varney Posted February 28, 2011 Share Posted February 28, 2011 About six months ago I restored a 30 key mahogany lachenal anglo. One small problem was air leaking at certain areas around the edges where the bellows frame and the action box meet. As a temporary fix I followed a suggestion from an earlier thread here - i.e. put strips of thin cloth tape around the edge of the action board base to create a cushion between it and the bellows frame. This worked and no more air leaks. However, in the last while my daughter has been playing away and while there are no air leaks, or air escaping via pads, pans etc there is an air loss of some kind. This is obvious when she's playing as it requires a lot of bellows movement to play through a tune. The bellows is airtight but when I play the isntrument it's apparent there's a loss in bellows efficency happening somewhere. On examining it seems to me the cloth tape is preventing the air leaking out the sides but the marginal lift this is giving means the top of the reed pan and the base of the action board means these are not sealing fully. No ghosting from air leaking between chambers, but I do feel this is where the air is going. I took a straight edge to the bellows frame and I found there are a couple of these which are not flush ( the straight edge rocks a little side to side ). This must be what caused the original air leaks. So how best to fix the problem? I thought of peeling back the bellows leather and in turn peeling the chamois from the top of the bellows frame back and putting very thin shims of card in to try and level these. Seems possible but I'm worried it might make a mess of the bellows leather etc. I could lift the chamois from the interior but it seems like a very intrusive way of going about it. Has anybody else had this problem and how did they handle it? Thanks, Michael. Link to comment Share on other sites More sharing options...
Theo Posted February 28, 2011 Share Posted February 28, 2011 You might need to do one of these: Adjust the height of the reedpan support blocks to get the top of the pan flush with the bellows frame. Replace the entire chamois gasket that runs round the top and inside edges of the bellows frame. Link to comment Share on other sites More sharing options...
varney Posted February 28, 2011 Author Share Posted February 28, 2011 Hi Theo, the pan is flush with the bellows frame. It's the slight uneveness of the tops of the bellows frame at certain points which was allowing air to escape in the first place. Another correspondent has suggested changing out the chamois in the bellows frame. I'm reluctant to do this as I've only performed this job once before and couldn't get a very good join between bellows and action box without the new chamois being slightly visible. This despite my best efforts at lapping it under the bellows frame leather.... If I can't figure out another less drastic way of solving the problem will have to try the job again... thanks, Michael. Link to comment Share on other sites More sharing options...
Theo Posted February 28, 2011 Share Posted February 28, 2011 If I can't figure out another less drastic way of solving the problem will have to try the job again... I don't think there is a less drastic method. For a neat result you will also need to rebind the outside of the bellows frame with new leather. Link to comment Share on other sites More sharing options...
Chris Ghent Posted February 28, 2011 Share Posted February 28, 2011 If the place where the straight edge rocks is in the centre of a segment of the bellows frame the problem could be a captive nut which has pulled up. This happens sometimes when there is a leak and rather than fix it people try to seal it by tightening the screws ever harder. The solution is to cut around the chamois carefully to create a flap hinging at the outside of the bellows, lift the flap, remove the screws and nut, repair the wood, reinstall the nut and screws and then glue the flap down. What I have just described is what would happen if everything went well; that might happen but as with all repairs be prepared for anything. With your chamois showing at the edge of the action box, depending on the state of the rest of the concertina, ie. it might be a little obvious if the concertina is immaculate, dye the chamois black. Doesn't have to be everywhere, just on the edge. If its not rocking on the captive nuts you may need to bite the bullet, remove everything and start again. Chris Link to comment Share on other sites More sharing options...
