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Braces · Attaching the soundboard · Fingerboard · Finishing · Gallery of the completed oud
After straightening the third set of ribs in the jig I resumed work on the back. The fifth set went on smoothly, but was a bit off so I clamped it in the straightening jig as before. This time I left it in the jig for four days. (just by chance- I was out of town for that amount of time) It did not spring back at all. The shape was excellent. The sixth set went on the same way. I made absolutely sure that the ribs were as close to the shape and as absolutely flat as possible against the previous rib. This is the most important aspect of building the back because it ensures the back maintains its proper shape. See comments about the seventh set below.
The far left rib is somewhat narrower than the far right one. This was done to balance a discrepancy on the right side. I took off a bit too much material getting it to lay flat and now the left side is about 4mm different than the right. I thought of using a new rib, but it fit so well that I hated not to use it. I will have to correct this again on the right side, but spread over the remaining three ribs on each side, it will not add up to much difference visually. Making sure the ribs fit flat is paying off. The seventh set matches the profile pattern very well.
Here is a view of the neck end joints. This is a very close shot under raking light. Thus, the tearout and grain is accentuated. The joints are pretty good. The widths of the ribs are not all the same, however. Good thing I didn't use contrasting wood or purfling. This would look even more crude. Ending up with equal ribs is proving to be more difficult than I had anticipated.
As I built up the back I decided that I would start getting extra finicky with the joints and test them with a flashlight from inside the back. A good joint is light-tight. This is an excellent way to test if your joints are going to close up perfectly at glue-up. Simply tape the fitted rib without glue in place and shine the light from inside toward the joint. It will tell you immediately where you need to improve the fit. Up until the seventh set, I did this without the light, so the seventh set joints are indeed light-tight. As I was doing this, I discovered on a previous joint (between 3rd and 5th set) some light peeking through. Luckily this was only in a very small area. Most of the area is glued, but there are some "pins" of light visible where there is no glue. (see photo with light off at left, and on, below) The joint is very tight and not loose in any way. After the paper gets glued to the inside of the joint, it will strengthen it considerably. Of course it is not ideal, it is a weak spot, but hopefully not enough to cause any problems in the future. Incidentally, I once heard an oud whose back had been accidentally broken by a dancers' sword--the ribs were shattered and there was a large hole in the back. Interestingly, the sound was virtually unaffected.
The pins of light shining through the imperfect area of the joint.
The ninth set of ribs completed.
Ninth set, front view. The back is a bit, in total, narrower than it should be at this point, about 1.5cm on each side. They are however the same width on either side of the center line of the back, which is good.This is a result of removing too much material in fitting the ribs. I will make up the difference in the last two ribs.
After joining the ninth set of ribs I discovered that one of the blocks had shifted at some point. Here the end block shows the discrepancy. I was told that this is not so uncommon, although I was fairly disappointed when I discovered it. As a result, one side of the back leans about 1cm lower than the other. After I complete all the ribs the back will be planed flat and this mistake will be removed in the process. I will lose a bit of the extra depth of the back, but it shouldn't be much. And the top ribs will not be perfectly symmetrical. (I will disguise this with a tailpiece which will distract the eye away from the discrepancy.) The majority of the material will be removed toward the tail end and not at the neck block. The neck block needs to keep its dimensions in order for the neck to meet up with the body correctly. A future prevention of this problem was related to me by Richard Hankey: use two screws in each block to prevent twisting.
Eleven ribs completed
It is very difficult to make the ends of the ribs at the tail end finish in a point. I have seen ouds that come very, very close. Some sort of decorative cover plate or inlay is always used. My attempt is obviously a ways off from ideal. I removed too much material at the ends when making the ribs lie flat. There is a certain technique involved to keep the correct dimensions when jointing the ribs that cannot be explained. One must learn it in practice.
Here I trimmed the junction smooth for the last two ribs. I extended a line from each of the two ribs until they met and removed the excess material. The remaining areas of the end block are fairly symmetrical.
The oud back with eleven ribs.
Here I am clamping the last rib on what will be the bottom of the back. The last ribs are bent while they are square. The rib is then placed in position on the neck and end blocks so one edge is proud of the tops of the block by about 5mm. (This is the front face of the oud) Then from the inside of the back a line is drawn along the edge of the previous rib to establish the contour. The last rib is then cut along this line and fit and glued. The extra 5mm is to allow for jointing the opposite edge and for flattening the face of the back when it is completely done. Hankey says to use the tacks to glue this part, but mine just didn't hold. I taped an angled caul onto the front of the back and used a clamp to close this joint. I am not forcing this shut due to bad joinery. The clamping pressure is very light, otherwise the tape would break.
I left the last rib about 2-3cm long. It ended up being a very handy choice. I was able to wrap some tape around this protrusion and pull the rib tight against the previous one ensuring that it didn't slip during glue-up.
The tail end is clamped in the normal manner except no extra caul can be used to discourage slippage because there is no tail block left. Four clamps are used because of the added surface area. It cannot be seen here, but the end of the rib is 90 degrees from the top of the end block and planed flat in order to meet up with the other rib end.