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faggiuols
Oud Junkie
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well...
Now I come to describe the problems!
when I cut the last rib, I cut it too close and now the bowl does not close the profile. The photo I uploaded explains better than many words.
what do I have to do?
what do you recommend? I do not know really how to solve this problem.
the ideas that came to be:
1 - smooth horizontal a few millimeters around the oud to commissioning profile quota.
2 - smooth sloping up to the elimination of the defect.
add a prosthesis to cover the gap it seems a dangerous thing for the subsequent fragility of the point.
the first is likely to lower the decoration back too close to the edge below with aesthetic effect bad!
me what you tell me ??
you have any advice for me?
I am desperate enough !!!
[file]36342[/file]
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jdowning
Oud Junkie
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Under the circumstances I would do a patch repair on the rib.
Select a strip of the rib material - ideally a piece with grain pattern closely matching that of the rib - the strip will be oversize, longer and
wider than needed to fill the gap. The strip must be made wide enough (say 1 or 2 cm wide) to ease handling and shaping without flexing too much.
Hot bend the strip to the rib profile and then concentrate on fitting the strip to the rib making the joint as perfect as possible little by little,
by trial and error.
Glue the strip to the rib and, after the glue has cured, re-level that section of the edge of the bowl - as you would when trimming and levelling the
edge of the bowl after removal from the mold.. The finished patched area will not be fragile and anyway will be further supported by the sound board
edge/edge tiles/banding.
Just take your time to make a close fitted well glued joint for the patch and only you will know that it is there once the oud is finished!
Good luck.
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faggiuols
Oud Junkie
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Quote: Originally posted by jdowning  | Under the cicumstances I would do a patch repair on the rib.
Select a strip of the rib material - ideally a piece with grain pattern closely matching that of the rib - the strip will be oversize, longer and
wider than needed to fill the gap.
Hot bend the strip to the rib profile and then concentrate on fitting the strip to the rib making the joint as perfect as possible little by little,
by trial and error.
Glue the strip to the rib and, after the glue has cured, re-level that section of the edge of the bowl - as you would when trimming and levelling the
edge of the bowl after removal from the mold.. The finished patched area will not be fragile and anyway will be further supported by the sound board
edge/edge tiles/banding.
Just take your time to make a close fitted well glued joint for the patch and only you will know that it is there once the oud is finished!
Good luck. |
thank you very much Mr. Downing ...!
Now I try immediately.
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faggiuols
Oud Junkie
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While I try to solve the problem, here are some more images.
before, the pegbox at an early stage
[file]36352[/file] [file]36354[/file]
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faggiuols
Oud Junkie
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and the soundboard...
the top is slightly "maschiata".
I do not know if there is an English term for defining small alterations of the wood grain I cercarto highlight the macro pictures.
I bought the soundboard directly in Val di Fiemme last summer but forcing the family to a detour of three hours from the way for our holiday ..
[file]36356[/file] [file]36358[/file] [file]36360[/file]
[file]36362[/file]
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faggiuols
Oud Junkie
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I post a picture of a soundboard very "maschiata".
I know that this feature of wood is only nell'abete of Val di Fiemme.
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SamirCanada
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My dear faggiols,
before you do a repair a slight dip like this at the level of the bridge is desirable. Please read some other posts and see for yourself especially
Manol's oud construction.
it could be possible to plane slightly in the front of the rib near the neck block. The gap between the flat surface on the lowest rib should be
around 7mm.
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faggiuols
Oud Junkie
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| Quote: Originally posted by SamirCanada | My dear faggiols,
before you do a repair a slight dip like this at the level of the bridge is desirable. Please read some other posts and see for yourself especially
Manol's oud construction.
it could be possible to plane slightly in the front of the rib near the neck block. The gap between the flat surface on the lowest rib should be
around 7mm. |
thank's my friend.
my gap is approximately 4/5 mm.
Now I look for the topic that you advise me!
in fact I am in crisis ..
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faggiuols
Oud Junkie
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could you tell me exactly where I find this topic?
thank you very much Samir
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SamirCanada
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http://www.mikeouds.com/messageboard/viewthread.php?tid=12883#pid87...
just 1 quick example, if you search "soundboard dip" you will find many related observations.
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faggiuols
Oud Junkie
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| Quote: Originally posted by SamirCanada | http://www.mikeouds.com/messageboard/viewthread.php?tid=12883#pid87957
just 1 quick example, if you search "soundboard dip" you will find many related observations. |
thanks a lot Samir
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jdowning
Oud Junkie
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If you are proposing to introduce a sound board dip into the design of your oud (by shaping the outer ribs of the bowl) the usual starting point is a
perfectly level plane i.e. the plane of the neck surface will be level with the edge of the bowl. Then the required amount of material from the outer
ribs may be accurately determined and properly executed.
