Doing the "crease" for a Selmer-Maccaferri model.

[Alain Bieber]

Bill,
If you have a look at the English version of the Wikipedia text on "chitarra battente" you will find a photo of a very good example of the instrument, with the "crease". It could have been the point of departure for Maccaferri. Who knows? MFA in Boston also has a nice example in its collection.
I wonder if Mozzani designed in his very creative life a guitar with this crease??

[Craig Bumgarner]

Craig, did you take that photo yourself? I ask because we only allow images to be uploaded to our server by their owner for copywrite reasons.
If you did not create the image yourself, you are able to link to a page where it is available.
I have hidden the attachment until you respond.

BUSTED! You can see it here, on its original web page:

http://gypsyguitars.com/instrument-closeup.php?id=134

I agree with Bill Raymond that making 3D comments about 2D images is tough.

[Craig Bumgarner]

Here is the source page for the picture I posted, dozens of pictures of Selmers. Even when the pliage shows in one picture, it does not in a picture of the same guitar from another angle.

http://gypsyguitars.com/makers.php?id=7&status_id=5

[Greg Robinson]

Thanks Craig.

[Bill Raymond]

Alain, thanks for pointing out that the creased top was not present on all chitarre battente. I found some nice photos on the site: http://www.alfonsotoscano.it/battente.htm . As to whether or not Luigi Mozzani conceived of a bent top guitar, that's an interesting question. I looked through Intelisano's book Luigi Mozzani vita e opere and found no examples there, nor any mention of such a guitar. All his mandolini did have, of course, the bent top and some of his mandolin basses look almost guitar-like in shape (to the extent that Mozzani could confine himself to a traditional shape <G>).

Thanks also for the lesson on French knives; I had surmised that "cutter" was an English loan word into French, but was unsure of the useage of these 3 words. Asking someone who speaks the language gives a much better nuanced idea than just looking in a dictionary for a literal translation.

[Alain Bieber]

I have the same feeling about Mozzani. He used the crease for almost all the big mandolonis he made ( or his pupils made, in his class) but I could not find an example of a guitar, whatever their shape, with the crease. Likely, Maccaferri left his Maestro's class impressed by the performance of his mandolonis (some had guitar shapes already) and decided to import the crease to the more specific "Jazz guitar" scene. Still an hypothesis of course.
The site you located his quite interesting for the guy hooked by battentes. An interesting example of an instrument who presumably started as very aristocratic and got transfomed over about four centuries into a local folk instrument.
By the way a GAL plan exists of a guitar presented as a simple baroque guitar. Looks to me as a typical battente, but without the crease. They pretended in the corresponding text that this guitar "belonged" to Marie-Antoinette?? Not easy to believe .. no record of this Queen playing more than (very) basic harpsichord.

[Craig Bumgarner]

Here is another little bit on inducing pliage I just discovered.

I'm working on a second guitar along the lines of a Castelluccia D hole (see "ala Castelluccia" thread here on MIMF). One of the things I was not so pleased with on the first one was that by the time the guitar was finished virtually all the 15' arch in the top was lost. I attributed this to humidity and bridge load, so I added some additional arch (12' radius) to the second top, but as I get ready to mount this second top, I saw what the problem really was.

Castelluccias (and Selmers and most of their decedents) have arched tops, but straight sides. The tops are not radius'd in all directions, just across the top. But if the sides are straight, that arched top has to come back to earth somewhere and it does so at the tail. The sides are not shaped up to the arch, the top is pulled down to the side. When a top is 2 to 2.5mm, this isn't too difficult, but with a 4mm cedar top like Castelluccia used, the brace collapsed under the strain. Adding arch had actually made things worse in that now the top had even further to go to get down to the tail piece. It was top vs. brace and the top was winning.

Now the brace stiffness was already targeted ala Castelluccia, .038" deflection under 20 pounds at the bridge location, so a stiffer brace is not the answer. What this thing needed was a pliage! But how to do this with a completed, arched top? Well, after worrying it for a couple days, here is what I came up with, see picture below.

