When it's not normal: fun, but the price is higher. Charango

[charangohabsburg]

Everybody knows (or should know) that it's a wise thing to not experiment on a first build. I knew that, I believed it (still believe it) and I tried to ignore it.

A charango, when you start to build looks like this:

This is a charango - or let's say it's nearly a charango...

IMG_5425.JPG (68.07 KiB) Viewed 35343 times

And you might think it would look now like this:

This is not yet a charango!

2010_A80_7868.JPG (84.77 KiB) Viewed 35343 times

BUT:

• What you can not see is that the neck and heel is not yet shaped.
• You also can't see that when some days later I tensioned the strings the upper bout which I designed to be independent from the soundboard would move towards the lower bout... Yes I admit that this was not only due to one but to several design errors. I'll come back to this later on
• Further on you can't see the saddle would just flip over under full string tension. Double design error, I'll come back to this later on too.

End of first in-tune-day which lasted about two minutes!

• You also can't see that when I had beefed up the bridge in front of the saddle slot the bridge itself flew off after being in tune for about 30 minutes. I have to say that I nearly expected this because I was aware of an mistake I committed when gluing the bridge on, but I hoped that my bad feeling about the glue joint would prove to be wrong. Well, I was right, at least that!

End of second in-tune-day (30 minutes).

The whole thing started by mistake: I didn't want to build a charango, I was planning to build a guitar or two, or more. I already own too many charangos. When I visited Peru in 2009 I brought some tools for my two luthier friends Julio and Edgard Jihuallanca with me. Spontaneously they decided I had to build my first charango right here and now, and they set up a workbench for me (seemed to be an old PingPong table, not really sturdy but putting on top a 25 kg wooden board provided enough mass to be able to use the plane) and let me use their tools. Wow! They even insisted that I would not pay for the wood i used, not for using their workshops and stealing their time either! Thanks a lot Julio and Edgard!

Brothers Julio and Edgard Jihuallanca, Luthiers in Arequipa, Peru.

IMG_5586.JPG (53.88 KiB) Viewed 35343 times

We had a great time. For two months I showed up two or three times a week to work a few hours on my charango. They didn't tell me much about how to do things but I could ask at any time. Edgard cut out the rough shape of the block of wood on the band saw and also did some sanding on his horizontal drill-sander attached to a not any more working tablesaw. The rest, except some posing for photos was done entirely by me, with hand tools. Unfortunately I couldn't see them work a lot on instruments, Julio, most of the time was occupied by a batch of chairs for a school - not exactly his dream job, especially not the sanding part, but it was what would pay his bills those weeks.

Well, as I told you quite a few things went really wrong, and for a long time I couldn't decide whether to take the whole thing apart to do a proper job and to get it right, or to tweak things to get it more or less working. A few days ago I decided I would try to do a clean job and to take the thing apart. There's nothing better than to practice on the own instrument!
(I do instrument repair on a hobbyist basis since about 10 years ago. Mostly I have to revive charangos which had been dropped to the floor (cracked soundboards and bodies), get right disintegrating guitarrones mexicanos which got exposed to hot and humid climate, broken guitar necks, charangos and guitars with the strings up in the sky or down on the frets, dismantle clean, repair and assemble cheap, wrecked charango tuning machines with weird roller distances, and, and... you name it.)

I think I won't show every step of making a charango because with the exception of the hollowed out body bowl it's very similar like building a guitar. I'll concentrate instead on all (or nearly all) the mistakes I made in design and workmanship, hoping to entertain you a bit.

My design mistakes are probably the best things that could happen to me. They really showed me where and why a guitar shaped instrument is getting to the structural limits.

- to be continued tomorrow -

[Kim]

- to be continued tomorrow -

Brilliant thank you Markus, I am 'really' looking forward to following this thread.

Cheers

Kim

[matthew]

Well, the only charango I have had in the workshop started out more like this



and ended up like THIS



I am reliably told that armadillos go to charango school for seven years until they learn to become fully tuned charangos.

[Steve]

Nice work Markus - looking forward to the next installment. I've never seen or heard a charango so I'll be following this with interest.
Steve

[Puff]

Sounds like there were a few Toyota moments in there Markus and I have a feeling I will not be the only one looking forward to and enjoying your "More on that later.."

[liam_fnq]

Nice work Markus. Years ago a mate of mine had a Charango with the bridge busted off. He threw it out. Pity really, if he had have kept it I would have had him playing it some time ago.

It wasn't an armadillo one though. Got me thinking though; if you were to make an all Aussie charango, what animal would use?

