Mike's Oud Forums

My first oud

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faggiuols - 10-8-2014 at 12:20 AM

Hello everyone
I write from Sardinia in Italy and I am about to make my first oud.
sorry for my English is very poor.
I just built a guitar in my life during a course and now I am begginning to start the most beautiful hobby in the world with the creation of my first oud.
I will follow the text of Mr. Hankey.
I'll be grateful to anyone who will help me in this wonderful process.
The photo shows my mold.
I would also like to know: I'm going in the creation of the handle and lock the handle making the inner block in one piece.
what do you think? thanks to all !!
guido

jdowning - 10-8-2014 at 04:41 AM

When you refer to 'the handle' you presumably mean 'the neck'? If so then are you are proposing to make the neck and neck block in one piece and attach it to the mold before fitting the ribs?

It is standard practice for a guitar built in the Spanish style - where the neck and neck block are carved together from one piece of wood and the two sides (ribs) of the guitar fit into slots cut into the side of the neck/neck block.
However, for an oud bowl - having the neck attached to the neck block prior to constructing the bowl - would make construction of the bowl/accurate fitting of the ribs rather difficult without good reason. The usual and most practical method is to fit the ribs with the neck block in place on the mold - the ribs overlap the end of the neck block and the surplus waste material is then cut off when the neck joint is made (prior to fitting the neck) after the bowl is complete.

A detailed step by step procedure for building an oud with images can be found here - which may be of interest in clarifying some of the building procedures.

http://www.mikeouds.com/messageboard/viewthread.php?tid=8488

A promising start so good luck with your project.

SamirCanada - 10-8-2014 at 04:55 AM

great job so far! I wish you the best with this project.

I would take the pencil lines from your mold and also draw them on the tail block up to the point where you want the ribs to end, this will help you greatly.

Are the dimentions from the book? the oud looks very high and round from the picture, usually the divider section right after the tail block is about the highest point in in the whole oud. It looks like the highest point of the bowl is located at the middle of the bowl where it should really be at the 2/3 and 1/3 meet

faggiuols - 10-8-2014 at 11:34 PM

thanks for the replies.
I had not thought about the problem of the accuracy of the ribs arrival on the handle.
I'll have to be very precise. But I think that the structure is better .. I would will easily. I'll post pictures of the work.
I attach the image of the patter. the size of the book are those in effect even if the mold came a few millimeter grade of the design that I had done with the cad.
anyway thanks for the advice. will verify the accuracy of the mold.
do you think the line is correct?
to me it seems quite similar to that shown in the book. what do you think?
thanks so much

[file]32725[/file]

faggiuols - 10-9-2014 at 12:19 AM

the pencil lines on the block of the queue I have not yet designed, but it will be the next step. Tomorrow I hope to send the first images of the neck - block unfinished.

SamirCanada - 10-9-2014 at 02:30 AM

Yes that looks great. It was just the angle of your first picture.
Making the neck block and neck of neck like a guitar is something I want to try so I am interested to see how you achieve this.

faggiuols - 10-9-2014 at 11:24 PM

Hello everyone.
I put the raw block handle internal lock. was made with 4 pieces.
The first two panels forming the side of T. later the block was planed top and bottom to make it perfectly flat and finally I glued the last piece. the photo shows the last gluing (glue bone). The fourth piece does not belong to the same tree. aesthetically shame because I really like the dual color even if it is internal to the instrument.
I hope the inside painting eliminate the defect.
wood is cedrela.


[file]32746[/file]

faggiuols - 10-9-2014 at 11:25 PM

here the block instead of the tail finished.
wood is cedrela also

[file]32748[/file]

faggiuols - 10-9-2014 at 11:29 PM

.. and the template of the ribs.

Microber - 10-10-2014 at 02:52 AM

Thanks for sharing the process.
It is always a pleasure.
Even if I am not concerned directly.
(I have never built any instrument and it is not one of my future projets)

Robert

faggiuols - 10-10-2014 at 07:09 AM

thanks robert

in any case if you think of any advice or suggestions would be greatly appreciated!

jdowning - 10-10-2014 at 11:53 AM

"I hope the inside painting eliminate the defect."

Why are you planning to paint the inside of the bowl faggiuols?

muhssin - 10-11-2014 at 03:55 AM

what does he mean by inside painting???????

faggiuols - 10-12-2014 at 11:13 PM

hello jdowning and mhussin
thanks for assistance!
please you read what I write to remind you that I speak very little English and I write it even worse.
Unfortunately, you have to always interpret my words because those are almost never accurate !!
to respond to your questions:
when do made ​​my guitar before gluing the soundboard and then shut down the harmonic box I gave him a coat of shellac with a brush. when I wrote to paint the inside of the oud intend this procedure to make the interior "finished" ..

faggiuols - 10-12-2014 at 11:34 PM

update job:
I started modeling the group neck - block.
I roughed with the Japanese saw the first elements but I went too deep at one point !!
mistake!

