Repair of 12-string Mandolin circa 1907

It's been a while since I wrote on my blog but haven't had a vacation. I was going to spend a week paying for old repairs, but it was 4 weeks and I didn't get everyone. Now I'm at least running a new batch of Old Gura and it feels very good!

In addition to daytime repairs, I have spent a lot of time cleaning up the hard drive on my computer and reinstalling Windows due to problems with the program I am recording with (Pro tools). One gave the other and now I am making myself a portable studio that can be rolled into a venue for recordings. A smaller new computer was needed for it and it was extremely much faster than my old desktop which clearly needs to be upgraded. A larger screen has also been purchased. Stuck in old recordings and other things when cleaning the hard drives, cassettes and the burned CDs. Not finished yet 🙂

Well. Will write a bit about some repairs and the upcoming batch. Starting with a really bad conscience, a 12-string mandolin that I started the renovation of about 5 years ago… Started but realized that it was a huge job that I then did not know how to solve, then it was forgotten in a box . Some pictures of what it looked like when it was bought from eBay and Germany after the first disassembly.

Besides having 12 strings instead of 8, there are many unique details. Both the oversaddle and the stables are metal and the tuning screws have the smallest knobs I have ever seen. One must pinch with the tip of the thumb and forefinger when matching 🙂 The sound hole decoration is also unusual in 3D in black painted wood with veneer inserts. Unusual is also the celluloid decor around the lid, think there is an Arabic pattern on it. One not so good detail is that the brown strip around the celluloid on the lid is made of a pulp, probably skin glue mixed with rosewood dust. It had broken loose here and was, when I dismantled the bottom I saw that the lid basically just stuck to the pulp along the sides. It was cracked almost all the way around. The lid had a simple ladder bracing and the lid had folded around the sound hole of the string.

The label says “Friedrich Idinger, Wiener zither instruments and sites - Fabrik, Berlin“. First interpreted the surname as "Jdinger", but "Idinger" is correct. There is almost nothing online about him, the only thing I found was a classified ad from 24/9 1907 where someone tried to sell a harp guitar with a double bottom. In any case, indicates that the mandolin is from about the same time. He also took out some patents in 1892 and 1899 on construction details on a zittra. It was probably the people he worked with the most.

Started by making a cut out counter as a pretzel in plywood around the edge and the celluloid decor to be able to glue a new notch between the lid and the side. The lid has a vault and the 3D shaped sound hole decoration made it impossible to have a flat counter. The brown mass was released. Had to do a double carving to reach the lid tree to tie the lid with the side. Gluing the carving is difficult as you have to glue both to the side and the lid at the same time.

Has come to the conclusion that an X-ribbed is the best fit for floating stables. Makes it easy to give the lid a nice arch. Made the ribbing at the top strong to hold for 12 strings. In addition to the X, I applied some thin ribs to reinforce the sound hole and resist cracking. Could possibly plan down the height if it did not sound good, but it was not necessary.

The neck needed a neck change, but instead of loosening the neck, I let the bottom hold the neck block in a new position. The bottom stuck out a few mm at the neck pad after gluing. The new shape on the side made it necessary to cut a rosewood mold around the bottom. The sizing was done with a metal beam behind the mandolin along the neck and a fairly high abutment where the stall is placed which ensured that the neck got the right angle.

The lid also got a rosewood strip frozen and glued all around to keep from bumps, between the strip and the celluloid decor there was wood pulp of skin glue and rosewood. A messy step!

With the help of files, razor blades, planers and sandpaper, the draft was removed. The celluloid was scraped clean from the yellow membrane with the razor blade and became dazzling white.

A new grip board was made when the old one was thin and broken, the neck was given a minimal carbon fiber rod and the grip board was glued with skin glue. A lap of clear liquor was placed on the body and black liquor on the neck and head.

The tuning screws were in good condition but were cleaned and got some lubrication. Replaced the rather awful string holder with only 8 attachment points to a smaller and better one with 12 holders from the scrap box. A funny little metal knob was in the original bar below the sound hole, I put it in the bar above the sound hole. The only function I can think of is that it is an attachment point for the long silk ribbons á la Taube that were inside when it went! The metal upper saddle could be folded in at the top of the new fingerboard, a bit tricky to file down to the right level but it went well. Succeeded well with the "neck turnover" and was able to adjust the height correctly with the adjustable stable with patent number 5151. Used two sets of mandolin strings to triple all the strings. Tested with an octave string on the bass string but it just sounded weird.

Did not like this before it was finished (a whole lot of trouble!), But well done I must say that it was good. The taste for sustain I have not met in the past, clearly audible sustain for 20 seconds and probably twice the time before it disappeared completely with the ear to the sound hole 🙂 A large part of the secret is probably oversealed and the stall in metal. Would love to have kept it, it got better than expected!

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