[pianotech] Lock Rail Puzzle

[Paul McCloud]

Hi, JD:
	Thinking about how this might be assembled, if there are indeed lockplates
embedded in the bar, with screws in the lid, I would probably arrange the
plates so that the bar would slide into place in a direction away from the
edge moulding.  In that case, the strip you removed would keep the bar
secure and not allow it to slide out of the lock plates, and also hide any
scratch marks or at least prevent the possibility of marks on the polished
side.  I would doubt that the bar would be removed by hammering from the
side, but I suppose it's possible.  I would try to hammer (?) the bar
towards the moulding and see if it doesn't move.  Or maybe you've tried
that and I misunderstood.  
	
	Interesting dilemma.
	Paul McCloud


> [Original Message]
> From: John Delacour <JD at Pianomaker.co.uk>
> To: <pianotech at ptg.org>
> Date: 04/26/2011 1:22:32 PM
> Subject: Re: [pianotech] Lock Rail Puzzle
>
> At 21:26 -0400 24/04/2011, Philip Jamison wrote:
>
> >Take a small "rare earth" magnet (the little, very powerful ones) 
> >and run it across the top...
>
> That was a very good tip.  I used a not very powerful 3/8" x 1/4" 
> magnet today and it gave me the position pretty accurately of 8 
> equally spaced ferrous things, central along the rail.  So far so 
> good.
>
> At 23:40 +0100 24/04/2011, John Delacour wrote:
> >If you look at the bottom of the picture you will see there is a 
> >thin strip between the lock rail and the moulding.  This is a 
> >separate part from the lock rail proper and probably holds the 
> >secret of how the rail is attached.
>
> Following this line of enquiry, I knocked out this fillet using a 
> mallet and first a 1/2" chisel and then a long strip of hardwood 1/2" 
> x 1/4" with a chiselled end.  The fillet was glued in but the glue 
> was sparse so the fillet came out with no trouble.
>
> One thing is certain, I think, and that is that the screws, if that 
> is what is there, have not been turned in and then veneered over from 
> either one side or the other, because I know it is impossible to make 
> such a job perfectly invisible over 140 years.  And besides, it's 
> just bad workmanship and would never have been considered by 
> Brinsmead.
>
> Next thing I did was hammer the lock rail, at the points where I know 
> there are ferrous things, towards the gap left by the fillet.  My 
> original guess when I puzzled over the point of that fillet, was that 
> there are short screws with countersink heads in the top front half 
> that engage with keyhole plates in the hidden face of the lock rail, 
> the same method used by other makers in the longitudinal arrangement 
> whereby you need to hammer the *end* of the rail (after trying to 
> remember which end!) to release the rail.
>
> For a while I had no joy.  I then fed in a little spirit under the 
> rail from the fillet side in case glue was involved.  In several 
> places the spirit wicked wight through to the blind side of the rail 
> and I had to keep a rag handy to wipe it off quickly and avoid 
> burning the polish.
>
> The stage I'm at now is that I've managed by hammering to move the 
> rail in about 2 mm at one end, and I'm leaving it at that until I can 
> be sure I'm not heading for disaster.
>
> There is no polish between the rail and the top and none there the 
> fillet was, but I think it more likely that this was masked while the 
> top underside was being polished than that the thing was polished 
> with the rail attached.  Any French polisher knows that you don't 
> make things so that you need to polish into corners.
>
> Finally I can see no other possible use of that fillet but to lock 
> the rail in position.  It adds nothing visually -- in fact it looks 
> strange -- to it must have a mechanical function.
>
> If anyone has time to dream up or puzzle out the ultimate solution, 
> I'd be mode grateful.  I should have though of the magnet trick 
> myself, but I didn't, so that was a bit of progress already...
>
> JD