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Building English Bellows.


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I'll give the old "suck test" a go first, and thank you very much for the offer.

 

No worries. The suck test should be fine as a go/no-go test - it's a bit harder to be quantitative about. You could try sucking on a piece of tube with the fabric clamped over the far end. You'll soon know if you can pull a vacuum - the tube will stick to your lips. Under this sort of test, the length of time the tube sticks to your lips becomes the quantitative value. I imagine though you'll have trouble sealing the folds of the fabric where it wraps around the tube. A cruel reminder that the best material in the world won't help if your construction isn't sound!

 

On the plus side, the suck test actually tests at a pressure much higher than bellows pressure. Human lungs can get up to about 1psi (700mm of water) - more if you are a trained blower, eg glassblower, bagpiper, trumpet player, or are in the business of siphoning petrol out of cars. Chris Ghent and I did tests which suggest bellows only get up to 140mm of water (playing "really loud") or 200mm compressing really hard with no buttons pressed. Not what either of us expected!

 

"And the fourth little piggy built his house out of concertina reeds, and, when the Big Bad Wolf came along, he huffed, and he puffed, and...... played quite a merry little tune."

 

Terry

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Hi John, I have been interested and involved with concertinas for over 20 years. Having limited financial resources I have had to learn how to restore insruments myself. I guess it was helpful in that I had previously restored many antique furniture items and clocks etc. Many of the restorations I started with a great deal of trepidation. I was fortunate that so many members of concertina net are ready to share their knowledge and experience with others. I have restored to playing condition several concertinas, many of which I would describe as 'wrecks'. Before retirement I was a builder and if I were to multiply the hours spent by the going hourly rate for builders these instruments would be very very expensive items. I eventually decided to build a set of bellows, many thanks to Bob Tedrow and others, I had to modify some details to fit the tools and equipment I have but it worked.The first set was usable but rather stiff, the second set was better but still not as I would like , the third set I'm very happy with. I would say go ahead ,it's not rocket science, and if you are prepared to be accurate and very patient you will get a lot of satisfaction from your efforts. Good Luck. Geoff.

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A correction to the cotton tapes - I read Chris' comments, and thought "Is it really so thick?"

No, they are not: the cotton tapes I use (Gold-Zack or Prym) are 0.23-0.24 mm.

 

Henrik

I have not found anything as thin as you quote in an Australian habadashery and I anticipated John would be looking in similar shops.ie. Spotlight. I will look for the brands you quote, thanks for the names.

 

John, if you do cut your own, cut them on the bias (ask someone who does their own sewing)!

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It is my experience the cotton tape available in habadashery stores is thicker than is comfortable. Cotton which is thinner can be bought by the yard/metre. Linen is slightly thicker but still not as thick as cotton tape. All of the strain is taken by the leather anyway.After writing the last I started to wonder if the tape I bought locally was as thick as I thought so went and measured it, came up with .38mm. The cloth I cut tapes from is .22mm.

 

 

 

A correction to the cotton tapes - I read Chris' comments, and thought "Is it really so thick?"

No, they are not: the cotton tapes I use (Gold-Zack or Prym) are 0.23-0.24 mm.

 

 

 

I was going to go to my local framer's store to see if he had any linen hinging tape before I go to Spotlight. If they don't have anything in that thickness range I will simply find linen or calico to use (I have plenty of fabric in the sewing cupboard).

 

John, if you do cut your own, cut them on the bias (ask someone who does their own sewing)!

 

I do some of my own sewing. A lot of my hiking kit (tarps, bivys, packs, sleeping bags et al.) as well as my caving and canyoning gear (harnesses, etriers, packs) were made by me. (I have a lot of very thin and strong nylon ripstop, spinnaker, and cuben fibre fabric around, but I don't think it is suitable.)

 

I assume the bias cut is just to stop fraying.

 

Thinning the bottom of the cards makes no sense. Thinning the top is cosmetic rather than structural, and you can't even see the bottom.

 

I can't find a good reason to make the valley leather that thin. I know the Tedrow method relies on it but you can compensate by leaving a small amount of slack in the underside valley hinge, say 1mm, and using the leather in stretch across mode rather than along.

 

 

I was thinking that I could rebate the leather into the card. I wouldn't have to skive it, and it would appear flush with the surface of the card. I understand that it's mostly hidden. Maybe gluing the leather before the underside valley hinge would create the ~1mm gap.

 

Skiving is a skill but not a terribly hard one to develop. The secrets are a good knife (single sided grind), get it extremely sharp and then sharpen it again, and find leather which skives well. Do it on a flat piece of glass. You need to have a few failures. While a straight edge is nice, don't worry if the resulting edge is not perfectly straight, especially at first, it is amazing how a ragged edge which tapers to nothing will disappear once glued if the leather is black.