Ardie Posted March 1, 2011 Share Posted March 1, 2011 I just want to mention a method that often works, also when the problem is a (slightly) warped action board or reed pan. Particularly when you are not tempted to undertake the rather complicated work to grind the action board and reed pan and put on new chamois all over. You simply add a loose gasket underneath the action board, just punching holes in it for the pad holes and end bolt holes. Use a flexible but airtight material 2-4mm thick. An un-orthodox but easy fix that changes nothing else. Link to comment Share on other sites More sharing options...
varney Posted March 1, 2011 Author Share Posted March 1, 2011 Thanks so much Chris and Ardie... Chris.........Yes, it is in the centre that the slight raising has happened on three of the edges. However, as this is a mahogany Lachenal the nuts which the bolts fix to aren't surface mounted under the chamois, but inset half way down the wall of the bellows frame. Therefore I can't see how these would have been able to raise slightly - unless you've found this before? I ended up having to use black ink on the visible chamois on the last job! It worked but the suggestion seems to be a rebinding of the endbands with leather and lapping these over the new chamois. Ardie..........Your suggestion is very interesting, and like something I did for another problem. I had an action board on another instrumet which had some ripples in the base and a few gouges here and there. The slight warp meant it wasn't seating properly with the top or the reed pan, but only marginally. Rather than try and compensate by raising the chamois in parts, or sanding / filling the base of the action board, instead I cut a hexagonal piece of really strong manilla card to match the base, cut out around the pad holes, then lightly gummed the card to the action board base. Worked perfectly and no more ghostings etc. Your idea sounds similar, but I wonder would a piece of soft material of this kind deaden the sound of the instrument? The notes wouldn't have the hard wood of the board to reflect off any more........Would that have an effect I wonder? I think I'll give it a try Thanks again for the suggestions....much appreciated folks. Michael. Link to comment Share on other sites More sharing options...
Ardie Posted March 1, 2011 Share Posted March 1, 2011 Your idea sounds similar, but I wonder would a piece of soft material of this kind deaden the sound of the instrument? The notes wouldn't have the hard wood of the board to reflect off any more........Would that have an effect I wonder? I think I'll give it a try In theory you do expect 'some' effect on the sound but in practise it is expected to be negligable since the area of the inside of the reed chamber is so small compared to other structures ( in the compartment between endplate and action board) and I can't say I have heard any sound difference.Finding a suitable material often is the clue with repairs of all kinds. I use "Isofoam" sheets( a soft polyurethane stuff) of a kind which is used for isolation of flooring or package (for musical instruments..) Link to comment Share on other sites More sharing options...
Wally Carroll Posted March 1, 2011 Share Posted March 1, 2011 Check first the potential problem that Chris identified and correct as needed. If that doesn't do it, I agree with Ardie's suggestion and I suggest using 2mm EVA foam. Here in the U.S. this can be found in just about any craft store (not sure about Ireland). I would go one step further by cutting out a hexagon that will fit over the bellows frame on top of the reedpan then punch out the bolt holes. At this point don't cut out any other holes but instead screw the instrument together and let it sit for several hours (of course you won't be able to play it because all of the air holes will be blocked). Later, open it up and remove the foam which now will have an indentation of the reedpan walls on it. Using a razor blade, cut out the areas that aren't compressed and you will have a gasket that fits perfectly over the reedpans while leaving the action board exposed in the same manner as the original chamois gasket does. Wally Link to comment Share on other sites More sharing options...
varney Posted March 1, 2011 Author Share Posted March 1, 2011 Thanks for all the good advice here folks... Ardie and Wally - I'll certainly try to find some suitable material to give this a go, and as luck would have it I'm going to be in the states this weekend so will certainly check out this EVA foam. Couple of small questions - when the sheet of material is inserted between action board base and reedpan top, and the necessary cut outs have been performed, do you glue it in place? PVA or something lighter such as PRITT Stik? Does the EVA show up externally between the bellows and action box? Will I need to get out the black felt tip pen, or can the material be obtained in black? Thanks, Michael. Link to comment Share on other sites More sharing options...
