This is a commissioned instrument, not for sale
second bass

This is my second doublebass, a commission for a bassist living in Oregon. The model is virtually identical to the first but about an inch longer in the upper bouts. It is also to have a D neck, where the first had the thumb curve of the heel at E flat. He has supplied the woods for body and neck, which came via a shop in Alberta, but originated with Reid Hudson in Duncan - I've been buying wood from Reid since the mid-1980's, and recognised the maple as being from the same tree as my first bass. I made a mould of birch plywood lightening it for ease of handling, and fitted that with spruce blocks at the corners and ends which were then trimmed to shape. After thinning the ribs I bent them on the iron I built many years ago for bass number 1, then glued them to the blocks and trimmed them. Next came spruce lining strips again bent to fit the ribs and glued in. The back face of the ribs was shaped to meet a deep longitudinal concavity in the back, which achieves much of the arching at the glue line and makes for a more supple, responsively shallow back shape, as it needn't be so deeply arched in the middle.

bass rib corner
trimming bass ribs on mould

bass ribs on mould bass ribs on mould

bass ribs on mould bass ribs on mould

The linings went in, then I began work on joining the two pieces of the back and carving and fitting that to the rib face, a rather difficult long curve to carve and perfectly join, but worth the effort in acoustical terms as well as contributing to the overall ease for the player in approaching the bass without compromising structure, as happens with bevelled upper backs. It was exciting to finally get close to the carving of the back. Once the back is carved to the outline of the ribs the mould will be removed and the ribs joined to the back, leaving the pattern available for future projects.

Got the back edge rib linings bent and fitted, glued in and trimmed. Starting work on the back now. Not a lot to show with linings... so here's one close-up of a corner with two linings coming to their ends, the C-bout one mortised into the corner block and the other just a pressed fit.

back rib linings done

Now work's begun on the back, which came to me as more than 50 pounds of maple in two big rough wedges - finished back weight will eventually be about 6 pounds - more than 80% of the wood ends up in the shop floor. The centre joint is quite difficult with curly maple, and this one fought with me for quite a while before meeting properly and being ready for gluing. Then the ribs were used to transfer the shape, plus a centimetre or so all the way around, and sawn out. Next a circular saw was used to cut various depths into this to begin the hollowing for joining to the ribs. I've not seen any other basses using this approach but perhaps they exist; most things do, after all. The idea is simple enough. Instead of having a flat line for the ribs and back to meet as usual then perhaps a kerf cut into the upper bouts and a forced bend in the upper back to make it narrower for ease of playing, I choose to render a curved back with no bending. There is a substantial portion of the long arch contributed just at the glue line, which leaves relatively little maple in the back for the remainder or the central arch. The result is a shallower arching in the back which is more free to vibrate than a more deep, stable sort of arching when looked at in cross section from side to side. But the longitudinal arch is if anything deeper than usual, making for a substantially stiff spine to help in resisting the pulling forward of the strings at each end of the body. Many basses suffer a cupping distortion over time. My idea is to combine resistance to this distortion while freeing the back to move with the belly more easily, and further improving power of the instrument by means of the long parabolic reflective surface of the inside of such a back. Okay, perhaps not so simple... but it worked out well with the first bass and I'm developing the same features in this one, which is slightly longer in the upper bouts. Here is the rough carving of that inner curve, as I'm chipping away between the many saw cuts, then a picture showing the rib garland upon the back as it comes closer to the desired fit. It is not the easiest curve for me to quantify, but at its most basic you can get the idea from rib depths: 15cm at the neck joint, 19cm at the lower C bout corners, and 18cm at the bottom block.

roughing out inside face of bass back
ribs close to fitting inside face of bass back

I recorded some circular chainsaw carving of the back. This tool cuts very smoothly, so much so that the back is just resting on rubber pucks on the workbench, not clamped at all. As I explained to my son today while sweeping up the many pounds of shavings, this tool is my apprentice. In olden days apprentices would spend long hours hand carving to bring the pieces to the luthier in a state of readiness for final carving. Today's economic realities don't allow me such a worker (though several have briefly tried, before realising just how arduous is the work and turning their interests elsewhere) so the power tool saves many days of carving. It will be some weeks after this stage before the external arching is shaped and smoothed with gouge and planes and I begin work on the inside thicknessing. Be aware that the angle grinder is quite loud... probably a good idea to turn down your speakers or headphones before hitting play.

