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by Hendrik Broekman

Hendrik BroekmanUpon occasion, one comes across the odd wrestplank that has decided to leave home and run off with the bentside. In polite harpsichord society, such notions of independence are to be deplored. Only if the wrestplank stays in its place will the instrument be functional. This sheet will outline some steps that can be taken to restore the wrestplank to its proper place in life.

First it is necessary to make distinctions between degrees of waywardness. The symptoms displayed by a loose wrestplank, aside from tuning instability, can range from a barely perceptible lifting of the cap moulding to full-blown loosening at both ends with the forward edge grossly tipped up. Attention should be paid to the glue joints at either end of the wrestplank to be certain that they have not failed. In some cases, the wrestplank and the sides were not adequately clamped together to begin with. In some plywood cases, the glue joint between the wrestplank and sides is just fine, but the plywood itself is delaminating. If the wrestplank has warped over time, this movement added to the constant stress from the strings may have been sufficient to break the glue joints at the ends. In others, for whatever reason, the joints have simply failed.

Having determined the degree of failure, it becomes necessary to decide what to do about it. If the wrestplank has come totally adrift or nearly so, then the decision is a no-brainer. The wrestplank must be removed, the joints cleaned and the wrestplank replaced. In our experience, this is seldom the case. For a wrestplank to fail so completely, it must have been installed very poorly. In this case, either a new wrestplank should be fitted or the ends of the wrestplank shimmed so that there will be tight joints where it counts. If there is only a slight bit of movement evident, one can either enter watchful waiting mode or try to arrest the movement. Between these two poles, there is a large gray area in which factors such as the worth of the instrument if restored to function, available shop facilities, or even one's own squeamishness (cosmetic or otherwise) enter into the resulting decision.

Consider the problem. In a five octave instrument with three sets of strings and depending on the pitch and stringing schedule, the wrestplank joints must be secure enough to resist approximately a ton of pull. At each end, the wrestplank has approximately 16 square inches of endgrain-to-edgegrain glue joint as well as approximately 8 square inches of edgegrain-to-edgegrain joint underneath. But in both cases, there are large discrepancies in the amount of expansion of abutting surfaces to be expected. Further, the stress of the strings is way off center, attempting to tip the wrestplank up and out of its seat. Neither type of joint is well suited to resisting this pull. The joints at the ends of the wrestplank are weak by virtue of a large endgrain component coupled to a shear joint. The joints underneath are weak since they are under tension, wood's great weakness. If one wished to play to wood's strength, one would arrange the wrestplank with a compression joint overhead. This is our current practice.

Three possibilities come to mind to simply stabilize the wrestplank. Our favorite is to glue a 1" w x 1/4" th x 71/2" or 8" long (depending on the width of the wrestplank) piece of hard wood (maple or such) to the (cleaned-to-bare-wood) insides of the spine and cheek bearing directly on the wrestplank. The 71/2 or 8 square inch parallel-grain glue joint is quite sufficient to resist the shear forces exerted by the wrestplank. Two other cheaper and dirtier possibilities involve drilling through the case sides into the ends of the wrestplank (attempting to miss the wrestpins) and doweling or screwing the wrestplank in place. Obviously this general approach raises cosmetic issues for those who were not planning on repainting their instruments in any case.

Otherwise, it is probably best if the wrestplank is removed and either refurbished or a replacement piece fashioned (or bought from us) before reinstallation. Avoid the poor initial repair. It is likely to result in more work in the long run. It would be difficult in a sheet such as this to cover all possibilities since it is likely that the range exceeds the powers of imagination. We are, of course willing to consider specific cases individually by mail or phone.

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