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Author: Subject: Angle between body - neck? Please help
Luttgutt
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[*] posted on 4-9-2010 at 06:35 AM


Hey Toni Glad to hear! :)

That went fast :applause:
I tald you you'll do it better then me.

What did you use? I used everything you mentioned. Tried at least...




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fernandraynaud
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[*] posted on 4-9-2010 at 03:44 PM


Oh, no Geko, nobody works not THAT fast. :(

I just meant that the poor Damascus oud was so sad and neglected, I never play him, but he has a plain fingerboard and a neck like a Syrian wine merchant, so I WILL be able to shave it down. I'll get you some pictures when I actually complete the job. This apparently not so obvious trick is maybe what DrOud once mysteriously alluded to in mentioning preferably making a fingerboard thicker at the back, but I'm amazed nobody else did. Did you find this trick somewhere or just come up with it out of desperation?
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Luttgutt
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[*] posted on 4-10-2010 at 03:38 AM


I see :-)

No, not heard of it been done before...

True I am no oud maker, but I am a matematition, so it was not that difficult for me to "visualize" the effect of the angle shift and the result rather fast actually.

But the actual work took long time. I had to resting and tune at least 20 times before I got the result that I wanted!!
That is why I was shocked when I thought you did it already :)

And I still think you can do it faster then me :)

Good luck
and just ask if you need info..




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[*] posted on 4-10-2010 at 03:38 AM


A good 'quick and dirty' fix if you have a thick enough neck, but I tried it on an El Cheapo Turkish oud with a neck of average kind of thickness and over the next few weeks it started bending up from the nut for a couple of inches.:(



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Luttgutt
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[*] posted on 4-10-2010 at 03:41 AM


Hmm strange!

Why would it bend just by loosing a mm or so!?

How much did you take off it?




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[*] posted on 4-10-2010 at 03:44 AM


Probably about 1.5 mm, but obviously it was too much! It was a veneered neck with a spruce core.



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[*] posted on 4-10-2010 at 03:47 AM


I see!!

I thought that spruce should NOT be used on the neck!?!

I can brake spruce with my bare hands :)




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[*] posted on 4-10-2010 at 03:59 AM


Well I have pulled apart a few necks now and have found that it is quite common to use spruce, (well quartered with tight grain), covered with veneer, (the combination of veneer and fingerboard strengthens them) at least on Turkish ouds anyway, I believe lutes are made the same way. All my Iraqi ouds have had solid rosewood or walnut necks.



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[*] posted on 4-10-2010 at 05:40 AM


For information.
Surviving lutes from the 16th/17th C have necks with a core of light but strong and stable wood (usually Poplar but also Lime wood, Spruce or Fir) veneered with a hard wood such as Ebony. As far as I know ouds were once made the same way. A solid neck is of course easier and cheaper to make so is likely to be the modern standard among many oud makers.
Lutes were also made with the fingerboard thicker at the nut end than at the neck joint - to allow the fingerboard to be shaved down for action adjustments. This adjustment can also be achieved by removing the finger board, shaving down the neck and then re-fitting the fingerboard. I have used both methods.

The attached images show the neck construction of an old Egyptian oud (late 19th/ early 20th C?) that I own. The neck core is a softwood - Spruce or Fir (?) - veneered with the same woods used for the bowl. Veneer thickness is about
2 mm +. The fingerboard thickness tapers from about 2.5 mm at the neck joint to about 1.5 mm at the nut - indicating that at one time in the past the action may have been adjusted by shaving down the fingerboard.

Old Egyptian Oud neck comp (515 x 739).jpg - 83kB
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Luttgutt
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[*] posted on 4-10-2010 at 08:22 AM


Thanks for the info, jdowning!

So Tony, it seems that I m not the first to do that :)




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[*] posted on 4-10-2010 at 07:58 PM


Ah, seems it was John and not Richard who was mentioning the thicker fingerboard at the nut?

I can visualize the issues better now. It's funny but my wife who has no math background can immediately see it, and me (who has had to work with partial derivatives and such), it takes me a sketch and algebra to fully grasp it.

If you need to lower the action by say 2 mm, you need to shave the neck down by MORE than 2 mm, namely 2mm * 1.5 = 3 mm (because the neck-body junction, the Tiz Neva Point, is at 1/3 the scale length). My wife immediately said 3mm - how did she know?. That's not "a little". Certainly if the neck is not solid wood all sorts of problems can develop. If we limit the shave to 1.5mm, the action will drop by only 1 mm. The rule is 1 mm change at Neck-Body = 1.5 mm change at nut.

So maybe combining a drop at the bridge by drilling lower string holes, AND a fingerboard tapered shave?