Basically clamped the entire top ala my sketch early in this tread and heating the top while clamping with a LMII fingerboard removal heat blanket. Supported the top with three 12' radius cawls at each of the three braces and a straight 18" block of wood under the tail block end, about 25mm higher than the center line height of the cawls. Then laid the heat blanket just north of the third brace and clamped it with an 18" piece of wood with a 12' radius on it. When pulled down tight, this put about twice as much angle into the top between the bridge location and the tail block area as desired in the end, allowing for spring back. Set the heat blanket to 250 degrees for about 10 minutes. Observing no ill effects, took it up to 300 degrees for more 5 minutes and then shut it off, let it cool back to 72 degrees over a couple hours. Unclamped, it held the 7 degree bend or close to it that was desired.

I was worried about the heat breaking the glue joint between the top halves and/or the third brace which was right next to the heat blanket, but figured the top was a bust anyway if this didn't work, so what the heck. The fingerboard heat blanket certainly helped out in that it heated only the area where I wanted the bend, about two inches wide. I did not use any moisture at all, completely dry, in a further effort to not compromise the glue joint. Put a couple pieces of tape over the glue joint, not sure if that really helped but it made me feel a little better. Anyhow, glue joints and bend both held once cooled. This all worked so well, I would consider doing it this way again as saving the pliage until last simplifies top joining, rosette installation and other top prep tasks.

It's worth mentioning that I think this works only with a single brace in the bridge area design like Castelluccia or Patenotte. If using the more standard standard Selmer bracing, a pair of braces either side of the bridge location and the two short joining braces that support the bridge, I can't see what I did above would work.

[Steve Senseney]

Hot hide glue will tolerate temperatures up to 250 Fahrenheit or more before releasing (or failing).

Aliphatic glue (white glue or yellow carpenters glue) will release at about 150 Fahrenheit or less.

[Jason Rodgers]

It's worth mentioning that I think this works only with a single brace in the bridge area design like Castelluccia or Patenotte. If using the more standard standard Selmer bracing, a pair of braces either side of the bridge location and the two short joining braces that support the bridge, I can't see what I did above would work.

But it would work if you did this procedure prior to bracing the top, right? Or does that introduce issues with clamping the braces in at the appropriate radii?

[Craig Bumgarner]

Jason: Yes, your right. I was thinking about this after I posted, one could join the top first and then bend it regardless of which bracing pattern would eventually be used. Joining flat plates is certainly easier than with bent plates . Heating the glue joint is still a concern but my experience suggests the with some care, Titebond is up to the job. Using a controlled heat source such as the silicon heat blanket is a help. I was also pleased to see that the top could be bent dry. Moisture, even a little bit tends to warp the top some. This comes out by the time the top is fully braced and mounted, but not having the warp at all is preferable.

[Alain Bieber]

Thanks for such good inputs Gentlemen. Back to a question that might reveal my lazyness <g>. Apparently, if I judge by the recent revival of a basic Busato model by the Maurice Dupont "Atelier", the crease seems to me ignored in this peculiar small mouth model. Was Busato doing that without taking the risk to be acoustically off the road?
This raises other logical questions. Have you an idea about the minimal values of two basic features of such "simplified Selmers", so to speak:
1/ minimum angular change of the strings at the saddle?
2/ minimum doming in the bridge area?
I know I will hurt the purists but I will keep that kind of questions in a corner of my head.. if I do not dare to ask.<g>

[Craig Bumgarner]

Alain: Are you saying the Dupont Busato has no dome? Or just no crease? I have not seen one, but my understanding is they have a substantial "bombe" dome like the original Busato Model Gran. I think Busato formed the dome without a sharp crease, instead he spread the angle change over a larger area, giving an spherical appearance to the top in the vicinity of the bridge.

Angle change of the strings at the saddle (also known as Break Angle): On Francois Charles' Selmer #807 plan, he shows the break angle as 12 degrees. That seems close to the maximum for this kind of guitar, I've occasionally seen more, more often less. I once saw a guitar that had so little break angle that the bridge was easily knocked out of place when playing. Sounded great though.