[Kim]

Got me thinking though; if you were to make an all Aussie charango, what animal would use?

A mud crab.

[charangohabsburg]

I am reliably told that armadillos go to charango school for seven years until they learn to become fully tuned charangos.

I can confirm this. Ernesto Cavour, one of the most famous charanguists of Bolivia has written an epic song about the life of a armadillo charango: the little hero of the story had to go to the conservatory for many years to learn to sing.

It's a controversial issue whether the charango originally was made of the armadillo shell or of wood. According to the few written sources (from the early to middle 19th century, some of them referring to the second half of the 18th century), the instruments called charango were just little noisy guitars. There are no armadillos mentioned, and no hollowed out pieces of wood either. In fact, in some parts of Peru charangos are just some small five course guitars with 10 or also 6 strings. The fist armadillo charango mentioned and also photographed I know of appears in a book written by the French couple Raoul and Marguerite D'Harcourt just before WW I, published first in Paris, 1925. I believe that the wooden, hollowed out version may be just a copy of the armadillo shell, appearing first somewhere around 1950.

I've never seen or heard a charango so I'll be following this with interest.

Here you have a handful of charango music of different stiles (browse through), and here you can see some of the charangos I bought through the years.

Got me thinking though; if you were to make an all Aussie charango, what animal would use?

A mud crab.

Or a kangaroo, using it's skeleton and the epoxy reinforced skin ... a bit big, but size doesn't really matter. Or does it? At least to some Bolivian it seems it does. They are proud of building the world's the biggest and tiniest charangos.

[charangohabsburg]

This is the bridge how it looked like before gluing it on:

Bridge-2010_A80_7614.JPG (64 KiB) Viewed 35229 times

• Further on you can't see the saddle would just flip over under full string tension. Double design error, [...]

My two design mistakes were to copy the horizontal dimensions of an existing charango-bridge but having been so distracted that I applied the vertical dimensions of a classical guitar bridge, thus leaving the remaining wood in front of the saddle slot too thin for the relatively high saddle.

On a charango with nylon strings the saddle height (string height above the soundboard) normally is somewhere between 6 to 7mm, on this bridge it was 10.5 mm. This meant a highly increased torque force on the bridge which caused the saddle to break the wood in front of it within 20 seconds after having tuned the charango to it's final pitch.

Today I was searching the photo of the broken bridge but i seems that it remained on the PC in Peru. You have to imagine how it looked like. The pried off part of the bridge just flipped over like a hinge. Edit: here it is, it was still on the mobile hard disk...

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I glued it back in place an glued a 3mm thick piece of rosewood in front of it to beef it up:

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I clamped it with this go-bar setup:

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On the picture above you also can see that the rosewood part of the soundboard is broken at lower edge of the treble side soundhole. This occurred due to another series of design mistakes.

When glued on, I planed the reinforcement down to it's size:

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Done. Ready to string up again...

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[charangohabsburg]

On the picture above you also can see that the rosewood part of the soundboard is broken at lower edge of the treble side soundhole. This occurred due to another series of design mistakes.

The problems here arose because the upper bout of this charango is not well supported by the soundboard. I had chosen to decouple the active part of the soundboard completely from the upper bout part:

Plantilla

plantilla-IMG_4845.JPG (38.1 KiB) Viewed 35203 times

This is not my own idea. But here, on this charango built by the Dutch luthier Jeroen Hilhorst (owned by my friend Patrick Zeoli) it works very well. He simply left off the whole upper bout part of the soundhole! Note that he also built in a sturdy, longitudinal center wall which handles the forces acting from the neck on the upper bout. In 2004 I tried to take a picture of that center wall but it was a bit difficult because the charango body is made of massive ebony (!) and taking a photo of black wood in a hole at night is a bit of a problem:

Try to see the center wall of the ebony body (1).

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I cheated a bit with this picture by lightening up in Photoshop the dark part of the instrument:

Try to see the center wall of the ebony body (1).