Ardie Posted March 2, 2011 Share Posted March 2, 2011 Couple of small questions - when the sheet of material is inserted between action board base and reedpan top, and the necessary cut outs have been performed, do you glue it in place? PVA or something lighter such as PRITT Stik? Does the EVA show up externally between the bellows and action box? Will I need to get out the black felt tip pen, or can the material be obtained in black? Never glue anything that wasn't glued before and always use methods that you can un-do unless the measure is meant to last for ever.The gasket stays in place anyway so no need to fasten it. If you just cut it 1-2mm smaller at the edges than the measure of the two parts you will not see the gasket when it is pressed.Since the gasket is more elastic than the chamois you don't screw the parts together as tight as you would normally, it shall keep its elasticity.When that is gone you make a new one. Link to comment Share on other sites More sharing options...
Wally Carroll Posted March 2, 2011 Share Posted March 2, 2011 I agree with Ardie - don't use glue. The perimeter of the new gasket lays on top of the bellows frame and the bolt holes that you punch in will keep the whole thing lined up correctly. You can get the foam in black. Two stores in the US that carry the material are Michael's and Hobby Lobby. I believe they are both national chains. Get the type that is not self-adhesive as you don't want it to be attached permanently. Link to comment Share on other sites More sharing options...
Stephen Chambers Posted March 2, 2011 Share Posted March 2, 2011 ...I suggest using 2mm EVA foam. Sounds interesting. So what's the life expectancy of the foam Wally? Hopefully it's longer than the foam gasket that's commonly used on accordions, but probably not as long as chamois... Link to comment Share on other sites More sharing options...
Ardie Posted March 2, 2011 Share Posted March 2, 2011 So what's the life expectancy of the foam Wally? Hopefully it's longer than the foam gasket that's commonly used on accordions, but probably not as long as chamois... The elasticity of the material I have used has stayed for 20+ years which ought to be "enough". It hasn't dried or decomposed in other ways.Chamois as we know has been superb as long as the parts fit pretty well anyway.Those glued on little corner supports for the reed pan that constantly come loose is a weak point really in the trad concertina construction is it not? Hasn't any maker found out some more stable and lasting variant? Link to comment Share on other sites More sharing options...
Wally Carroll Posted March 2, 2011 Share Posted March 2, 2011 ...I suggest using 2mm EVA foam. Sounds interesting. So what's the life expectancy of the foam Wally? Hopefully it's longer than the foam gasket that's commonly used on accordions, but probably not as long as chamois... I just did a quick check and wasn't able to immediately find anything on projected life expectancy. I do know that it is commonly used for making gaskets. Regardless, in this case chamois is not doing the job. As was stated earlier, chamois works well when you have a relatively good fit, but doesn't work as well when the parts don't fit cleanly together. EVA, and similar foams, have the benefit of greater compressibility with good resilience. Wally Link to comment Share on other sites More sharing options...
Stephen Chambers Posted March 3, 2011 Share Posted March 3, 2011 (edited) I just did a quick check and wasn't able to immediately find anything on projected life expectancy. I do know that it is commonly used for making gaskets. ... EVA, and similar foams, have the benefit of greater compressibility with good resilience. Wally, That's why I was thinking of experimenting with it next time I have a gasket to replace - though it isn't very often that I have to do so with old chamois gaskets, unless they've been abused. But I've sometimes seen very poor/disastrous results with non-traditional materials/methods, in fact the last concertina gasket replacement I did was of a recent man-made one, and I've often had to replace foam gaskets on accordions. Hence my question. Regardless, in this case chamois is not doing the job. As was stated earlier, chamois works well when you have a relatively good fit, but doesn't work as well when the parts don't fit cleanly together. Without examining the instrument it's pretty much impossible to say what's causing the problem here, though it sounds like there may well be some warping going on. The foam sounds like a good "quick fix" that shouldn't do any harm. Edited for clarification Edited March 9, 2011 by Stephen Chambers Link to comment Share on other sites More sharing options...
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