 

 

Ease and consistency was my goal, that's why I was thinking of making a jig. However, I completely understand that it is something that I should spend time getting better at.

 

 

Terry

On the plus side, the suck test actually tests at a pressure much higher than bellows pressure. Human lungs can get up to about 1psi (700mm of water) - more if you are a trained blower, eg glassblower, bagpiper, trumpet player, or are in the business of siphoning petrol out of cars. Chris Ghent and I did tests which suggest bellows only get up to 140mm of water (playing "really loud") or 200mm compressing really hard with no buttons pressed. Not what either of us expected!

 

 

That is interesting. That seems like so little pressure. Good to know the suck test will suffice. I assume you have done the pressure testing for the pads on your flutes?

I have been going to the National for a long time so It is likely that I have come across you there.

 

Geoff

Thanks for the words of encouragement. I understand exactly what you mean about the man hours that go into instrument building. I've found myself many times staring at the wall for hours thinking of how I will make the jig to make the jig to accurately do some simple task. I wish I were paid for all the jigs I've made.

 

 

Henrik

Good Lord! He speaks Swedish now ;-)

 

Nej, jag kan inte tala Svenska. :( However, I have watched an embarrassing amount of Scandinavian TV. Languages are one of the things that I really love. Whilst I have to read the subtitles, I actively listen to the dialogue and constantly pause to translate things. It doesn't take long before some basic phrases get stuck. ( Saga Norén, Länskrim, Malmö )

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Being a bit OCD I also have gone the route of making my own bellows.

 

The card stock used is difficult to match up to the thickness of of antique bellows materials. The sample bellows from a Lachenal that I disassembled has card stock that is .036" thick (with some inconsistency. I found this to be in between the available rag board thickness and typical mounting board thickness. In both cases, the modern materials are not quite as stiff as the antique card stock. More careful examination of the card stock used is that particular bellows shows that it is not a single thickness card stock, but two layers of a thinner material glued together - which accounts for both the "odd" thickness and the apparent stiffness of the card stock used. It may well be that this particular bellows was made from stock that a craftsperson made up due to difficulties in obtaing just the right material.

 

I have successfully made EC bellows from both ragboard and mounting board. Ragboard is better.

 

The leather material I use is goatskin. Purchased off ebay for economic reasons, and it is just fine. 1 oz hide for the top runs, 1-1/2 oz for the rest. Skiving is done with a 'safety skiver" also purchased off ebay (the one that looks like a curved paring knife - buy lots of blades). Don't know why, but skiving the edges "cross handed" works the best for me, holding the strip with my left hand, and skiving the left side of the strip toward me. I use a simple wedge made from plywood with a smooth arborite surface glued on as a skiving base. I don't skive the hinge leather - again taking a cue from the antique bellows, which do not have skived hinges.

 

Tricky part is making the assemnly jig, similar to what Bob Tedrow uses, as the hex has to be accurate, or the end result will be lop sided.

 

Unless you have a lot of experience, the most consistent results will be achieved using PVA (white wood glue) and lots of damp paper towels for clean up as you go. While I have tried other glues, that's all I use now.

 

I use bookbinders preglued linen tape for inner hinges top and bottom. Just makes the process simple.

 

I cut strips of card stock 11-12" long - making sure that the cuts are very straight and accurate. The strips are then made into hinged pairs using the linen tape. After the tape dries, I check the "hinging" and discard the odd pair that are warped/unsuitable. Then these pairs are "top hinged" together with the linen tape (forming the inner hinge at the top of the bellows). Top hinging does make the bellows a little thicker - but also more durable, as well as compensating for the more flexible modern material. This linen taped card set is now like a 12" long bellows side. Note that the end strips are slightly wider to recess the bellows (if desired) per antique style.

 

Using a template of an indivual card (cut from a scrap of mat board) I mark and lay out lines for the "run" of cards that will form one side of the bellows. Then I glue in the leather for the inside bottom hinge - just rectanguar pieces about 2-1/2" long. 2 pieces of 2 x 2 wood and some clamps are applied to this "set" (1/2 a hex bellows) and it is allowed to dry for about an half an hour before flexing out.