How much do we need to drop the bridge holes? The 1.5 leverage is reversed at the bridge. For a drop of 2mm at the Tiz Neva Point, we need a bridge-side drop of 2mm * 3 = 6mm ! That's generally out of the question. The rule is 1 mm change at Neck-Body = 3 mm change at bridge.

Assuming the strings are 1 cm above the raqma to start with, we can afford a 3 mm drop. I would say 7 mm is a minimum string height above the soundboard, I have one oud that's about 7 mm and it's OK but darned tight.

So we can achieve the desired 2 mm action drop by drilling new bridge holes 3 mm lower AND shaving the neck so the fingerboard is 1.5 mm lower at the nut (and with the fingerboard perfectly tapered). The hardest thing probably will be sanding/filing/planing the neck so it is really flat. Maybe once I look at the neck construction I can decide how much of a shave I can do.

That leaves raising the fingerboard as a contributing solution to consider - maybe not adding a flat board, but as the very ramp we wanted to shave out of the neck? The 1:1.5 rule still holds as long as the other end of the string is the "hinge", so first let's consider adding a 3 mm thick level fingerboard. That raises the strings at the nut 3 mm so at the Neck-Body junction they rise 3 / 1.5 = 2 mm, but that's over a 3 mm higher fingerboard, i.e. in effect we have lowered the action by 1 mm at the neck-body junction. Now if the fingerboard is 3 mm thick at the neck-body junction, but in addition we taper it down to 1.5 mm at the nut, we are dropping the strings 1.5 mm at the nut, so the strings are dropping 1 mm at the neck-body junction (towards the fingerboard). Adding that to the 1 mm we gained with the untapered fingerboard, and we have met the target 2 mm drop. Is that right? Can someone pls. check this?

No need to wreck the existing neck? All the tricky wood-working is done off-oud (in vitro) on a disposable board? No need to lower the strings at the bridge?! Wow, that sure is appealing as long as the glued-on fingerboard doesn't kill the tone.

Need to see how much acoustic damping occurs vs. how long a board I can afford to glue on. One could even shave/undercut the fingerboard a millimeter and let it "float" over the body portion of its length instead of gluing it down, flying it a little like a violin fingerboard? That sounds doable!

BTW I'm enclosing a translated Turkish document that is a goldmine of oud construction details, including recommended dimensions.

Attachment: TECHNICAL_STRUCTURE_OF_THE_OUD_AND_ITS_FEATURES.rtf (54kB)
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Luttgutt
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[*] posted on 4-11-2010 at 07:14 AM


Tony,

1- the "flying" finger board is doable.. I have seen it on oud.

2- I don't see why you need to lower your action so much! 3mm is more then good enough!! What hight are you seeking?

3- Your calculations assume that everything is leveld! But it is not always the case. It is almost NEVER the case on cheep, and old ouds (and i dare say on ALL ouds)
A litle twist on the bridge would make a big angle difference, and "ruin" your calculations.
The finger board on most old ouds is NOT level. It is curved a litle on perpous (on old syrian ouds the nut is LEVELD with the finger boars. So the later HAS to be curved).

So I suggest you do the same as I did:
Shave off a little, tighten the strings (the dd strings to begin with) and TRY and see what change you produced.
Repeat the process to the level requierd.

P.s. I don't think it is practical or feasable to aim at 2mm action




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[*] posted on 4-11-2010 at 07:41 AM


No, no, I am aiming to lower the action by 2 mm, not TO 2mm.

The action is now almost 5 mm, i want it down to 3 mm. So I need to drop it 2 mm.

I went into too much detail (as I often do), because I was thinking it through as I wrote it. So I confused you. Sorry.

What i finally came to (much to my surprise) is that I can drop the action 2 mm (down to 3 mm) by making a little fingerboard starting from a brazilian rosewood board that is 3 mm thick, and tapering it down 1.5 mm (to about 1.75 mm) at the nut. What the calculations show is that gluing such a fingerboard on top of the neck (and raising the nut of course), the effective action drops 2 mm. Without having to shave the existing neck at all! If you have a moment see if my reasoning is correct: a) I gain 1 mm just by adding a level 3 mm fingerboard and b) I can gain another 1mm from tapering it towards the nut by 1.5 mm.





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[*] posted on 4-11-2010 at 08:35 AM


This sounds sound to me...

Will it be a short finger board? Or are you going for the "flying" type?

A question on the side:
I read the "turkish" attachment. This is a sentance that is confusing me

"Due to the same reason, the bridge is glued on the board so that the higher tip is 1 mm closer to the bottom side and not parallel, for all the string lengths to be equal."

