Upright pinblock question

[Michael Magness]

On 10/28/07, John Ross <jrpiano at win.eastlink.ca> wrote:
>
> Why don't you just get a piece of angle iron, then you would also have
> rigidity.
> The original lag bolts are normally close to the top, so I think angle
> iron
> would work.
> You might have to route an indent, so the lid will lie flat.
> John M. Ross
> Windsor, Nova Scotia, Canada
> jrpiano at win.eastlink.ca
> ----- Original Message -----
> From: "gordon stelter" <lclgcnp at yahoo.com>
> To: "Pianotech List" <pianotech at ptg.org>
> Sent: Sunday, October 28, 2007 9:18 PM
> Subject: Re: Upright pinblock question
>
>
> >     I put the bolts in from the front, but with a
> > BUNCH of fender washers under the nut on the back:
> > lest the nuts/washers get sucked into the wood.
> > ( Nobody should put an upright right against the wall,
> > anyway. )
> >     On a very rare and costly upright I may soon be
> > working on, I intend to have a 1/8 inch ( at least )
> > steelplate made to stretch all the way across the
> > back, with holes drilled in it, for the bolts to go
> > through.  Not very pretty, but the most stable,
> > long-lasting solution. ( Should help keep the back
> > from "cupping", too! )
> >
> > Peace,
> >     G
> >
> >
> >
> > --- Willem Blees <wimblees at aol.com> wrote:
> >
> >>
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Tired of spam?  Yahoo! Mail has the best spam protection around
> > http://mail.yahoo.com
> >
>
> Hi Terry,

I have done the exact repair you are contemplating on the exact piano you
are referring to. First of all, the reason it seperated is because Kohler &
Cambell in their very wise woodworkers way made their back structure from
spruce and glued the pinblock to it. Since spruce expands/contracts at a
differing rate than maple it seperated at the glue joint! Surprise! <g>
Now to the fix, first of all you need PIPE clamps not c-clamps c-clamps will
warp and not give you nearly the holding power that pipe clamps will, I know
I've tried both! You can get Pony brand pipe clamps at any home center, get
the 3/4" , you can also get the threaded pipe you'll need, I'd get 12"
lengths, that's long enough for any old uprights you may want to bolt in the
future. I have about 8 clamps but usually only have space for 6 of
them. Place a clamp near each screw bore the screw hole and pinblock behind
it all the way through, I use 1/2" carriage bolts about 1/2" longer than the
thickness of back and plate, If there isn't room for 1/2" use 7/16" or if
that's still too big then you have to use 3/8" but then go to the grade 5
hardened bolts, the standard grade 3/8" snap off way too easily. They come
in half sizes to 6". I use a large flat washer under the head of the bolt,
one large enough for the square heade to fit through it but for the round
lip to catch on it, in back, a small flat washer and a lock washer and nut
in front against the plate. Snug them tight until the bolt tries to turn, If
they turn too soon, put a clamp on them at an angle to hold it while you
tighten.
There is no need to lower tension since your clamps will maintain the hold
that the screws did. You will need a good drill, a cordless won't do the
job, something with at least 4 amps of power. A good metal bit and depending
on how thick the back is, perhaps a longer auger bit to finish out the hole,
lengthwise.
As for glue, I've always just used Titebond since it serves more as a filler
than anything else and mostly squeezes out anyway.
The plus side of investing in the clamps is you can invest in longer lengths
of pipe to use them for case repairs on pianos, bench repairs, wherever you
need a clamp of whatever length you need since you can combine lengths of
pipe w/couplers as well as get longer lengths.

Mike
-- 
Learn from yesterday, live for today, hope for tomorrow. The important thing
is to not stop questioning.-- Albert Einstein



Michael Magness
Magness Piano Service
608-786-4404
www.IFixPianos.com
email mike at ifixpianos.com
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