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This instrument sounds amazingly loud. When Patrick Zeoli got this charango the pianist José Cibils said: "Finally I can open the lid of the grand piano!"
It really works:

youtu.be/

Nonetheless Patrick complained about lacking mellowness and warmth of the sound and I thought that instead of this huge opening which is replacing the soundhole was a bit too much, allowing a too high air resonance. Nothing easier than to cover part of the opening I thought, but I didn't thing that this centre wall was really necessary and I reduced it to a mere support for the fretboard:

Small center wall - fretboard support

fingerboard-support-IMG_5428.JPG (51.72 KiB) Viewed 35203 times

I thought it might be an intelligent idea to have an upper bout rosewood part of the soundboard that could vibrate freely and not only not let it be touched by the fretboard but also make it thin (down to 1.0 mm except the borders). But I grossly underestimated the forces from the neck, mistakenly believing the 6 mm thick bowl walls would be enough strong:

Small center wall - fretboard support

fingerboard-support-IMG_5427.JPG (55.41 KiB) Viewed 35203 times

When strung up the upper bout got squeezed like a rubber ball (the soundhole positions helped ) and the centre part of the rosewood board moved about 1 mm south (of course cracking). The gap I left between the two soundboard parts nearly closed under the string tension.

There was even another mistake I made which helped the structure to fail. While the harmonic bar of the spruce soundboard is sitting in recesses like this one...

recessed-IMG_5534.JPG (32.77 KiB) Viewed 35203 times

... the transverse bar of the rosewood board is not touching the walls but ends just before the weakest spot of the part! Too stupid.

Upper bout part of the soundboard with floating harmonic bar and center strut.

golpeador-IMG_5484.JPG (65.72 KiB) Viewed 35203 times

I simply relied too much on the 6 mm "thick" bowl walls.

[Puff]

Markus - surely this is an outstanding candidate for a pair of flying braces/spreaders/buttresses between 'neck block' and heel and just clear to the 'top'.

[charangohabsburg]

Puff, that's more or less what I thought of. First I just was thinking of putting two sturdy rosewood braces between the top edge of the "centre wall / fingerboard support" and the waist, working through the soundholes. But this would only have remedied the giving in upper bout. As you will see in my next post the repaired bridge failed again, this time not braking but flying off for several reasons I think, one of them being that the torque force on the bridge was too big because of the excessive height of the saddle. If I want to bring down the saddle I have to change the neck angle which can be done by tapering down the fingerboard. But it would have been a bit difficult because of the not really well supported floating part of the fingerboard. Also, with the "upper bot - top" off I can replace the floating harmonic bar with one that rests in recesses like it's counter part of the spruce soundboard. So the decision to take off the fingerboard and the rosewood part of the soundboard was a relatively easy one.

[charangohabsburg]

As promised some pictures about the flown off bridge.

First of all I have to say that I already knew that it might not hold well because gluing the bridge on already suffered from an accident. I used hot hide glue and steel location pins, pre-warmed bridge and top with a hairdryer and applied "clamping" pressure with some lead pieces:

Location holes - Removing french polish

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Dry run

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"Clamping"-caul

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Lead-"clamp"

glue_bridge-2010_A80_7866.JPG (84.14 KiB) Viewed 35160 times

The accident: The charango was not camped firmly enough in the vice. Under weight of the lead, after a minute or so it tilted a bit and the leads slipped off, onto the soundboard . To my surprise, when I pressed the bridge with my fingers I noticed that the glue was still liquid at the inside of of the squeeze out which meant that the bridge and soundboard were really well pre-warmed an I had much more working time than I had believed before. So I simply put the leads back on top of the bridge and heated the whole area a little bit more with the hairdryer. But probably, by releasing the pressure on the bridge, at some spots air entered the gap between bridge and soundboard and let some glue cool down too much, and the heat applied with the weights on could not get through to the glue line. Next time I surely would repeat the whole glue process!

This is the soundboard and bridge after the bridge's furious "take-off":

That's where the bridge sat on.

Underside of flown off bridge.

You'll note that I had felt it would not be a challenge big enough to only minimise the bridge's footprint but I also had drilled some holes in it's bottom to reduce weight - an insignificant amount of weight but a significantly further reducing of gluing surface...

You also can see how this accident visualised the runout of the spruce top. On the bass side (on the left half in the picture above) the fibers obviously dive into the top in direction of the neck, while on the treble side there is no tearout because the runout of the bookmatched half runs in the opposite direction. I think you can consider this amount of runout as minimal, it's about 1/4 mm on the length of 20mm. that's a ratio of 1:80, or ca. 0.7°. It's Florinett's AA quality, the same stuff as I have seen on Tim Spittle's website (go for it ).

Well, that's the end of the easy part (building and destroying).

During the next few posts I'll pass on to business as usual (for me): repair, fix problems, etc.!

