[pianotech] glue sizing balance holes

[Joseph Garrett]

Mark D. said: "I've just been doing this job myself on a keyboard that I'm
    rebushing. I've found that introducing steam before glue sizing will
    cure even very extreme cases of loose balance holes. I used a Singer
    Steamer on these, but I've used a simple tea kettle in the past. The
    glue sizing by itself doesn't seem to swell the wood nearly so much
    as when steam is used (well, duh!). This before and after shot of
    the same balance hole shows the elongated hole (left) made more
    round after steaming (right). Immediately after glue sizing I
    burning lightly with a dummy keypin, then let them dry overnight
    before placing them back on the keyframe to "set". After rebushing,
    they will need to be eased for proper fit. I've found that applying
    some teflon powder to the holes with a small nylon brush will reduce
    the amount of easing required. I burnish this into the wood somewhat
    by using the tapered easing tool from the bottom of the key, but
    without using any pressure at all so as not to enlarge the hole. <br>
    <br>"

Mark et al,
I agree that stream needs to be entered into the equation, for glue sizing
to be effective. The system that I use is to steam out the bushings from
the top, with the keys elevated, which lets the steam pass through the
balance hole in the process. I then flip all the keys over and apply the
glue/water to each hole with a pipe cleaner, making sure there is good
saturation, but not drooling down inside the mortises. I've had good luck
with cold hide glue and water, (50%-50%). However, I agree with Ron N. that
the likelihood of noise is greater with that mixture, if the fitting is not
precise. Whatever glue is used, that works for you, is fine, imo. Once the
holes have been swabbed, I insert a balance rail pin in each hole and leave
for at least 24 hours for the glue to set up. This leaves the keys at a
state, where light easing only is required. I also use brass culls for the
bushings, heat with an iron and let set overnight, at least. Inserting the
balance rail pins gives me information, as well. If the balance rail pin
falls through, that tells me I need to add material to the hole, in some
way. I use several things to make the hole the correct size: travel paper,
veneer, or in extreme situations a balance hole insert made out of hard
wood. I have a "Bling", (necklace sign), hanging in the shop that says: If
The Keys Are Not Right, Then Nothing Else Can Be. That says it all. (used
to was a poster, but it wore out.<G>)
Joe


Joe Garrett, R.P.T.
Captain of the Tool Police
Squares R I