I have to insert a prosthesis to fill the depression created!
the aesthetic problem is not great because it is my intention to cover the neck ..
below I post some pictures of the work ...

faggiuols - 10-12-2014 at 11:36 PM

more images here ..

faggiuols - 10-12-2014 at 11:39 PM

as seen in the side I went deep into the saw cut in the middle of the neck!!!!!
any advice would be greatly appreciated!

[file]32838[/file]

[file]32840[/file]

jdowning - 10-13-2014 at 04:31 AM

Thanks for the clarification faggiuols. Definition of technical terminology between language translations is often a problem - which is why it is sometimes necessary to ask questions for clarification. Not to be taken as a criticism!
You did suggest that you wanted to eliminate the mismatching wood colour in the exposed internal neck block face by 'painting' over it. Opaque paint would serve that objective but not transparent shellac varnish (unless you add some kind of dark opaque pigment to the varnish). Why do you want to shellac the entire inside surface of the finished bowl anyway?

faggiuols - 10-13-2014 at 07:33 AM

Hi Jdowning
I did not I took your post as a criticism! indeed I am very pleased that a connoisseur of oud as you have the desire to follow my topic.
I hope you have a desire to follow the whole process of construction of the instrument with your valuable advice!
I hope I understood your question!
My idea is to paint the inside of opaque shellac for "clean look".
shellac by brush brightens the wood without being polished, but always transparent.
I will use shellac for varnishing transparent end of the instrument outside.
I understand that the shellac you can end both glossy and matte, changes the method of painting. polished is more difficult, is that correct?
to complete, my intention is to put in oud between the ribs is not a tape of heavy paper such as is usually done, but very thin strips of wood to seal the joints of the ribs. I would also like to mount the kerfed linings as in the guitar. I think the best bonding of the soundboard ..
what do you think?

jdowning - 10-13-2014 at 12:06 PM

No harm in experimenting with construction/finishing methods that deviate from well established centuries old traditional methods if you have time and are prepared for encountering difficulties but be careful about applying modern guitar methods to oud construction or you may end up with an oud that sounds more like a guitar.

Kerfed linings are not necessary on an oud and may adversely affect the sound board acoustics due to excessive stiffness at the edges. I don't know by how much as I have never used linings on either ouds, lutes (or early guitars) for comparison.

Paper strips glued in place with hot hide glue is the best and easiest way to go for a strong rib joint reinforcement. As the glue cures it shrinks and pulls the rib joints tightly together. Paper is after all made from wood fibres and is flexible enough to fill all of the slight internal bowl surface undulations at the rib joints when saturated with glue.
Of course, once all of the paper strips have been applied on a 19 ribbed oud, the entire interior of the bowl is more or less coated with hide glue - so no need for any other internal finish (that will only add extra unnecessary weight to the bowl for no good reason).

Following progress of this topic with interest.





SamirCanada - 10-13-2014 at 03:26 PM

I would avoid applying kerfing at all especially directly perpendicular to the soundhole to quite a bit bellow the bridge.


faggiuols - 10-13-2014 at 11:23 PM

thanks Jdowning and Samir
you convinced me! was not difficult.
I would like to build an oud according to classical rules even if some of the details seem me unclear and improvable.
I joined this forum in order to have some experts that would follow me in this process not easy.
So thank you very much!
certainly I'll follow your valuable tips.

faggiuols - 10-13-2014 at 11:24 PM

spero quanto prima di poter post i prossimi aggiornamenti sul lavoro.

SamirCanada - 10-14-2014 at 05:33 AM

I think if you built a guitar before, some things like the way the soundboard of a oud is attached will seem too weak and its natural to think there is a way to make it attached stronger.

The soundboard is suposed to be very thin able to vibrate a lot, if a soundboard is weakly attached to the bowl, chances are the sound will be better. This may be against all your pre-established ideas and principles but its how it works :)

faggiuols - 10-14-2014 at 11:16 PM

thanks Samir
I wish the sound of my oud is like a real oud, warm and poetic.
I will do definitely you suggest and I will stick strictly to the rules of construction standard.

faggiuols - 10-14-2014 at 11:25 PM

an update on job:
I'm shaping the neck, first with the saw, then with the belt sander and now with the rasp.
I'm taking wider than I can with the utmost care.
I would like to know: I'll clothe the neck with the same wood of the bowl. what coating thickness must have? how much thickness I must remove yet compared to the finite to take account of the coating?
or that the coating thickness has more glue?
Thanks.
some pictures to understand what I'm doing.


[file]32875[/file] [file]32877[/file]

jdowning - 10-15-2014 at 04:03 AM

Rib thickness should be uniform so will be the same thickness over the neck block as elsewhere. Only use as much glue as is necessary. As there is some end grain in the neck block, the surface should first be given a priming coat of diluted hide glue to seal the grain and prevent glue later being absorbed into the wood that can lead to a weak joint between the ribs and neck block.
The contour of the neck block should exactly match that of the rest of the mould.

faggiuols - 10-16-2014 at 06:19 AM

thanks Jdowning
I thought finished to a thickness of 2 mm.
This means that I have to reduce the neck of the other two millimeters compared to the finite to cover it?
about glue: I have to apply two layers? one to seal the grain and one to paste?
I understand it well?

faggiuols - 10-16-2014 at 06:21 AM

I'm finishing to smooth the neck and the neck block.
I now have to remove the coating thickness of the neck.
tomorrow I hope to be able to post pictures of the work done so far in order to be more clear in my doubts.
excuse me for the language problem.