 

Each "set" is then marked using the template, and cut on a small bandsaw (fine tooth blade), which results six organized hex bellows side sets. These are placed on the jig, using rubber bands to position them exactly, and small pieces of thin cloth (light linen, cottom, or even silk) are using to join the top corners. After the corners have set, the skived gussets are then glued in. Two pieces of 1" plywood (actually made up from doubled 1/2" scraps) are used to apply clamps to the bellows at this stage. After about 20 minutes of clamping, I release the clamps, gently flex the bellows to make sure that it isn't gluing itself into a solid mass, and reclamp overnight. Note that I don't "top run" the bellows with cloth, just pieces at the corners. This helps to keep the thickness down, and with the internal linen tape top hinge, I think the cloth top run is redundant.

 

Back onto the jig, and skived top runs are applied. Clamp and check as previous. Then on to mounting, papers etc.

 

Obviously, my inspiration comes from Bob Tedrow's video, but adapted for the limitations of my less "industrial" equipment.

 

The end result is both functional and cosmetically good. Would they stack up against the real pro bellows (like Concertina Connection's)? Probably not, but only the most discerning player would be likely to notice.

 

It is a lot of work. But like tying your own flies for fishing, it has a satisfaction.

 

But beware, the first set of bellows I made (before refining my techniques) is on my list of "winter projects" for replacement for cosmetic reasons. Hard to get the results you want the first time around.

 

Have fun.

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  • 2 weeks later...

I find 2ply rag overly soft and prefer what is known as presentation board which is harder. The normal stuff is too thick really, but there is a half thickness version that is just right. The stuff I use is Bainbridge Black on Black at .037" or .98mm. It only comes in 11"x14" though, but it works very well. It is black, but there is nothing wrong with that.

As far as cotton tape, I just use old bed sheet or light weight plain cotton fabric from the cloth store and cut it on the bias ( diagonal at 45 degrees ) into strips with one of those rolling disc cutters. It is cheap and thin, Cutting on the bias makes it not fray, and gives it stretch for going around the corners. It is a good bit thinner than normal cotton "bias tape".

I make Wheatstone style bellows, and you can use very thin leather for the butterfly's which are just hinge and card covering. The top runs can be slightly thicker, but should be edge skived nearly to the center to a feather edge so you don't get a ridge where it meets the leather on the card. Gussets can't be too thin or they pop in and out. Chris has good dimensions. I can't imagine a home built splitter. The kind with a roller and blade that you pull the leather through by hand will stretch out such thin leather. I have a used band knife splitter which I use, but they are seriously complicated. The guys at The Button Box use the Scharfix splitter which can be set for splitting and skiving and isn't that expensive. Skiving can be done easily (with practice) with a sharp skiving knife which for a single bellows might be worth it, but I prefer to use the knife just for touch up to get good feather edges everywhere. Unless you use paper thin leather, ( not strong when split that thin) I like to skive all edges of each part to a distance of 1/8" so that the edges don't telegraph through the layers as you see on some bellows where there is a distinct level change on the card faces where the leather overlaps. Ideally, the pieces should make a perfect scarf joint. What I really hate to see is a top run that isn't skived and leaves a ridge at the edge where it is glued over the card leather. You can make a workable bellows first time around. A good looking one takes a bit of practice to develop your technique. You can make one and later if you want to sell the concertina, send out the frames to someone who will make a good replacement bellows.

Dana

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Re bellows making. I thought it would be really hard work, but providing you have a bellows jig with the dowels extending through the ends of the jig it is simple. Follow Ted's advice. Use rabbit skin glue. A boiler can be made from a rice boiler from Kmart and float a cup in it pegged to the side. NOW I am not boasting, or exaggerating in any way, but if you set up the glue pot alongside the bellows jig, with someone the other side of the table to slowly turn the jig by the handles, the cloth strips can be drawn from the glue pot through a set of large tweezers to remove excess glue and with another other set of tweezers laid flat onto the bellows ridges as the other person turns the bellows jig handles. For 7 fold bellows this take between 11 and 15 minutes.

 

Leave on the jig until nearly set but still pliable. Remove. Compress back and forth so the bellows don't set open. Now when the glue is still slightly flexible but not tacky place the bellows one edn down on a flat board, put another flat board on top, and I then put a 10 kg piece of old railway line on top of that.

 

Come back in half an hour, flex the bellows again, recompress.

Come back in an hour reflex and compress. Leave compressed for 24 hours.

 

Follow Teds advice (see his site)about gussets and putting the cover leathers on.

 

Carefully consider if you are going to put on bellows papers, they take ages, the most time by far in making bellows.

 

I have sent some images of my equipment for different sized bellows to Terry in the hope he will post them as I have never worked out how to do so.