Unfortunately there have been many unlucky bassists and other players with damaged instruments, calling for my attention as there are now very few skilled luthiers in this region. My schedule for carving the bass back kept being delayed. It's hard to say 'no' when musicians have busy calendars and need their only instruments restored to playing condition just so as to work again. With some luck the burden of saying 'yes' will soon be shifting to a new luthier here, whose training I'll be helping to complete in the context of a part-time gig at Tapestry Music on Broadway in Vancouver. I'll be letting my clients know he's available and has talent as the calls come in, as soon as he's set up in the new workshop they've built for us there. Anyway, here's progress on the bass back:

roughing outside of bass back carving progress on outside of bass back

bass back nears final contours carving inside bass back

bass back scraping smoother
Work on the outside of the back is close to finished, with final edge work to be completed once the back is joined to the ribs. I've put a coat of shellac over the wood after polishing with dried horsetail weed leaves to cut away any fibres standing on the maple from the scraping. Inside is still roughly carved, and over the next week I'll be tuning it in modes 2 and 5 of the Helmholtz series which are key to plate tuning in the Hutchins-Saunders method, which reverse engineered about 30 ancient master violins from Cremona. Once mode 2 and 5 are an octave apart the rest of the series fall into line, providing an optimally open vibrational nature to the plate. The belly will be tuned a semitone lower in pitch, also an octave apart in its own mode 2 and 5 patterns of vibration - the 'peanut' and 'X' patterns as expressed when vibrated with powders on the surface. Listening and tapping while holding along nodal lines, then carving away wood in some areas while leaving wood in others, gradually results come into line with the desired relationships within a plate and between belly and back. The upper back button area will be trimmed away to suit the neck heel once that stage arrives and has no significant role in this tuning, so is left over-sized for now as a matter of convenience; it will assist in clamping the belly to the upper block and may then be trimmed.
bass back smoothed bass back protective coat of shellac

The back plate tuning is complete, ringing nicely at F# in both modes 2 and 5. Now moving on to final shaping of the block surfaces and rib faces after removing them from the mould, then joining the back to the rib garland. It'll be time to make upper linings soon and start work joining the belly halves and shaping the belly...

inside bass back smoothing
inside bass back smoothed, tuned

The ribs and back are together at last. Still a long road ahead, but it's starting to look like a bass. I'll be doing a bit of shaping of the upper block and levelling the front face of the ribs next, as well as putting in about half of the linen strips which will reinforce the ribs against impacts and low humidity shrinkage cracking. The other half of the linen will go in after the belly edge rib lining is installed and carved to shape, as those strips will partially bridge between ribs and linings.

ribs joined to back
ribs joined to back

Makers of various instruments in Europe hundreds of years ago frequently lined their ribs and even backs to some extent with raw linen fabric, or in the case of lutes often long fibre papers. Weisshar was working with Japanese washi repairs during his last couple of years - various grades of long fibre mulberry paper and rice glue, a technique long used for restoration of scrolls and other artwork. Fibre repairs have tremendous strength for their low weight, and I've been using linen patching since the mid-1990's for many repairs. So far none of that work has come back to haunt me. The Bohemian bass I restored 10 years ago was recently on my bench and has zero new cracks still, thanks to the stepped back brace contact and extensive linen reinforcements. So in this context, I use linen along the ribs in new instruments. Anticipating this reinforcement I was able to make the ribs thinner than is normally seen in new instruments. I've also put small diagonal spruce cleats along the back seam (as I will on the belly), and overlaid this with silk, also bonded and saturated with hide glue. All these will likely need replacement within the next 100 to 130 years owing to embrittlement of the cloth, but this is a relatively trivial matter involving a bucket of hot water and a washcloth to remove the patches one at a time then replace them with similar material.

linen lined ribs
linen lined ribs

The belly is roughed out, first with the chainsaw wheel, then planes and gouge.

belly roughed out
rough planing of belly
belly shape getting closer to finished

I've finally managed to find time to get the outside of the belly close to finished smoothness, the arching established to a point where I am happy. Now to flip it over and carve out everything which doesn't sound like it should...

belly becoming smooth
belly becoming smooth

The beginnings of hollowing the belly...

belly hollowing begins
belly hollowing with Lancelot tool

belly tuning begins
belly tuning continues

belly thinner
belly close to final thickness

A couple of defects discovered in the carving; a small pitch pocket in the upper region, and a long pin knot, residue of a long twig, right across the middle of the upper bassbar side. No matter, such things get found and worked around, and I am grateful the twig line doesn't manifest as more than a wiggle in the grain on the outer face.