SamirCanada - 10-16-2014 at 06:31 AM

You can cover the neck with a thin veneer, its not important that the neck cover also be 2mm like your ribs will be. but if you want to use leftover wood from the ribs that is already 2mm thick you can then shave down the neck 2mm all around as you are doing, make sure the neck joing is filed square.

I would also use a small detail saw to cut the tip of the ribs at the neck just after you glue each one, it will save you lots of work at the end.

faggiuols - 10-16-2014 at 06:47 AM

very clear.
then I prefer to remove a maximum of 1 mm and in the case to reduce the thickness of the coating to be applied.
about the final cut of the rib I think to run it before to attach the rib, after it has been measured well. I think it's easier to apply the rib.

faggiuols - 10-19-2014 at 11:21 PM

hi all
to finish the neck I made a template of the attack on the internal block and with a chisel I modeled until a perfect match with the template.

[file]32963[/file]

[file]32965[/file]

faggiuols - 10-19-2014 at 11:33 PM

Then I started modeling the neck, first with the belt sander and then with sandpaper until to the linearity of the piece.
obviously along all lines.

faggiuols - 10-19-2014 at 11:38 PM

Then I corrected the vertical symmetry on the block.
easier to see the picture then to explain.

[file]32971[/file]

faggiuols - 10-19-2014 at 11:40 PM

I later corrected the block up to the perfect symmetry and compatibility with the mold.



[file]32987[/file]

faggiuols - 10-19-2014 at 11:44 PM

the piece is not perfect yet .
the neck should be finished in the middle because still high.
instead the inner block seems too low compared to the line of the patter.
I think it is not difficult to remedy later.

I also overlaid the two pieces internal (back and front- last image) to see if there were elements of concern but I would say that the parts are compatible.

few hours of work you need to put




[file]32983[/file]

[file]32985[/file]

[file]32991[/file]

faggiuols - 10-20-2014 at 12:35 AM

In the photo you can see the rosewood that I will use for the ribs.
is very nice but the grain is very crooked and it seems difficult to cut. I have 14 pieces and I have to do 19 ribs. therefore 1 piece should go out 2 ribs.
someone can help me figure out what is the best way to cut?

I was thinking of keeping near the ribs extracted from the same piece, but the second turned, in order to have a rib with a grain right and a rib with a grain left. if this is right, but I do not understand how must be put the first rib in the middle of the bowl, that will have the grain or right or left. in any case I lose the symmetry of the grain..




[file]32981[/file]

faggiuols - 10-20-2014 at 09:04 AM

I realized that I did not post my project.
I remedy immediately. of course the design is done by following the text of Hankey.

I precise that it seemed to me that the book has some inaccuracies mainly on the size and location of the bridge. I could be wrong view to have understood my difficulties with English.
in any case there are small differences with respect to what is written by Hankey in my project.

the file is not easily readable.
if anyone is interested I can send it in a format heavier or even in dwg.

[file]32993[/file]

faggiuols - 10-20-2014 at 11:07 PM

Hello everyone
reading the threads of this forum I understand that I'm missing a lot in terms of knowledge of the oud.
I would like to know where can I find information about the types of oud and most important luthiers .
could someone indicate me to a website or a book that can give me greater culture on the subject?
thanks to those who wish to respond.

SamirCanada - 10-21-2014 at 06:36 AM

If you want perfect symmetric grain as you say you can't have an uneven number of ribs, and the apex should be a joint not a rib. I don't think its a big deal once it's done because it will be hard to see an issue with symmetry even if you use the uneven number of ribs. Now for the famous makers research Nahat, Manol, karibyan, you will get ideas of bracing. There are no reliable books or resources other than the net, Oud makers are a secretive bunch :)

faggiuols - 10-21-2014 at 11:30 PM

hello Samir
so ... I joined a secret society !!!
Wow :))


about the grain of the ribs I cut the first two ribs from the same piece.
in this position have the grain parallel.
I think that one will be turned away and joined. I have to try with all the ribs side by side the best option before assembling .
the first rib to cut it in a different way trying to reproduce a design that is in the middle between the right and left ribs. I hope to do
then I'll post the picture of the ribs before installing.

[file]33002[/file]:D

SamirCanada - 10-22-2014 at 02:48 AM

I hope you didn't cut those to final dimensions right away before bending. You need to bend them first then shave to final dimention on a long inverted plane so the edge can connect properly to the next rib.

faggiuols - 10-22-2014 at 05:46 AM

hello Samir
are about a mm over the right fit on each side. something more if I consider the white strip between the rib and the rib.
I saw that all bend the rib before cutting it, but for me the cut seems to be easier on the straight piece and then finish the rib bent before installation.
what could be the problem with my way?
I only cut two ribs and are in time to change ways of working ...

faggiuols - 10-22-2014 at 05:53 AM

I add that I'm not sure that I want to use the hot iron to bend the ribs.
I think that I will warm the ribs long in hot water and then put them in shape without glue stuck with elastic. after 24 hours should be perfect.
Otherwise I'll give them a shot of hot iron ...
I think that to do this I will have to bring the ribs to a maximum thickness of 2/2.2 mm (now they are at 2.8 mm.)

faggiuols - 10-22-2014 at 07:01 AM

may I know from jdowning, or anyone else, if for the classic oud also the size of the holes to be less than 7% of the total area of the soundboard.
in my case are around 10% and I would know if I must decrease the holes.
I read this on one of the jdowning's topic.

