jdowning
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Fibreglass Bowls?
During the course of a recent thread forum member Aymara expressed an interest in the experimental fibreglass bowl lutes that I made in the early
1970's as this might have a practical application for ouds.
Although now a dim and distant memory I do have a few vintage photographs on film (remember those days?!) so will first post these for information
before going into details on how to make this kind of bowl.
I made about half a dozen of these instruments - some as arch lutes with extended necks. The neck was molded integral with the bowl complete with
arabesque inlay. Fibreglass molding can be made any colour desired. The bowl on the bench in my workshop at that time (a ccnverted horse stable) was
bright orange in colour!
The custom fitted plush lined case was also made of fibreglass made using the same process as the bowl.
The original objective was to make low cost lutes - however, as the historical lute market requires 'authentic' instruments (made from wood) and
because fibreglass is unpleasant stuff to work with, production of these instruments soon ceased never to be resurrected.
Note the deeply fluted 'ribs' of the bowl.
More to follow
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fernandraynaud
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I remember when Ovation introduced the fiberglass back guitar. They cleverly presented it as high-tech and premium, in short supply. Talk of aircraft
material a little like Mr. Turunz. When a few star endorsers played them, the initial redistance to the idea faded, it tipped, and people actively
wanted them, more than a wooden one. And it had a specific very bright sound.
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Brian Prunka
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I never cared for their sound, but it is a sound I guess. They can made to be sound decent in loud live situations, which is really what they are
for.
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jdowning
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When I made these fibreglass lutes in 1973 I had never heard of Ovation or ever had an interest then or after in this type of modern guitar!
Here I am not promoting fibreglass bowls as a way to go I am just sharing my 'hands on' experience in once having actually made these items - just in
case someone may be interested.
I really couldn't care less if Ovation guitars sound (subjectively) good or bad.
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fernandraynaud
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<"I really couldn't care less if Ovation guitars sound (subjectively) good or bad.">
I said "a specific very bright sound". No harm intended. I don't get your moods. Of course the fiberglass-bowled guitar is relevant to
fiberglass-bowled ouds and lutes. I for one would be very interested in how this type of lute, modern or not, sounded - as well as how you made them
in that converted horse stable in 1973.
I really enjoy your posts, and I don't question your motives, whether your experiments are rigorous enough, whether what you write is "on topic".
Cheer up, life's challenging enough as it is, this is not an examination, I think this is supposed to be enjoyable.
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jdowning
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Thanks for your opinions fernandraynaud!
If you read Brian's post you will understand that I was not making comment about your posting concerning the sound of Ovation guitars - and I would
not dispute Brian's assessment - its just that the acoustic performance of Ovation guitars is surely not relevant to the acoustic performance of an
oud or lute with a fibreglass bowl.
So - enjoy the rest of this thread - and then by all means go ahead and make an oud with fibreglass bowl so that you can assess and compare the
acoustic properties at first hand. Don't forget to post the results of your experiment on this forum - rigorous or not - so that we can all
benefit.
Be happy!
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Brian Prunka
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I apologize if you thought I was derailing your thread or somehow disparaging your experiments.
What was implicit in my comment was that, since you have built lutes with fiberglass bowls, I would be interested in your comments on your
impressions of the sound. I think the sound of the resulting instrument is certainly a topic of interest relevant to any construction thread.
I very much enjoy hearing about your fascinating experiments, and look forward to hearing more about these instruments.
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jdowning
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No offense taken Brian.
Unfortunately I no longer have access to those instruments to test and somehow compare acoustically. The prototype version was loaned to the Early
Music Centre, London, England to be rented out to budding lute players. When the organisation went defunct some years ago, the lute was never
returned. After 40 years or so I can not now objectively comment on how those instruments sounded but I used the prototype for a year or two without
being concerned about acoustic performance.
As I have no interest now in making lutes (or ouds) of non historical construction it will be up to others who might interested to try their hand at
making them and hopefully report back the results. I can only share my experience here as a possible starting point for others to further
experiment
For me, working with fibreglass lamination is unpleasant - the resin fumes are toxic, the microscopic glass fibres penetrate the skin to cause
irritation and in dust form (after sanding or grinding) can damage the lungs - so adequate safety precautions and equipment are essential when
operating in a production environment - less so for 'once off' experimental work.
On the other hand, once a durable fibreglass master mold has been made it might be used for laying up not only glass fibre laminates but paper
saturated with a hard setting glue (papier mache) - which might just be a better viable alternative for someone to test.
The original objective was to make a low cost lute that would perform reasonable well acoustically without aspiring to be a 'master grade' instrument
(although one never can tell as it is the soundboard and bracing - not the bowl material - that essentially dictates the acoustic performance.