What does that mean?? :)
Where is the "higher tip"? and what is the "bottom side"? of what?? :shrug:




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[*] posted on 4-11-2010 at 09:35 AM


Yes that was my favorite sentence too. That's in the same league as Sukar's "horse". I pondered until I came to this hypothesis: maybe he means the bridge is crooked, not perpendicular to the oud's midline, the same way a guitar saddle is compensated? I have seen a number of bridges built with scientific obedience to this principle, in all three axes, and with all sorts of ideas as to what is parallel to what and what this sentence means ;-) This goes with the "Oud as chicken coop ornament and fern planter" school of woodworking.
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[*] posted on 4-14-2010 at 04:31 PM


Translating things sure can be really confusing!

In reference to the oud, at least in the Arabic articles I have read, "horse" means bridge (as we know it) whereas "bridge" actually means brace.

Haven't got a clue what the Turks mean though, but there is a discussion around here somewhere on that bridge/compensation thing.




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[*] posted on 6-14-2011 at 11:20 AM


Quote: Originally posted by Sazi  
...aluminium pegs could be worse than you think ebony pegs are, unless the oud never leaves a controlled environment, as it expands and contracts quite a lot with temperature fluctuations... (the reason why you don't see aluminium tuning forks) ...


There actually are aluminum tuning forks, and they sound much better than steel ones (higher stiffness-to-mass ratio, see for example: http://www.petesummers.com/tools2.html ) Aluminum does not have a high temperature expansion coefficient. The reason why, correctly, you would not want to use an aluminum peg, is that the expansion/contraction of the wood is orders of magnitude higher than that of aluminum (or any other metal like steel or copper).
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[*] posted on 6-14-2011 at 11:34 AM


I would like to consider the following citation: Lets vary the angle of the neck and keep the action fixed at, say, 2mm. To do this, we would need to adjust the bridge height, in the case of a floating bridge.

What is the impact on the instrument's sound if the bridge were raised or lowered significantly? I observe that a higher bridge means more normal force on the resonator, which can amplify or dampen the certain frequencies. The violin has a very high bridge, and a raised/angled fingerboard. Has anyone experimented with such designs, or perhaps only changing the bridge height a few millimeters?

This topic also relates to this discussion http://www.mikeouds.com/messageboard/viewthread.php?tid=9959#pid664...
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[*] posted on 6-19-2011 at 10:37 AM


Quote: Originally posted by oudmaker  
It is wrong. Make your oud such a way that the neck will hold on its original posture under normal standard tuning. I consider to expect any movement on neck is not acceptable. That is the most important part of the oud building next to the sound of course.


Iam with you master. Luthier must give an angle that will be in in correct position after tunning.




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[*] posted on 2-16-2012 at 11:03 AM


This conversation seemed to deviate at times, but I want to return to the core of the topic.
So there are several variables one must consider when working with the fingerboard to achieve a good action across the plane of the fingerboard and avoid slapping or buzzing of the strings.

*Angle of the bridge platform to the neckjoint.
*Height of the string holes in bridge
*Off set of neck angle at the nut end
*Height/thickness of fingerboard (which alters the angle)

I have seen a few types of configurations of neck angles, off sets, and string heights at the bridge contribute to good actions.

What I want to do is have a formula for the ideal proportions in order to render a good action without buzzing... very consistently.
I have a lot of measurements, but its hard to formulate a single standard, since there are many variables. But lets say even in the case of a bowl that is concave and has a "scoop" for example, it shouldn't matter I believe. Why? Consider the bridge platform, and the neck joint area as your first or main point of reference. That should be a straight line, even if the face dips down in that area.

So if that area is a straight line, what should the ideal neck angle be?

Please note, this is obviously not to scale!
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[*] posted on 2-16-2012 at 01:11 PM


I like this subject very much. I am willing to pitch in my 2 cents.

I think there will be a range of acceptable combinations here. We can discuss their theorical feasability but in the end we also need to use our experince in playing this instrument and rule out the combinations that, yes may work on paper, but wouldnt be comfortable to play or would put to much stress on the materials used ( a 10cm high bridge is out of the question, right? RIGHT?)

Some questions remain though,
- What is the ideal string height on the bridge? Here again there is a range of acceptal combinations (between 0.7 cm to 2 cm)???
Of these potential string heights on the bridge what height provides the optimal playability and optimal sound production? I am not a physician but I think the tension / torque on the soundboard goes up as we move the strings higher on the bridge.

With that ideal bridge height a constant, we can determine the rest of the ideal configurations for the string scale we are using say (60 cm) we know the neck is 30 cm and we can then determine the combination of angles on the neck which will give us a neck action between (2mm to 4mm)

Now who is good in trigonometry?





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[*] posted on 2-19-2012 at 06:17 PM


By the way. I have come across ouds in which the necks bend under tension. This depends on neck thickness and the grain orientation.
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[*] posted on 2-20-2012 at 10:45 AM


Also, another factor that changes the angle aspect is the bridge platform lifting due to string pressure (mostly in fixed bridges).

The top can lift up maybe as much as 1mm-2.5mm as far as I've seen.
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