Tunnicliffe estimates that it takes some 35-40 hours to make a bass bow, as much as ten hours more than it takes to create one for a violin. The bass bows take longer to complete because they are so much stronger and take longer in the bending: 'Getting the spring and curvature in the stick in the first place and readjusting when the bow is tensioned with hair are the most difficult part of making a bass bow.' To avoid splitting the wood, bending has to be done gradually. Tunnicliffe has devised a very simple technique that reduces both the time and effort involved, comprising three sets of two pieces of wood - one concave and one convex. Tunnicliffe heats the pernambuco stick to around 65-70 degrees Celcius using a dry heat from his portable electric stove. It is then clamped in a vice between the first set of templates, each of which is used in four different positions along the stick starting at the head.
The second set has slightly more curve with the third set having a curvature that slightly overbends the stick from its final camber. 'There just doesn’t seem to be any point holding the bow over heat for ages,' Tunnicliffe points out. 'Just clamp it up and get on with some rehairs or something else.' A fourth set of templates with a tight curve is used for the head underneath the throat, before the whole stick is checked for length and approximate curvature according to the cambers on Brian’s template. Continental players seem to prefer octagonal bows, so I follow suit. Some makers - not Tunnicliffe - charge more for an octagonal stick as it is more difficult to make and can take three or four more hours to obtain a good, even taper towards the head, while the eight corners have to be very precise. While working on the stick, Tunnicliffe clamps it in his vice or simply holds it by hand. Both taper and corners have to be in complete proportion to each other, and Tunnicliffe judges these purely by eye. He can make each facet incredibly flat, consistently even and sharp at the edges.
The frog for each bow can take two days to complete. Each task is a precise engineering job in itself. The three sides for the under slide are milled out, followed by the hair groove, mother of pearl groove and the hair with wedge mortise. The frog is placed vertically in a vice and the ferrule tongue cut to the required D section. The recess for the back slide is cut by hand and the sides of the frog roughly hollowed out. Once the underslide has been pressed out and fitted, it is fixed in position using an epoxy resin-type glue and tiny threaded silver or gold pins. The semicircle of the ferrule is shaped around a former using 0.8mm gauge silver or gold which is then soldered to the thicker (2mm) flat section. A mother-of-pearl slide is made and fitted to align exactly with both the ferrule and back slide, both previously fitted. The Parisian eye recesses are cut to a depth of 1mm and the mother-of-pearl dots and rings are made and fitted, glued in place, filed flush with the surface and polished. If engraving work is required on the Tunnicliffe 'shield' trademark or the Tudor Rose emblem he inherited from Bultitude then the whole frog is sent away. Finally the screw and adjuster are made.
Tunnicliffe may work on two or three frogs concurrently, although to proceed he must have one ready once the stick has been planed to the required weight: 'The dimensions for the frog across the bottom slide recess and for the adjuster are standard, so that the handle part of the stick will have matching measurements in all bows of the same type. But because a dense piece of wood is heavier than one less dense, weight will establish the ultimate dimensions of the stick further along.'
Both stick and frog are now planed to fit perfectly together. Once the head mortise has been milled out and an ivory or metal face has been fitted and shaved or filed roughly to shape, the frog is aligned with the head through fractional adjustments to the handle facets, especially the three upon which the frog fits.