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jdowning
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Fiberglass laminates are heavy so for a lute or oud bowl the laminate should be made as thin as possible without sacrificing stiffness. For my
experimental lutes I used thin woven fiberglass cloth - a couple of layers (about 0.5 mm ?) perhaps but I can no longer remember the details. To
provide maximum stiffness to the bowl it was designed with deeply fluted 'ribs'. As well the bowl was further stiffened with narrow carbon fiber tapes
incorporated into the laminations layed longitudinally as well as crosswise - at wide spacing (carbon fiber was then an expensive material - perhaps a
bit less so these days?).
My experimental lutes were made with integral necks filled with expanding foam (a type that is not soluble in fibreglass resin!). The foam was then
'trapped' inside with the application of another layer of laminate to form the flat upper face of the neck to which the finger board is glued. Because
with this design the neck cannot be adjusted for 'pull up' under string tension (should the stiffness of the design prove inadequate), the thickness
of the fingerboard (at the nut end) should be sufficient to allow 'planing back' the surface for future action adjustment.
However, this complication can be avoided by laying up a bowl with a conventional wooden neck block worked into the lamination - the neck then being
made from wood assembled in the usual way.
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jdowning
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Fibreglass is a synthetic resin reinforced with very thin and flexible glass filaments - very strong and light (compared to steel) - it has many
applications ranging from highly stressed components such as aircraft structures to automotive repair.
The most common and cheapest resin used is a two part polyester - a catalyst (or hardener) being added to the resin to promote rapid hardening. The
glass fibre reinforcement is available as a woven cloth or a chopped strand mat (short fibres laid in a random fashion and bonded with a binder that
is soluble in the resin). Both the cloth and mat come in various weights and thicknesses. The resin is applied to completely saturate the cloth or mat
which becomes embedded in the resin upon hardening - a process known as 'lay up'.
Materials are readily available from specialist suppliers or from automotive stores for bodywork repair (although more expensive)
The fibreglass is used here to first make a master mold for an oud bowl and then for making the bowl using the master mold - laying up the fibreglass
inside the mold.
To make the mold a pattern must first be made. The pattern represents the finished outer surface of the bowl so must be perfect in all respects as any
blemishes will appear replicated in the finished mold and any bowl cast from the mold (although small blemishes in the mold surface may be repaired
before the mold is put to use).
The pattern may be made from wood, clay or plaster built up on a sturdy flat baseboard. The most straightforward pattern might be a scrap oud bowl
(refinished to remove any blemishes) or a bowl quickly made in the conventional manner from wooden ribs using a low cost wood. For my prototype lute
bowl with its deeply fluted ribs the pattern was made from plaster.
It is recommended that fibreglass oud bowls should not be made with an integral neck but should be fitted with a wooden neck block glued in place with
epoxy resin cement after the bowl has been completed in the mold. This is simpler to make and allows more flexibility for future repairs and
adjustment. To allow for final trimming of the mold at the neck joint the pattern should be made a little longer at this location.
Once the pattern is complete it should be sealed with shellac and finished to smooth glossy finish (or dull if preferred) - the quality of the surface
finish will be reflected in the completed bowl. Time spent on carefully finishing the pattern will pay dividends later in the appearance of the bowl
molding.
The finished pattern and baseboard surface must then be treated with a wax paste polish (or other special 'release agent') to prevent the resin from
sticking to the pattern.
The pattern is then coated with a brushed on 'gel' coat. This is equivalent to a varnish coat separating the glass fibres of the lay up from appearing
on the inner surface of the mold and creating a smooth surface. Care must be taken to avoid any trapped air bubbles that might blemish the surface of
the finished mold.
Once the gel coat has hardened chopped strand mat is laid in convenient pieces over the pattern (similar to making papier maché) saturated with resin
using a stiff brush to press the resin into the mat and eliminate any trapped air bubbles.
The lay up should extend around the sides of the pattern to form a flange to stiffen the completed mold.
The mold should be built up of several layers of fibreglass (allowing time for each layer to cure before applying the next) so that the completed mold
is completely rigid once removed from the pattern. For a one piece oud bowl mold a final thickness of about 3 mm should be sufficient but additional
reinforcing layers can always be added later if necessary.
Once the fibreglass lay up has fully cured the mold may be released from the pattern by carefully prying up the flange. If the waxing of the pattern
has been properly done the mold should release easily - if not the mold may be damaged and made unusable.
Next to make a bowl.
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jdowning
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Laying up a fibreglass oud bowl is essentially the same procedure as laying up the mold.
The mold inside surface is cleaned of any loose dirt or debris and waxed to prevent sticking of the fibreglass laminations to the mold.
The mold interior is then coated with a gel coat which is allowed to harden and cure. The gel coat should be coloured (available pre-coloured or may
be coloured with special resin colouring agents). Black or dark brown are good but pretty well any colour may be used - green, blue, yellow,
'psychedelic pink' or whatever for those wanting to create an eye stimulating conversation piece.