SamirCanada - 10-22-2014 at 08:36 AM

I dont think you can bend the ribs like that... rosewood is pretty easy to bend on the hot iron.

faggiuols - 10-22-2014 at 08:48 AM

I'll do a test and let you know! it seems to me that if the wood is very hot and humid there is no need for hot iron.
about to cut the ribs before to bend them you think there could be problems?

SamirCanada - 10-22-2014 at 09:19 AM

I cut them after I bend them. I find it much easier to fit each rib after that.
You need a band saw.

If you want to cut them before bending you should make them at least 5mm larger than final size so you can plane them and have the correct angle on the edge

faggiuols - 10-22-2014 at 09:37 AM

I'll try to bend these first two and I'll try to mount them without glue.
if it will be complicated I will modify and enlarge the cut.

abc123xyz - 10-22-2014 at 10:17 AM

Quote: Originally posted by faggiuols  
I think that I will warm the ribs long in hot water and then put them in shape without glue stuck with elastic. after 24 hours should be perfect.

Is that possible?

I know that one can very succesfully use heat alone to bend wood, without wetting it at all, but I didn't know it would permanently assume a desired curve from soaking and drying in place alone.

It seems too that, even if it's possible to bend the wood that way, a wet rib would shrink after drying, and so change its proportions, at least slightly, including possibly its curvature, and ideally the ribs should fit exactly during assembly without one having to push them to correct the curve. Othewise stress is being built into the instrument from the start.

For that final "microfit" during assembly most people hit the ribs with a little dry heat in just the right place, and you might end up having to do the same, even if you manage to do your initial bending without it.

David

jdowning - 10-22-2014 at 03:20 PM

If there is a direct relationship between sound hole size (area?) and sound board area I am not aware of it but would be interested to learn more.
Where did you say that you read about this on the forum?

faggiuols - 10-22-2014 at 11:21 PM

hi David, thanks for your post.
when I find a process difficult I think an easier alternative. is the way my mind works .
as for the neck-block. it seemed me too difficult to make the snap so I chose to do one piece .
the bending of the ribs with the hot iron seem to me difficult and dangerous so I thought I find it easier to do without.
is also a suggestion of a luthier who produce mandolins. He said that when ribs are small you do not need a hot iron. perhaps mandolins have the ribs much smaller and the mode can not be used for oud.
I try, then I say as gone it.

faggiuols - 10-22-2014 at 11:26 PM

hello Jdowning
maybe I misunderstood .. my English is limited !!!
I do not know how to point your post ..
you wrote:
"It so happens That the total area of the three sound holes is Within 7% of the area of the large sound hole single taken from the oud sound board geometry".

topic - Old Oud - New Project
Posts: 2881
Registered: 03/08/2006

jdowning - 10-23-2014 at 04:24 AM

OK found it!

http://www.mikeouds.com/messageboard/viewthread.php?tid=8488&pa...

This concerns the sound board of a reconstruction of the 14th C 'Urmawi' oud drawing.
I was just making an observation - for the record - that the total area of the three sound holes was within 7% of the alternative single sound hole area based upon the mid 15th C Arnault de Zwolle lute geometry.
I did not draw any conclusions from this observation (or say that the area of the sound holes was within 7% of the total sound board area according to your previous post).

You will find more information about the relationship between sound hole diameter, bowl air volume and bowl geometry etc. here (Helmhotz air resonance)

http://www.mikeouds.com/messageboard/viewthread.php?tid=14874

So far my experimental results in this field of research only apply to single sound hole arrangements. The next step (time permitting) will be to test triple sound hole arrangements - found on surviving old ouds - using an acoustic chamber. The MIT research paper referenced in this topic makes geometrical generalisations about oud and lute triple sound holes that do not seem to correspond to any old lutes or ouds that I have examined to date.

Note also that the Urmawi oud geometry - as drawn - has a two sound hole arrangement that you will not find on any surviving oud that I know about.

faggiuols - 10-23-2014 at 05:33 AM

thanks so much Jdowning

faggiuols - 11-7-2014 at 01:03 AM

help !!
Samir ... Jdowning ... Fritz ... I need you!
I cut the ribs of rosewood and I started folding step.
I have let the ribs to the thickness of 3 mm. and I think this is a mistake!
maybe I have to take them to 2.2 / 2.3 mm.?
I have folded the first 4 ribs with about 20 minuts heating in boiling water and I bent with a hot iron with the utmost care, but:
1- the ribs are bent in an uneven manner in the sense that some points, being harder then other, left the portion with transverse deformations!
2 - two of them broke again in the same exact spot ..
I am attaching a few pictures of the tragic work done by me!

faggiuols - 11-7-2014 at 01:04 AM

this is the bending system ..

faggiuols - 11-7-2014 at 01:06 AM

the ribs before to bend..

