'Vintage' Italian engineering

[KiwiSqueezer]

(Not a 'How do I...?' post... This is just for the interest of any engineers lurking here.)

I'm getting deeper into the restoration of an old Scandalli 'wreck' (one of the models with six mute flaps). I'm more at home with precision engineering, and the restoration of machine tools, so restoration of an accordion or two is a journey into unfamiliar territory. I was surprised to discover that the Scandalli's treble switch mechanism contains fixings with 1/8 inch Whitworth threads. By the 50s, this was a more-or-less obsolete thread standard in its country of origin (UK), so what was it doing in an Italian accordion? I thought Italy was metric by then. There are metric standard fixings elsewhere in the box. And others I have yet to identify. Very strange...

 

[Ventura]

just try and find a replacement bellows screwbolt for an old Super 6 !

the thread pitch never matches up with anything in my huge box of odd
spare parts or trays of nicely sorted more-than-ones

 

[Ffingers]

A lot of stuff from black-marketing of WWII military supplies, US and British, lasted for decades in the small manufacturing enterprises.
I came across ex-US equipment still in use in small repair shops and mechanics’ garages in Sicily as late as 2006.

 

[Glug]

You'll probably find the bass strap adjuster is 3/16" Whitworth too.
I think that spec is still in use, you can certainly buy them from Hohner etc.

 

[boxplayer4000]

KiwiSqueezer: You’ve raised an interesting subject.
You haven’t given an estimated age of your Scandalli ‘wreck’, or supplied a picture. I can’t recall seeing many pre-war accordions with mute flaps but no doubt somebody will correct this if it’s wrong. You say “I thought Italy was metric by then’ but it would be my impression that Italy was never anything else. The theory that military black-market stuff was around is very plausible as the amount of stuff left over, everywhere, was just colossal following the end of the war and while both Italy and Germany didn’t seem to take very long to recover it’s entirely possible that there may have been a stage where a supply of foreign hardware, nuts, bolts etc. would come in handy.
(A very popular TV series which ran in the UK and which was based on the novel ‘The Darling Buds of May’ by H.E.Bates was about the Larkins family who lived on the English south coast in the period following the war. ‘Pop’ Larkins was a very shrewd operator and became rich buying and selling the masses of military and wartime equipment left in that area following D-day.)
I think it was later than the 50s before the UK’s imperial standards started to recede. I was active in naval engineering in the 60s and tools and parts were mostly in BSW and BSP etc. As far as I remember I had to update my toolkits in the 70s and 80s when I had cars with metric parts.
Glug makes the interesting observation that some bass strap adjusters are BSW. It seems strange from a European supplier. Another anomaly is the common use of a 1/4” whitworth screw in many camera mounting points; not many cameras are made any longer in the UK as far as I know.

 

[Dingo40]

.. so what was it doing in an Italian accordion? I

Those Italians got around!

 

[KiwiSqueezer]

Ah, yes, I'd forgotten about bass strap adjusters. The current Italian standard does indeed appear to be 3/16" Whit., although it's possible it's 10-24 UNC, or even #10 ANC - they're the same pitch, with the last two, American, being 0.0015" greater diameter (nominally). I can't tell whether the thread angle is 55 degrees, which would be Whit., or 60 degrees, American. I hadn't thought about war surplus equipment - good point! Also, I hadn't thought about the US-Italian connections either. From now on, I'd better not make any assumptions about anything to do with accordion construction...






What it looked like, when rescued.




What it's supposed to look like. There's a bit of work to do...

Just look at those mute flaps! Original, two-part pattern. I wonder how that's possible - this is a contemporary picture.

 

[boxplayer4000]

KiwiSqueezer:
Although I studied thread design in an earlier college life, which centred on British Imperial standards, you have obviously made a closer study of the alternatives. You make a good case for the fact that there might be a bit of confusion between some threads because there is only very slight differences in sizes in some cases. It looks like another case of 'beware' when it comes to things accordion and not jump to the first conclusion.
Will the Chinese products muddy the waters still further?

 

[Dingo40]

Will the Chinese products muddy the waters still further?

Left-hand threads?

 

[boxplayer4000]

Left-hand threads reminds of the story about the parachute instructor dealing with a nervous trainee. The trainee was being assured that even if his parachute failed his reserve 'chute would kick in. This was not enough for the trainee so the instructor said if his reserve 'chute did not activate then he should cross his left leg over his right. 'What good will that do?' was the question to which the answer was 'We find it easier to unscrew you from the ground with left hand thread'.

 

[Rosie C]

I think it was later than the 50s before the UK’s imperial standards started to recede. I was active in naval engineering in the 60s and tools and parts were mostly in BSW and BSP etc. As far as I remember I had to update my toolkits in the 70s and 80s when I had cars with metric parts.

That sounds about right. Ford UK marketed the mk3 Cortina as their first "metric" car. There are a couple of bolts not metric, but nearly every one is.

 

[JKJ]

just try and find a replacement bellows screwbolt for an old Super 6 !

the thread pitch never matches up with anything in my huge box of odd
spare parts or trays of nicely sorted more-than-ones

A machine shop (or a friend with a decent metal lathe) can make from scratch a screw or bolt of nearly any size, pitch, thread shape, and material. On many lathes a custom pitch is a matter of choosing the gear ratios. Thread shape is primarily a matter of tooling. Non-standard diameters and such are trivial. If you need a duplicate of one in hand take it when consulting with a machinist.

I’d hate to be without a lathe and mill and a few other tools for working with metals, plastics, etc. Sometimes it’s easier to make some missing or broken part from scratch than locate a replacement.

 

[debra]

Left-hand threads?

I have not encountered left-hand threads in an accordion until now. But they are not all that uncommon. On a bike one pedal has left-hand threads so it doesn't unscrew itself as you pedal. And propane tanks for a barbecue have left-hand threads too. (I believe this is to have unique combinations of hose and tank threads so you don't try to hook a tank with the wrong type of fuel to the barbecue.)
With accordions I'm just careful not to loose bolts and screws while I work. And as I work mostly on somewhat recent instruments they seem to be all metric and using the same type of thread, even the Russian ones. I used to work a lot on computers as well. Nothing was metric there...

 

[Rosie C]

What it looked like, when rescued.




What it's supposed to look like. There's a bit of work to do...

Just look at those mute flaps! Original, two-part pattern. I wonder how that's possible - this is a contemporary picture.

I was at our community jazz band rehearsal last night and thought of this. I was sat behind the tenor saxes and their saxophones have similar "mute flaps"

 

[boxplayer4000]

Rosie: If you can get your hands on some of those saxophone 'mute flaps' maybe you and KiwiSqueezer can come to some kind of deal.
More seriously: Many accordion parts can be sourced, or as a last resort, made, but KiwiSqueezer's missing flaps are not the sort of thing that come along often and would not be an easy DIY project.

 

[Rosie C]

Rosie: If you can get your hands on some of those saxophone 'mute flaps' maybe you and KiwiSqueezer can come to some kind of deal.
More seriously: Many accordion parts can be sourced, or as a last resort, made, but KiwiSqueezer's missing flaps are not the sort of thing that come along often and would not be an easy DIY project.

I think the sax section might get a bit annoyed with me!