[charangohabsburg]

There's not a lot to say about re-gluing a bridge. Before using the steel needle locating pins I wipe them with a slightly oiled rag so that the pins can not get glued in by the hide glue:

2011_D70_2800-1.jpg (78.87 KiB) Viewed 35121 times

After releasing the clamps I proceeded to loosen the fretboard with an electric iron (temperature setting between wool and cotton)...

2011_D70_2899-1.jpg (56.75 KiB) Viewed 35121 times

...and my "Wombles-steamer"

2011_D70_2903-1.jpg (75.42 KiB) Viewed 35121 times

The fretboard came loose without any damage at all. I had glued it on with Titebond (the original one with the red label).

This steamer is one of the greatest improvements in my workshop (I have it since last July after I had read an article by James Ham in American Lutherie AL#102 and this one), an yet I first didn't recognise Matthews one - must be the colours...

I clamped the loosened fretboard upside down to a flat surface while still hot from the removing operation:

2011_D70_2908-1.jpg (90.32 KiB) Viewed 35121 times

The next step was to loosen the bindings in order I could remove the upper bout part of the soundboard. Here I only used steam as heat source. When I wanted more heat and less water I let rush out the seam rapidly, when I needed more water I only let come out few steam so that it wouldn't blow away but have time to condense on the wood. Before, when cleaning up the surface of the fretboard I was surprised that when the steam exited at full power the fretboard surface would dry out! The steam had not enough time to condense on the surface, it just heated it up.

I used a thin blade I had dulled before on a coarse sharpening stone. I pushed it against the glue line and simultaneously heated both, blade and glue line with the steam. As a good side effect, like this I also dampened the wood and glue line.

2011_D70_2919-1.jpg (48.65 KiB) Viewed 35121 times

I had glued on the binding with hot hide glue. The two binding strips only did not separate one from another because I had glued them together with Titebond III (the green label). If I had foreseen the binding removal I had been quite smart, don't you think?

2011_D70_2924-1.jpg (62.35 KiB) Viewed 35121 times

I was very lucky, indeed. As you can see the pear wood strip wanted to fall apart because of it's less than perfect grain orientation. Fortunately it was inseparably glued to the maple strip:

2011_D70_2929.jpg (58.14 KiB) Viewed 35121 times

... and I got the whole thing off without really big problems. As I wanted only remove the "pickguard part" of the soundboard I stopped at the waist and wedged in a small steel ruler so that the binding would not glue back on it's own:

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Then the same procedure on the bass side. The white rag in the soundhole sits there to prevent get too much steam into the bowl:

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Loosening the rosewood plate was peanuts. A question of three minutes (again Titebond original):

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That's the "end" result I got four days ago:

2011_D70_2939-1.jpg (73.06 KiB) Viewed 35121 times

Well, of course not really the end result... But before doing the repair and closing the box again I decided to start this thread.

I guess this weekend I'll try out my recently arrived Friendly Plastic. When I ordered it I didn't yet know what exactly I would use it for... Sometimes I only get the good ideas when I see the tools on my own bench. If you don't guess what I will use it for you'll see it in one of the next two postings .

[jeffhigh]

Looks like you need either that centre wall shown in ine of your pictures or the equivalent of a banjo neck stick.
With the soundboard discontinuous in the middle like that you need to transfer neck loading to the tail end and then by tension in the soundboard to the bridge area
I guess you are looking at using the friendly plastic to get the shape of the interior at the tail end.

[matthew]

Markus that looks a very fiddly repair. You must be young and have good eyesight and fingers that don't tremble!

I reckon your first bridge-gluing failed because the hide glue HAD gelled when the lead weights fell off. After that, if its not really liquid again, it won't stick no matter how hard you clamp it. And heat on its own sometimes dries out the glue rather than melting it

[jeffhigh]

That sort of bridge clamping situation without internal access is an ideal situation for vacuum clamping.
I know you hace redone it now with long clamps after removing the upper bout.
You had what 5 pounds maximum in those lead weights, vacuum clamping would have given you around 50 pounds without distorting the soundboard.
Just a thought for the next one.

[charangohabsburg]

Jeff, to fit a whole centre wall would be a bit difficult, and in addition I had to remove the small one that is already epoxied in there. A the banjo style rod is out for two reasons: it would press against the butt of the bowl which is end grain and in addition, the butt is an acoustically active part of the charango (like the back of a guitar). Yet, with your guess on my use of friendly plastic you are pretty close...

