Hi, a friend of mine has an oud, which I thought was a sukar but no mention inside, that has a scew in the pegbox.
The screw is right where the pegbox meets the fingerboard and seem to go in there horizontally with the fingerboard. Now I am looking to know if this
will lower the action. can you help?
I will take a photo next time. thanks
chaldochaldo - 7-23-2012 at 09:38 PM
there
jdowning - 7-24-2012 at 04:41 AM
The screw would seem to be in an awkward, inaccessible place if it is part of some kind of an action adjustment system?
Perhaps the screw was used to provide convenient clamping pressure when gluing the pegbox to the neck? This might be the case particularly if the
luthier has used slow setting synthetic glues that often require application of clamping pressure for several hours before the glue has fully cured?
It might also have been left in place in an effort to provide addition security to help prevent future separation of the joint? It is also possible
that the screw is the only device holding the pegbox in place!
chaldo - 7-24-2012 at 07:06 AM
well, this is not the real photo, in real it is somewhat accessible.
I think I should try it, since high.
thanks for your help.oudistcamp - 7-24-2012 at 07:43 AM
Chances are, that is a Zeryab oud from Syria.
Is there a brand at the bottom of the bowl?
The screw is for adjusting the angle of the neck.
well my friend, thank you so much as this answers our questions! most importantly it will lower the action! fernandraynaud - 7-24-2012 at 01:06 PM
Both the Fadi Matta and the Sukar mechanisms operate where the neck meets the bowl and control the angle of the neck to the head block. If this screw
is at the end of the neck, at the pegbox, I don't understand how it can adjust the angle of the neck. jdowning - 7-25-2012 at 04:57 AM
I was first under the impression that chaldo was describing a wood screw rather than an Allen type bolt. If this has been identified as part of a
mechanical neck adjustment device then it could be what guitar makers refer to as a 'truss rod' - readily available from luthier suppliers? I have no
experience of truss rods but - if I understand correctly - they are inserted into a neck for the whole length anchored at one end. By tightening a
tensioning screw at the other end the truss rod bows (takes up a curve - a similar action to a violin bow or an archery bow for example - the greater
the tension the greater the curve) causing the neck to bow as well. The adjustment in a guitar can be accessed from the pegbox end (if there is
sufficient material thickness (as there is in an oud) or from the neck block end where adjustment is made through the open sound hole. In the case of
an oud with enclosed soundhole, the adjusting screw would have to be accessed from the pegbox end.
However, as a truss rod works by physically bending a neck along its length in order to achieve adjustment to the string action fernandraynaud is
correct in observing that it is not the neck angle that is adjusted.
Otherwise, if rotating the screw does not result in action adjustment then this might be a bolt extending the length of the neck - screwed into the
neck block - to allow easy removal of the neck for adjustment by wedging the neck joint for example.fernandraynaud - 7-25-2012 at 02:57 PM
Truss rods indeed affect only the bowing of a long neck against string tension. They used to be unidirectional, so tightening would pull the rod
against a block in the middle of the neck, causing greater convexity. New methods have created the two-way rod that can impart convexity or concavity to the neck. They are very important on fretless electric bass, where the action is critical, the neck is long and the tension of the strings is very high. But this works only on flexible long necks and
wouldn't do much on a short oud neck that is designed to retain its shape over the years, and doesn't flex under string tension. I suppose one could
run a long rod inside the neck all the way from the pegbox to the headblock to control an adjustable neck angle like the Matta/Sukar mechanism, but
this would certainly be a first. jdowning - 7-26-2012 at 04:56 AM
I have not taken time to do the engineering calculations for comparison but would be rather surprised if a truss rod would not work on a relatively
short necked instrument like the oud. The amount of deflection (bend) in a neck is proportional to the bending force and the length squared and
inversely proportional to the stiffness of the neck material (measured as Young's Modulus) as well as the cross sectional area/geometry of the neck.
So - not surprisingly - a long neck will deflect more than a short neck for a given bending force and it will also deflect more if the bending force
is increased. On the other hand a stiffer neck (higher Young's Modulus) will deflect less than a less stiff neck and - assuming an approximately semi
circular cross section geometry - a neck with a smaller cross section area will deflect more than a neck with a larger area.
Therefore it all depends upon how the neck and truss rod combination is designed, material selection etc. Note also that the presence of a truss rod
requires that a neck be hollowed out - reducing cross section area.