[file]33172[/file]

faggiuols - 11-7-2014 at 01:14 AM

the ribs at the point of rupture. is the same for both. obviously there is a weak point along the rib. you think it is possible?

faggiuols - 11-7-2014 at 01:21 AM

see the rib .. is not uniform. I definitely do not bend well, but any advice would be greatly appreciated!
thanks to all



[file]33182[/file]

faggiuols - 11-7-2014 at 01:23 AM

Now the ribs are so ...

faggiuols - 11-7-2014 at 03:19 AM

could be a solution?

jdowning - 11-7-2014 at 05:07 AM

Your bending iron is too small in diameter and is not hot enough. The small diameter results in line contact with the wood so that the heat is focussed in a narrow line rather than more widely distributed. It also results in high local stress in the wood at the point of contact.

My bending iron is made from 4 inch diameter thick walled copper tubing flattened in a vice to an oval section heated with a small propane torch. See here:

http://www.mikeouds.com/messageboard/viewthread.php?tid=6869&pa...

The bending iron should be heated so that it will almost scorch the wood. Test the temperature with a drop of water which should immediately turn to steam. Then you should have little problem in bending the ribs even when 3mm thick. No need to soak the rib in hot water just a wipe with a damp cloth will do.
Also the crooked grain of your ribs may cause problems in bending (e.g. twisting irregularly to one side).

SamirCanada - 11-7-2014 at 05:30 AM

you can also bend the ribs with the heat gun only, just put it in a vise and point it up.

faggiuols - 11-7-2014 at 09:00 AM

thank you all.
immediately try to seek a copper pipe of that size.
it seems easier than using only the heat gun.
I will update you.
thanks

faggiuols - 11-7-2014 at 09:02 AM


Quote:

Also the crooked grain of your ribs may cause problems in bending (e.g. twisting irregularly to one side).

in these cases, how can you do?
Use a press or put in shape like I did is good for something?

faggiuols - 11-7-2014 at 09:09 AM


Quote:

My bending iron is made from 4 inch diameter thick walled copper tubing flattened in a vice to an oval section heated with a small propane torch

the copper pipe must have a minimum thickness or can also use those of 1 mm. thick?
those of 1 mm. I find them easily!

jdowning - 11-7-2014 at 12:51 PM

The pipe must have sufficient heat retaining capacity to maintain the required temperature (as well as being rigid enough not to flex or bend). 1mm wall thickness pipe may not provide the required level of heat control (?) but you could always make a 'heavier' bending iron from two (or three) pipes of 1 mm wall thickness. Just make a longitudinal cut in one pipe and slide it over the other for a reasonably tight fit. The two pipes would be held together when bolted to an iron bracket necessary for supporting the iron and mounting the propane torch. I have not tried it but it should work.
For information I will post some detailed images of my bending iron to show the mounting bracket.

I always use straight (longitudinal) grained wood for ribs but any localised unevenness across the width of a rib can be 'ironed out' by working the rib at an angle to the axis of the bending iron. With a bending iron you can have quite precise control.

My very first bending iron (made way back in 1963) was fabricated from a sheet of 1.5 mm thick copper formed into a 'tunnel' and mounted with screws on to a slab of wood. Heat was provided by an element from a radiant heat electric fire. Not the best arrangement but it did the job. Others have used an aluminium tube with an electrical light bulb as an heating element.
A propane torch can give ample heat and is quickly adjusted to provide the correct temperature.

A heated mold for forming ribs is a method used by some luthiers (guitars and ouds) - best suited for mass production work I imagine.

jdowning - 11-8-2014 at 05:29 AM

Here for information are a couple of images of my bending iron should you decide to make one. The overall length of the copper tube is 17 cm (6.5 inches) including the rib fillet bending attachment, wall thickness 3 mm and it is bolted to an iron bracket that in turn is screwed to a wooden block so that the assembly may be held in a vice. The propane cylinder is clamped to a piece of angle iron with a standard cable 'U' clamp so that the flame position may be infinitely adjusted relative to the tube surface allowing a wide control of temperature. It works for me.

Regarding the boiling of ribs prior to bending the only reference I have found to this method is described in 1966 by Irvine Sloane in his book 'Classic Guitar Construction'. I am not sure if this is a method adopted by other guitar makers rather than the traditional hot bending iron (regardless of heat source). Sloane's method involves boiling the ribs until the wood is plastic (for about 1.5 hours) at which point the ribs are removed from the water and rapidly clamped to a mold before plasticity is lost as the wood chills. The ribs are left on the mold to dry for about a week. The success of this method according to Sloane is the use of straight grained, seasoned wood of uniform thickness free of 'figure' (such as flamed maple). The ribs when removed from the mold may be subject to 'spring back' requiring the ribs to be forcibly bent for a few days to correct this fault. Furthermore the boiling process removes natural residues from oily woods such as rosewood. Sloane considers this to be an advantage as it removes the oils that make rosewood otherwise difficult to glue but one has to wonder how boiling might adversely affect the wood structurally and/or acoustically.
So this would appear to be a guitar maker's method that is much more complicated and restrictive, for no good reason, than the traditional hot iron bending.

