
What comes with each kit? (Mannino & Steinway)
From your original post, it sounds like the problem is more towards
excess friction, not looseness. Where are you located? I ask
because if you are in a climate like the northeast, with fairly
severe climate swings, you have to try to adapt your target friction
for the season you're working in. In other words, if I am repinning
teflon in the middle of winter, I will aim for the higher side of
tolerance, since, in the summer, that pinning will get
looser. Usually you have to go through a complete seasonal cycle or
two before you've moved all centers into the middle of the
range. And still, if piano is in an uncontrolled environment, you
would probably never get it perfect. But of course, you're selling
this, so your objective is more limited.
I respectfully disagree with the Luau Meister. I would, unless
absolutely unavailable, use the polished (end) pins, for two
reasons. First, I do believe the burr from cutting can affect the
way the pin moves in the bushing, but you can also reuse that pin,
since the rounded end seems not to enlarge the hole in the flange the
way the regular pin does. The whole basis for the Steinway method of
adjusting tight bushings depends upon being able to push the pin
part-way out and then back, after you've reamed, one side at a time.
(Either end of a standard pin would likely abrade a teflon bushing
when being repositioned.) It also allows fine tuning of the total
friction by being able to modify the two sides independently.
I have a set or two of carbide reamers (4 flutes) - .0490" to .0530"
by .0005" graduations, which I had made by Johnson Carbide a number
of years ago - when Steinway was supplying those spoon-type
reamers. I like them, mostly, but I tend to switch off with my
homemade set of graduated roughed center pins. With them, there is
less of a possibility of the tool "digging" in, like planing into the grain.
Unlike Fred's experience, I think I found that using the same size
of reamer as the pin you are fitting ends up being too little
friction. Maybe that's what he meant. I usually start with an
under-size reamer and work my way up.
But again, you are mostly trying to ease existing bushings. I have
had success with going in only part way with the reamer and not even
making complete rotations. Again, don't automatically assume that
you need to ream both sides. You might get the result you want by
just easing one, which is fine, as long as there is no wobble.
As far as Wim's suggestion about installing new parts, he may be
correct about the improvement in performance, but in the current $
climate, it isn't at all certain that you would even recover your
investment, let alone realize any significant increase in the sale
value. It should, but...
By the way, how many bushings are in a set from Steinway?
David Skolnik
Hastings on Hudson, NY
>Date: Sat, 06 Dec 2008 10:04:29 -0700
>From: Fred Sturm <fssturm at unm.edu>
>Subject: Re: [CAUT] S&S teflon bushings - reaming procedure
>Sender: caut-bounces at ptg.org
>To: caut at ptg.org
>Reply-to: caut at ptg.org
>Original-recipient: rfc822;davidskolnik at optonline.net
>
> Well, I won't claim to be an expert, but I have done a fair
> amount of
>work with teflon, mostly the early, thinner bushings. They can be
>troublesome to get "just right."
> With wool bushings we have a lot of options: remove
> material (ream);
>pack the felt (burnish, using different sizes of burnishers, create
>enough friction to heat up the fibers or not; sizing pin and wetting
>agent, with or without heat); and lubrication.
> With teflon, there is only the option of removing material. This
>needs to be done with a parallel tool, and the fluted reamers Steinway
>provides are good for that. But the problem is that the reamers and
>the pins are precisely the same size (precisely within our realm of
>measurement), and, in my experience, the result of reaming with a .
>050" reamer for a .050" pin is somewhere around 6 - 10 grams of
>friction, which is generally too much.
> So how do you get that friction down? You have to remove a little
>more material. I experimented with those "half size" reamers Pianotek
>used to provide (maybe still does), graduated by .0005" (midway
>between the .001" increments of the Steinway ones), and the result is,
>in my experience, 0-2 gms, too little friction, and a wee bit of
>wobble. There isn't anything between those sizes, to my knowledge. So
>I have tried using "modified technique" of reaming with the standard
>sized reamers, pressing against the sides, trying to make it even all
>the way around the circumference of the bushing. I had some success
>with that, but it's a little iffy.
> What I have ended up with is initially sizing the bushing with the
>fluted reamer, then following with a Mannino style reamer,
>experimenting with size and amount of reaming. George Defebaugh used
>to recommend rolling a centerpin on a table with a file to scuff it
>up, and using that. That works, but doesn't last too long, as the
>material of the pin is soft. The Mannino reamers are essentially piano
>wire given the same treatment, with a segment roughed up. This raises
>some filings around the circumference of the wire that act as cutting
>surfaces, but making them is inexact (the precise size will vary - and
>with teflon we are wanting to be within .0001 - .0003"), and they wear
>down with use. (you can re-rough them with a file as needed). With
>felt, it is more forgiving to use one of these. With teflon, you have
>to be more careful and experiment.
> One thing I have thought about but haven't actually looked into is
>the possibility that metric sizes might be "just right" as an in
>between size, and produce just the right friction with the fluted
>reamer. If you have some, it might be worthwhile experimenting.
>Standard pins (as opposed to Steinway's which are smooth both ends and
>already the right length) work just fine in teflon (in removing a
>standard pin, press it out from the side that wasn't cut, as the cut
>side would score the teflon during removal).
> In the end, once you figure out what will work for the particular
>application, teflon is very easy to deal with, or can be. It's very
>predictable, if you use precise tools and techniques.
> Your 80g DW probably includes other sources of friction,
> though. Key
>bushings, wipp cushions, capstans, knuckles, etc. The teflon probably
>only accounts for about 10g or so. (And, of course, there is the
>question of how much might be friction, and how much geometry, but
>let's not go there for now <G>).
>Regards,
>Fred Sturm
>University of New Mexico
>fssturm at unm.edu
At 09:44 PM 12/5/2008, you wrote:
>Mark
>
>Buy Manino's reaming kit, and ream out the bushing and repin to get
>the right friction. It will take a while, but well worth the effort.
>You don't need polished pins, but if you've got them, use them.
>
>On the other hand, if you're going to sell this piano, it might be
>worth it to replace the h/s/f. Customers who know, would think twice
>about buying a 30 year S&S with Teflon bushings. The piano will most
>likely sound and play a lot better with the new parts.
>
>Willem (Wim) Blees, RPT
>Piano Tuner/Technician
>Mililani, Oahu, HI
>808-349-2943
>Author of:
>The Business of Piano Tuning
>available from Potter Press
>www.pianotuning.com
>
>
>-----Original Message-----
>From: Mark Dierauf <pianotech at nhpianos.com>
>To: College and University Technicians <caut at ptg.org>
>Sent: Fri, 5 Dec 2008 3:57 pm
>Subject: [CAUT] S&S teflon bushings - reaming procedure
>
>Well, I managed to survive 30 years in business without having to
>deal with these by simply replacing teflon vintage parts, but now
>I've got an L action on the bench that needs sprucing up to ready
>for sale. Some of the keys are at 80g DW(!), and quite a bit of that
>excess seems to be in the hammer flanges. So I've gotten the "kit"
>from Steinway, but now I'd like to hear from the experts on the best
>way to proceed. My 1972 S&S Service Manual isn't much help ("ream
>the bushing accordingly", with a target of "3 to 6 grams"). This is
>one of the later teflon pianos, with the improved (ribbed) bushings.
>Any takers?
>
>Thanks,
>
>Mark Dierauf
>
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