Scandalli Treble Pallets

[Glug]

I'm having a real problem with a 1950s Scandalli LMMH - the treble pallets are a really silly design.
The basic issue is there's almost no position adjustment available and some are about 3mm out of position. This causes a massive air leak because even with new facings the air holes wouldn't be covered properly.

Here's the original pallets:



As you can see they're held in place by bent aluminium tabs (which get a bit loose) but the only adjustment is to bend the key arm left or right.

Possibly the keyboard has sagged over the years, but for whatever reason quite a few need adjustment in the longitudinal axis. You can see on the pillows that they have been out of position for years.

As far as I can see I've got 3 options:
1) Glue new facings on offset by the required amount - a really bad idea
2) Give up
3) Make some new pallets that can be adjusted.

Since I've currently got too much time on my hands, and I'm slightly mad, I had a quick go at making a new pallet:





There's an M2 countersunk bolt holding the pallet to the arm with 1mm of neoprene in between. Then there's a spacer and the M2 nut. If I superglue the bolt to the pallet this should allow the nut to be loosened with a nut spinner for the pallet to be positioned. There should be 11mm of longitudinal adjustment and they can be rotated. Luckily I had all the parts lying around.

Anybody think this has a chance of working, or got any suggestions ?
Other than 'you need to get out more' that is

 

[debra]

The risk with your new design is that the nuts may work themselves loose over time. (After all, the pallet gets a lot of beating while you play.
Why not remove grind off that whole "side part" and just keep the plain arm and then use new wooden pallets (with felt+leather underneath of course)?

 

[jozz]

you need to get out more

 

[Glug]

Yep, I agree the nuts coming loose is possibly the main issue.
I think the neoprene will provide some tension to reduce the risk, or there's always Fabric-tac on the threads.

On the up side, I can try this without altering anything original, so if it doesn't work I'm no worse off.
It's too cold to go outside anyway.

 

[Ventura]

i partly agree with Debra's idea, but am not sure the aluminum arm
can then be re-bent to compensate for the off-center position it would be in
(with attachment ground off)

aluminum can be bent in minor increments a number of times,
but Thick aluminum can seldom be bent extremely more than once or twice

therefore, my suggestion would be to SLOWLY bend ONE of the pallet spurs
that come through the attachment hole, allowing you to lower
one side of the pallet then the angle will allow the other side to slip out
without bending (rather than bend both of them back... less risk of a break)

THEN grind off a minor amount of aluminum from each side of the two
spurs (so that they will have a tiny bit MORE play when you put the
pallet back on

then a new felt and leather of course

mark pencil lines on the main baffle as guides so you know when
you have aligned each re-furbished pallet perfectly

NOW when you put the key back in, you can wiggle the pallet enough to
get it spot on, then SILICONE CAULK it into place by filling the
wiggle room where the spurs come up through the mounting hole

yes yes i know this is not the correct method, and is sort of permanent,
but your repair will likely outlive the rest of the accordion

and silicone caulk never really turns rock hard, so you could make a spot
repair in Future if one was ever needed

i have worked with this stuff for decades now, we had it early on for Car repair
and making difficult Gaskets and such and it really is reliable and easy to use...
small tubes of clear, white, or black can be had inexpensively from any hardware store,
while the high temprature Blue and red caulk is in the Automotive section

Scandalli improved it's attachment method after this, with a slightly flexible system,
and you might even find your exact model with an improved mechanism that
you could swap out (if you have an accordion graveyard somewhere nearby)

but i think you can fix this one with patience...

 

[Glug]

Yep, I do want to avoid bending the aluminium too much.

Unfortunately your suggestion won't work: I need to move the pallet 3mm in the direction of the long axis.
With the tab attachment method there's zero adjustment in that direction.

 

[JIM D.]

I must echo Paul's advice and recommend grinding the lugs off the rods & use wooden pallets. Wooden pallets when waxed
on can be adjusted in the future. Find an old for parts only box with wood valves and remove them. Best if the pallets are bigger
than yours so that you can cut them the size you need. You of course must be aware than an accordion with this pallet design
was built with planed obsolescence. Is the rest of the box savable ???

 

[Dingo40]

Glug,
I admire your inventiveness ??
As far as keeping the nuts tight goes, there is this ( very effective) product available from hardware, fastener, and car parts stores:

loctite threadlocker - Google Search

www.google.com.au

 

[Ventura]

yup.. that blue liquid threadlocker is handy... you can get it in
both more or less "permanent" or "snug but you can unscrew it wthout damage" formula

and Dingo, i have even used it where wood-threads were half-stripped and i was
not anticipating ever removing the screw again... like a leaky bellows strap mount...
i mean you can only use bigger and bigger screws so many times !

 

[Glug]

I was looking at Loctite threadlocker yesterday.
I need the countersunk M2 head to stay fixed in the pallet while the nut is loosened/tightened since the head will be under the pallet facing.
It's a bit small to use epoxy so I'm trying https://www.amazon.co.uk/gp/product/B001C0G1X2/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
I'll soon find out if it works.

 

[Dingo40]

Glug, you appear to have enough room to add a second nut as a "lock nut ". A second nut plus loctile should make it pretty permanent!?

 

[Glug]

Well said, I just had a similar thought:

The orginal spacer between pallet and arm is 1.7mm thick, the neoprene I tried is 1.75mm thick, the m2 nuts I'm using are 1.5mm thick.
Therefore I can punch a larger hole in the neoprene and fit a lock nut on the top side of the aluminium sheet to lock the bolt in place.

It did occur to me that if I was really really clever I would work out some way of making the space betwen the arm and the sheet adjustable.
Then I could level the keys too

Actualy I could fit a shim on top of the neoprene ....

 

[Dingo40]

Glug,
Another thing you could use is self locking nuts. These have a nylon insert that prevents the nut working loose, but is removable using a spanner. I'm sure they are available in M2 size.
Over here, you can find them in your local hardware stores.?

 

[Glug]

That's a damn fine thought

They're 25 for £10 on Amazon, and probably cheaper other places.
I should have thought of that - I've rebuilt car/bike engines before.

 

[Glug]

And here's the new design:


I tested it using an old Hohner Lucia pallet facing (4mm) and it seems to work fine, I even adjusted the tilt to make it close evenly.

I'm guessing the original pallets used the 6mm facing to get them to close evenly without having any adjustment.

 

[Glug]

I think there's a fair chance this is going to work:



I've done half the pallets so far and the only real issues so far are:
1) Bolts hitting the grille on leftmost white key. So I put shorter bolts in the top row and omitted the spacers: you can still get a 4mm spanner on it when it's in place.
2) I'm recycling some old Lucia facings and the old glue is quite lumpy and can't be removed easily - causes problems with the facing sitting flat.

I also had a go at levelling the more errant keys (left half only):



(curvature is wide angle lens distortion) Needs a bit more work but is obviously getting there.

 

[Glug]

And it worked (after a long delay messing around with celluloid).

I've fitted some new facings and done basic adjustments and I'm getting 42 seconds on a master/master drop test. There's still room for improvement by more careful adjustment but 42 seconds is usable. And I haven't done anything to the bass pallets yet.





And it's now levelled with approx 4.7mm keyboard action:

 

[debra]

Great job! Must have been quite an adventure, but it's the final result that counts! Congratulations!

 

[Glug]

Cheers, it took a while but seems to be a success.
I can now adjust the pallet positions with a nut spinner (and bending irons when required).
The keyboard is actually fairly pleasant too, but I haven't played it much yet.

 

[Dingo40]

Glug,
I'm impressed!
Perseverance pays!??