Checking my 'dog-eared' copy of the 'Luthiers Mercantile International' from some years back I find two pages listing various truss rods including
one-way, two way, compression and double action types. These all appear to be designed to run the full length of a neck and are anchored at one end -
not mid way.
The two-way and compression rods both include rods 8.5 to 9 inches in length designed for mandolins - so a short length of neck would not appear to be
a problem.
Why are truss rods for ouds not listed? Most likely because there has been no demand for them and likely because a truss rod looks to be an easy thing
to fabricate for any one handy in metalwork. fernandraynaud - 7-26-2012 at 07:41 PM
I didn't say that the old truss rods were anchored in the middle.
If the oud neck was as flexible as a guitar neck, flexing against the tension of the strings, and fitted with a truss rod, you'd probably start to
modify the whole instrument to adjustable, starting with the bridge. Unimaginable and unnecessary headache, when all that's needed is a way to adjust
the neck angle a bit. And even with an adjustable bridge and truss rod, most electric bass necks are bolted on, and are shimmed at the junction to
adjust the angle. The reason for an (adjustable) truss rod is the undesirable flexibility of a thin long neck. It's not needed if the neck is stable,
right? Very thin necks became popular on guitars and that's apparently when the adjustable truss rod appeared.
My Shehata has a quite thin (flat) neck and as far as I can tell contains a fixed metal I beam. I can just glimpse the end of it. Apparently the
adjustable truss rod originated on guitars with the use of such beams. I had often wondered how those modern thin oud necks kept their shape, and I
guess I have my answer.
Back to adjusting the screw in Chaldo's oud, it will be interesting to see what happens. jdowning - 7-27-2012 at 05:09 AM
The proof will indeed lie in the testing - so let us know what you find chaldo.
Thanks for the informative link fernandraynaud which makes the picture clearer for those who do not use truss rods. Note however that the author
states that "It's extremely important to remember that truss rods are for adjusting neck relief only" so he presumably means that they are otherwise
not there to stiffen or provide stability to a long necked instrument? A long thin neck will require less mechanical bending force from a truss rod
than will a short neck in order to provide the same level of longitudinal deflection of the neck - all else being equal.
Truss rods appear to be used successfully on mandolins that have much shorter necks than guitars.
Note also that as a truss rod bends the neck longitudinally, which has an added advantage for fretted instruments in providing graduated string
clearance over the frets along the length of a fingerboard. Some lute makers will provide a longitudinal curve in a fingerboard - higher at the nut
end - for the same reason. Alternatively a lute fingerboard may be deliberately left thicker at the nut end to allow for future adjustment by planing
down the fingerboard - easy when frets are tied on and removable.
Mechanically, the weakest part of an oud in resisting bending forces due to string tension is at the neck joint where the stress concentration is
highest (due to an abrupt change in section longitudinally) and where the depth of section is relatively shallow. The bowl of an oud from neck block
to bridge - despite the thinness of the ribs - is much more resistant to longitudinal bending by virtue of its deep section.
So a truss rod should probably also work (to provide a small degree of action adjustment) on a short oud neck - if the rod and neck are properly
designed - without causing problems further down from the neck block to bridge but in cases of excessive pulling up or warping of a neck due to string
tension the traditional method of making the adjustments at the neck joint is likely the only way to go.
screw-on pegbox
spyrosc - 7-27-2012 at 04:40 PM
Maybe it's there to remove the pegbox for transportation and travel. The pegbox is the most fragile part and it sticks out the most.
fernandraynaud - 7-28-2012 at 07:51 AM
@Spyrosc, if that's the purpose it will be very entertaining to loosen it with the strings in place.
@jdowning. My 1950s Martin guitar is a steel stringed "dreadnaught". The strings develop enormous tension yet the neck has been stable for 60 years.
No adjustable truss rod. Apparently they used an ebony rod at times of steel shortage during WWII, but steel pipes, square hollow rods and I beams
were mostly used. Stiffening the neck is the sole purpose. But the neck is fat and the action isn't as low as I like. The scale is long. With a set of
"medium" Western strings it's a cross between a tank and a proletarian piano. When I started playing oud my mixed feelings towards the Martin became
something more akin to hatred.
It was when very thin necks and lower actions became the rage that there was no longer room in cross section for an I beam, so the thinner adjustable
truss rod appeared. Anyone who deals with adjustable truss rods curses them, as the neck profile often develops an S shape, and adjusting the rod is a
tragic game of compromises, like playing "whack-a-mole" on a camel, or is it a dromadary? Believe me, John, theyy are just there to try to keep the
neck straight. If a thin long neck could be made that didn't flex and warp, all forms of truss rod would vanish like a bad dream.
