This was a very rewarding side project to our usual harp guitar and flat top new builds in the shop. Dave spent several hours designing a new top for a 100 year old Herman Lowendall doublebass made in Berlin, Germany. Anthony purchased this bass from Arvid Lundin back in the late 90’s and we recently decided to use some of Arvid’s redcedar to make a new top for it. The original top had collapsed and been repaired at some point in its life, but never was performing up to its full potential as the bass bar was compromised, and it was not holding its original arch any more. Regardless, it still worked well for us to record our first album “Out of the Wood Work” and our 2nd, “Silver, Wood and Steel: Engine 7” but we felt it was time it got some upgrades.
After Anthony removed the old top, Dave photographed the rim and imported the picture to a new CAD sketch and began to build the 3d model to match it. The rim is not exactly symmetrical so it had to be done this way. Some symmetry points were added because it is a two-sided CNC route. Center holes were routed in and Dave used 1/2″ wood pegs as indexes to align both sides of the stock to the CNC machine. It was 1/2″ wider than the max width limit of the CNC deck (x-axis). Dave had to factor that into the tool path which left some additional material around the lower bout to be contoured by hand. This added design time but also taught some advanced experience in modelling and creating tool paths using Autodesk Fusion 360.
It is difficult to get the same contour on the bottom of the bass bar as the inside of the carved top, but Dave was able to draw the bass bar as a new model, subtracted the original model surface from it and got an exact surface profile matched for the bass bar to be carved on the CNC and glued onto the top. It turned out perfect as you can see in the photos. Cleats were also added to of each lamination of the 3 piece top for reinforcement. Anthony also glued in a sound post patch for additional support on the cedar.
As of writing this, the top is being glued onto the rim. It was finished with shellac before it was glued on and will be sounding nice very soon! There will be a custom tailpiece made out of Macassar ebony to match the fingerboard of the bass. It will be a great upgrade for this 100 year old German box, and we are thrilled so far how it is turning out!
Scroll right in this instagram post to see video of the purfling being routed just before the final outline contour was cut:
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