Below are two images of Overs Pianos' custom made sound board panel drying box. The left image shows an inside view from the loading/unloading door. The air inlet holes (14 in number) can be seen along the bottom of the sound board drying bay, with the return holes (12) along the top.
The right hand, outside, image shows the mounted heat gun and the centrifugal fan enclosure visible at the back. The ribs on the side of the box prevent the sound board bay from bulging outwards with the positive pressure from the internal fan. The small viewing window and internal illumination light allows the operator to check meters for the temperature/humidity of the cycling air, and the wood moisture content. The sound board panel moisture meter is made of spruce. The drying unit is designed to accommodate sound board panels ranging in size up to a 9'6" concert piano panel. The in-built fan pushes air continually past both sides of the sound board panel, recycling air continuously while a 2000W heat gun introduces a controlled quantity of heated air to the air stream as it travels from the return manifold back to the fan. A small volume of air is allowed to escape from a port (not shown) just below the fan. Considerable flow testing was undertaken, prior to construction, to ensure that the design of the air distribution manifolds and delivery ports yielded a uniform airflow across the entire face of the sound board or sound board panel. The temperature of the cycling air is maintained at 40 degrees C or below with a heat input of around 1000W. The drying unit is capable of lowing the moisture content of a sound board panel from its workshop-equilibrium level of 9 - 10 %, to around 6% within three hours.
The small stack of sanded wooden strips just to the right of the drying box loading door are ready to be glued together to form a sound board cut-off.
To view an image of the drying box taken during construction, with the side and fan cover removed to show the internal air delivery ducts, click here.