For all the talk of ouds being all wood, and Sukar being criticized for his metal adjustable neck mechanism, Sukar's necks are traditional in that
they don't use a metal stiffener beam. That's why they are fatter than say the Shehata's. I wonder how many other oud and saz necks hide a metal
skeleton! jdowning - 7-28-2012 at 12:17 PM
Thanks fernandraynaud - I do believe you even without having any experience whatsoever of those highly stressed long necked monsters! The neck is a
beam and deflection is proportional to the length squared (length X length) so the longer the neck the greater the deflection for a given bending
force - all else being equal.
Like you, I doubt if a truss rod mechanism designed for long necked guitars will work very well on the relatively short neck of an oud (although they
apparently do work on mandolins?). However, in an effort to 'prove' that we are both right (or completely wrong) in this idea, I am going to run some
trials on a test neck of typical oud proportions using just a simple tensioned screwed rod running the full length of the neck (as described on the
link that you previously posted). Just looking at the mechanical design and forces involved I have some doubts that this will work very well in
bending an oud neck to provide significant string action adjustment - but let us see how it goes with open mind.
If it works then - although I am unlikely to be using the concept on any of my instruments - others might find a useful application for it.
To avoid cluttering up this thread any further with my inexperienced thoughts about truss rods I shall post the results of this experiment as a
separate topic on the forum. fernandraynaud - 7-29-2012 at 09:17 PM
This is not my field by any means, but I have heard many different folksy explanations of truss rod mechanisms, actions, and mountings. Most seem
installed in a channel right under the fingerboard, not low. Maybe there is more than one mechanism of action? The only type I fully comprehend is the
one that's self-bending.
It's very unlikely to change anything on a traditional oud neck, they are not even common on mandolins, but before you put all your eggs in the
"compression at the bottom" model, might it make sense to really get familiar with patents, models and actual installations in guitar and bass necks? jdowning - 7-30-2012 at 04:50 AM
I don't have time at present to look into the range of truss rod variants applied to guitars and other instruments (and I am not really that
interested in those mechanisms anyway) - so I shall stick with the offset screwed compression rod as it is as simple as it gets and I understand the
mechanics of what is going on theoretically. Whether or not it works in bending an oud neck sufficiently to be useful for action adjustment is the
question that hopefully will be answered by the trials.
Anything further to report chaldo? Does the screw adjust the action (by some means) or is it there only to bolt on the pegbox or neck or both?fernandraynaud - 7-30-2012 at 04:51 PM
Not to be a nuisance, but on basses and guitars the rod does not adjust the action. Once the neck is at the right very slight curvature, effectively
straight, the action is adjusted by the height of the bridge, or if out of range, the neck angle has to be adjusted. Using a truss rod to touch up the
action is a desperation measure, over a very narrow range, or buzzing develops in other spots. Can we agree that even if you can bend an oud neck, it
can't ever bcome a method of "action adjustment", just straightening a curved neck? It seems that the action on ouds most often rises because of other
changes, and adjusting the angle, as in Fadi Matta and Sukar ouds, is the only logical method of "action adjustment". Unless Chaldo's screw is a rod
that runs all the way to a head block neck 'hinge", it cannot adjust the action.
Come on, Chaldo, please relieve the suspense! jdowning - 7-31-2012 at 04:35 AM
OK - I think that the problem here for me is one of terminology. It seems that modern guitarists differentiate between 'action' (the height of the
strings above the fingerboard or fret at the neck joint) and 'neck relief' (curvature along the fingerboard to provide consistent clearance for a
vibrating string over all of the fingerboard/frets) whereas I consider 'string action adjustment' to include both 'action' and 'neck relief'. Bending
a neck longitudinally with a truss rod will surely affect 'neck relief' but will also have a secondary effect by slightly raising or lowering the
'action' - although in the absence of a mechanical device to adjust neck angle, adjusting string height at the bridge will have a greater effect on
'action' adjustment on an oud or lute (due to the geometrical ratio of neck length to string length).
Lutenists (and oudists) can and do provide the required 'neck relief' by shaping the fingerboard into a slight longitudinal upward curve (towards the
nut) or more complicated by also shaping the fingerboard across its width (slightly lower at the nut on the treble side). Alternatively a lute player
with a flat fingerboard can use graduated fret diameters to produce the same effect.
