Category: on the workbench

On double basses, the protruding edges of the top and back sometimes break off or splinter. On laminated double basses, this often only affects the outer layers of plywood.

On some basses, however, the purfling is merely painted on — especially plywood basses, but also many old Bohemian basses have no inlaid purfling. In violin-making literature, inlaid purfling is said to have a protective effect: cracks that run from the edge to the center are virtually “stopped” by the purfling running perpendicular. But is this really the case?

The plywood bass shown here clearly shows how the missing (and already replaced) pieces extend exactly to the inlaid purfling. Continuous cracks, which the purfling could stop, do not generally occur in plywood. But with some plywood basses, I have the impression that the narrow veneer edge splinters more easily precisely because the veneer has been cut through for the inserted chip.

In this respect, a painted purfling on plywood basses is not a “cheap trick,” but rather offers structural advantages.

This bass came to my workshop because the neck had come loose. After I removed it completely, it became clear that there was so much air in the glue joint that it couldn’t hold…

The neck joint on this bass is designed as a hidden dovetail joint, but it is so imprecise and has so much play that the glue joint to the back plate alone actually bore the entire load. We therefore decided to chenge the neck joint to a screwed connection. The reason for converting to a detachable neck was not easier travelling, but the screw promises to be the most durable connection here (a completely new and cleanly inserted neck was ruled out for cost reasons).

During the renovation, it became apparent that someone had already attempted to solve the problem of the loose neck with a screw: someone had screwed it in from above through the neck foot, but it was crooked from every angle. It eventually broke, and during another repair attempt, the screw hole was doweled again. However, the broken-off remainder of the screw is still stuck in the neck block.

After patching the dovetail joint, the neck is now securely held in place by an M8 screw—the counter thread was inserted into the neck block from the inside (bottom).

A double bass with six strings?!? No, a violone. This instrument, which belongs to the viola da gamba family, looks quite similar to a double bass, but the body is slightly larger than that of a ½ bass, while the scale length is slightly smaller at 90 cm.
This G violone was built in 1962 by luthier Uebel in Celle/Germany. The tuning pegs are mounted in such a way that the direction of rotation of the pegs is the opposite of what you would expect from a bass. This means that you have to turn “downwards” to tune up. At first, I thought this was a mistake… something that can happen even to the most skilled instrument maker. However, I now assume that the tuning pegs were deliberately mounted this way so that the gut strings could be threaded over the pegs from below, rather than from above as is usually the case. This makes the angle at which the strings run over the nut slightly more acute, and the relatively thin and soft gut strings lie with a little pressure on the nut. The fairly wide notches in the original saddle indicate to me that the strings were previously strung in this way.

This Gofriller model bass had a neck break at the scroll box — one of the weakest points on a bass. Sometimes it is possible to repair this quite well and make it durable (I like to use carbon dowels for this), but in this case the customer opted for a new neck.