Where sound board 'dip' is to be created by shaping the outer ribs of the bowl (from the initial overall level plane starting point), the maximum
amount of removal of material at the widest point of the bowl can vary between 3 mm to 5 mm among luthier practicioners. A dip of 7 mm may be
excessive? The ribs on either side of the bowl must then be equally shaped to blend smoothly between neck block and tail block.
A sound board will, over time, dip - in the central area between the bridge and sound hole - due to the stresses (bending moment) on a bridge under
string tension. There is some debate, however, as to whether or not shaping the side ribs of a bowl to artificially introduce a further dip is
necessary.
If you can use this error in cutting the rib to conveniently incorporate a soundboard dip - as suggested by Samir - will depend upon the overall
alignment of neck to bowl edge surfaces. Only you can now make this measured assessment one way or another.
Good luck!
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faggiuols
Oud Junkie
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goodmorning Mr. Downing
I have carefully considered the possible solutions.
adding a piece of rib seemed very difficult for the lack of a piece of rosewood with identical grain. Samir yesterday suggested to me the possibility
to smooth the bowl until the commissioning plan. my tip was 4 o 5 mm. I therefore tried to see what happens.
I used a table covered with sandpaper 120.
after a few minutes I realized that the result would have been good and I continued until the total closure of the tip.
I consumed, in addition to the lateral ribs, also the inner part of the neck, especially the inner block. I not think I've taken more than 2 o 3 mm in
the inner portion of the neck.
Now the bowl is completely resting on the ground!
Now it seems that the problem is solved, I hope that does not create problems later ..
thanks for your advice!
I'd be lost without you and Samir
[file]36368[/file] [file]36370[/file] [file]36366[/file]
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faggiuols
Oud Junkie
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Yesterday then I polished the bowl a little.
the thickness at this time is about 3 mm.
hankle book says I have to bring the thickness of the bowl to 1.5 mm.
it seems too thin ... what do you think?
I am attaching some pictures after cleaning with a damp cloth.
it begins to show the final appearance
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SamirCanada
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Che Bellezza!
you did the right thing with the sanding table. I don't see there being any issues with this technique. In fact now the soundboard will rest perfectly
on the neck block and tail block. Sometimes when you take the bowl off the mold the shape shifts a little bit if you have stressed the ribs together
slightly. so now it will be aligned.
I think once you scraped it smooth and round leave it as is and don't concern yourself with the thickness 3mm is fine. You can create more trouble
than fix anything by scraping.
also for "maschiata". I know that this feature of wood is only nell'abete of Val di Fiemme." I have heard some English description as "bearclaw"
spruce. it is a figure very appreciated in guitar but not so common in oud. I am sure it will be nice either way. Are you planning to put shellac
(gomma lacca) on the top? if so make sure its very light blonde dewaxed shellac.
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faggiuols
Oud Junkie
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hello Samir
thanks as always for your valuable suggestions!
I do not know yet how I will paint it.
I would like the soundboards very clear and not too bright, but a little satin finish.
I do not think I will use shellac, but I have not decided. I'm far away!
about the thickness of 3 mm bowl you think affect the sound of the oud?
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jdowning
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Samir is correct in describing the figuring of the sound board wood as 'bear claw'. It is also known as 'haselfichte' (hazel spruce). It is quite
commonly found in the spruce wood species but also occurs in other softwood species such as cedar. I have some 'bear claw' figure in Canadian Sitka
spruce timber logs purchased from a non luthier supplier years ago. So it is not special to sound boards coming from the Val di Fiemme region. I am
not sure but the 'haselfichte designation likely also applies to the more usual uniform fine 'cross-silk' figuring seen in top quality perfectly
quarter cut sound board material?
Interestingly, until recently, this particular extreme figuring was once regarded as a flaw in sound boards to be avoided by t luthiers. Due to recent
demand by the guitar community, the best of the wood cosmetically now fetches quite high prices. Another example perhaps of the luthier industry
finding an excuse to jack up the price!
The extreme distortion of the wood cells in 'bear claw' samples can adversly affect the modulus of elasticity compared to samples that do not have
that degree of figuring - ie the M of E can be a lot lower in bear claw wood. The M of E is a measure of stiffness - and in turn speed of sound in
wood is directly related to its stiffness (as well as inversely to wood density). High speed of sound along and across the grain in sound boards is
considered to be acoustically beneficial.
Having said all of that your sound board should work out just fine and will be very attractive in appearance (in my opinion) when finished.
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faggiuols
Oud Junkie
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Thank's Mr. Downing
for observations always interesting and instructive.
it is true that the fir 'bear claw' is fashionable, but many makers of high level in Italy are using this material for the construction of violins,
cellos, etc. because they consider it the best wooden sound. they believe it is the best performance of harmonics.
also with regard to the grain equal and they are constantly changing their minds, they think that unequal aid grain to produce tools with better
voice.
anyway my oud is an instrument that does not want to be a great liuthery instrument. I just hope that sounds decent. I would like it have a hot
item.