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David Hornett asked me to post this response - seems his computer is being fussy about who it speaks to...


post-11004-0-89504900-1403326984_thumb.jpegpost-11004-0-70290900-1403326987_thumb.jpegpost-11004-0-53028000-1403326986_thumb.jpeg


There are two jig barrels above allowing for different size folds.


The glad wrap stops the glue adhering to the jig, it also keeps in place the rag boards (black on the jig) which allow for different fold depths congruent with different lengths..


The dowels through the red barrel allows for different bellows lengths (6 or 7 fold bellows), or adjustment for fold depth. (The dowels pull out)


The slide operation -- on the roller on the jig -- compensates for differing fold depths allowing fine adjustment.


The jig is turnable by a second person to allow ease of application.


The ends slide off and on to allow attachment and securing of end frames and are the exact dimensions of the end frames, I have different sized end to allow for the different widths of instruments.


The barrel is held in place by two knitting needles.


NOTE: When one gets into the swing of it, it is far better, and easier to make a new set of bellows than try to patch an old set because any set that required patching, due to age is worn out all over, hence a patch is a very temporary measure.


(PS: This jig is not for sale, irrespective of what my wife might say)


David

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And the third: (click on any of these images for full size).

 

post-11004-0-85300400-1403336765_thumb.jpg

 

[i do have these images even larger, but I don't think you'd learn anything more.]

 

David adds further:

 

"It takes 11 - 16 minutes for all 7 pieces of fabric to cover the outer ridges. By the time I got to 7 Fold Bellows Number 10 we decided to clock ourselves -- 11 min.
It is absolutely critical the bellows are taken off the jig and flexed when firm but not fully set (if you don't, they will set in position and rip the cards to pieces when you try to flex them). AND also absolutely critical that the 1st compression is checked after half and hour, and then again an hour later to ensure the folds don't set together.
If after you have put the gussets in and the covering leathers on and recompressed for 24 hours* so they fold, and they then spring open slightly (after decompression), mist the inside with water and recompress (Don't be too liberal with the water.)
Leave for another 12 hours. Should there be any spring left get some Kiwi self shinning polish and liberally while under compression sponge the bellows leathers that are showing when the bellows are undecompression. Do this a few times. I can guarantee that when removed, and assuming you have correctly cut gussets, fabric bellies, and covering leathers the bellows will have not a ghost of spring in them and will be absolutely flexible. When held out parallel with the ground there will be absolutely no sag, none.
*NOTE: I use15 - 20 kgs, a piece of railway line on top of a biscuit tin of nails, but if this is not absolutely vertically above the bellows the end frames will asunder
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Jig is for 7 fold bellows, although will accommodate 8 fold. 41 cm between endplates, adjusting slide 3.5cm, fold depth 3cm, 3.2 with black rag-boards removed. And as I cannot work out how to attach an image I have sent some to Terry in the hope he will oblige, again.

 

David

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David says:

 

In the image of the open bellows, on the corners you can see the compression marks, interestingly one cannot see them when looking in natural light, only in the photo, in fact every fault that ever was is shown in this photo, none of which can be seen in natural light, This is the last set I made, Number 10. Sorry Dana, but I don't skive in the gussets or the covering leathers, except for the outer overlap. I have found that with the gloving kangaroo skin, which is very tough stuff, and then putting the bellows under compression it is pretty hard to see the joins. I did skive my first three sets, two of which were non roo leather because they did leave a nasty ridge but when it came to the thin roo leather the cosmetic effect was so limited that I gave up. The edges don't flatten the same on normal hide compared to the fine roo: and thin gloving leather because of its stretch is almost impossible to skive well.

 

post-11004-0-46167100-1403410536_thumb.jpg

 

post-11004-0-54224400-1403410566_thumb.jpg

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David continues:

 

It takes about 4 hours to cut and apply 7 fold bellows papers -- 96 papers -- because of the need for absolute accuracy, about as long as it takes to make the rest of the bellows (when end frame construction is excluded), even the gussets are considerably quicker. Here I have the templates, slightly different sizes for different bellows depths. Also shown is the gusset template, note the sides have been built up due to being worn away with the scaple as the leather is cut (There are in fact three templates her, one glued to the top of the other.) The gusset template has glass-paper on the bottom to hold the leather, the huon pine bellows form has a ruffled bottom for the same purpose. The holes in the bellows papers templates are for alignment on the sheets of papers so that the end products are identical.

 

post-11004-0-55289500-1403410802_thumb.jpg

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  • 3 weeks later...

All good stuff folks, but can anyone be specific about what brand of glue to use for applying the decorative bellows papers? I know it has to be water-based and water-soluble, so that some poor soul can remove then in 100 years time, but what do I actually buy?

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