Clamping pressure is not an issue with hide glue, and internal access is not really bad. I used the lead weight to try it out - pure curiosity. I think it would have worked well if the whole thing would not have moved in the vice, throwing off the weights in the most critical moment. In fact, recently I recommended a friend to vacuum clam his charango bridges because he has really bad access to the interior:


With my charango (no the one in the pic above) I could not use vacuum clamping because of the locating pins which perforate the bridge and top. But surely it's on my long term list of "want-to-haves", not just for bridges.

Matthew, this repair can't be fiddly because the charango does not belong to the fiddle-family!
I'm not really young any more, you are only winning for something like 4 years. Eyesight is not bad, but dwindling, 15cm is now the shortest distance I can see really sharp.
Not much trembling allowed, that's right. The down side of not to tremble: I'm slow!
I also believe that the glue has gelled, and with that oversized clamping caul the hairdryer's heat simply could not heat through the caul and bridge to the bridge surface. Lesson learned. On the other hand the gluing surface of my charango's bridge is 4 to 4.5 times smaller than the one of a classical guitar, but string tension is the same!

[ckngumbo]

Markus,
Thanks for this post! For a rookie like myself the mistakes are a real education.
Rob

[jeffhigh]

[quote="
With my charango (no the one in the pic above) I could not use vacuum clamping because of the locating pins which perforate the bridge and top. but surely it's on my long term list of "want-to-haves", not just for bridges.[/quote]

I use locating pins too
2mm diameter plastic drilled through bridge slot and top
I just CA them in place in the top and they are sealed for vacuum clamping with HHG
I leave them in place.

[charangohabsburg]

As I mentioned earlier I wanted to stiffen the upper bout in some way.
The method of flying buttresses between the neck area and the waist would have looked like this:

Diagonal flying buttress (player's view)

2011_D70_2951-1.jpg (44.16 KiB) Viewed 35010 times

Diagonal flying buttress

2011_D70_2953-1.jpg (45 KiB) Viewed 35010 times

Not very pretty.

So I thought I would run two parallel flying buttresses from the neck end of the upper bout to a sturdy, firmly anchored transverse bar at the waist:

More-sturdy-than-it-looks-like transverse bar

2011_D70_2966-1.jpg (41.44 KiB) Viewed 35010 times

If you think that this slim maple bar wouldn't do it you are right and wrong: it is a carbon fibre bar covered with maple veneer. The black carbon fibre would have been just ok at this spot, but I didn't want to glue that bar in with epoxy, that's why I epoxied some veneer on it.

Now Friendly Plastic comes into play. Taking the inner shape of the bowl where the transverse bar's beefy anchors will sit:

Friendly Plastic

2011_D70_2957-1.jpg (40.61 KiB) Viewed 35010 times

For each side one:

Friendly Plastic

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Then I put both of them in the freezer, heated more Friendly Plastic and made then the custom shaped sanding blocks:

Making a custom shaped sanding block

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From neck cut-off cut out the approximate shape of the two anchorage pieces...

Cut out anchorage pieces

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...pre-shaped their inner curves with a gouge...

Preshape

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...clamped the in the vice and started to sand in the final inner shape. I glued the sanding paper with Titebond to the Friendly Plastic, works great:

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Done. The not sanded upper right corner lies outside the planned shape an will be carved away later:

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....ooops, maximum of allowed pictures per message exceeded... I'll continue in the next one.

[charangohabsburg]

The final shape:

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It really plopps in at the right place and I trace a line for not smearing glue all over the place when I'll glue it in::

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Streamlining, step 1:

2011_D70_3002-1.jpg (26.53 KiB) Viewed 35008 times

Then I cut out the recesses in those little blocks and glued them in with forgiving gap-filling epoxy.

More pics tomorrow, it's already too late over here.

[charangohabsburg]

Markus,
Thanks for this post! For a rookie like myself the mistakes are a real education.
Rob

Right. I feel that the more mistakes I make the faster I learn!

[Kim]

Very clever work Marcus, I knew I would enjoy this thread and we are all picking up some great tips to.

[charangohabsburg]

With my charango (no the one in the pic above) I could not use vacuum clamping because of the locating pins which perforate the bridge and top. but surely it's on my long term list of "want-to-haves", not just for bridges.

I use locating pins too
2mm diameter plastic drilled through bridge slot and top
I just CA them in place in the top and they are sealed for vacuum clamping with HHG
I leave them in place.

I wouldn't feel comfortable with glued in locating pins. Although nobody wants to remove bridges some day it might be necessary and glued in locating pins will complicate bridge removal. I also don't want to imagine what to this charango top would have happened with glued in pins when the bridge flew off. Although this kind of punishment would have been well deserved!