I have used a boiling water/mold method in conjunction with chemicals in my experiments to successfully form deeply fluted ribs - reported some time ago on this forum. The chemicals modify the structure of the wood (making open cell wood species more dense and harder which might be a good thing acoustically) and temporarily - together with heat from the water - soften the wood so that it is soft and plastic enough to be both deeply fluted in section and curved longitudinally.

[file]33190[/file] [file]33192[/file]

faggiuols - 11-8-2014 at 12:17 PM

thanks Jdowning
you are very clear. use the lamp seems easier.

now I procure the copper pipe. as soon as I have everything, I try to do it.
remember that you are good with wood and even metal, but I am unable with wood and even metal !!
I see from the photos that the tube is open on both sides, so the flame of propane is not like a blowtorch, but type gas stove!
Thanks, as always, for your valuable advice.
will update you

jdowning - 11-8-2014 at 01:01 PM

The pipe is open at both ends.
The flame of the propane torch is more like a blow torch as you can see.

faggiuols - 11-8-2014 at 01:13 PM

but then put in so that the flame goes on the inner surface of the cylindrical tube? otherwise the heat comes out the other side.
I got it right?

faggiuols - 11-8-2014 at 01:19 PM

how do you make the temperature of the tube uniform? turn the tube? or heat goes alone in the remaining part of the tube?
maybe it needs to be hot only on the top?
Thanks.
I'd be lost without you!

Fritz - 11-8-2014 at 01:49 PM

Quote: Originally posted by faggiuols  
here the block instead of the tail finished.
wood is cedrela also



Hi faggiuols

Cedrela ist a very good wood for the blocks ! Very light in weight, and almost uneffectable by changes of humidity.


Fritz - 11-8-2014 at 01:53 PM

Quote: Originally posted by faggiuols  
see the rib .. is not uniform. I definitely do not bend well, but any advice would be greatly appreciated!
thanks to all





Hey

Sometimes its a change of the direction of the grain what creates some probs bending the rib in the right curve. So you have to adapt the stress to the rib on the grain and the abilitư of the wood to be bent. The wood "says" if it will bend more wet or dry, more in a bigger area or in small steps...

It´s a dialog between you and the wood...

Try to understand the reactions of the wood... use different wood as testwoods. Use swap wood to see how it will be bent.

Fritz

Fritz - 11-8-2014 at 01:58 PM

Quote: Originally posted by faggiuols  
the ribs at the point of rupture. is the same for both. obviously there is a weak point along the rib. you think it is possible?


This is the result of bending too fast and on a too small diameter ! A very small area is heated and the further areas aren´t ! So the wood will break if too many stress while bending.

Use a more oval tube with enough diameter and make the wood wet enough.

Allways keep a small sponge beside to re-wet the wood when it becomes too dry.

faggiuols - 11-8-2014 at 03:13 PM

thanks Fritz
I am happy that you have come to give me advice.
I need it as you can see!

faggiuols - 11-8-2014 at 03:24 PM


Quote:

Sometimes its a change of the direction of the grain what creates some probs bending the rib in the right curve. So you have to adapt the stress to the rib on the grain and the abilitư of the wood to be bent. The wood "says" if it will bend more wet or dry, more in a bigger area or in small steps...

Unfortunately I do not have many cartridges in my gun. if I break a lot of ribs will be a big problem.
first of all, I organize a hot iron better than mine and I see if it improves the work.
when I made the guitar I have bent the wood with a liuther's hot iron and the work was not that complicated.
with my hot iron made by me I felt it was much more difficult.
I'll try with better equipment.

faggiuols - 11-8-2014 at 03:36 PM


Quote:

This is the result of bending too fast and on a too small diameter ! A very small area is heated and the further areas aren´t ! So the wood will break if too many stress while bending.

surely, as I noted Jdowning, also the temperature of the iron was not sufficient even.

for this I may have forced too much wood, breaking it.
However, the fact that the break is in the same position in both ribs suggests a weak point in all ribs.

I thought I would find the point on the ribs before folding and mark it with a sign to increase attention during bending.

What do you think?

jdowning - 11-8-2014 at 04:55 PM

The temperature of the upper surface of the bending iron tube is infinitely variable - dictated by where the flame is applied on the underside of the tube and the intensity of the flame. The uniformity of the surface temperature also depends upon the heat capacity of the tube (greater wall thickness = greater heat capacity).
The tube MUST be open at both ends as a propane torch requires air for combustion. Do not attempt to close the end of the tube. At best this will cause 'flame out' due to lack of oxygen or worse, flame 'blow back' that could cause personal injury.