You feel that there is some secret to getting this?
thanks a lot
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faggiuols
Oud Junkie
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mr downing and all other liuthers of this forum
I wonder if you have heard of the "change Theta" patented in Italy by a Florentine luthier named Fabio Chiari. He is well known in Italy for their
instructive video on youtube about violin making.
after, I post some links on changing theta.
I wondered if he had debated about the "change theta" also on oud ..
best regards
http://www.fabiochiariliutaio.com/pdf/Modifica%20Theta.pdf
although it is in Italian, you can clearly understand what is changing and the consequences.
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jdowning
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My grasp of Italian is not sufficient for me to understand details of the 'Theta' modification. It appears to be a system that eliminates the 'sound
post' in a violin (that connects the front and back plates) replacing the sound post by one (or two?) straight, parallel rods built into the neck and
tail blocks. I am not clear how this arrangement is supposed to work physically so cannot comment about if there might be a potentially useful
application for the oud. Note, however, that the physics of a violin and oud are not comparable - violin acoustics depending upon the coupled/tuned
vibrations of the front and back plates.
I am not aware of any luthier secrets that will provide an easy route to making a 'good' oud. The only way (at present) to make consistently 'good'
sounding ouds (or lutes, guitars, violins etc) is to make a lot of them and learn by the experience (selecting materials etc.) - combined with precise
craftsmanship.
Making an exceptional instrument may be largely a matter of luck even for an experienced maker - given the wide range of variables involved in making
an instrument.
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faggiuols
Oud Junkie
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hello mr Downing
I did not understand what you mean by "Sound post".
the method theta basically get two results:
1 - improves the overall performance of the instrument (it was tried in the violins and cellos)
2 - lengthens the life of the principal harmonics of many seconds.
the results were obtained with a scientific method.
they removed the strings to a violin and measured with precision instruments duration harmonic urging the sound box with a tuning fork. then
opened the violin and inserted the change and found the points 1 and 2.
in practice they added another "anima" ..
I think it could be positive for oud.
first, structurally oud it would be better, in fact, the rotation of the bridge would be lower. then allow better transmission of vibrations between
the blocks with improved reverb inside the bowl ..
what do you think about it?
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jdowning
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If you look at Figure 1 on page 5 of the 'Modifica Thete' paper previously posted you will see - if I understand the sketch correctly - is the
standard set up for a violin where the bridge is located. One foot of the bridge rests over the bass bar (Italian 'catena' ?) and the other the sound
post (Italian 'anima' ?). The bass bar is glued to the sound board (front plate) and runs almost the full length and the sound post is set between the
front and back plates under slight tension (it can be repositioned to obtain the optimum acoustic result). It helps to support front plate against
string tension and transmits vibration between the front and back plates (coupling). The dimensions of the sound post - diameter and length - are
critical. A correctly set sound post is so important to the tone of a violin it is sometimes known as the 'soul' of a violin - without it the tone is
harsh and feeble.
Remember that the mechanics/construction and acoustics of a violin are quite different from that of an oud. The violin is an instrument where string
vibration is sustained by a bow whereas the oud is a plucked instrument where string vibration by comparison fades rapidly. The resonance chamber
(bowl) of an oud is of a different geometry and much larger than that of a violin.
An oud bowl is already very stiff structurally so I do not see how anything would be gained acoustically by connecting the neck and tail blocks with a
thin rod. Bridge rotation is dependant upon sound board stiffness all else being equal (string height and tension). The air resonance frequency would
also not be influenced - if that is what you mean by improved reverb inside the bowl?
Of course you could always find out for yourself - by before and after trials - to see if there is any significant acoustic effect beneficial or
otherwise.
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faggiuols
Oud Junkie
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goodmorning Mr. Downing
if I understand it, the method theta does not eliminate the "anima" of the violin, but it adds a further between the tail and the neck. the anima of
the violin remains!
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jdowning
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OK - so the rod passes between the bass bar and sound post positions? So the essential acoustic arrangement for a violin is even further removed from
that of an oud.
I must spend some time to learn more basic Italian/vocabulary so that I can better understand technical papers as I am having recently to refer to
more research articles by Italian authors. I would like also to get a better understanding of the Neapolitan dialect (for my current research into the
'tiorba a taccone'/calascione instrument) but - short of spending some time living in Southern Italy - that would be asking too much for a beginner! I
find that the free on line translation services are so limited as to be more or less useless in all practical respects.
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faggiuols
Oud Junkie
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Unfortunately my English is not very good, however, if I can help you for a small part of italian, I will do this with pleasure. You can find my email
in my profile, it will be a privilege to help you!
Neapolitan language is very difficle also for Italians. When I was in the military (in Italy was mandatory until a few years ago) I could not
communicate with the Neapolitans because I did not understand anything!
The rod passes between the bass bars and sound post positions! it's right.
Even this short essay about changing theta is quite interesting and the luthier Fabio Chiari is a craftsman very prepared.
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