The big daddy of the string family the double bass often makes an appearance in my workshop, and when they do they usually get A list high priority treatment from me. Why you might ask?…well double bass repairs take up a lot of room in the workshop so I can’t let them sit for too long. The repair principles for the double bass are similar to that of the violin and cello repair (in particular the necks), but because of their size they have added structural components on the inside which tends to make them a bit more agricultural to look at (and work on). Thus where possible because of their size I try to leave the tops on as many repairs can be done from the outside and taking a top of takes time…and time is money (well your money anyway )
They also bring other challenges, there are a lot more pieces of wood (and obviously bigger pieces of wood) in a double bass , with the bracing required for the instrument. This brings with it some challenges around differential expansion of these timbers. On comparatively small pieces of timber a few percent shrinkage is a small number but on a double bass this is a much bigger number. Ebony, maple and spruce all shrink differently with moisture and age and this is a bigger deal on a double bass. The top plate for example is a comparatively huge piece of spruce and with the normal contraction in the lateral direction to the grain as it ages it amounts to a lot more movement than you might see on a violin. If you’re lucky this just means some open seams (the glue on the top plate is a weaker glue to allow is to break rather than the top plate) but more often that not it will crack. On old basses you can count them on one hand if you’re lucky.
Internally with the cross bracing, running, well cross wise to the grain, if the back shrinks a bit laterally the cross grain piece won’t, so there is a tension between the two pieces that means a crack or a join between the pieces will open up. Happy days this is all repairable and to a certain extent normal, it is something that comes with the territory of owing a double bass.
The other significant challenge with basses is their sheer size necessitates large tools, in particular clamps to work on. Many of these tools are the province of a luthier to build their own, according to what works for them and they are not generally available at Bunnings any way 😉 Mine are no exception, the collection grows and are constantly being modified and tweaked for the job at hand – String instruments are ready designed for ease of clamping thats for sure!