But what if the 'neck relief' curve built into a fingerboard turned out to be excessive under full string load after things had settled down
structurally? A quick solution - so avoiding a trip or successive trips to a luthier to rework the fingerboard to a shallower curve - might be to use
a compression truss rod to 'back bend' the neck and so flatten out the curve in the fingerboard. That possibility is what I want to test.chaldo - 8-1-2012 at 07:06 PM
ok, let's stop the suspense... sorry I was away on a business travel.
so I went back to see the oud yesterday to help out my friend with his oud and to answer the questions we all have here. My first reaction was to
loosen the strings to see if there was any kind of wing screw inside the oud where the neck meets the bowl (just like sukar ouds have). the answer is
that there was no screw but there is a piece of metal (crew ending?) that come out of the bowl block (had glue on it too). So that could
mean that the piece of metal that joins the bowl block to the neck is the same all the way to the pegbox.
Then the Allen type bolt could be a truss rod.
So we got the Allen key and did tight it up to see the result. We tighten it up until I couldn't anymore, that, did give a minimal result; the stings
got a little closer, and the oud was now more playable, although the result was not so convincing because it just didn't give me that option to bring
the action even lower. anyhow it is now playable.
thanks for your help.oudistcamp - 8-2-2012 at 06:09 AM
Chaldo,
I wanted to hear from you first before going around in circles....
If you need to lower the action more, loosen the strings and bolt, then push in a very thin sliver of wood veneer in the neck joint. Be aware that if
you do this, the finish/varnish at the back of the neck joint will crack. It's just cosmetic....
If the neck joint does not show a tiny space after you loosen the bolt, place the oud face down on your lap with the neck joint located in the space
between the lap, and give the back of the joint a light smack to loosen the neck from the face/bowl. Then a sliver of veneer can be
tapped into the gap. Remove any excess veneer.
Only use the thinnest sliver of veneer to avoid overcorrecting which may lead to buzzing after tightening the bolt. If the action is perfect after the
thin veneer insertion but there is buzzing, you need to slightly sand the fingerboard, but that is another epic topic .......fernandraynaud - 8-3-2012 at 04:33 AM
So it sounds like the rod goes into the headblock? It's still impossible to be sure, but likely not a truss rod so much as a neck angle adjustment.
It's not surprising that it has very little range. The same is true on the Sukars, that unless the mating faces are sanded/filed, the adjustment runs
out of range. But this is a very interesting special case, as so far only the Fadi Matta and Sukar designs were known. Curious if what you saw of the
rod inside the bowl turns when you turn the allen head at the pegbox. If you have an ohmmeter, you can test for continuity between the two apparent
ends of the rod. If the neck is articulated as in the Sukar design below, and you can see a tiny gap in the fingerboard when you work the adjustment,
Oudistcamp's suggestion to shim on top at the junction is excellent.
@jdowning, yes it's terminology. On the guitar/bass the word "action" originally meant "how well it plays", and that came to mean the playability
resulting from the height of the strings over the ENTIRE fingerboard. A good action is low AND even. On the oud we pick the neck-body junction to
measure the string height, because the neck is so short and stiff that if it's good at the junction, it will be predictable elsewhere unless the
fingerboard is uneven.
I just adjusted my 6 string bass today. Adjusting the "action" on a long neck starts with getting the right "relief" or very slight curve to the neck
with the rod, so notes fingered near the nut will clear the fingerboard, then adjusting the bridge and possibly touching up the nut to go as low as
possible without the strings muting or buzzing on the fingerboard ANYWHERE along the neck. I've had situations where the problem is a slight bulge two
thirds up the neck and have to sacrifice by adding curvature with the truss rod. Then the bridge is brought down so the action is as low as possible
at the end of the fingerboard, but the action in the middle might now be too high. It's what I mean about compromises and playing "whack a mole" on a
camel's back jdowning - 8-3-2012 at 12:17 PM
So it is just a ' bolt on' neck as suggested earlier in this thread?
What may have happened is that the combined compressive loadings of the rod and string tension perpendicular to the neck joint surface may have
exceeded the compressive stress limit of the wood cells on either side of the neck joint resulting in a relaxing of the joint and a consequent higher
action. This can happen over a period of time even if the crushing load limit has not been exceeded (known as 'creep').
This has now been corrected by taking up the slack (by re-tightening the bolt) to what may have been the original factory setting.
Whether or not the bolt may also provide a significant bending moment on the neck depends upon its position within the neck relative to the neutral
axis. If it is located along the neutral axis it will only provide a compressive force on the neck joint - if below the neutral axis it will provide
some degree of backbending of a neck which may or may not be significant.