A woodworker must learn to 'read' the grain of a wood in order to work it effectively - not only when planing wood but when bending it. The wood will tell you how it can best be fashioned.
If you have identified a weak spot in your ribs 'the hard way' (by breaking a few) then by all means mark the weak spot on the remainder of the ribs to take greater care when bending in that location.
You may find that with a hotter and larger diameter iron the breakage problem will disappear. You may even be able to recover those ribs that are intact but uneven in curvature by re-working them on the new bending iron.
I would suggest that, once you have made a new bending iron, to trial bend the broken rib pieces or non uniform ribs to gain experience with finding the best temperature and the method before working with the rest of the ribs.


faggiuols - 11-8-2014 at 11:34 PM

thanks Jdowning
the procedure you described is exactly what I had in my mind.
well.
Now I have to do a hot iron.
I tried to buy a tube of 3 mm aluminum but they sell only 6 meters long!
I have to turn some places.
do you think I can recover broken ribs putting some glue in the breaking point? or are they lost forever?
thanks

jdowning - 11-9-2014 at 05:39 AM

Copper makes the best bending iron. Aluminium is OK but has only about 60% of the heat conducting capacity of copper. Iron tubes were used by the old Spanish luthiers - mounted vertically over a charcoal fire - but iron has only about 10% of the heat conducting capacity of copper so plenty of heat required but iron (steel) might work with a strong propane flame.

Some of the old lutes seen in paintings had two piece ribs of contrasting woods (i.e. with a horizontal joint at the mid point of each rib) so a cracked and repaired rib would be structurally viable - although it would be practically difficult if not impossible to make a crack invisible. You might also have problems re-bending the ribs to a smooth curve across the cracked area. One approach might be to glue strong paper reinforcement over the cracks (with hot hide glue scorched in place) - on the outside surface of the rib, of course. This might be sufficient to hold everything together during bending - the paper can then be removed with hot water and scraping at a later time. Only one way to find out - try it and see.
Another alternative, if you do not have enough rosewood ribs remaining, would be to make up extra ribs in a contrasting colour wood so the ribs of the bowl would be arranged as alternating dark/light colour. Be aware that the oils in rosewood can stain lighter woods - particularly during finishing work on the bowl.

faggiuols - 11-9-2014 at 09:49 AM

thanks Jdowning
your posts are always very interesting. I reread some of them many times to store them.
I have several pieces of rosewood, so I think I have enough wood, unless I keep breaking them.

So I hope I haven't the need to repair the broken ribs, at least I hope so. but if I had to break them all maybe it's better if I stop doing oud and start working to make jerseys and socks!!:D
But what you write is very interesting and important. repair errors is an art, perhaps making strengths.
so thanks again

jdowning - 11-9-2014 at 04:08 PM

With experience and skill an oud may be created with some of the most basic tools. The simplest possible rib bending apparatus and procedure is shown here on the video at 0.45 to 0.49 minutes. Sufficient heat is all important.

http://www.youtube.com/watch?v=kpr9pXEni3I

Just for information!

faggiuols - 11-10-2014 at 12:20 AM

I saw this technique on youtube and Samir suggested it to avoid the hot iron.
it seems more difficult then hot iron.
But I can try.
I'll tell you later.

faggiuols - 11-10-2014 at 12:27 AM

practically this technique is that of this video ..

https://www.youtube.com/watch?v=rvsdS9sbuq0

I have an identical gun!

jdowning - 11-10-2014 at 05:08 AM

Your choice faggiuols - whatever works for you.

When I started making lutes over 40 years ago some lute makers simply held the ribs in front of a radiant heat electric fire to bend them - but then lute ribs are usually only 1.5 mm or less in thickness so are easier to bend uniformly than thicker ribs with such a heat source.

I suspect that the preferred method among most luthiers is a bending iron as it provides greater control over the bending process as well as providing support of a rib to minimise risk of breakage during bending. This is particularly important in fabricating a lute bowl as the rib profiles must match each other more precisely than the ribs of an oud bowl - the ribs of an oud bowl having extra thickness to allow the exterior (and sometimes the interior) surface of the bowl to be shaved down to a finished smooth profile.

Richard's video was only a quick demonstration of the principle behind using a hot air gun as a heat source but the bent rib blank looks a bit non uniform in its curvature?

I doubt if a hot air gun would work very well with the wider and relatively thick ribs of a guitar - but that's another story.

faggiuols - 11-11-2014 at 01:00 AM

Hello Jdowning and everyone
I tried to bend the ribs with just a heat gun and I must say I am very happy because the work I was very easy. I tried without water. when the wood is very hot it becomes plastic and workable.
before using rosewood I tried to use the mahogany that I had. Mahogany is easier and above all it does not have that damn weak point that my ribs of rosewood.
in any case it seems feasible in this way.

I inquired to find a piece of copper tube as which ones you suggested me. The price of copper is very high. if you add the rest of the components and the time to build it I almost should buy a bending iron professional!

faggiuols - 11-11-2014 at 01:01 AM

here's the first rib bent.
the second that has been worked much better but I forgot to photograph it.
has some flaws, but in the second I easily corrected these flaws.
I think the next will be in a satisfactory manner.
[file]33281[/file]

faggiuols - 11-11-2014 at 01:08 AM

Now I let them fit in the mold.
I saw that with time the bending is released and the rib loses curvature.

those bent yesterday with pins white!
the work seems good enough.
improvement but good!

