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Steven Hollander

Attaching Ends To Bellows Frame?

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Are there any guidelines about how tight/loose the endbolt screws should be? Can mistakes be made by how tight/loose you adjust the screws? If too loose, will it lose air more quickly or if too tight can it damage the ends; ie - cause the sides to warp. I am asking this question because I have sent the endplate units to get repairs done on the button mechanisms ( I still have the bellows and reeds/reedplate). I just got word that the repairs are done and the ends are on the way back. I want to make sure that I reattach them properly with the right amount of torque (or what ever that term is?)> any help would be greatly appreciated- Steven

Edited by Steven Hollander

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Hi Steve

 

I seem to remember someone telling me it should be finger-tight plus a quarter of a turn. Geoff Crabb's words I think. :ph34r:

 

Pete

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"How tight is tight" is a beginners question in all mechanical endeavours. There are only two ways I know of to answer this question satisfactorily; get someone to set the tightness on a screw for you and then feel it with a screwdriver, backing it off to see how much force is needed to bring it back to the same position, and, using a torque wrench set to a specific weight/length.

 

Presumably neither of these are available to you, but take heart, most others were in the same position and coped. All your questions are spot on so your thinking is right. Keep thinking while you do them up; remember underdone is better than overdone because the consequences are temporary.

 

Chris

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Are there any guidelines about how tight/loose the endbolt screws should be?
If you use a jeweler's screwdriver (6mm knurled shaft) you'll have a lot of feedback on the amount of torque you're applying and the resistance offered by the procedure. Don't get this kind with a plastic sheath over the knurls as you may be hard pressed to get enough purchase to tighten the endbolts enough.

They cost from about $1 for a set of 4 to about $20 each. Even the cheapest ones have hollow-ground hardened tips. The "lower" quality ones like these are more free of manufacturing burrs and will have a smoother turning cap would be perfectly adequate for most people's needs.

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Are there any guidelines about how tight/loose the endbolt screws should be? Can mistakes be made by how tight/loose you adjust the screws? If too loose, will it lose air more quickly or if too tight can it damage the ends; ie - cause the sides to warp. I am asking this question because I have sent the endplate units to get repairs done on the button mechanisms ( I still have the bellows and reeds/reedplate). I just got word that the repairs are done and the ends are on the way back. I want to make sure that I reattach them properly with the right amount of torque (or what ever that term is?)> any help would be greatly appreciated- Steven

 

 

Good question,

 

Let's hope you maintained the orientation of the original screws. They can and do "marry" each other over time and are best maintained in their original positions, particularly in older instruments.

 

 

The screws are meant to hold the concertina together and not to mechanically winch the two ends into submission.

 

The screws should be "snug" and turned a bit past the point where one feels modest resistance to the correct screwdriver. Nothing is gained by an overtight screw. The six or so screws will provide plenty of pressure to ensure a good seal between the bellows leather and the wood of the ends of a concertina in good repair. Install them as mentioned below in the next post, 1,4; 2,5; 3,6 (thanks, Ian)

 

Also, before screwing clockwise to tighten the screw, turn the screw counterclockwise and listen for a "click" then proceed. This helps ensure the threads will not cross and create a new problem

 

 

Unless.... of course you have warped ends; dry, hard bellows leather, cross threaded screws, mismatched screws; bunged up screw heads; too small or too large screwdriver; dull screwdriver etc.

 

all of which can appear in a concertina...particularly an old instrument with a shady screwdriver history.

Edited by Bob Tedrow

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As well as the previous advice. Always tighten the nuts a little at a time and in sequence so that the grip on the bellows is always more or less evenly spread. eg if you number the sides of the concertina 1 to 6, tighten 1 a little followed by 4 then 2 and 5 then 3 and 6, then tighten 1 and 4 a little more etc etc.

 

Do the reverse when undoing them.

 

Also a good idea in future, so that the nuts always go back in the same place that you took then out from, is to store them in a numberd location. I use an old toothpaste tube box with numbers written on next to small holes for the nuts. Works fine so long as you remember which end you decided was number 1 and whether you numbered it clock or ant-clockwise :)

 

Ian

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Also a good idea in future, so that the nuts always go back in the same place that you took then out from, is to store them in a numberd location. I use an old toothpaste tube box with numbers written on next to small holes for the nuts. Works fine so long as you remember which end you decided was number 1 and whether you numbered it clock or ant-clockwise :)
Interesting! I would imagine we all have our own arrangement of dealing with the order. We use a paper cup turned upside down and draw a hex on the bottom with handle position and have holes where the bolts "should be". No numbers. Simple!

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A factor to consider with old vintage instruments regarding end bolts: Frequently you will find stripped end bolts. The cause of this can be the unthreaded holes of the action box that the end bolts pass through on their way to the threaded plates of the bellows frame. You will often find the end bolts binding in the holes in the action box due to corrosion of the screws, shrinking of the wood, etc. This puts a drag on the end bolts causing wear on the threads which will sooner or later wear out. The end bolts should pass easily through the action board. If they don't, you need to take action or it is only a matter of time before the threads are worn out. This problem also puts more stress on the heads of the end bolts, wearing out the slots and making it more likely that the screwdriver will slip.

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A factor to consider with old vintage instruments regarding end bolts: Frequently you will find stripped end bolts. The cause of this can be the unthreaded holes of the action box that the end bolts pass through on their way to the threaded plates of the bellows frame. You will often find the end bolts binding in the holes in the action box due to corrosion of the screws, shrinking of the wood, etc. This puts a drag on the end bolts causing wear on the threads which will sooner or later wear out. The end bolts should pass easily through the action board. If they don't, you need to take action or it is only a matter of time before the threads are worn out. This problem also puts more stress on the heads of the end bolts, wearing out the slots and making it more likely that the screwdriver will slip.

 

With any screws where there is a danger of slipping - it will be found that as long a screwdriver as is practical will ensure proper alignment with the screw head and minimise error when turning. Its a given that the the tip should be a snug fit, and it only takes a few moments to file a tip to size. With rusted screws heating the tip and then applying it to the screw will help to loosen it. Working the screw in a little as well as out will be found of advantage.

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Thank you all for your replies and good advice which I will use when I get the ends back. It is helpful to know that I did a few correct things before sending it off for repairs such as laying out which screw go in which hole, and having jewler's screwdrivers on hand. I'd like to add an additonal question: A friend advised (some years ago) to put some parafine wax on the threads to provide lubrication when tightening the screws which can also aid the reverse. Is this good advice? I have used this technique on some of my other concertinas and it seemed to work well--Steven

Edited by Steven Hollander

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