Minimum Doming? Not sure there is a "minimum", there is lots of variation. FC's plan shows the top braces at about 7' radius or about 10mm of camber over 400mm (the maximum width at the lower bout). The Castelluccias I've seen are all over, 15' to 7'. I've not measured a Busato, but they appear to have even more arch. Many other Selmer style replicas though have less arch, some approach zero, that is, flat. They all work to some degree or another.

By the way, while bending in a pliage to a braced top as described in my earlier post, I measure the deflection of the top in the bridge area under a 20 lb load before and after adding the pliage. The deflection did not change at all (.038") which tells me that my pliage did not add any structural rigidity to the top of its own. Frankly, I was surprised, I would have expect some increase in stiffness.

The more I think about it, the pliage is just a way to get the top back down to the tailblock without bending it over the lower brace(s). Otherwise the forcing of the top down to the tail block pulls much the arch out of the braces and locks stress into the top. Making the braces stiffer for this reason only makes the braces too heavy and stiff. So the Selmer pliage or Busato's bombe is just a necessary element of the arched geometry. Whether it is done by a sharp crease or a more gentle radius would not seem to make much difference.


CB

[Alain Bieber]

Craig,
This is very helpful. THANKS. I plan to build this "kind of" manouche guitar to be able to serve as a "mini" rythm section for a good friend of mine (a young lady with perfect English) who sings quite nicely some good pieces of the swing period. I will try to follow her in her training sessions <g>. BUT,as I am totally unable to be faithful to a model whatever the style ( and I usually build classicals) I decided that this guitar will be a "Selmerita". I apologize much for this (likely) stupid idea, a Selmerita will be much inspired by the Selmer ...but reduced a bit in its dimensions. I have the Charle plan for the large mouth which looks a good basis. You have been very helpful here at MIMF. I still have a month and a half before starting this guitar, so some more bizarre ideas could reach my old, but still active, brain <g>.
Back to the Busato shown by Dupont (you can google on his site to see pretty good photos of this "série"). I have the feeling that for the precise Busato model he chose to redevelop, he has used a little trick since the fingerboard looks "as if" it would be thicker in the trebles than near the head. If this is confirmed, I interpret it as a way to obtain a rather high saddle level without having to crease or dome a lot. Maybe yes may be no, your advice interests me much.
For my project I have in mind a very limited reduction longitudinally (could be .984 since I could go to a 630 mm string length) and a more important reduction transversally, something between .95 or, limit, .90 to be in the realm of the standard classical guitar in terms of width.
I hope you will accept to (still) advise me in spite of this typical unfaithful character.

[Bill Raymond]

Alain, the first "Selmeroid" I built was before the availability to me of plans. I dreamed up the plan myself from the few photos I could find. I hadn't known of the two small braces under the feet of the bridge, nor just where to put the lateral braces nor the degree of dome, so I opted for about 6mm of dome (as I recall) with lateral braces put, I fear, a bit too far from the bridge, so I made the top a bit thicker (I had no idea what the thickness "should" be). To top it off, I hadn't considered carefully enough the break angle over the bridge, so I ended up tapering the thickness of the fretboard--thicker at the bridge end. About the only thing I got "right" is the shape and look of the Selmer grande bouche. Still, the sound of the guitar is very Selmer-like, despite all these miscalculations, and the instrument has held up for nearly 20 years. The point of this long and embarassing story is that I believe you can make many modifications and still end up with a good instrument that will perform to your satisfaction.

[Alain Bieber]

Thanks Bill,
I am quite able to innovate in the wrong direction anytime..
I will be revisiting a part of my youth with this guitar. I spent many hours trying to grasp a bit of Django's art when in my twenties. Without success of course. But I kept a sustained interest for jazz all my life. I even exposed myself, with a very limited repertoire, in a piano trio (Teddy Wilson was the model, it remained distant really) who dared to play sometimes in a "rathskeller" around Berkeley U.... in the sixties! The piano player was good, fortunately. The double bass very special. I was seating in the middle.<G>
Back to the present, I will do my best to keep the main part of the design OK. Now, Maurice Dupont has a nice showroom near Opera Bastille in Paris. I will go there and have a look at his different models.

[Craig Bumgarner]

Alain: You can't go wrong using Dupont as a model, great guitars. Glad to hear you like Django, he's my hero. I'll never even come close, but sure fun trying.