For the bowl lay up fibreglass cloth is used (not chopped mat) as this provides a very strong thin smooth laminate of controllable thickness. The bowl
may be made stiff enough with a fairly thick (but heavy) laminate or a lighter (but more costly) alternative is to stiffen the moulding with strips
of carbon fibre ribbon laid longitudinally and cross wise. I can no longer remember the details of my prototype lute bowl lay up so some
experimentation would be necessary for anyone wanting to make oud bowls this way.
It is recommended that a separate - pre-shaped - wooden neck block be glued to the finished bowl molding using epoxy cement. Epoxy cement is a gap
filling adhesive so will accommodate any slight misfit between the block and laminate. To allow the oud sound board to be glued to the bowl in the
conventional way, a wooden liner strip should be hot bent to fit the bowl profile and glued in place with epoxy cement. The fibreglass should be
tapered to a thickness of about 0.5 mm or less around the edge of the bowl. See attached sketches.
On release from the mould any surplus fibreglass may be carefully trimmed away with a sharp craft knife (glass fibre is tough on edge tools) and
finished with sand paper or abrasive cloth.
Of course, the mold may be re-used many times to make identical oud bowls quickly and in quantity. I do not know the typical production life of a mold
but would guess around 50 bowls or so if the mold is carefully used.
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jdowning
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It is worth mentioning that the N.R.I. company (Northern Renaissance Instruments) were also selling 'student' lutes with fibreglass bowls during the
1970's. As I recall these instruments were quite successful and responsive acoustically. The bowls were white (to simulate ivory) and had 9 'ribs'. As
far as I know they are no longer being made by N.R.I. (because they are not authentic?).
Another factor to remember is that most lute players then - being former classical guitar players - played with their nails (rather than soft
fingertips as is more the general practice these days) which, together with nylon wound basses, produced a brighter tone that may have benefited a
fibreglass bowl construction.
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jdowning
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Here for information is one of my fibreglass bowl lutes of 1970's vintage - currently for sale on line by Glasgow based owner Dr Ian Strang. Asking
price £500 sterling - UK customers only.
http://homepage.ntlworld.com/hamamelis/music/InstrumentsForSaleWith...
Scroll down to 'Chiterone'
http://homepage.ntlworld.com/hamamelis/music/Chitarone1.jpg
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jdowning
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Out of curiosity, I have checked the N.R.I. website to see if they are still making low cost student lutes with resin/glass fibre/carbon fibre
reinforced laminated bowls. Alas there is no mention of them so I assume that they are no longer being made which is a pity as there might still be
some demand from those wanting to learn the lute who cannot otherwise afford the high cost of an all wooden instrument.
I assume that they were being made by John Duncalf who was and still is - the resident luthier with N.R.I at the time (1970's). If so then it is
possible that the original molds still exist. Anyone interested in learning more about the instruments might consider contacting John Duncalf at
N.R.I. for more information.
http://www.nrinstruments.demon.co.uk
As I recall the N.R.I. lutes were based upon an historical model (Hans Frei?) and had eight courses (?). Everything was made in wood in the
traditional way apart from the bowl which was white in colour with 9 (?) non fluted 'ribs'. To my ear at the time they sounded well. I think that they
cost about £75 sterling when the cheapest of the all wooden instruments cost around £200.
I was charging the same price (£75) for my more complex version of fibreglass lute and was approached by Eph Segerman of N.R.I. in the mid 1970's who
was interested in purchasing a copy of the mold - but nothing came of it. I eventually gave the mold (and the matching mold for the case) to friend
and lute maker/player Neil Morrison who now resides somewhere in France (?) - but I am not aware if he ever made any more lute bodies from the mold as
we lost contact soon after.
All part and parcel of the modern revival of the lute since the 1960's I suppose.
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jdowning
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Although I no longer have the molds for my fibreglass/carbon fibre lute, this morning I did find my original full size working drawing. It is dated
October 1972 so the prototype was built in that year - a bit earlier than I remember. The string length is 62.5 cm and
9 courses were fitted (not typical - should have been either eight or ten courses to be historically correct). The pegbox was initially made with an
open back - it should have been a closed back - an oversight easily corrected. In those days nearly all lutes were being made with open back pegboxes
but we were all on a learning curve then with no established lute makers to teach us about 16/17 C methods of lute construction.
The original design of the integral neck was to make the neck lamination a lot thicker than that of the bowl from the area of the neck block into the
neck itself. The open upper face of the neck was then filled with a thick wooden plate (to support the fingerboard) which was in turn supported by
wooden bulkheads fitted into the neck. This design was later changed to a foam filled neck.
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