Multi-part guitar ribs - at what stage are they bent?

[Bill Samson]

First of all, thanks are due to the many makers who shared their wisdom on the question of molds.

A related question now - Many early guitars have stripey ribs, made from two or more pieces of wood.  The question is - are the ribs glued together before bending, or are the individual pieces bent first, then glued together?

It seems to me that gluing first would give a high probablility of the ribs coming apart when they are being bent.  Gluing after bending means that the bent components would have to match perfectly unless some kind of jig is used to assemble them.

Thoughts?

Bill

PS The reason I'm asking is that I'm about to start making a 4c guitar and I have plenty of nice wood, but in narrow widths.  Being a parsimonious Scot, I'd rather use what I've got than buy wider, and possibly not so nice wood.

[Michael. N.]

They are roughly cut out, bent and then joined on the mould. On a round Back it would not be possible to join them and bend after. Not because of the glue but rather that the bend/curve is in two planes or directions. You are really looking at a similar construction to a Beer (sorry Whisky!) Barrel or at least a section of one.

This may give a reasonable idea of how it is done.

http://www.youtube.com/watch?v=Ys5deCIvCGk

Of course that is for a Lute/Round Back Guitar.

As far as a Flat Back is concerned you can simply edge joint all the pieces. No bending to be done. Any subtle curve is given to the harmonic Bars, with the Back glued to these. Providing you keep the Back relatively thin (circa 2.5mm) it will take on this curve.

[Bill Samson]

Hi Michael,

It wasn't a vaulted back I was thinking of, but the sides of the instrument made up from several narrow strips, maybe with purfling in between them as so many old instruments seem to have.

Bill

[Bill Samson]

Here's an example of the kind of thing I have in mind for the sides:

http://tinyurl.com/6bnn4rp

[Michael. N.]

Sorry. I misread the title.

The ribs can be joined and then bent after. Hide glue won't delaminate under heat unless you wet or dampen the rib. Allow the glue to dry thoroughly! Titebond and PVA will soften and release. If you really want to be safe you can use the non historical glue known as Cascamite or Extramite - it can take both serious heat and water.

I've been able to do it with Hide glue though.

The original method would be to build it up in strips, around a former/mould. So edge joined first (so that they are very  close to fitting), bent individually and then refined/glued.

Which method you choose is entirely up to you. The first method is easier/ quicker IMO, providing you think you can bend them without delaminating.

[Bill Samson]

Thanks Michael - Looks like some experiments are called for.

[Scot Tremblay]

I had no problem bending the multi-piece sides as one piece as long as I used hide glue as Michael suggests. I use a variation of the Fox side bending machine (this brings up an addition to the form discussion...my stack of inserts for the Fox machine) rather than freehand for the bulk of my bending so that holds the pieces in place quite well.

 

I tried Titebond III once for this operation. It's supposed to be waterproof so the thinking was that I could add a bit of moisture to the operation but when combined with heat it tends to creep (It's great for boat building though). It was an easy fix but I think it's better not to have to reglue in the first place. I've used fish glue as well but it doesn't seem to take the heat as well as hide. 

 

I've also tried the traditional way of bending all the pieces then building up in strips and gluing together in the form. This works pretty well in the Fox machine with a little tweeking on the bending iron after but freehand I find it's a bit fussy work.

 

I saw a photo a while back of the inside of an original baroque guitar wnere the sides were built up of a half dozen or more strips. The interesting and telling feature of this photo was that there were a number of burn marks from the builders bending iron which went straight across all the strips indicating that the sides were glued together then bent. So that appeared to have been the prefered method employed by that particular maker.

[Akira Sakamoto]

I'm afraid I have no experience of building an instrument myself, but I've found that Alexander's website offers some answers to your question.  I hope he would allow me to link to the page of his website:

http://www.vihuelademano.com/vgcrossroads.htm

 

In the second paragraph of the section I., Alexander refers to the way in which multi-rib sides are made.  Actually, the whole article is a very interesting read, even for the unexperienced like myself.

[Bill Samson]

Thank you very much for directing me to that link.  It is, indeed, a very interesting read.

[Peter Forrester]

A renaissance guitar does not need to be very deep. Shallower instruments than those I've made work very well.  But with striped sides you have opened a potential can of worms.  I attach a quick drawing to demonstrate that it is impossible to glue a set of (straight-edged) side ribs together before bending them if the depth of the guitar tapers.  The lower drawing represents the "proper shift" of the planks of the (much simplified!) guitar and their shape if the stripes are to appear straight.  In practice of course, the angles would be joined by curves, but would still be present.  Again, in practice makers have found ways to simplify the problem - some of the top strakes of Voboam guitars are approximately parallel to the belly.  (Which is at right-angles to the sides on the  French guitars that I measured in the past - I suspect, although I'm prepared to be corrected, that Italian guitars have a right-angle to the back, or perhaps averaged).  Photos (all pre-digital!) attached.  I shall attempt to add more to my page.

[Dave Bucher]

This is a question I asked many years ago when I began building.  I was enamored of the Palmer Orpharion and chose this as one of my first builds.  To do this task I bent first and joined later.  I did not use a mold but did use the edge planing methods  for lute construction which I had already used for lutes and clamped the ribs together using stick guides for registration and sanded flush inside and out..  The results were very good and the instrument, after 18 years and a big move from west coast ocean's edge N. California to the middle of the continent here in KC, has remained tight.  There used to be a rather common practice of laminating multiple rib sides to a substrate in Miracourt and I have worked on many of these guitars.  These were, I'm sure, bent after as they were composed of glued veneers.  200 year old plywood if you will.  I will do this again soon as I have resolved to construct an early five course this winter.  It will not be a copy, as I don't do that unless prodded but will embrace the features of several of the celebrated makers.  I did NOT reinforce the joints of either the back or sides of the Orpharion but the sides have held up very well.  I WOULD reinforce the joints with grosgrain ribbon or parchment for future work though.

 

Dave Bucher

[Bill Samson]

Thanks Dave.  I'm interested in what you say about the lamination of ribs onto a substrate in Mirecourt guitars.  Do you know when these guitars would have been made?

Bill