Αποστολή από: umuterakman στις Φεβρουαρίου 20, 2020, 11:59:33 μμ
Αποστολή από: umuterakman στις Φεβρουαρίου 21, 2020, 07:36:24 πμ
Αποστολή από: umuterakman στις Φεβρουαρίου 21, 2020, 07:46:51 πμ
Αποστολή από: Μάνος Τουρπάλης στις Φεβρουαρίου 21, 2020, 09:17:24 πμ
there are plenty of matters to discuss about this construction; whilst it's easier than building a full scale bouzouki, "basic principles" of angles, curves etc. are still applied.
We shall have to deal with each matter separately and this may take some time, as this is the very first discussion over details in English here - according to my knowledge, at least.
To start with, your design is generally correct, except for the thicknesses shown - a bit "overdimensioned" : soundboard and bowl staves ("leaves") initial thicknesses should be approx. 2.50 - 2.80 mm. Staves of 4.00 mm thickness are difficult to shape, and the bowl needs to be thinner for resonance reasons (you can search for mandolin bowls construction, same principles).
More important : a 4.00 mm soundboard won't vibrate properly, leading to poor sound (Greek baglamas, bouzouki etc. soundboards have braces, unlike the saz family instruments, if that was in your mind for its thickness). One brace is the most common practice for a baglama soundboard, but you can also have two. In that case, the soundboard could be even thinner, sanded down to 2.20 - 2..30 mm.
The neck width is also correct (26 mm at the nut, 32 at the joint) but it needs to be a bit "shallower" at the nut. My suggestion is 16 mm ("clear" - no fretboard measured). The total "depth" at the nut to feel comfortable is approx. 21 mm. (16 neck + 5 fretboard). Accordingly, if you ever choose to use a thicker fretboard, you should consider a neck "depth" of 15 mm at the nut (15+6=21).
The depth at the joint could be lowered down to 20-21 mm., but 22 is also fairly acceptable.
I will try to make a brief guide to upcoming issues - about the bowl construction - but this will take a few hours as I will have to gather photos etc.
Αποστολή από: Μάνος Τουρπάλης στις Φεβρουαρίου 21, 2020, 09:32:04 πμ
Αποστολή από: umuterakman στις Φεβρουαρίου 21, 2020, 01:10:29 μμ
Thank you for your attention. I planned to use walnut tree for bowl, spruce for soundboard, ebony for keyboard, walnut for handle, wenge or rosewood for bridge.
Αποστολή από: Μάνος Τουρπάλης στις Φεβρουαρίου 21, 2020, 01:55:40 μμ
Thank you for your attention. I planned to use walnut tree for bowl, spruce for soundboard, ebony for keyboard, walnut for handle, wenge or rosewood for bridge.
walnut is not a good option for the neck. It has risks of twisting over the years to come. We usually use linden tree, with a reinforcement strip if needed (for 36 cm. scale it won't be necessary, but if you have doubts e.g. for the proper age of the piece - not dry enough - you may consider it).
The wenge wood - according to my sole experience only - is likewise a not-too-good option for the bridge, it tends to produce a harsh sound - in my opinion.
Αποστολή από: Μάνος Τουρπάλης στις Φεβρουαρίου 21, 2020, 02:11:05 μμ
you will have to use a mould. In order to design and make it, you should first take some critical decisions.
First, notice the differences between the oud bowl shape (all ribs alike, the longitudinal section is identical to the soundboard’s outlines) and the baglamas / bouzouki / mandolin bowl: different shapes, due to different longitudinal section – outline’s traces.
Most important is to understand how the ribs are meant to hold together, while still having to transform the longitudinal section curve to the symmetrical sounborad’s outlines.
This is a critical as much as a difficult task, because the outermost ribs that support the soundboard have to be shaped and curved following different properties to each side : “internally” should follow the trace of the precedent rib, whilst “ externally” should have to be trimmed flush to provide the flat soundboard outlines.
This is the reason that these outermost ribs are generally made wider, providing enough surface to shape accordingly. But this practice creates the two next issues:
1) the mould sides to the soundboard outline edges (exactly at the areas that will be covered by the outermost ribs) must be absolutely flat crosswise (the wooden rib cannot be curved in two directions)
2) This is quite important: you need to determine the "convergence point". It is the point that all ribs’ edges meet at the back of the bowl. Often, there are more than one of these “points”, in that case usually three: one for the central area ribs and (one + one) for each side (see the last picture attached).
……
I didn’t have time to search photos etc. Instead, I found a few videos that may help even better at this point:
Mandolin bowl construction
https://www.youtube.com/watch?v=45tqCDxOeaM (https://www.youtube.com/watch?v=45tqCDxOeaM)
(part 2)
https://www.youtube.com/watch?v=ObKHrcG3MfA (https://www.youtube.com/watch?v=ObKHrcG3MfA)
(part 3) at 0:31.... notice the two outermost-wide staves
Here is the YouTube channel of a fellow amateur luthier (member here) about bouzouki construction with many helpful videos
https://www.youtube.com/user/TheBouzoukimaker/videos?view=0&sort=p&shelf_id=2 (https://www.youtube.com/user/TheBouzoukimaker/videos?view=0&sort=p&shelf_id=2)
watch this one
https://www.youtube.com/watch?v=UMiNrQfyMQc (https://www.youtube.com/watch?v=UMiNrQfyMQc)
at 10:30... wide side-ribs
here are some photos of my first (bouzouki) bowl with a single "convergence point":
not a very nice work, but at the end this wide curved piece (I don't know the term, I will search for it) covers everything
and this is my first attempt (prior to actually working on the mould) to check the matching, point etc., maybe something like that will also help you
this is a 3 points mould (design of another fellow member): extending the rib lines you can "see" that clearly: the 7 "central" ribs will meet downwards, quite near to the "soundboard level line" at the bottom.
in this latter image you can also see clearly the "flat crosswise" surface of the outermost wide ribs at both sides.
Also notice this: the number of the ribs is odd. It is easier to make it this way, achieving a good fit for the first (central) rib which later on will be used as a "guide" for the next and the latter for the next...and so on.
Happy homework! ;D
I don't have a descent internet connection at home, so most likely I will not get in touch until after the weekend.
Αποστολή από: umuterakman στις Φεβρουαρίου 21, 2020, 07:19:35 μμ