Back in the Harpsichord Registers (Next Phase) I showed a pair of Upper Registers that I really wasn’t happy with. Registers are complicated and must be extremely precise, and straight. These were not. Here you can see that when laid together there is a decided warp to them. This is probably due to the amount of liquid (glue) applied during the clamping process and perhaps from the ‘pink’ paper templates glued to the top of the registers.
These registers should lay together perfectly straight, no space between.
Luckily I have the Register Cutting Jig, and so I set off an built a new pair of Uppers which came out much better. They are perfectly straight and the only real difference is the poplar I used had some color in it, which I have to admit is kind of interesting. The big difference in the process I used was to make the ‘shoulders’ of these registers much wider to allow them to be clamped without twisting, unlike the first set which just felt too thin and flimsy.
Interestingly the weight difference between the first pair at 3.2 oz vs. the new pair at 4.15 oz may contribute to the stability. When I drill for the capstan screws in the ends of these registers I am hoping that the wood will hold the screws (which are used for adjustment left to right) more securely. I am still exploring the idea of ‘tapping’ the ends, but poplar is pretty soft and initial experiments are not that hopeful. If I were to make registers again, I would definitely make them from maple which is hard enough to cut threads into for the screws. Here are both sets of registers laid side by side and the gaps are more evident here.
Two Sets of Upper Registers
Looking close up you can see the detail. These registers still need to be carefully cleaned up to ensure the proper clearance for the jacks to pass through without binding.
Bass End of Upper Registers showing orientation of holes allowing the jack tongues to pivot
To install the upper registers will require a 3/4 x 3/4 x 1 1/2″ oak block as a support that will hold the registers dead even with the soundboard once it is installed. The soundboard is expected to be 1/8″ when finished so the support is installed using a spacer block to get it at the right level.
Upper Register Support Block with Spacer – pinblock on left, belly rail on right, register window behind
And finally a view of the two upper registers being test fit into the harpsichord before trimming to install the capstan screws. They are perfectly level, although the coloring of the poplar creates somewhat of a shadow effect which makes it look as if they’re not!
Test Fitting Upper Registers
Confessions of an Amateur Luthier 