Hook Pivots...?

[Jack Bradshaw]

What is the best design for (or source of) "Lachenal" rod pivots ?? The scrapper for reeds had what looked like simple staples, not the cutout plates that I see in pictures....

 

Jack

 

Er, Jack, what is the objective here?

 

1. to refurb a damaged action plate?

 

2. to refurb a damaged pivot post or two?

 

3. to re-develop a concertina with different fingering etc? more keys or what ever.

 

Dave E

 

Mmmmm....#3.....to make up a 30+ Anglo out of whatever I can get my hands on.........(the Naval Jelly arrived last night..for reed cleanup)

 

The action plate is the current center of attention......needs to be made (or revamp an English...probably better made new)

 

Jack

[Jack Bradshaw]

This is where I have a problem with terminology. A 'staple' to me is simply a piece of round wire bent into a 'u' shape and I have seen a concertina (a Wheatstone in fact) with just such an action. Lachenal's 'standard' slotted pillars, whilst not being ideal, are much more sophisticated - but I guess it would take an engineer to say if the degree of sophistication had any material effect compared to a simple piece of bent wire.

 

The point is that the action you have is just about as good as Lachenal ever got so unless you want to go down the road of fitting a complete replacement riveted action (expensive!) there isn't much you can do other than a straight replacement if the existing action is so badly worn.

 

The main issue between the Lachenal 'window frame' post and the staple is the lever arm's flank support where the arm is subject to axial turning moments. These situations only become a problem:

 

a, if the lever arm is in anyway cranked,

 

and

 

b, the legs of the staple are splayed.

 

The resultant problem will be the same as the 'Edeophone Cranked Arm Syndrome' previously discussed on this site.

 

Dave E

 

Right...you want to minimize side friction and the pivot to be a pure rocking motion...the staples I had showed little or no side wear but quite a bit of rod wear at the joint between the rod and the staple....as if the rod bend was too tight......I would suspect that the punched frames might be better in this area.

[Jack Bradshaw]

It's not so much that it's worn or that a "staple" action couldn't be good (although the wear marks on the rods would seem to suggest that it wasn't the optimum fit) as that it's the wrong action plate (just what I could find as junk)

 

I'm not convinced that "riveted" is necessarily the best action either.....(instrumentation background)...hence this topic.....

 

Come to think of it...and I just thought of (remembered) it....years ago, when I was making microindentors, we used "spring pivots" ....which combined both functions...I'll dig that up .....

 

Jack

 

Here's an example:

 

http://www.flexpivots.com/?source=ssi_gaw&...CFQolHgodgg_mFg

 

Of course, I have no idea if these are the "right" ones or pricing yet !