I'll second what Bill said, you can deviate from the ideal considerably and still end up a decent guitar. Bill babysat me through one of my early "variations". I got the neck angle "wrong" or at least different than I thought it should be resulting in a 12mm bridge instead of expected 19mm. Much hand wringing on my part but in the end I gigged with that guitar twice a week for over a year before I did something about it. Finally pulled the neck and reset the angle and ya know, it really didn't make that much difference. A little louder, a little richer, blah, blah....., but it did not make it a whole new instrument.

I'm sure there a lots of forum members who would be glad to help you along as your project progresses.

Craig

[Al Dodson]

Indeed, Bill R was a great help and offered much encouragement as I built my first Mac several years ago. Like you, Allen, I wanted something a bit different than a copy. My aim was to use the "standard" 25.5" scale, that I am used to playing, without radically altering the bridge location of the original Mac design. My solution was to reduce the size to about 95% or about15" across the lower bout and to shorten the upper a bit also. I also eliminated the cutaway to simplify the construction and, being strictly a rhythm player, I don't get up the neck that far very often anyway. I still play that guitar almost exclusively. I need to go now but will post my thoughts and observations on the pliage later.

[Peter Davies]

Hello, I just thought I'd say what a fascinating thread this is. I've struggled to get some idea how to construct a Maccaferri type soundboard for ages and the ideas here are a real eye opener. Craig and Al, you seem to have to down to a "T". With my limited woodworking experience I tried bracing alone to form a dome for the first one and later a heat bent top with a lightly scored line (pliage?) after asking F. Charle's advice on his plans. The project at present is one with a heat bent top, but no scoring - after looking at Leo Eimers site with photos of originals. No jigs I'm afraid, but after seeing your ideas I think it's in the future. I still don't have a clue how the originals were made but the the advice on this thread makes such sound common sense - thank you all it for making things much clearer. And a big thanks to you Bill, you started the ball rolling for me - so it's all your fault I spend my evenings up the attic.

[Al Dodson]

Some observations and a general ramble here to try and tie up my post on this. First, in my comments above on building a the 15" guitar, I forgot to mention that I also wanted to have 14 frets clear of the body so what I ended up with was a 14 fret neck on a Mac braced body. To better clarify what I mean, you must understand that the Selmer (small hole) has the bridge shifted forward about 1" compared to the Large hole Mac. I hope that helps to better explain my jumbled up thoughts and nomenclature.

Now to the pliage. Joining the bent halves of the top successfully is a matter of having a jig that holds the plates in alignment as is shown in Charle's book on page 162. This jig holds the plates in alignment with the bend in place; that is the jig is angled down starting at the bend. It does not induce any of the dome; this is done by the braces. The sound hole and rosette are done with the plates joined and the bent tail hanging over the edge of the bench or with the upper section raised up above the bench on supports.

As I have said; I score and heat bend the pliage. When this is done the plates show a remarkable transformation. I liken it to the transformation that takes place when the first brace is glued to the top in a flat top instrument. As you have probably experienced, the unbraced plate sounds limp and flabby when tapped the addition of the first brace causes the plate to take on a musical quality; the pliage does the same thing in my experience.

Another interesting observation on this style of guitar is the role of the back. In what I call the bed test (tm) these guitars differ from both flat and arch tops. The bed test (tm) simply involves laying the guitar on the bed and strumming the open strings and then lifting it off with the strings still ringing. If you do this with a flat or arch top, you will notice a brightening of the tone. In other words, damping the back dampens the sound of the guitar; doing this with my Macs, on the other hand, I notice almost no difference in the sound. Other experiments in dampening different areas of the tops of these guitars have led me to believe that almost all the sound is produced in the area just forward of the bridge. I'm not sure what any of this means but I am throwing it out there for you to chew on.

The greatest thing about these guitars however is the attack. I no longer take any responsibility for my rhythm mistakes but instead blame the guitar for any irregularities even to the point of arriving at the "B" part eight bars too soon. Here is a picture of the 15" incher for Allen, and for Craig, you can see my tailpiece solution for Non-Selmers.

[Al Dodson]

Well, let's try the attachment again.