Air Loss

[varney]

I'm in the process of trying to restore a 30 button mahogany ended lachenal which has a worn bellows. Have ordered some very fine sheepskin leather to rebind the bellows which have been temporarily patched to allow me play the instrument. It lacks air which is obviously due to the worn bellows, but there's also a great draught of air coming through the left grille when the bellows is pushed shut.

 

I've read back through the forum and found some similar situations where this was dealt with. I've tried several of the suggestions:

 

1. Lifted chamois on bellows frame interior and packed with thin card to make reed pan sit tightly in the frame.

2. Ensured corner blocks are holding reed frame at the right height to form a good seal with the base of the pad board.

3. Ensured chamois on top of reed chamber walls is roughed up to help form a good seal.

 

None of these seemed to help the situation so I put tape over all the pad holes in case worn springs were allowing the pads to lift with air pressure from the bellows. To my surprise this only marginally stopped the gust of air which seems to escape the left hand side. There's a small gap between the body of the pad board and the glued- on edging at one point on the underside. I had thought this to be the certain culprit, but when I taped this AND the pad holes it still made no difference to the air escaping.

 

Can anyone suggest any other things I might try?

[Frank Edgley]

Perhaps the tape is not doing the job you thought it was. You best bet would be to seal the edges where the action board meets the walls of the box with carefully applied glue. I use Weldbond as it is very vicose and is good for sealing small leaks. Probably the hide glue has dried out and cracked over the years. Use a very fine applicator, like the broad end of a toothpick. Next, replace the pads. Make sure you have "pad mounts" on the tops of each pad. These are small cicles of leather which allow the pad-to-mechanism joint to remain flexible for a better seal. Check to see that each pad is sealing by blowing through the vent hole from the back side. You can make a tool for doing this using brass tubing a small bit of wood and some leather for a seal, but you can get by without it. Check to see the spring pressure is OK if you have replaced the pad and some of the vent holes still leak. Lachenals are very difficult to make very airtight, compared to some other makes, but you should be able to make some significant improvement.

[varney]

Perhaps the tape is not doing the job you thought it was. You best bet would be to seal the edges where the action board meets the walls of the box with carefully applied glue. I use Weldbond as it is very vicose and is good for sealing small leaks. Probably the hide glue has dried out and cracked over the years. Use a very fine applicator, like the broad end of a toothpick. Next, replace the pads. Make sure you have "pad mounts" on the tops of each pad. These are small cicles of leather which allow the pad-to-mechanism joint to remain flexible for a better seal. Check to see that each pad is sealing by blowing through the vent hole from the back side. You can make a tool for doing this using brass tubing a small bit of wood and some leather for a seal, but you can get by without it. Check to see the spring pressure is OK if you have replaced the pad and some of the vent holes still leak. Lachenals are very difficult to make very airtight, compared to some other makes, but you should be able to make some significant improvement.

Hi Frank,

 

thank you for the fast and helpful reply. I used a clear plastic packing tape as I thought masking tape might be too weak or porous. Had thought of using gaffa tape but that stuff is relatively thick and would create a gap of its own between chamber wall tops and base of the action board.

"............. seal the edges where the action board meets the walls of the box......"

 

Are you saying glue up the small opening between the frame edge around the action board and its hexagonal base? I will certainly try that but I had thought taping this up along with the pad holes would have revealed either / both as the problem. Perhaps the tape was the problem.....

 

The pads do need replacing so that will be the next job. Is the 'pad mount' the smaller disc of leather which connects between the pad and the lever? There are gunky corroded bulbuous things on the end of the levers which I feel need replacing. Are these 'sampers'? What do you use to make them?

 

Thanks again....

Michael.

[Frank Edgley]

The corroded bulby things are leather nut on the ends of the mechanism arms. The pad mounts are the small leather discs which form the connection between the pad and the leather nut. The purpose of the leather nut is to fucus the pressure on the centre of the pad. The purpose of the pad mount is to provide some flexibility to the joint. It's a bit of a job removing the leather nuts, and messy, too, as they will crumble into dust and small bits. If you choose to remove them you can crush them with small pliers. Replacement nuts can be obtained from Organ Supply Industries in Erie Pennsylvania. This is where it gets a bit tricky. Nuts with a similar outside diameter have a hole which is too small for the arm. Nuts with a suitable hole size have a larger O.D. than the original. You can either try to make the hole larger on the smaller nuts, or grind down the tops of the larger nuts so they don't hit the end grill when the button is pressed and the pad end rises. Maybe you can find some suitable small beads at a shop which sells craft supplies. As far as sealing the edges with tape, it's probably not the tape which is porous, but whether the tape can make that sharp 90 degree bend bewteen the action board and the walls of the box. Even a microscopic difference will show itself as a leak. Don't be nervous about using glue as this joint is never intended to be taken apart. The best time to do this job is when the pads are off as it will give you room to work. Be neat and clean up eveything not serving a useful purpose. Now the bad news... The more you make some areas more airtight, the greater the pressure inside the instrument, and the more other leaks will show up. But don't dispair. With perseverence, you will make improvements, and a playable instrument.

[varney]

Frank,

 

Thanks for the words of encouragement! I was thinking that very thing about the bellows being more pressurised if the end leak is sealed. I'm working to get a new bellows ( or even an old replacement ) but want to do a rebind and a patching job on the current one just for experience. I also hate to throw anything away that has survived on an old instrument.

 

With that in mind, I won't be crumbling off the leather nuts but will try to clean and reuse them. I'll certainly look into finding something like you suggested or adapting those sold by the Erie Organ Co. ( why are all the organ supply companies in Pennsylvania??!!)

 

Incidentally , can you tell me if the Carinis in Italy are the ones who supply basic black leather concertina bellows? I see a couple of people offering them for sale and am trying to find out where they come from.

 

Many thanks for taking the time to help me with this, FRank. I'll post my progress...

 

Michael.

[Jim Van Donsel]

Air Loss, eh? Well, me 'ead is gettin balder too, so welcome to the club.

 

-jim

[varney]

Very good Jim! Will need to title my messages a little more thoughtfully....??!

[Frank Edgley]

Frank,

 

Thanks for the words of encouragement! I was thinking that very thing about the bellows being more pressurised if the end leak is sealed. I'm working to get a new bellows ( or even an old replacement ) but want to do a rebind and a patching job on the current one just for experience. I also hate to throw anything away that has survived on an old instrument.

 

With that in mind, I won't be crumbling off the leather nuts but will try to clean and reuse them. I'll certainly look into finding something like you suggested or adapting those sold by the Erie Organ Co. ( why are all the organ supply companies in Pennsylvania??!!)

 

Incidentally , can you tell me if the Carinis in Italy are the ones who supply basic black leather concertina bellows? I see a couple of people offering them for sale and am trying to find out where they come from.

 

Many thanks for taking the time to help me with this, FRank. I'll post my progress...

 

Michael.

 

I don't know.