[file]33283[/file] [file]33285[/file] [file]33287[/file]

SamirCanada - 11-11-2014 at 02:18 AM

:xtreme:

Yes keep going ragazzi! Make sure the bend is perfect against your template. Also it's a good idea to bend each rib again to the final shape before you glue it.

faggiuols - 11-11-2014 at 08:00 AM

Quote: Originally posted by SamirCanada  
:xtreme:

Yes keep going ragazzi! Make sure the bend is perfect against your template. Also it's a good idea to bend each rib again to the final shape before you glue it.

Samir, thanks for sharing.
do you think it would be better to use the water too, or is it better to fold in the dry?
I think I'll try to get wet ...

faggiuols - 11-12-2014 at 12:17 AM

another bit of work done.

faggiuols - 11-12-2014 at 12:20 AM

I leave the ribs to take shape about 24 hours, then I take off them from the mold and I keep them that way. if you look closely you can see differences in the curvature.
those differences can be a complication later during bonding?

faggiuols - 11-12-2014 at 12:25 AM

as the weak point of the ribs I still had problems, I developed a reinforcement to be used during the bending of the ribs.
with a small vise block the weak point and do not submit it to bend.
I hope that it bent during installation in the mold.

faggiuols - 11-12-2014 at 12:29 AM

I tried to soak the wood during bending but did not find a difference.
in any case it is necessary to proceed very slowly and carefully. if you try to speed up the work the wood rebels and the job is bad.
under the image of the heat gun.

[file]33327[/file]

jdowning - 11-12-2014 at 05:57 AM

Your current difficulties are due primarily to insufficient heat in bending. Wood takes a permanent bend due to softening of the 'glue' (Lignin) that binds the wood cells together. If the heat is insufficient and so does not penetrate the full depth of a rib, the Lignin in the outer layers will only be partially softened or not softened at all so may cause difficulties in bending a rib or result in significant 'spring back' of the rib curvature on cooling. Bending a rib with heat should not be a slow process or require application of significant force - as you report - if heat is sufficient. Spring back should be minimal or non existent.

The irregularities currently visible in your bent ribs may well cause problems when you come to assemble and fit the ribs on the mold due to mismatched rib profiles along the glue joints. The ribs should match the mold longitudinal contours with some precision without forcing a rib to fit the mold as you are proposing. That is not the function of a mold as some may assume.

You may be able to literally iron out the local irregularities in your ribs (or even bend the ribs entirely) with a standard electric household iron (used for ironing clothes) set at high heat - ironing the rib over a piece of suitably curved wooden mold held in a vice. This no doubt will also give you better control over the bending process.

To reinforce the weak spot in your ribs you might try gluing paper reinforcement over the area with hot hide glue as suggested earlier in this thread. The glue soaked paper on the rib should then be heated to immediately form a hard crust (scorched) using a hot iron. A household electric iron will do the job but use an old iron as hardened glue residues will stick to the sole of the iron. These residues can be removed with hot water (first unplug the iron from the electrical power source!) but it is advisable not use your wife's best household appliances for luthier work.


SamirCanada - 11-12-2014 at 06:26 AM

Quote: Originally posted by jdowning  
You may be able to literally iron out the local irregularities in your ribs (or even bend the ribs entirely) with a standard electric household iron (used for ironing clothes) set at high heat - ironing the rib over a piece of suitably curved wooden mold held in a vice. This no doubt will also give you better control over the bending process.


this is great advice... I have done this before and it works to get you close, you can then use the heat gun to get you close.

faggiuols - 11-12-2014 at 06:56 AM

thanks Jdowning
your posts are always interesting and instructive.
I did not know of lignin!
very good idea to iron the rib before bonding.
will definitely help when it alongside the ribs.
of course this work will be done before working on the ribs to finish, otherwise you will not be able to see when the ribs coincide perfectly! I got it right?
Instead I've not understood well the reinforcement rib paper with glue. The glue when I switch the iron on the rib should return to liquid preventing the completion of the bent! I can not understand how the iron would "burn" the glue does not melt glue, or when the card is cemented?
I have seen the hot glue burn, but when subjected to great heat as the heat gun!
if I remember correctly I have an iron at home that I could use!

I'll take it in secret from my wife !!
then I will tell her that the economic crisis is turning a lot of people thief, and I doubt the next-door neighbor !!

faggiuols - 11-12-2014 at 06:58 AM

Quote: Originally posted by SamirCanada  
Quote: Originally posted by jdowning  
You may be able to literally iron out the local irregularities in your ribs (or even bend the ribs entirely) with a standard electric household iron (used for ironing clothes) set at high heat - ironing the rib over a piece of suitably curved wooden mold held in a vice. This no doubt will also give you better control over the bending process.


this is great advice... I have done this before and it works to get you close, you can then use the heat gun to get you close.


thanks Samir

I will try this way. I update you on the results!

... If my wife does not notice anything ....

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