belly tuning
belly tuning

Inside smoothing done, carving the f-holes, looking for the right balance between symmetry, harmony with the C bouts, and just the right tonal darkness. Too much opening and the bass gets lost in the mud of 'player tone.' Too narrow and the tone becomes perfect for a chamber ensemble but lacks the power of a truly bass instrument.

shaping the f-holes

The f-holes fairly nearly done, just minor smoothing along their edges, I fitted and glued in an oversized bassbar then carved that down until the pitches of modes 2 and 5 were getting close to where I want them. Slowing down, refining the curves while adjusting stiffness of the bar... at last it was in just the right relationship to the belly, restoring the modes to where they were before the f-holes were cut.

rough bassbar glued in place
bassbar tuned

A last look at the inside surfaces before closing up the body. Again, linen cleats prevent key areas from suffering damage, insurance averaging about a century as evidenced by typical European instruments of 300 to 400 years ago. I've used these to pin down the bassbar ends, reduce risk of cracks along the centre join, around the lower f-holes, and across the region of the lower belly where I see so many cracks related to winter dryness. Even if conscientiously using a humidifier through the furnace-heated winters, cracks during travel can still be a problem. A bass can become extremely stressed in just a few hours at humidity below 30%. Linen helps to spread out these stresses and usually prevents any damage at all. Apparently Weisshar was experimenting with long-fibre Japanese mulberry paper for similar applications before his death. I am sad to see that the re-adoption of linen generally has been minimal, but in the roughly 30 years since I started using it (in my own first 'cello, lining the ribs) I have yet to see a similarly treated instrument suffer significant winter damage. And it has prevented damage from impacts on a number of occasions, as reported to me by bassists whose instruments I have restored. The weight added is negligible compared to 'traditional' wooden cleating and similarly offers no significant resistance to the movement of the wood in musical terms.

inside belly before gluing
outside belly before gluing
inside body before gluing

Owing to the sheer size of a doublebass it is necessary to glue the belly to the ribs and blocks in stages. As it must be clamped while in liquid phase, before cooling and becoming a jelly and thereafter being considerably weaker, I tend to glue on a belly in 3 to 4 stages. Use of small wedges to keep an area open for application of glue with a pastry knife is quite straightforward. Next I'll be shaping the outer edge of the belly in preparation for inletting purfling.

clamping on the belly

Had a flurry of repair and rehair work during October, as it seems musicians were suddenly optimistic that opportunities to perform were imminent. That has now stopped entirely so I am able to get back to working on the new bass, while trying to figure out how to meet financial obligations... So the purfling channel is nearly finished, one side of the belly has the wenge-yellow cedar-wenge purfling glued in and roughly trimmed, and I'm fitting the inlay along the treble side today, November 14, 2021, my 60th birthday.

Purfling is trimmed. Edge hollow is smoothed. Some final polishing with dried horsetail weed to follow, then a couple of thin coats of shellac to protect the wood until varnishing time. Next up; drawing and cutting out the neck!
roughing groove at belly corner
putting in the purfling
belly finished
belly coated with shellac

The neck joint is lined with wenge veneer along the sides, a hard wood which will protect against incidental bumps when putting the neck in and taking it out for travel. The bottom of the joint is lined with a ramp of padauk wood, a very resilient wood which I've taken to using for C-extensions for its dimensional stability and toughness. The neck's curving lower face will ride along this when adjusting neck projection to modify string heights. And it's finally time to cut up the maple neck block. Lots of cracking along one end and across a couple of edges, but there's enough good wood in there to make a neck I think.

neck pocket lined
neck pocket lined
block ready for cutting
scroll roughly carved

The sapwood which makes up the neck edge of this block is somewhat less stiff than ideal, so I've put in a carbon fibre tube - 12mm diameter with 2mm walls, woven tube of a high stiffness, bonded into a snugly fitted channel with JB Weld steel-filled epoxy, a material I have found to be very durable and stable. There is an aluminum tube fitted similarly along the diagonal of the heel, as in the first bass. This prevents breaking of the heel at the adjuster/retention fitting. The epoxy used to bond this tube is slightly less stiff, accomodating some seasonal movement of the heel. The scroll is taking shape at last. Lots of scraping yet to be done to smooth it all, then before too much longer I can get busy with varnishing.

scroll carving
neck reinforced with carbon tube
pegbox carved

The carving and smoothing done, time for a some pictures.

scroll carved
scroll coated in shellac

With most of the neck mechanism made (and awaiting a bit more metal to finish that) it is time to begin varnishing.
back started varnishing

belly started varnishing scroll started varnishing